Final Weeks Content

Movement

Sensory systems provide input to the brain

Most of the output is movement

Your brain perceives things from the world and does different things with the information

We perform very complex movements

Synchronize sensory input, lots of muscles

Different kinds of movement:

Slow, careful, detailed

Fast, automatic

Movement pathway

Basic:

Primary motor cortex

Spinal cord motor neurons

Muscles

Lateral and medial (anterior) corticospinal tracts:

Lateral controls contralateral lateral muscles (arms, legs); specifically on one side of our body

Anterior controls both sides’ medial muscles (neck, torso)

A lot of movement requires action from both sides of our body

It is contralateral

Cerebellum

Also projects to the corticospinal tract

Via the red nucleus (cerebellum unique neuron)

Mostly inhibitory input

Involved in

Fine motor control, motor patterns

Timing of movements (through inhibition); if you need something to happen right at that moment, we need to plan for that movement

Feedback circuits are found everywhere in our brain

Shifting attention

[Textbook ‘the cerebellum’]

Before you move…

Primary motor cortex ‘executes’ movements (can be referred to as the ‘line cook’ at a restaurant)

Spinal cord and cerebellum control and coordinate movement

Where does the planning happen?

Inputs to the primary motor cortex?

Posterior parietal cortex

Premotor cortex

Supplementary motor cortex

Basal ganglia [not shown; not cortex] they’re in the limbic system

Prefrontal cortex (involved in pretty much everything)

Planning motion

Posterior parietal cortex

Tracks the position of the body relative to objects in the world

Related to the visual ‘where’ pathway

Involved in initial planning to move

Activated (well) before a movement is initiated (if i have a method to report the decision of movement, i can see activity in the parietal cortex before you even do the movement)

Damage causes apraxia: inability to perform actions intentionally (but can move spontaneously)

e.g., difficulty making the correct movements to control a tool

Encodes only what action is planned, the goal

Actotopic encoding

Independent of which part(s) of the body are involved

Actoptopic activation

The goal of the action determines the activation

All these activate the same parts of the posterior parietal

These activate different areas

Away vs. towards

Other cortical areas

Premotor cortex

Involved in targeting (body part to goal)

Encodes which part of the body is involved

Supplementary motor area

Involved in fast sequences of action

Also (maybe) in balance, coordination of sides of body, spontaneous motion

Very little is known about either

Prefrontal cortex

Value of action, quality of movement, prediction…

Executive functioning (makes big decisions)

Basal ganglia

Part of the limbic system (not the cortex)

Involved in:

Automation of movements, habit formation

Controlling eye movements

Superior colliculus (SC; in midbrain) has a retinotopic map

SC is inhibited by the substantia nigra

Release of inhibition causes looking towards that point

Diseases of the basal ganglia

Parkinson’s disease

Caused by death of neurons in substantia nigra

Patients have trouble in

Initiating spontaneous movement

Planning movements without an external guide

Switching between different movement patterns (movement schema’s)

Huntington’s disease

Almost entirely genetic, late-onset

Caused by massive neuronal loss, much of it in basal ganglia

Patients have uncontrollable twitches and tremors and, eventually, movements (and death)

Mirror neurons

Found throughout the cortex

Mostly in premotor area, parietal cortex

Respond to

Performance of a particular movement

Seeing the same movement performed

Hearing the action, remembering it, reading it...

Possibly form the basis for imitation (& empathy?)

Controversial

No clear result on their function, if any

How are they tuned?

By learning (at least sometimes)

Are most motor cortex cells sometimes “mirror-like”?

