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I'm going to start by saying something
you think you know to be true.

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Your brain creates
all facets of your mind.

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So then why do we treat
mental and physical illnesses

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so differently,

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if we think we know
that the mind comes from the brain?

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As a neuroscientist, I'm often told

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that I'm not allowed to study
how internal states

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like anxiety or craving or loneliness

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are represented by the brain,

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and so I decided to set out
and do exactly that.

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My research program is designed
to understand the mind

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by investigating brain circuits.

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Specifically, how does our brain
give rise to emotion.

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It's really hard to study
feelings and emotions,

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because you can't measure them.

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Behavior is still the best and only window

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into the emotional experience of another.

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For both animals and people,

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yes, self-report is a behavioral output.

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Motivated behaviors
fall into two general classes:

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seeking pleasure and avoiding pain.

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The ability to approach things
that are good for you

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and avoid things that are bad for you

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is fundamental to survival.

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And in our modern-day society,

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trouble telling the difference
can be labeled as a mental illness.

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If I was having car trouble,

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and I took my car to the mechanic,

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the first thing they do
is look under the hood.

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But with mental health research,

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you can't just pop open the hood
with the press of a button.

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So this is why we do
experiments on animals.

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Specifically, in my lab, mice.

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To understand the brain, well,
we need to study brains.

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And for the first time, we actually can.

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We can pop open the hood.

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We can look inside

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and do an experiment
and see what comes out.

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Technology has opened new windows
into the black box that is our minds.

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The development of optogenetic tools

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has allowed us unprecedented control
over specific neurons in the brain

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and how they talk to each other
by firing electrical signals.

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We can genetically engineer neurons
to be light sensitive

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and then use light to control
how neurons fire.

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This can change an animal's behavior,

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giving us insight
into what that neural circuit can do.

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Want to know how scientists
figure this out?

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Scientists developed optogenetic tools
by borrowing knowledge

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from other basic science fields.

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Algae are single-celled organisms
that have evolved to swim towards light.

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And when blue light shines
onto the eyespot of an algae cell,

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a channel opens,
sending an electrical signal

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that makes little flagella flap

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and propels the algae towards sunlight.

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If we clone this light-sensitive
part of the algae

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and then add it to neurons
through genetic modification,

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we can make neurons light-sensitive, too.

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Except, with neurons,

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when we shine light down
an optical fiber deep into the brain,

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we change how they send electrical signals
to other neurons in the brain

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and thus change the animal's behavior.

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With the help of my colleagues,

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I pioneered the use of optogenetic tools

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to selectively target neurons
that are living in point A,

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sending messages down wires
aimed at point B,

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leaving neighboring neurons
going other places unaffected.

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This approach allowed us to test
the function of each wire

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within the tangled mess that is our brain.

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A brain region called the amygdala

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has long been thought
to be important for emotion,

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and my laboratory discovered

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that the amygdala
resembles a fork in the road

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where activating one path
can drive positive emotion and approach,

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and activating another path
can drive negative emotion and avoidance.

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I'm going to show you
a couple of examples --

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a taste of raw data --

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of how we can use optogenetics
to target specific neurons in the brain

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and get very specific changes in behavior.

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Anxiety patients
have abnormal communication

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between two parts of the amygdala,

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but in people, it's hard to know
if this abnormality is cause or effect

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of the disease.

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We can use optogenetics
to target the same pathway in a mouse,

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and see what happens.

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So this is the elevated plus maze.

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It's a widely used anxiety test

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that measures the amount of time

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that the mouse spends in the safety
of the closed arms

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relative to exploring the open arms.

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Mice have evolved to prefer
enclosed spaces,

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like the safety of their burrows,

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but to find food, water, mates,

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they need to go out into the open

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where they're more vulnerable
to predatory threats.

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So I'm sitting in the background here,

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and I'm about to flip the switch.

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And now, when I flip the switch
and turn the light on,

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you can see the mouse begins to explore
the open arms of the maze more.

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And in contrast
to drug treatments for anxiety,

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there's no sedation,
no locomotor impairment,

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just coordinated,
natural-looking exploration.

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So not only is the effect
almost immediate,

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but there are no detectable side effects.

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Now, when I flip the switch off,

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you can see that the mouse goes back
to its normal brain function

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and back to its corner.

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When I was in the lab
and I was taking these data,

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I was all by myself, and I was so excited.

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I was so excited,
I did one of these quiet screams.

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(Silently) Aah!

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(Laughter)

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Why was I so excited?

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I mean, yeah, theoretically,
I knew that the brain controlled the mind,

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but to flip the switch with my hand

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and see the mouse
change its behavioral state

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so rapidly and so reversibly,

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it was really the first time
that I truly believed it.

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Since that first breakthrough,

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there have been a number
of other discoveries.

