0:05

Welcome to Brain Science, the podcast

0:07

that explores how recent discoveries in neuroscience

0:10

are helping unravel the mystery

0:12

of how our brain makes us human.

0:14

I'm your host, Dr. Ginger Campbell, and

0:16

this is episode 207. You

0:20

can find complete show notes and episode

0:22

transcripts at brainsciencepodcast.com,

0:25

and you can send me feedback at

0:27

brainsciencepodcast at gmail.com.

0:30

I also want to mention that

0:33

the free Brain Science mobile

0:35

app is now called Brain Science

0:38

Podcast. This app is

0:40

available for all mobile devices, and

0:43

it is a great way to access both free and

0:45

premium content.

0:47

This month's episode is an encore

0:51

of an interview with Dr. Luis Pessoa

0:53

about his book, The Cognitive Emotional

0:56

Brain,

0:57

From Interaction to Integration.

1:00

When we first talked back

1:02

in 2014, some of the

1:04

information we discussed was quite surprising. We

1:08

learned that subcortical

1:09

brain structures like the amygdala

1:12

and the thalamus do much more

1:14

than scientists once assumed.

1:17

They are both involved in learning

1:20

and decision making.

1:21

Another key discovery was

1:23

that emotion and cognition are

1:26

deeply entwined at

1:28

all levels. This has many

1:30

consequences for how we imagine

1:32

and understand what our brain

1:34

does. I am replaying

1:37

this conversation now to prepare

1:39

you for an upcoming episode where

1:42

Dr. Pessoa and I will discuss his

1:44

latest book, The Entangled Brain,

1:47

How Perception, Cognition, and

1:48

Emotion are Woven Together. If

1:51

you would like to get episode show notes automatically

1:54

every month, just sign up for the free Brain

1:57

Science newsletter, either at brainsciencepodcast.com

1:59

or at brainsciencepodcast.com.

1:59

or by texting BRAINSCIENCE

2:03

all one word to 55444. That's

2:07

BRAINSCIENCE all one word to 55444.

2:12

When you sign up, you'll get a free gift

2:14

entitled 5 Things You Need

2:16

to Know About Your Brain.

2:19

BRAINSCIENCE relies on the financial

2:21

support of listeners like you. You

2:23

can learn more at brainsciencepodcast.com

2:26

forward slash premium.

2:28

Be sure to keep listening after the

2:30

interview because I'll review the key ideas

2:33

and share a few brief announcements.

2:40

My guest today is Luis Pessoa. Luis,

2:43

I'm really happy to have you on the BRAINSCIENCE

2:45

podcast. Yeah, I'm thrilled to be here.

2:48

Writers like Antonio DeMasio have done

2:50

a lot to make people aware that our emotions

2:52

play a vital role in every aspect

2:55

of our modern lives, including decision

2:57

making.

2:57

But there tends to be a tendency

3:00

to see emotion and cognition as

3:02

separate and often opposing functions.

3:05

Your book, The Cognitive Emotional Brain,

3:07

argues that because cognition

3:09

and emotion are so deeply intertwined at

3:11

every level, it doesn't make any sense

3:14

to view them as separate. So you take

3:16

this different approach in your book. So would

3:18

you give us a brief overview of your book? Yeah,

3:21

sure. I'm happy to do that. That's exactly

3:23

right. So the approach that I take in the book

3:26

is that emotion and cognition are in

3:28

a way the opposite. They're very intertwined.

3:31

They're always interacting. And in fact, the

3:33

book tries to discuss many ways in which their signals

3:36

are integrated. So in that sense, they

3:39

become sort of emotion cognition signals

3:41

and the emotion, pure emotion part and

3:43

the pure cognition

3:44

part sort of dissolves and becomes

3:47

something that really in a deeper

3:49

sense can't really be taken apart.

3:52

So in one sense, you can view the book as three

3:54

parts. One is discusses the amygdala,

3:56

which is a structure that a lot of people have heard

3:59

about and it's due to is really important for emotional

4:01

processing. And I try to discuss problems

4:03

with this typical standard view of

4:06

amygdala function and propose some alternative

4:08

frameworks that take into account lots of recent

4:11

data and a lot of recent thinking about

4:13

how individual structures might be communicating

4:16

with lots of other structures in the brain in

4:18

sort of a network type of perspective.

4:21

Another part of the book discusses emotional

4:23

and motivational processing in general. By

4:26

motivational, I mean things that might be related

4:28

to reward and competitive things

4:30

that people are willing to put

4:32

effort and work to attain a goal.

4:35

And I look at these interactions between emotional

4:37

and motivational processing

4:40

with cognition to, again, illustrate

4:43

the many levels at which these things are

4:45

communicating with each other.

4:46

The last part of the book is a broader

4:48

perspective on how to understand.

4:50

How can we go about understanding the brain and

4:53

how there's specific functions that

4:55

we study in the lab or observe in

4:57

real life sort of emerge from either

5:00

individual structures in the brain, which is one

5:03

view that has been prevalent in neuroscience, or

5:06

according to sort of network interactions of

5:08

many regions, which is my view and also

5:10

many other people's view of how function

5:13

emerges from

5:14

interactions across many brain regions.

5:17

So that summarizes the three main

5:19

parts of the book. Yeah, I guess people

5:21

can't tell when I was saying the name of your book.

5:23

You've got cognitive, emotional, with

5:26

a dash between it to illustrate the

5:28

idea that the two really are so

5:30

interconnected as to make separating

5:32

the words even not make

5:35

any sense anymore. That's exactly right,

5:37

yeah. Well, before we get into some of these key

5:39

ideas,

5:39

would you tell us just a little bit about

5:42

yourself and maybe about how you became

5:44

a neuroscientist? Sure, it's actually

5:46

maybe similar to other people's

5:49

experiences. It's quite a torturous, nonlinear

5:51

sort of trajectory. I grew up in Rio

5:53

in Brazil, and I was

5:55

always interested in math and physics

5:58

and eventually decided to

6:00

do my bachelor's degree in something

6:02

a little bit more applied. So I went into computer science,

6:05

but also always interested in the more

6:07

formal aspects and mathematical

6:09

aspects of computer science. And then

6:12

I got involved in projects and also

6:14

honors thesis-like activities

6:17

and research in artificial intelligence.

6:20

Gradually, I started becoming more and more

6:22

interested in intelligence in general, what

6:24

are the biological basis of intelligence.

6:27

And so one thing led to the other, and eventually

6:29

I came to the US, to Boston, Boston

6:31

University to do a PhD in computational

6:34

neuroscience in a department that had been recently

6:37

created in 1989. I arrived

6:39

in 1990 to do a PhD in computational

6:41

neuroscience, with really a focus on how

6:44

networks of neurons, either

6:46

artificial or natural neurons,

6:49

compute. And so the idea

6:51

is that we can understand computation

6:53

from a distributed standpoint, from very

6:56

simple elements.

6:56

And so that was my beginning in

6:59

more computational and away from the empirical.

7:02

We're interested in empirical data to understand it, but

7:04

eventually after this PhD,

7:06

I started becoming more and more interested in more

7:09

empirical work. So that's a lot of my work

7:11

right now is more under empirical and trying

7:13

to understand it via experiments with humans.

7:15

Do you by any chance know Miguel Nicolailas?

7:18

It's funny because I've never met him. But

7:21

obviously, being a Brazilian in many conferences

7:25

or circles, we

7:26

hear of him a lot. No, I haven't met

7:29

him, but I've seen him give talks, and I

7:31

just haven't had a chance to meet him in person.

7:33

But he does fascinating

7:34

work. Yeah, I interviewed him, I

7:36

guess it's been about three years ago now, when

7:39

his book came out, which is more

7:41

aimed at a general audience. And

7:43

he does a really good job in demonstrating

7:46

the idea of networking. He

7:49

has a story in there about a time

7:51

in Brazil. I guess you had some kind of almost

7:53

like a dictatorship, and the people

7:56

were sort of protesting, and they were all

7:58

clapping together.

7:59

how it was the number

8:02

of people that made it happen.

8:05

Individuals dropped in and out, but it was the

8:07

mass effect. That's right. It was

8:09

really great illustration of the idea because

8:12

one neuron can't do anything, but

8:13

billions of neurons gives you

8:15

a human. Yeah. And I extend

8:18

that exact same concept to brain regions.