March 12th- Sleep

Sleep

Functions of sleep:

Body: energy conservation, muscle (and immune system) repair

Brain: Adenosine clearance, memory consolidation, reorganization (in children), REM [many functions]

Animals can be active at different times:

Diurnal – during the day

Nocturnal – during the night

Mammals evolved from nocturnal animals

A Lot of mammals are still nocturnal

There are animals that sleep during the day and the night

You’ve got rhythms

Many actions have to be rhythmical

Heartbeat, walking, breathing

Many different scales:

Heartbeat: ~80 times per minute

Eating: ~8 hours

Ovulating: ~1 month [in humans], ~6 months [in dogs]

Sleeping: ~24 hours: circadian rhythm (so important it has its own name) your internal clock isn't actually 24 hours

Different brain mechanisms for generating these rhythms

Simple pattern-generator neurons (for fast rhythms)

Hormonal fluctuations (for long-term rhythms)

The wakefulness pathway

Light enters the eye

Strikes intrinsically photosensitive retinal ganglion cells (ipRGC), which express melanopsin (they themselves are sensitive to light)

Melanopsin is sensitive specifically to blue light

Project directly to suprachiasmatic nucleus (SCN) sits directly above the optic chiasm

Paraventricular nuclei of the thalamus

Down into spinal cord

Superior cervical ganglion

Back up to pineal gland

Releases melatonin

Hormone that affects waking

Seeing the light

Melatonin causes sleepiness

Mostly released in the few hours before sleep

The wakefulness pathway is inhibited by light

Cells of the SCN are rhythm generators

Can continue to generate a rhythm even in vitro

Molecular mechanism:

PER and TIM genes [textbook, ‘the biochem. of the circadian rhythm’]

Individual differences

Different individuals’ SCN and pineal are more active at different times

Melatonin production varies with age:

Younger adults usually more alert later in the day

Older adults usually more alert in the morning

Individual differences in peak alertness times

“Larks” and “Night owls”

Activity cycles can change circadian rhythm

Night shift workers have suppressed melatonin production (because of light during their ‘night’)

Jetlag: light at the ‘wrong’ time fails to entrain SCN (the best way to combat this is to expose yourself to a lot of light)

Stages of sleep

5 different ‘types’ of sleep

Normal sleep alternates between them approximately every 90 min

Stage 1

Shallow sleep

EEG: very little activity

Stage 2

Shallow sleep

EEG: activity erratic

Stages 3 & 4

Deep sleep

EEG: large, slow waves

REM (paradoxical) sleep

EEG activity irregular, low amplitude

Large, rapid eye movements back and forth

Paradoxical because

Lots of brain activity

Body relaxed, muscles paralyzed

PGO waves (pons, geniculate, occipital)

REM is important

Dreams (mostly, probably) occur during REM

Sleep deprivation leads to

Increase in REM

REM deprivation leads to increases in REM

PGO-like waves during waking (possibly with hallucinations)

Eating and drinking

Internal regulation

Body needs to maintain certain levels of chemicals

Body requires glucose at a certain minimal rate

Blood concentration and volume require water (the salt in our blood is important because of osmosis)

Parts of the body need to be ‘rebuilt’, which requires raw materials

Mammals: body temperature has to be maintained, which requires burning chemicals

Mechanisms controlling substance intake (eating, drinking) mostly depend on hormones and neuropeptides

We will talk a lot about the hypothalamus

Regulates a lot of hormone release

Water

Concentration of the blood and volume of blood (blood pressure) must be kept within a very narrow range

Brain regulates water intake by thirst

Two kinds:

Osmotic thirst:

Consuming salty food increases the concentration of the blood

Drink water to reduce the concentration

Hypovolemic thirst: the volume of your blood is too low

Sweating or bleeding or vomiting reduces the volume of liquid (including blood) in the body

Drink/eat salty things to increase volume but maintain concentration

Mechanisms of thirst

When decreased water volume is detected

Brain releases vasopressin

Constricts blood vessels, increases BP

Reabsorbs liquid from urine

Body releases angiotensin II

Detected by neurons around third ventricle, which projects to hypothalamus, makes you drink

When blood concentration increases

Concentration of salts outside cells increases, cells lose water

Neurons in OVLT (organum vasculosum of the lamina Terminalis), SFO (subfornical organ) detect loss of water

Hypothalamus makes you drink

You are what you eat

We must ingest all the things our body needs for

Energy, repair, chemical balance, growth...

Brain needs to control

What we eat (not very well)

When we eat

How much we eat

Several different mechanisms – for safety

Foods (may) contain chemicals that affect the brain

Tryptophan, beta-adrenergic blockers, caffeine...