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Finding specific neural circuits
that can elicit dramatic changes

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in animal behavior.

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Here's another example:
compulsive overeating.

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We can eat for two reasons.

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Seeking pleasure, like tasty food,

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or avoiding pain, like being hungry.

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How can we find a treatment
for compulsive overeating

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without messing up
the hunger-driven feeding

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that we need to survive?

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The first step is to understand

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how the brain gives rise
to feeding behavior.

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This fully-fed mouse
is just exploring a space

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completely devoid of any food.

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Here we're using optogenetics to target
neurons living in the hypothalamus,

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sending messages down wires
aimed at the midbrain.

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When I turn the light on, right here,

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you can see that the mouse
immediately begins licking the floor.

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(Laughter)

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This seemingly frenzied behavior

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is about to escalate into something
I find really incredible.

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It's kind of trippy, actually.

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Ready?

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It's right here.

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See, he picks up his hands
as if he is eating a piece of food,

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but there's nothing there,
he's not holding anything.

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So this circuit is sufficient
to drive feeding behavior

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in the absence of hunger,

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even in the absence of food.

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I can't know for sure
how this mouse is feeling,

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but I speculate
these neurons drive craving

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based on the behaviors we elicit
when we target this pathway.

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Turn the light back off --

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animal's back to normal.

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When we silence this pathway,

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we can suppress and reduce
compulsive overeating

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without altering hunger-driven feeding.

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What did you take away
from these two videos

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that I just showed you?

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That making a very specific change
to neural circuits in the brain

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can have specific changes to behavior.

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That every conscious
experience that we have

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is governed by cells in our brain.

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I am the daughter
of a physicist and a biologist,

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who literally met on the boat
coming to America

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in pursuit of an education.

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So naturally,

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since there was "no pressure"
to be a scientist ...

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(Laughter)

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as a college student,

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I had to decide whether I wanted to focus
on psychology, the study of the mind,

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or neuroscience, the study of the brain.

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And I chose neuroscience,

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because I wanted to understand
how the mind is born

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out of biological tissue.

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But really, I've come
full circle to do both.

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And now my research program

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bridges the gap between
the mind and the brain.

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Research from my laboratory

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suggests that we can begin
to tie specific neural circuits

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to emotional states.

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And we have found a number of circuits

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that control anxiety-related behavior,

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compulsive overeating,

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social interaction, avoidance

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and many other types
of motivated behaviors

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that may reflect internal
emotional states.

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We used to think of functions of the mind
as being defined by brain regions.

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But my work shows
that within a given brain region,

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there are many different neurons
doing different things.

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And these functions
are partly defined by the paths they take.

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Here's a metaphor to help illustrate

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how these discoveries change the way
that we think about the brain.

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Let's say that the brain
is analogous to the world

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and that neurons are analogous to people.

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And we want to understand how information
is transmitted across the planet.

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Sure, it's useful to know

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where a given person is located
when recording what they're saying.

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But I would argue
that it's equally important

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to know who this person is talking to,

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who is listening

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and how the people listening respond
to the information that they receive.

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The current state
of mental health treatment

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is essentially a strategy
of trial and error.

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And it is not working.

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The development of new drug therapies
for mental health disorders

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has hit a brick wall,

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with scarcely any real progress
since the 1950s.

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So what does the future hold?

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In the near future,

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I expect to see a mental health
treatment revolution,

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where we focus on specific
neural circuits in the brain.

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Diagnoses will be made
based on both behavioral symptoms

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and measurable brain activity.

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Further in the future,

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by combining our ability
to make acute changes to the brain

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and get acute changes to behavior

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with our knowledge of synaptic plasticity
to make more permanent changes,

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we could push the brain
into a state of fixing itself

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by reprogramming neural circuits.

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Exposure therapy at the circuit level.

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Once we switch the brain
into a state of self-healing,

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this could potentially have
long-lasting effects

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with no side effects.

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I can envision a future
where neural circuit reprogramming

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represents a potential cure,
not just a treatment.

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OK, but what about right now?

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If from this very moment forward,

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each and every one of you left this talk

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and truly believed that the mind
comes entirely from cells in your brain,

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then we could immediately get rid
of negative perceptions and stigmas

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that prevent so many people

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from getting the mental health
support that they need.

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Mental health professionals,

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we're always thinking
about what's the next new treatment.

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But before we can apply new treatments,

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we need people to feel
comfortable seeking them.

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Imagine how dramatically
we could reduce the rates of suicides

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and school shootings

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if everyone who needed
mental health support actually got it.

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When we truly understand
exactly how the mind comes from the brain,

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we will improve the lives of everyone

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who will have a mental illness
in their lifetime --

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half the population --

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as well as everyone else
with whom they share the world.

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Thank you.

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(Applause)