8:20

So one region doesn't do much in my view, but

8:22

when immersed in cooperating and interacting

8:25

and exchanging signals with many other regions,

8:27

that's when things really happen and that's

8:29

where the human comes from. Yeah, that's

8:32

exactly right. Okay. So we're going to spend a lot

8:34

of time today talking about two

8:37

of the deeper structures in the brain, the amygdala

8:40

and part of the thalamus called the

8:42

pulvinar nucleus. These

8:44

may be unfamiliar structures to many

8:46

of my

8:47

listeners. So would you start up just

8:49

by telling us a little bit about these

8:51

structures and help us visualize where they are?

8:54

Sure. So I think to understand where

8:56

the amygdala and the thalamus are in the brain, think

8:58

of the brain as having two parts, sort

9:00

of like a blanket, an outer part, which

9:03

is the cortex. This outer blanket,

9:05

cortex, is thin, but

9:07

it's actually can be seen as having

9:09

these layers. So it's a set of

9:12

really thin blankets that stack on top

9:14

of each other. So that makes it the outside.

9:17

And so it has this kind of layered structure.

9:19

Underneath, there is the subcortical

9:22

part, which is much deeper and

9:25

have these subcortical regions

9:27

or nuclei. And these

9:29

are kind of masses of neurons. So

9:31

they don't have that organization that cortex

9:34

has. Both the amygdala and the pulvinar,

9:36

the thalamus, which is a bigger structure

9:38

and the pulvinar being the smaller part

9:41

or nucleus of the thalamus. Both

9:44

of these are actually subcortical structures.

9:46

So sort of deep inside the brain

9:48

and the amygdala, as

9:51

many of you or listeners will know, and having read

9:53

many newspaper type of pieces,

9:56

that it's traditionally associated with fear

9:59

processing. automatic threat detection

10:02

and things of that nature. And hopefully we'll get a

10:04

chance a little bit to talk about how some

10:06

of my work and the work of many people challenges

10:09

those notions. And the Bolviner

10:11

is part of the thalamus, as I said. And

10:14

the thalamus has been traditionally conceptualized

10:17

or thought of as sort of a passive relay

10:19

station in which signals

10:21

from the periphery, sensory signals pass

10:24

through the thalamus on their way to the cortex.

10:27

And again, we'll be talking about many ways in

10:29

which

10:29

this view needs to be updated. And in

10:32

fact, we'll see that the Bolviner and

10:34

the thalamus in general is really critical for communication

10:36

of signals across the brain. And

10:38

so really this communication and integration

10:41

of signals really critically depends

10:43

and involves the thalamus.

10:45

The amygdala and the thalamus are in

10:48

the temporal lobe, but they're like in the inside

10:50

part that's deep and considered subcortical

10:53

because it doesn't have the layers.

10:55

Yeah, that's right. So the amygdala is in part

10:57

of this kind of system called the medial temporal

10:59

lobe system that has other

11:02

structures like the hippocampus, which is very

11:04

important for memory processes and many other

11:06

things. And the amygdala is a very

11:08

small structure actually. It's funny how some of these

11:11

small structures can become very

11:13

famous and have very important roles in

11:15

fact in the brain. But in this case, the name

11:17

itself reflects the fact that the

11:19

amygdala is sort of kind of like the shape of an almond

11:22

and then a little bit the size of a regular almond

11:24

in a sense, a little bit bigger

11:25

maybe. The pulvin itself is

11:27

not in the medial temporal lobe and the temporal

11:29

lobe is actually sort of at this

11:31

kind of central base of the brain

11:34

where the brain stem, the top

11:36

of it has this larger structure called the thalamus

11:38

and the pulvin is one nucleus of

11:41

the thalamus. Okay, so the thalamus is

11:43

that thing that whenever you see the pictures

11:45

of the brain stem that have the superior

11:47

colliculi and the pons and all that, it's

11:49

kind of the thing right up at the top, right? That's

11:52

exactly right. It's not at the top, yeah, at

11:54

the top.

11:55

So one of the key ideas I

11:57

want listeners to remember is that

11:59

the amygdala is a very

11:59

it does more than process fear.

12:02

And I want to also, before we get

12:05

into that, remind listeners that

12:07

back in episode 91 Jacques

12:09

Pangsepp talked about the evidence

12:12

that fear itself actually

12:14

originates lower in the brain

12:16

than the level of the amygdala. So just

12:19

with those pieces

12:19

of information in mind, can you give

12:22

us a brief overview of

12:24

what the current evidence shows that

12:26

the amygdala actually does?

12:28

Yeah, I can try to do that. That's very challenging because

12:31

there are whole books or even series of books

12:33

dedicated to that with each one with many, many chapters.

12:35

But I can say a few words about that. Well,

12:38

I think that listeners should have in mind that to

12:40

start off, the amygdala is not one thing.

12:42

So that already poses a huge challenge

12:45

because in one sense, in a very concrete

12:47

sense, anatomically, one can subdivide

12:50

the amygdala in at least, let's say, 12 or

12:52

even more sub parts or nuclei

12:55

based on their morphology of the neurons,

12:57

you know, the histochemistry and lots

12:59

of fine properties that allow us

13:02

to segregate the amygdala in these little parts.

13:04

But in a very coarse manner, we can

13:06

think of the amigulas having basically two

13:08

parts. One is so-called

13:11

lateral amygdala, again, more towards

13:13

the outside of the brain. Again,

13:15

it's deep inside, but the part that

13:17

is the lateral amygdala is within the amygdala,

13:20

but towards the outside and the central

13:22

amygdala, again, more central. And it's interesting

13:24

to think of these two parts because the lateral

13:26

amygdala and the central amygdala are quite distinct

13:29

in one sense. So for instance, the lateral amygdala is

13:31

quite a bit more cortical like it's

13:34

almost like a little piece of cortex

13:36

in a sense that its organization is a little

13:38

bit more cortex like in terms

13:40

of doesn't have layers itself, but it's

13:43

a little bit more organized. And it's also highly

13:45

connected to cortical regions. So

13:47

it has broad connectivity with cortical

13:49

regions. The central amygdala, in

13:52

contrast, is actually connected to a

13:54

lot of subcortical regions at the base of

13:56

the brain. And it's inherently more subcortical

13:58

like.

13:59

One important property of the central amygdala is

14:02

that it's heavily connected with many structures

14:04

in the brainstem, literally underneath going

14:06

down all that trunk, that stem

14:09

that we can picture when we see pictures of the brain.

14:12

Those parts of the brainstem are really fundamental

14:15

for controlling many autonomic functions.

14:17

The amygdala, the central amygdala, is sitting

14:20

at the top of this and has the ability

14:22

to engage all these autonomic

14:25

related structures that really

14:27

have a direct effect on bodily functions,

14:29

how you feel and blood pressure

14:32

and respiration and all those really

14:34

emotion related things, for instance. We

14:37

can think of the lateral amygdala and the central amygdala,

14:39

but more broadly, in terms of thinking

14:41

of the many functions that these two

14:44

structures and many others in

14:46

the amygdala are involved in, we can think

14:48

of a very diverse set of functions,

14:50

including general arousal, such

14:52

as controlling the levels of vigilance of

14:54

an organism, detecting novel

14:57

stimuli, having sort of like

14:59

surprise

14:59

related processing when something is unexpected,

15:03

so the amygdala is really critical for that. More

15:05

broadly, in sort of attentional functions,

15:08

by that I mean, so

15:09

what is important for the organism

15:12

and what deserves further processing?

15:15

The amygdala is heavily involved in these

15:17

attention-like functions. It's

15:19

also involved in value representation.

15:22

What's the value of specific objects outside

15:25

in the world, both on the negative side, which is

15:27

the typical story that we hear a lot in the

15:29

news and newspapers and magazines, but

15:31

also on the positive side. So what's the

15:34

reward associated with a certain stimulus

15:36

that I have seen in the past, for instance?

15:39

So because of all these properties

15:41

of attention and value representation,

15:44

there's, I think, growing amount

15:45

of evidence that the amygdala is involved

15:47

in simple forms of decision making,

15:50

not the super complex decision making

15:52

that you might think of, I don't know, a mathematician trying

15:55

to decide how they're going to prove their

15:57

theorem, but decision making as to what

15:59

approach, what you avoid, what's the value

16:02

of things and how that influences your actions.

16:04

The way that I like to summarize it, it's a

16:07

way that was conceptualized actually in the

16:09

70s by Carl Pribble and colleagues, in

16:11

a sense that MIG was involved in determining what

16:14

is it that is out there. So it's what is

16:16

it functions. And once you determine

16:18

what it's out there, what are you going to do with them? So

16:20

what's to be done function? It's not just

16:23

a simple threat detection engine,

16:25

but it really is much broader involving

16:28

understanding what's out there and

16:29

what the organism should do in the face

16:32

of those things it's encountering. Okay.

16:35

I'd like to talk a little bit about how

16:37

you figure out what the amygdala does.

16:39

How do we know about these connections? You've told me

16:41

that the basolateral and the central amygdala

16:44

have different connections. Is our

16:46

knowledge of this based on the anatomy

16:49

in animals or exactly

16:51

how do we figure this out?

16:53

That's a really tricky question because for obvious

16:55

reasons, the bulk of the research

16:58

is not done with humans. And

17:00

so we have a lot of the anatomical work

17:02

done in rats and also

17:04

done a lot in monkeys. And so careful

17:07

anatomical work with careful histology

17:09

and the resolution that we need

17:11

to understand the connectivity and understand

17:13

the anatomy is done in these species,

17:15

especially the work with monkeys. Then

17:18

the hope is that what we're learning from them

17:20

really translates to humans. Obviously,

17:22

there is a step there and obviously we're not

17:25

larger monkeys. But from what

17:27

we know about the anatomy, a lot is

17:29

also seen in humans. For

17:32

instance, when they study actual humans

17:34

like post-mortem brains and there's

17:36

a little bit of research on actual human

17:39

anatomy itself. But you're right that

17:41

there's that indirect aspect

17:43

that we're inferring from other species and

17:46

trying to make this connection which has

17:48

to be checked in and understood

17:50

properly in its own right. The

17:52

monkey does provide a good starting point and

17:54

what's feasible for us to do in trying to

17:57

understand these systems. And now there's a

17:59

lot of

17:59

roasting techniques in humans

18:02

based on MRI of getting better

18:04

estimates of anatomy itself. We're not quite

18:06

there yet, but I think maybe in

18:08

a few years we'll be able to do a lot

18:10

more in terms of anatomy itself in

18:13

humans with magnetic resonance imaging

18:15

MRI techniques.

18:17

But as far as functional imaging

18:19

goes, you can't tell which part of the

18:21

amygdala is lighting up. If you read

18:23

some magazine article that says your amygdala

18:26

lights up when you see a picture of a

18:28

politician you like or don't like, that doesn't

18:30

tell you anything about which part

18:32

of the amygdala is involved, does it?

18:34

You're right there, but interestingly we are right

18:36

at the cusp technologically that

18:39

we're starting to be able to do that. So we're

18:41

starting to be able to do higher resolution

18:43

functional imaging that will be able

18:45

to distinguish nuclei within the

18:48

amygdala. So I think there's a little bit of work

18:50

on that already and that work needs to be

18:52

validated and extended, but we're

18:54

really coming to a time now in which

18:57

functional MRI is going to be done with

18:59

regions that are much smaller. Basically pixel

19:01

size, the resolution of the camera

19:03

if you will,

19:04

is such that we're going to be starting to be able to separate

19:07

things like lateral, amygdala, central, amygdala,

19:09

and so on and so forth. So we're not far from that

19:11

actually. It's an exciting time in that sense.

19:14

And then the other part that you definitely

19:17

rarely would be able to do in a person

19:19

would be direct recordings from

19:21

the neurons, right? And that seems to

19:23

be very important in a lot of the studies that

19:25

you discuss in the book. Again, for

19:27

obvious reasons, we'll not be doing routinely

19:29

recordings in humans, but the fascinating aspect

19:32

that I myself have not been with,

19:34

but have been always interested in

19:37

trying to establish collaborations and

19:39

because it's really incredibly fascinating is being

19:41

able to do in a limited fashion, but

19:44

doing direct recordings of patients

19:46

prior to surgery or in between

19:49

surgeries. And so there are several

19:51

groups across the globe that actually

19:54

have published direct recordings from

19:56

humans, but in the big scheme of things, it's

19:58

a very small percentage.

19:59

of the overall number of studies. These

20:02

studies that look at physiology

20:04

are either in monkeys and

20:07

more commonly in rats, which I would

20:09

argue it's quite different even in terms

20:11

of there are many differences in the amyc line rats

20:14

and monkeys that are really critical in my

20:16

opinion. And unfortunately, we still need

20:18

to figure out how to have more direct measurements

20:20

in a noninvasive way. So hopefully there are

20:23

new techniques coming out in the coming years

20:25

or decades that will allow us to do those kinds

20:27

of things.

20:33

One of the experiments, your book, like I said,

20:35

is full of experiments and obviously that's one of

20:37

the time limit constraints that we can't really get

20:39

into a lot of the details of these experiments.

20:42

But one that sort of stuck out for me was

20:44

because it illustrates the idea

20:47

that the amygdala is doing

20:49

something more than just communicating

20:52

emotional information, was

20:54

the experiment that showed that

20:56

the responses of the amygdala were

20:59

context dependent and could even be

21:01

affected by expectation.

21:03

Do you remember that example?

21:05

Yeah, I think I know the experiment that

21:08

you have in mind. If I'm right, is an experiment

21:10

by Dan Salzman and colleagues that was

21:12

done a few years ago. They were studying

21:14

how the amygdala codes external

21:17

events and whether it would be sensitive

21:19

to both positive and negative information.

21:21

And one of the things that they did was they take a little

21:24

stimulus, let's say, I don't know, a picture of some

21:26

kind and associate every time that the monkey saw

21:28

that picture, they received a reward, a little

21:30

bit of water or juice. And

21:32

with another stimulus, they received

21:35

something that was aversive. So it was a little

21:37

puff of air to the face. It's

21:39

not painful, but just mildly aversive.

21:42

What they found in the amygdala, which was interesting, they found

21:45

neurons that were actually driven, meaning

21:47

they were spawned more strongly. When these

21:49

cues, the cues to reward

21:52

came up and when the cues to the punishment

21:54

came up. But they also responded to

21:56

the reward itself and to the punishment itself.

21:59

So they... class of neurons that was driven

22:01

by reward and another one that was driven by the punishment,

22:04

the aversive stimulus. One interesting

22:06

thing was actually trying to see what

22:08

would happen to these neurons if you

22:10

violated expectations. So for instance,

22:13

if you have a cue that signals reward,

22:15

the animal is expecting reward, but

22:18

if you now emit the puff of air,

22:20

so it receives the aversive stimulation, so

22:23

the aversive responding neurons

22:26

responded as they had before, but actually

22:28

even more strongly, so showing that

22:30

the context in which expecting

22:32

a reward but receiving punishment made

22:34

an important difference. And likewise, if

22:37

the monkey saw the little stimulus that it should anticipate

22:40

a puff of air, but instead it received

22:43

the reward, the neurons that were responding

22:45

to reward responded more vigorously.

22:48

So it really shows two important things,

22:50

I believe. One is that the responses are

22:53

coding both positive and negative events, which

22:55

is important given the emphasis that people have. The

22:57

tendency to people emphasize only the negative side

22:59

of amygdala processing, but also how

23:02

it's actually highly sensitive to context.

23:04

My lab and many other people have done other

23:06

experiments showing these context dependency,

23:09

whether something is relevant to the animal or

23:11

not relevant makes a huge difference between

23:14

the amygdala actually engaging with the stimuli

23:16

or not. So it's not just a passive

23:19

responder to negative items,

23:21

but it really is taking both positive

23:23

and negative and the context in which they appear.

23:27

What about studying the amygdala in

23:30

people? I got the impression that

23:32

for you anyway, this intentional blink

23:34

paradigm was an important tool,

23:37

although you mentioned several other paradigms

23:39

for studying this in humans. Is the

23:42

attentional blink a good example

23:44

of how you study this in humans,

23:46

or would you prefer a different paradigm?

23:49

No, I think the attentional blink is a really good one,

23:51

because attentional blink essentially refers

23:53

to... it's actually quite simple. The person

23:55

sees a series of pictures coming

23:58

very fast on the screen.

23:59

So let's say, imagine that I'm showing you pictures

24:02

outside scenes, you know, scene of a mountain,

24:04

a scene of a lake and lots of scenes that

24:06

you're seeing, but each one is shown very rapidly. So

24:09

you see, let's say 10 scenes per second.

24:11

So they're just coming by very, very fast

24:13

and you're just having this kind of overall visual impression

24:16

and you're asked to within that stream of

24:18

stimuli to report after the stream

24:20

is over. Let's say the stream takes two or

24:23

three seconds. So in that overall

24:25

stream, you're going to see 20 or 30 stimuli. So

24:27

after the stream is over, you're asked to report,

24:30

for instance, if you saw a male or female

24:32

face within that stream. And if you

24:35

saw, let's say a house or

24:38

a skyscraper type of building or

24:40

something of that nature, so within

24:42

a stream, you have to be looking at the stream

24:44

and trying to detect two targets, a

24:47

face, let's say, and save the face as male or female

24:50

and an outdoor type of building

24:53

or house.

24:54

This task is not challenging in itself,

24:56

detecting a face or house where you're extremely

24:59

good at it. The tricky part is when

25:01

the second stimulus, let's say a house,

25:03

comes very close by after

25:05

in succession to the face itself. So

25:08

you detect a face and very

25:10

soon after that, the house is shown.

25:12

What happens is this sort of attentional

25:15

blink, not a physical blink, but

25:17

attentionally blinking, if you will, so

25:20

that you don't see the house that

25:22

follows the face because you were processing

25:24

your first target, the face, and

25:27

you sort of miss the second. And

25:29

so you're not aware. You actually at the end

25:31

of the stream, the person asks you, did you see

25:34

a face? They say, yes, I saw

25:36

a male face. And did you see a house?

25:38

They say, no, in this trial, I didn't see a

25:40

house. And actually, it was physically

25:42

shown. So you actually weren't aware of them. So

25:45

what this really shows is kind of the limited processing

25:47

capacity of the visual system of the brain in general,

25:50

that once it's engaged on something

25:52

because it's task relevant, I have to detect

25:54

this face and I have to later report whether it's male

25:57

or female. I was engaged in that.

25:59

that I kind of lost track of what

26:02

was happening and I missed the second stimulus.

26:04

So it's really an important aspect of

26:06

these capacity limitations of visual

26:08

processing. The interesting thing about the attentional

26:11

blink that has been of interest to lots of

26:13

us is that if the second stimulus, for

26:15

instance, a house, is emotional,

26:18

if it's been linked to some emotional

26:21

content by its history,

26:23

it will blink less often.

26:25

In other words, you actually won't miss it as

26:27

often. So for instance, in the experiments that we've done

26:29

in the lab, we pair,

26:31

let's say, houses

26:32

with mild electrical stimulation,

26:34

mild shocks. So you do some kind of classical

26:37

conditioning to start the experiment

26:39

and later you test it in the attentional blink. And what

26:42

we see is that the houses that have been

26:44

paired with shock, mild shock obviously,

26:46

they're actually detected more

26:49

reliably, so there's less of a blink. So

26:51

it's a very important paradigm for lots of different

26:53

reasons, including the fact that emotional

26:55

stimuli survive this attentional blink

26:57

more strongly.

26:58

So how does this relate to the amygdala?

27:01

So the way that it relates to the amygdala is

27:03

that our work and many people's work

27:05

has shown that when the amygdala

27:08

is engaged by the emotional

27:10

stimuli, it actually enhances

27:12

visual processing and that enhanced

27:15

visual processing allows it to sort

27:17

of survive so that it's not missed.

27:19

And so if it otherwise didn't have

27:22

emotional content, it might be missed,

27:24

but because of its effective significance,

27:26

it actually survives the blink. So it actually, the

27:29

amygdala really helps in guiding the

27:31

brain, the visual system in determining

27:33

what is of relevance. So it won't get

27:35

missed out there because we have certain

27:37

things that we should be paying attention to. And

27:40

the amygdala helps guide this process

27:42

together with many other structures, but having

27:44

any important role in this.

27:45

Well, I know we've only scratched

27:47

the surface here, but I hope we've given people

27:49

sort of an idea of how fascinating

27:52

this work is and that there's much more

27:54

to it than they

27:55

might have imagined. Given the

27:57

rich interconnections that the amygdala

27:59

has, both to the higher and the lower regions

28:01

of the brain, how can we possibly

28:04

credit it with any particular function of

28:06

its own? Or should we? Well,

28:09

I don't think we should. We can't. I mean, that's

28:11

my view. This is not a universally

28:14

accepted position, but my view is that it's

28:16

exactly that. The fact that it's actually so

28:19

richly interconnected and interacting

28:21

with so many other structures that we should see its

28:24

functions as emerging from its interactions

28:26

with other regions. So in a framework

28:28

that I describe in the book, I call it the

28:30

multiple waves model, what the amygdala

28:32

is doing is really participating in many circuits.

28:36

And when it's participating with certain circuits,

28:38

it's actually important for attention. With other

28:41

circuits, it's important for decision-making,

28:43

and so on and so forth. So I view the

28:45

interactions as really the unit of

28:47

interest, not the region itself, but how it

28:49

interacts with other regions.

28:51

So if you were writing the

28:54

21st century medical dictionary

28:56

next to the word amygdala, how would you

28:58

summarize what it does based on our current

29:00

knowledge? I think that it's a huge

29:03

challenge, but I think that it clearly does

29:05

one thing, which has been the classical

29:08

emphasis, and we should keep that and not

29:10

throw it away, of course, is really important

29:12

in learning about the value of

29:15

things. It has been traditionally

29:17

associated with learning negative value.

29:19

I would extend that to learning about

29:22

value of things in general, so both negative

29:24

and positive. But in addition to that learning

29:26

part, which is classical conditioning and many

29:29

other kinds of learning types of paradigms,

29:32

I think there's a long list of functions that we need

29:34

to be aware of and think of its contributions

29:36

to processes of arousal and vigilance,

29:40

novelty detection,

29:41

attention in general, and simple forms

29:44

and possibly a little bit more complex forms of decision-making,

29:47

so that it really is a larger catalog

29:50

of functions that it's at least

29:52

participates in, so that it's providing

29:54

important contributions to all of them.

29:56

We're going to take a short break, and

29:58

we'll be back in a few minutes. minutes and talk

30:01

some about the pulvinar nucleus

30:03

of the thalamus and how it connects

30:06

to the amygdala and the rest

30:08

of the brain. So we'll be back in just a minute.

30:14

Another key chapter in the emotional

30:17

cognitive brain is the one about

30:20

effective visual perception. Here

30:22

you challenge the standard hypothesis

30:25

that there's a low road that allows

30:27

visual inputs to go past the

30:29

cortex, and you do this by

30:31

demonstrating that the thalamus is more

30:33

than just a simple relay. I mean

30:35

that's what I learned in medical school that the thalamus

30:38

was, so I'm sure a lot of other people did too.

30:40

Could you briefly explain

30:42

the standard hypothesis and

30:44

then summarize the evidence that

30:47

led you to propose a different model, your

30:49

multiple waves model that you mentioned a few minutes ago?

30:51

Yeah

30:52

sure. So I think briefly I just

30:54

want to remind the listeners that the low road

30:56

is this idea that there's a fast,

30:59

the low road, or in a way we can say the

31:01

standard hypothesis is the way that I refer

31:03

to it in the book. So

31:04

there's this fast sub-quotical pathway

31:07

that essentially can convey threat-related information

31:10

to the amygdala very fast.

31:12

So essentially sensory information

31:14

comes, that's the auditory or visual information

31:16

comes, and it can reach the amygdala

31:18

very fast and doesn't have to go via

31:21

cortex to reach the amygdala according to this hypothesis.

31:23

And that's important because the idea is that

31:26

this property of being sub-quotical

31:28

is important because this processing would

31:31

be able to take place in a fashion that is

31:33

independent of attention, so whether I'm paying attention

31:35

to a certain sound or not or visual stimulus

31:37

or not, it's processed and very fast

31:40

and it's independent of awareness, so I might not

31:42

even be aware of something and it's

31:44

actually going to have an effect because it's actually going to stimulate,

31:46

engage the amygdala. And it's not just

31:48

a theoretical interest but the fact that

31:51

many of these processes might be altered

31:53

and modified in psychopathology

31:55

of anxiety disorders and things of that nature,

31:58

so the idea is this fast.

31:59

pathway is really important. It has guided

32:02

thinking in the field quite a bit. The

32:04

types of problems with this notion that I discussed

32:06

in the book is that the emphasis

32:08

has been on processing that is very fast

32:11

and sort of independent of attention. So

32:14

I review evidence showing that

32:16

in comparison to this kind of sub-cortical

32:19

processing, cortical processing is

32:21

also extremely fast.

32:23

So the notion that everything that

32:25

happens in cortex is laborious and

32:27

slow and very detailed,

32:30

that's just not correct. There are very

32:33

fast signals being communicated and

32:35

transmitted in cortex.

32:37

And I also challenge, based on my

32:39

own work and many people's work, this

32:41

notion that signals that reach the amygdala

32:44

are strongly, I challenge the idea that

32:46

they are strongly independent of attention and awareness.

32:49

Many experiments have shown

32:51

that attention is really critical to

32:54

the signals that you have in the amygdala. So whether something

32:56

you're paying attention to something or not

32:59

makes a difference on the extent to which these signals

33:02

are registered in the amygdala. So it's not

33:04

just reaching the amygdala almost

33:06

like in this obligatory fashion, regardless

33:09

of you willing or being

33:12

attending to something.

33:13

And another important piece of

33:15

information is that

33:17

many of these effects in which

33:20

processing of emotional information is enhanced

33:23

actually can be observed even in now

33:25

human patients that do not have

33:28

amygdala. They have, let's say, bilateral

33:30

amygdala lesions. And these effects

33:33

of emotional stimuli are not abolished, suggesting

33:35

that the amygdala is not the only player

33:38

that is capable of enhancing

33:41

processing given effective significance.

33:43

So with these properties and also

33:46

careful consideration about the underlying anatomy,

33:49

I have sort of advocated that we

33:51

should think of processing not in

33:53

terms of this fast, simple subcortical

33:55

pathway, but in terms of many

33:58

circuits or many

34:00

processing waves of information

34:03

that actually convey the effective

34:05

and biological significance of the information

34:08

out there in the world.

34:09

Okay, that's a good introduction.

34:12

One of the key pieces of

34:14

your argument is the fascinating research

34:17

about the pylvanar nucleus.

34:19

It's time for you to tell us a little bit about this and

34:21

why it's so important.

34:23

Yeah, the pylvanar is really fascinating. As

34:25

far as it's at alamus, in one respect,

34:27

we can think of it as, okay, it's sort of a boring

34:29

part of the brain because it's basically just a

34:31

relay station. Things are far in the brain,

34:33

so they stop in the thalamus and then they're transmitted

34:36

to the brain, they're passed on to the brain. But

34:38

the anatomy of the pylvanar is so fascinating.

34:41

It really is such that it's so intricately

34:44

and richly interconnected with the brain that

34:46

it really suggests, and now

34:48

with many kinds of evidence adding

34:51

to the anatomical evidence, that it's not

34:53

just the thalamus itself but especially

34:55

the pylvanar. It's not really just

34:57

simply a passive relay station, but

34:59

it's really critical for integrating signals

35:02

and in fact guiding how

35:05

cortical regions are communicating with

35:07

each other. One of our studies that showed

35:09

that it's not just a simple passive relay

35:12

station, showed that the pylvanar responds

35:14

only to stimuli that are consciously perceived.

35:17

So when the stimulus was of biological

35:19

significance because it had been paired with mild

35:21

shock in the past and the stimulus

35:23

was detected, the pylvanar was engaged

35:26

and I believe was part of amplifying the

35:28

signals related to the stimulus. But

35:30

when it was not perceived by a person

35:32

because it was presented very fast and the person actually

35:35

missed it, so it was physically shown to

35:37

them but they missed it. In those trials

35:39

in which the stimuli were missed, the pylvanar was

35:41

not engaged. So it really shows that I think

35:43

the pylvanar is really involved in amplifying

35:46

signals that are related to the information that is

35:48

relevant to the orbitism. Which is essentially

35:50

another way of saying that the pylvanar is really critical

35:53

for attention. Pay attention to the things that

35:55

are of relevance. And it has all

35:57

these bi-directional connections.

35:59

especially to the cortex. I think

36:02

you quoted somebody else as describing

36:04

the, I don't remember if it was the pulvinar or the

36:06

entire thalamus as having the cortex

36:09

shrink wrapped over it. Yeah,

36:11

it's the pulvinar. It's as if almost entire

36:13

cortex projects to the pulvinar. It's

36:15

an amazing property and I think it's very poorly

36:18

understood how that is actually

36:20

influencing and maybe even directing cortical

36:23

communication, which is an idea that several

36:25

people have been starting to advocate and

36:28

is an integral piece of understanding how

36:31

signals are communicating in cortex itself.

36:34

I also thought it was really interesting the

36:36

fact that the pulvinar fires

36:39

for things that are consciously perceived,

36:41

not for things that are missed. That

36:43

sort of goes against this claim,

36:46

we're in one of these fads where they're saying

36:48

everything is unconscious and there's

36:51

this idea that our emotions

36:53

are unconscious forces.

36:55

This kind of goes against that, doesn't it?

36:58

Yeah, I do think so. I think there's a

37:00

lot to be said. These circuits really

37:03

are not passive. It's sort of the opposite

37:05

of this traditional view that everything is passively

37:08

going by and almost like a hopeless

37:10

automata that are out there and just being

37:12

bombarded by stimuli and we're just not aware

37:15

of them. I'm not saying that everything is processed

37:17

to the same level, but structures

37:19

like the pulvinar and many

37:21

other structures in the brain, the superior colloquialist,

37:24

amygdala, and many parts of cortex

37:26

are really narrowing in, zooming

37:28

in into the things that are of frequent importance

37:31

and highlighting those. They often

37:33

rise to the level that we are aware of them.

37:36

I think that there's a great importance

37:39

to that kind of processing that people actually

37:41

traditionally attribute to them.

37:43

The fact that the connections are two-way is really

37:46

important to it. That's one of the things that goes

37:48

against the oil relay viewpoint. If

37:50

it was just a relay, we wouldn't need signals back

37:53

from the cortex, would we? Yes, you're exactly

37:55

right. The interconnectivity is both ways

37:57

and very dense in both ways. Yeah. Once

37:59

we know... now what the polenar is

38:01

doing, does that have any impact

38:03

on our view of the thalamus in general?

38:06

Yes, I think, again, the idea that really

38:09

the thalamus cannot be understood anymore

38:11

in terms of these passive relays. It's actually,

38:14

it really is something that we need to understand

38:17

in terms of this kind of a

38:19

central hub of communication that is

38:21

really affecting overall signals

38:23

in the entire brain, both subcortic and cortical.

38:26

So cortical communication is not just pure

38:29

cortical communication, it's communication that

38:31

also involves the thalamus.

38:33

So I think that's one critical

38:35

architectural feature that is really fundamental

38:38

for us to understand how signals are

38:40

being communicated in the brain.

38:42

Has anybody studied the other parts of the thalamus?

38:45

Do you think similar principles will

38:47

apply to other parts of the thalamus once

38:49

it's studied?

38:50

Yeah, so I think that there's a distinction, I'm not

38:52

an expert on the thalamus more generally,

38:54

but one distinction that is made is that the polenar

38:57

is considered and several other nuclei in

38:59

the thalamus are considered sort of second

39:02

order nuclei as opposed to more

39:04

first order, more relay

39:07

types. There is some truth to the fact

39:09

that some nuclei in the thalamus

39:11

are closer to being more of a

39:13

passive station and region and

39:16

others are much more involved in these large

39:18

circuits involving cortex. But in

39:20

general, I do think that the emphasis

39:22

is actually on both cortical thalamus

39:25

communication and we shouldn't view even

39:28

parts of the thalamus as pure, just simple

39:30

relay stations. I don't believe in that notion.

39:32

I think that there's a lot more interactivity

39:35

than we tend to assume.

39:36

So then how

39:38

does this knowledge change our

39:40

view of what the amygdala is doing in visual

39:42

processing? Well, I think

39:44

that the amygdala story is a little bit different, right?

39:46

So I mean, the amygdala, for instance, the amygdala's

39:48

role in visual processing to a large extent

39:51

has to do with its own anatomy

39:53

and projection. The anatomy of the amygdala is such

39:56

that it receives signals from visual

39:58

cortex, from parts of the cortex. that

40:00

have very elaborate response properties that

40:02

might respond to faces and objects and

40:04

complex visual properties. But

40:07

the amygdala itself, once it receives those

40:09

signals, it's able to, within

40:12

its own circuits, to process

40:14

them and assess their biological significance, their

40:16

effective emotional significance. And the

40:18

amygdala has projections to

40:21

all levels of the visual cortex itself.

40:23

So it's actually then able to affect,

40:25

to influence visual processing

40:28

at many levels. So not only the levels

40:29

that have complex response properties

40:32

from which it receives signals, but

40:34

also in so-called early visual

40:36

cortex, primary visual cortex, visual

40:39

area V2, V4, and so on, which

40:41

have similar response properties. So the

40:43

bottom line is that by being able to influence

40:46

visual processing at all these stages, it

40:48

really determines what we should see

40:50

out there. So it's actually this kind

40:52

of important highlighter. It's

40:55

saying, look there, look here. It's

40:57

really guiding this visual system and determining

41:00

what gets to be seen in this barrage

41:02

of stimulation that we always have. So it's really

41:05

picking out the important information, the

41:07

significance from what is not as significant,

41:10

and helping guide vision and visual

41:12

processing.

41:13

But this isn't just because it has the subcortical

41:16

connections that are the part of the traditional

41:18

model, but because it has all these extensive

41:21

connections to many parts of the brain, including

41:23

all parts of the visual cortex, right? That's

41:25

right. Not because it's receiving something in

41:28

a privileged fashion in subcortical pathway,

41:30

but it's receiving all sorts of signals from visual

41:32

cortex and in fact across the brain, integrating

41:35

them and based on context and relevance

41:37

and goals and all these factors

41:39

together,

41:40

then it's actually in a position

41:42

anatomically to influence a lot of things,

41:44

including visual cortex. That's exactly right.

41:47

So it seems clear that both the amygdala

41:49

and the pulvinar nucleus of the thalamus do

41:51

a lot more than I was taught in medical school.

41:54

And it also appears that effective

41:56

and cognitive processes are deeply intertwined.

41:59

One question that still sticks out

42:02

for me is what is the key difference

42:04

between the role of the pulvinar

42:06

and the role of the amygdala? Because

42:08

they do some similar things, so how

42:10

are they different?

42:11

Yeah, there's one key difference. So

42:13

again, there are many similarities because I think that

42:16

they're important in influencing the flow of

42:18

information very broadly. So they are

42:20

very broadly connected, so they function in

42:22

these really strongly connected hubs and

42:24

they have an ability to influence

42:26

processing. So in one sense, the

42:29

pulvinar fits very neatly into that. It's very

42:31

widely connected, in fact, much more widely

42:33

connected than the amygdala in a sense, as

42:35

you mentioned just a little while ago

42:37

about this remarkable connectivity with almost

42:40

all of cortex. So in one sense, the

42:42

pulvinar is very associational. It's

42:44

actually integrating signals and associating

42:47

signals and transmitting signals. The amygdala

42:49

definitely has some of these properties too. But

42:52

here comes the critical distinction. The

42:54

amygdala is very heavily connected

42:57

also to these very deep

42:59

subcortical structures in the brainstem

43:02

that are essential for autonomic functioning.

43:04

So for instance, it has very strong

43:07

connectivity with the hypothalamus and controlling

43:09

all of these autonomic functions

43:12

that keep us alive and

43:14

make us feel things and change

43:17

things like respiration, blood

43:19

pressure, and all these properties that are very

43:21

broadly in essence. So the

43:24

amygdala is more finely tuned, if

43:26

you will, in its connectivity to

43:28

cortical regions and has many connections

43:30

to other cortical regions that are important for

43:33

it. Did you mean to say the pulvinar? No,

43:35

actually I mean the amygdala. So the amygdala has connectivity

43:37

to both cortical and subcortical regions.

43:40

The subcortical regions, via the central

43:42

nucleus of the amygdala to this brainstem

43:45

autonomic centers, if you will, via

43:47

the lateral amygdala to cortical

43:49

regions, but a lot of the connectivity to

43:52

cortical regions, it's more limited

43:54

and focused and guided than the pulvinar,

43:57

which is very broad. And

43:59

many of the connections.

43:59

that the amygdala has, cortical

44:04

regions, that are important for stimulus evaluation.

44:07

So what's the significance of a stimulus?

44:09

So regions like the orbital frontal cortex,

44:12

regions like the insula,

44:14

regions like the medial prefrontal

44:17

cortex, and other regions that are very

44:19

important in these more evaluative

44:21

functions. So the amygdala has this

44:24

bodily component and this more

44:26

value angle to it, and

44:28

the pulvinar has a

44:29

broader sort of communication

44:32

that is helping the association

44:35

of signals and is also important for evaluation

44:38

for significance, but it's sort of broader.

44:41

Yeah, that's why you use the word integration

44:43

in your book when describing the function

44:46

of the pulvinar.

44:47

I think that's a good way of saying it. It's really important

44:49

for this broad integration of stimulus and

44:51

the amygdala has that, but it's through a kind

44:54

of an angle or a lens that is more

44:56

value-based. And

44:58

obviously the bodily part two, which is really critical

45:00

and changes everything, right? Because the hypothalamus

45:03

is controlling everything that is important for being

45:05

alive and then the amygdala is communicating

45:07

the hypothalamus and many other structures obviously throughout

45:10

the brainstem and the amygdala is right there

45:12

talking to them. So it will feel very

45:14

different when we get a jolt and emotion. You

45:16

feel it in your body obviously, that's one

45:18

thing that we always say, that's what emotion is

45:21

about.

45:27

We can't leave out the prefrontal cortex.

45:29

We've traditionally been told that the cognitive

45:31

processing of emotional information occurs

45:34

in the prefrontal cortex, but your work

45:36

seems to argue that the emotion and cognition

45:38

are deeply intertwined long

45:41

before they reach the prefrontal cortex

45:43

because they're

45:43

entwined in the amygdala and the thalamus. So

45:46

what does your approach tell us about

45:48

the prefrontal cortex?

45:50

I think that the prefrontal cortex is definitely,

45:53

again, because it receives

45:55

these signals from many places including Povina

45:58

and Miquelopa and many other places. place

46:00

and integrates many immediate. The prefrontal

46:02

cortex is the part of the brain that people

46:05

would associate with the greatest amount of signal integration.

46:07

So by that itself

46:10

it has the ability to receive signals

46:12

that have these emotion and

46:15

cognitive sides to them. So

46:18

it really is such that by its integration

46:20

of signals and its anatomy such that

46:23

emotion and cognition are heavily intertwined.

46:25

And so I do this property of communication

46:28

and integration interactions throughout the brain.

46:30

And the anatomy of the prefrontal cortex

46:32

is certainly one that is heavily able

46:35

and tuned to exactly that kind of integration

46:37

of signals. So there's no such thing as a purely

46:40

cold, rational

46:41

signal and a purely emotional

46:43

signal. Those things are emerging all the

46:45

time and the prefrontal cortex is receiving

46:48

all those influences. So whatever people

46:50

would label as cognitive is happening immersed

46:53

in a context that is motivational and emotional

46:55

at all times. Yeah, one of my guests

46:58

that I've actually had on the show a couple of times

47:00

is a retired neurologist Robert

47:02

Burton and he has said that the idea

47:05

that we could have autonomous rational

47:08

thought just doesn't fit how our brains

47:10

really work. I agree

47:11

with that completely. So even if for instance

47:13

the part of the brain that is viewed as the

47:15

most cognitive if you will, the lateral

47:17

prefrontal cortex, you know people will

47:19

invoke certain properties like oh the

47:22

amygdala doesn't have heavy connectivity

47:24

with the lateral prefrontal cortex. So

47:26

therefore the lateral prefrontal cortex is

47:28

pure cognition or the purest

47:31

form of cognition.

47:32

Even if it's true that the connectivity

47:34

is not very strong with lateral prefrontal cortex,

47:36

it only takes one extra synapse to reach

47:39

from the amygdala to lateral prefrontal cortex.

47:41

So the signals can go from the insula

47:43

to lateral prefrontal cortex, you know, amygdala,

47:45

insula, lateral prefrontal cortex, farmigula,

47:47

medial prefrontal cortex, lateral prefrontal cortex.

47:50

I think sometimes people make the mistake that the

47:52

communication has to be direct. So

47:55

if there's no connection between A and B, then

47:57

A is not influencing B.

47:59

that the architecture is such that this is

48:02

a network and so it reaches B

48:04

via some other node and what really

48:06

matters is the ability that these signals have

48:09

of reaching them. Obviously a direct strong

48:11

connection is very important. That's not to deny

48:13

that importance, but the importance of these indirect

48:16

connections is really key. So there's no little

48:18

place in the brain that is hiding and it's able

48:21

to do pure cognition.

48:22

Right. So is

48:24

there anything else that you would

48:27

like to share before we close?

48:30

Well, I think one thing that I would like to suggest

48:32

that I feel like myself and

48:34

I try to always remind people

48:37

in my own lab and people I interact

48:39

with is that I think humans have a great

48:42

desire to simplify things. I think

48:44

we love simplicity, but I don't know. I love

48:46

complexity. I think we need to embrace

48:48

the complexity of the whole thing and we need to

48:51

stop studying the brain one region at a time

48:53

and we need to understand how these regions

48:55

are talking to each other and this talking is

48:57

where the action happens. And again, let

49:00

go a little bit of the impulse that we have to understand

49:02

things in this kind of almost linear, simple

49:05

sense and be happy with

49:07

complex systems and embrace complexity,

49:10

if you will. If it's really true that

49:12

the human brain is the most complex system

49:15

known to man, then if we

49:17

really want to understand it, we don't have any choice,

49:19

do we? Exactly. So I think we need

49:21

to be bolder and to

49:24

not stick to these simple stories. They're

49:26

easy to communicate, they're easy to

49:28

grasp, they're easy to make connections,

49:31

but they're just too simple. I think that we really

49:33

need more complexity because what

49:35

we're studying is highly complex, absolutely.

49:38

So what about advice for students?

49:40

There's quite a few students that listen to this show.

49:43

Yeah, so obviously my advice

49:45

is through my own biases and the way

49:47

that I ended up in this field. And so

49:50

I think that if you want to study the mind,

49:52

let's say, by psychology, it's

49:54

wonderful, obviously, or you're more

49:56

biologically inclined, so you want to study the brain

49:58

biology. It is great

50:00

but I would say don't forget to study

50:03

and focus on what we call understanding

50:06

data. So data science

50:08

is something that people are starting to talk about now. But

50:10

it's really some combination of having some

50:13

familiarity with mathematical concepts

50:15

and being comfortable with computer science

50:18

and programming and definitely being comfortable

50:20

in learning statistics because what we really need

50:22

to do is make sense of very complex data.

50:25

And so we're talking about all these regions

50:27

talking to each other and communicating and

50:29

all

50:29

these complex data that are acquired

50:32

behaviorally, longitudinally and multiple

50:34

times. You study MRI with

50:36

multiple modalities and anatomical

50:39

aspects, functional aspects and other

50:41

sorts of imaging modalities. So we need to put

50:43

all these things together so that we need, you

50:46

know, for instance, in the mind and the brain, we

50:48

need the tools for that. And so it's a little bit

50:50

like physics, you know, they were interested in the universe

50:53

and natural science but

50:55

they have to approach it via

50:58

tools that are formal in nature.

50:59

And I think that the mind and the brain also

51:02

need those kinds of tools. So I definitely would encourage

51:04

students to don't give up on the math

51:06

and the computer science and the stats and learn that

51:09

because it really pays off. Yeah. And

51:11

I think we really need more skilled

51:13

people in this field so that we can

51:15

be generating good data and not bad

51:18

data. Yeah. Yeah.

51:19

So is there an unanswered

51:22

question that's currently driving

51:23

your work? Oh, yeah.

51:26

One thing that I'm always interested in is how things

51:28

are interacting with each other. And so right now,

51:31

one of the things that we were working on in the lab is understanding

51:33

a little bit like I hinted at during this conversation

51:36

is understanding interactions between

51:39

aversive and aperitive systems. So systems

51:42

that people have traditionally conceptualized as separate

51:44

things that are related to reward processing

51:47

and how I approach information, aperitive

51:49

systems, things related

51:51

to fear and threat and the negative

51:53

part of the spectrum and how many regions

51:56

in the brain are actually doing both and understanding

51:58

how they interact with each other.

51:59

and eventually their impact on behavior

52:02

via altering perception and cognition

52:04

by influencing how we perceive the world and how

52:07

we think about things. And that really

52:09

goes on with your everything's

52:11

intertwined view of the world because

52:13

now we've also not only have the emotions

52:15

intertwined with cognition, but the positive

52:18

and the negative are hard to separate too.

52:20

Yeah, that's my angle. I like to complicate things.

52:22

Yeah, well, that's real life

52:24

for you. Luis, I really appreciate

52:27

you taking the time to talk with

52:29

us today and I really

52:32

enjoyed

52:32

your book. I don't think it's

52:34

a great book for the general reader, but

52:36

this book is really aimed at scientists and students,

52:39

isn't it? Yeah, exactly. I do write

52:41

it as a general audience. I think in the

52:43

future I'll be interested in trying to convey these ideas

52:45

in a way that is more attractive and broader.

52:48

I'd encourage you to read Miguel's book

52:51

as a nice role model of an excellent

52:53

book of that sort. Actually, I put

52:55

his and Eric Kandel, their books

52:58

together, although his wasn't as much of a biography

53:00

as Kandel's, but there's a lot of similarity

53:02

in the things that make both those

53:04

books work.

53:10

Because I'm getting ready to interview Dr. Pozoa

53:12

again, I went through our first conversation

53:15

more carefully than I usually do, and

53:18

I've decided to include my original

53:20

episode summary. I will warn you

53:22

that it is fairly detailed, but

53:24

given the density of this episode,

53:26

I think you will find the repetition helpful.

53:29

You may also want to return to this

53:31

summary for review

53:33

before you listen to our next conversation.

53:37

I will try to keep my announcements short

53:39

today, but I have to remind

53:42

you that you will find complete show notes

53:44

and episode transcripts at Brainsciencepodcast.com.

53:48

Since this is an encore episode,

53:50

the transcript will be free

53:53

and I hope you will find it useful. You

53:55

can also send me feedback at Brainsciencepodcast.com.

53:58

I

54:00

know you don't want to miss the upcoming follow-up

54:03

interview, so please be sure to sign up

54:05

for the free Brain Science newsletter

54:08

so that you can get show notes automatically

54:10

each month. Just text BRAIN

54:13

SCIENCE

54:13

ALL ONE WORD to 55444.

54:18

That's BRAIN SCIENCE ALL ONE WORD

54:21

to 55444.

54:24

And of course you'll get your free gift, the

54:27

handout, five things you need to know

54:29

about your brain. I

54:31

want to thank everyone who supports

54:34

my work either financially

54:35

or by sharing it with others. I

54:37

have created a table to help you

54:40

decide whether myLipsen

54:42

or Patreon is best for you.

54:45

Patreon supporters who pledge at

54:47

least $10 per month, get transcripts,

54:50

ad-free episodes, and a

54:52

copy of my book, Are You Sure?

54:55

The Unconscious

54:56

Origins of Certainty. If

54:58

you're already a $10 supporter

55:01

but didn't get your copy, be

55:03

sure to let me know.

55:10

I want to thank Luis Pissoa for

55:12

talking with me about his book, The

55:14

Cognitive Emotional Brain, from

55:17

Interactions to Integration. I

55:19

think he did a good job of introducing us

55:21

to a fascinating new way

55:23

to look at the interaction between cognition

55:26

and emotion.

55:27

As I mentioned, this book is for

55:30

students and working scientists, but

55:32

I think the key ideas are relevant

55:34

to everyone.

55:35

It's important to realize that the old

55:38

way of seeing emotion and cognition

55:41

as separate and sometimes opposing

55:43

processes is becoming obsolete.

55:46

Before I start my review, I want to remind you

55:48

that detailed show notes and

55:51

complete episode transcripts are available

55:53

at brainsciencepodcast.com. In

55:56

the show notes, I will also include links

55:59

to all the previous episodes that

56:01

relate to today's conversation.

56:04

So in our conversation with Dr.

56:06

Pessoa, we were focusing

56:09

mainly on two parts of

56:11

the brain that you may or may

56:13

not have heard of before called the amygdala

56:16

and the pulvinar nucleus

56:19

of the thalamus.

56:21

The amygdala is in the medial temporal

56:23

lobe near the hippocampus, which

56:26

means if you think about pointing

56:28

in from your ears, it's kind of in the

56:30

middle there. The thalamus is at

56:32

the very top of the brain stem and

56:35

the pulvinar is its largest nucleus.

56:38

As Dr. Pessoa explained, you

56:40

could divide the amygdala up into

56:42

as many as 12 parts, but

56:45

he talked about two main parts,

56:47

the lateral amygdala, which

56:50

is almost cortex-like

56:51

and is highly connected

56:53

to the cortical regions of the brain,

56:56

and the central or more medial amygdala,

56:59

which is more primitive and connects

57:01

to the brain stem, which controls

57:03

autonomic functions like breathing and

57:05

blood pressure. You've

57:07

probably heard of the amygdala because

57:09

of its connection to

57:11

fear and other negative stimuli,

57:14

but what we talked about today is that the

57:16

amygdala is about more than fear. It's

57:18

involved in arousal and vigilance,

57:21

which you would consider these attentional

57:23

functions and also value

57:26

representation, which means

57:28

that it is involved in simple decision-making.

57:31

The key idea here is that cognition

57:34

begins before you get to the cortex,

57:37

and emotion and cognition can't

57:39

be separated in terms of where

57:42

they occur in the brain. We talked

57:44

about how the evidence for these conclusions

57:47

is mostly based on the work with animals,

57:50

but Dr. Pessoa did

57:51

tell us that the resolution for functional

57:54

MRI is approaching that

57:56

needed to be able to tell what

57:59

parts of the amygdala are.

57:59

are being stimulated or

58:02

firing. Now

58:03

a lot of the single cell recordings

58:05

taken from the amygdala are done

58:08

in animals like mice and

58:10

monkeys. The visual

58:12

system has been extensively

58:15

studied in monkeys because

58:17

it's assumed to be similar to that

58:19

of humans. And one reason

58:21

why there's an emphasis on visual processing

58:24

in this book is that this is the

58:26

system that we understand because

58:29

it's been studied the most. Another

58:31

key idea is the fact that the amygdala

58:33

does respond to both positive and

58:35

negative stimuli, returning

58:38

to my key idea that it's not just

58:40

about fear.

58:41

Now in trying to study

58:42

what's going on in the amygdala

58:44

in people, various paradigms

58:46

are used and one we touched on

58:48

during the conversation was something called attentional

58:51

blink, which refers to the fact that when

58:53

you see a visual stimulus there's

58:56

a brief period where your brain's processing

58:58

that stimulus and if something else appears

59:00

you might miss it. And so that's like a blink.

59:03

This period of time is about 200 to 500 milliseconds

59:07

and it turns out that if the second stimulus

59:10

has emotional relevance this

59:12

effect is diminished. That is you're more likely

59:14

to see the second object. It's

59:16

interesting to realize that the

59:18

responses of the amygdala track

59:21

perceptual responses. That

59:23

means that the amygdala is influencing

59:26

what we see and what we pay attention to.

59:29

But it's also important to realize that the amygdala

59:31

is not acting alone, but

59:33

rather it is an important part of what

59:35

you might think of as the brain's attentional

59:38

network.

59:39

After we talked about the amygdala we talked

59:42

about the pulvinar nucleus

59:44

of the thalamus. A nucleus is

59:46

just a cluster of neurons. The

59:48

thalamus is located, like I said

59:51

a minute ago, at the very top of the brainstem.

59:53

That is at the base of the brain proper. It

59:56

has long been thought to be the

59:58

major relay station.

59:59

between the brain and the body, but

1:00:02

Dr. Pessoa and his colleagues are

1:00:04

challenging this view.

1:00:06

He is also specifically challenging

1:00:08

what he calls the standard hypothesis,

1:00:11

which is that there's a so-called low road

1:00:13

by which sensory information goes

1:00:15

rapidly from the periphery through the

1:00:18

thalamus straight to the amygdala.

1:00:20

The assumption being that this is faster and also

1:00:22

essentially unconscious.

1:00:25

The challenge to this is based

1:00:27

on research that goes against all these

1:00:29

basic elements. First, there's

1:00:31

evidence that the amygdala is more

1:00:33

involved in attention and awareness

1:00:36

than we thought.

1:00:37

Second, as Dr. Pessoa mentioned,

1:00:40

it has been shown that the pathways involving

1:00:42

the cortex are faster than

1:00:45

was originally assumed so that we don't need

1:00:47

this low pathway from a speed

1:00:49

standpoint.

1:00:50

Finally, the anatomy just doesn't

1:00:53

support the idea that the thalamus is

1:00:55

a mere relay station because it has

1:00:57

extensive connections to many parts

1:01:00

of the cortex, including various

1:01:02

sensory areas and the frontal lobes, and

1:01:05

these connections are in both directions.

1:01:08

Pessoa's multiple waves

1:01:10

model reflects this by having information

1:01:13

come to the amygdala, not just from the

1:01:15

thalamus, but also from various parts

1:01:17

of the cortex. The reason we focused

1:01:20

on the pulvinar is that it's the

1:01:22

largest nucleus and it processes

1:01:24

visual information, and as

1:01:26

I said, vision is the most well studied.

1:01:29

So what is the function of

1:01:31

the pulvinar if it's not a relay

1:01:33

station?

1:01:34

First, remember that Dr. Pessoa

1:01:36

told us that it responds only to stimuli

1:01:39

that are consciously perceived. He

1:01:41

said that it helps amplify signals

1:01:43

that are important or relevant to

1:01:45

the organism.

1:01:47

The fact that it has extensive connections

1:01:49

to virtually the entire cortex is

1:01:52

particularly relevant

1:01:53

to this function.

1:01:55

He also said that instead

1:01:57

of thinking of the pulvinar and

1:01:59

the rest of the thalamus by implication as

1:02:01

a passive relay, we should

1:02:04

think of it as what he called a central

1:02:06

hub of communication because

1:02:08

it connects to both the cortex and the brainstem.

1:02:12

Returning to the amygdala for a few moments,

1:02:14

in terms of its role in visual processing,

1:02:17

the key idea to remember is

1:02:19

that it has extensive connections

1:02:21

in both directions to all

1:02:23

the various visual areas in the brain,

1:02:26

ranging from the primary visual cortex

1:02:28

to the association areas. So,

1:02:31

it has a key role in determining

1:02:33

what we see and what we pay attention to.

1:02:35

Which brings me back to the most important

1:02:38

idea of this episode, which is that

1:02:40

the emotional and cognitive processes

1:02:42

of the brain are deeply intertwined

1:02:44

at every level.

1:02:46

That's why this book is called

1:02:48

The Cognitive Emotional Brain.

1:02:51

As always, we could only hit on the highlights

1:02:53

of this fascinating topic.

1:02:56

We didn't have time to talk much about

1:02:59

what happens in the prefrontal cortex,

1:03:01

but here the evidence is also mounting

1:03:04

that cognitive and emotional processes

1:03:06

are not segregated, as

1:03:08

has long been assumed.

1:03:10

Another aspect of the book that we almost

1:03:13

totally ignored was the importance

1:03:15

of network theory.

1:03:17

For that I have to refer you back to my

1:03:19

previous interviews with Olaf Sporns.

1:03:23

I do want to point out that Pessoa and

1:03:25

Sporns both share the opinion that

1:03:28

network theory is essential for understanding

1:03:30

the complex functions of our brain,

1:03:33

because no

1:03:34

one section of the brain can carry

1:03:36

out its function in isolation.

1:03:39

So, I hope you'll come away

1:03:42

from this episode realizing that there's more

1:03:44

to the amygdala and the thalamus than

1:03:47

you might have

1:03:48

ever imagined and that

1:03:50

cognition and emotion are

1:03:53

deeply intertwined at every level.

1:04:00

I hope you enjoyed this encore episode with

1:04:02

Luis Pessoa. Stay tuned

1:04:05

for an upcoming episode about his new

1:04:07

book, The Entangled Brain, How

1:04:09

Perception, Cognition, and Emotion Are

1:04:11

Woven Together. This book is aimed

1:04:13

at listeners of all backgrounds. One

1:04:16

of the things it does is explain

1:04:19

why we should abandon the idea

1:04:21

of the so-called limbic

1:04:24

system. You can find more

1:04:26

episodes and sign up for the Brain

1:04:28

Science newsletter at

1:04:30

brainsciencepodcast.com. Please

1:04:33

send me feedback at brainsciencepodcast.gmail.com.

1:04:37

I also want to mention that the

1:04:39

Brain Science mobile app is now called Brain

1:04:42

Science Podcast.

1:04:44

It is available for all mobile devices

1:04:46

and is a great way to access both free

1:04:49

and premium content.

1:04:51

Finally, don't forget that I'm

1:04:53

moving to New Zealand and I would love to

1:04:55

hear from listeners in Australia and

1:04:57

New Zealand. Of course, I want to hear from you

1:04:59

wherever you live. Thanks again for listening.

1:05:02

I look forward to talking with you again

1:05:04

very soon.