Our current diet is not natural!

Brain mechanisms of eating

How much to eat:

Stomach distension

Full stomach stimulates vagus nerve (bring information from the viscera), affects hypothalamus (tells it to stop eating, i’m full)

Rich foods give more calories / weight

Food in duodenum (area right after stomach in the digestive system)

Releases CCK (hormone), stimulates vagus nerve, hypothalamus (tells us to stop eating)

Oral mechanisms (amount of chewing...)

If we chew a lot it tricks our brain into thinking we’re eating a lot

When to (stop) eat(ing)

Extraction of glucose has two stages

Eating, digesting, storing excess as fat

Entrance of glucose into cells

Needs transporters to enter the cell

Mediated by insulin levels (primary function is to help glucose get into cells)

Not enough insulin, the process still happens but can’t get into the cells resulting in too much glucose into your blood

Leptin

Long-term monitoring of fat levels

Level is mediated by fat reserves (more fat stores, more leptin circulating in the body)

High levels indicate satiety, reduce eating

Desensitization of the hypothalamus to leptin contributes to obesity (we don’t get the signals to stop eating)

Hypothalamus and hunger

Hypothalamus receives lots of inputs from brain and body

Ghrelin: hormone indicating hunger (increases appetite)

Leptin, insulin, CCK

Signals go to the paraventricular nucleus (PVN)

Hunger inhibits PVN; satiety activates it

Red arrows activation

Green arrows inhibition

PVN projects to lateral hypothalamus

Releases orexin which increases hunger and arousal

Modulates digestion, insulin levels, taste sensitivity

Hunger is the best flavoring (because of the lateral hypothalamus)

Emotions

What is emotion (affect)?

Three parts:

Cognition: evaluating the situation

Feeling: happy, sad, scared…

Action: run away, attack, cry…

The brain makes an unconscious decision about the situation

Quickly, automatically

Using heuristics: mental shortcuts and simple rules; not considering all the information

Emotion cause you to [want to] act (motion) or to inhibit action

Evolutionary aspects

Reacting quickly is often important

More important than considering all the information

Some situations are complex; emotion gives the simple answer

Iowa card sorting task

Eventually, subjects suspect there is a rule

GSR (Galvanic Skin Response) predicts it earlier

Emotionally, we ‘know’ which deck is better before it becomes conscious (explicit)

Specificity of action

Emotions motivate the action that is (usually) appropriate to the situation

Fear -> run away

Anger -> attack

Happy -> smile (so others know you are happy and react accordingly; social effect)

Disgusted ->

Raise upper lip, open mouth

Wrinkle nose: prevent smells entering

Tongue out: spit it out

Similar physical response to moral disgust

Similar (appropriate) reaction

Which emotions?

Which things count as emotions?

6 basic emotions:

Happiness, sadness, anger, fear, disgust, surprise

Can combine into compound emotions

Measured on 2 axes:

Valence (positive or negative)

Arousal (intensity: strong, weak)

Creating emotion

Emotional responses activate the peripheral nervous system

Sympathetic (fight-or-flight)

Parasympathetic (rest and digest)

What comes first,

Body or brain?

The James-Lange Theory

Emotion timeline:

Brain evaluates situation, decides on best response

Peripheral system ‘gears up’ for response

Sensing peripheral activation causes feeling

Response preceded feeling! (physical comes before mental)

Experimental evidence [textbook]

Forcing the response can increase the emotion

Smiling will make you happier (and reduce pain: releases endorphins)

Preventing the response can limit the emotion

Damage to body can limit affect

Where in the brain

Nobody has found an area where emotions are created, processed, controlled

Seems to occur all over the brain

No clear correlation between the valence (or arousal) and a particular region

The insula is involved in disgust

Also contains primary gustatory cortex

Possibly different emotions in the two hemispheres

[evidence in textbook]

Fight or flight

Activation of the sympathetic nervous system

Anger (attack), fear (escape)

Anger:

Some genetic effects, interact with environmental effects

Levels of MAO interact with childhood trauma

Some of the mechanisms are hormonal

Slower, longer lasting response

Triple imbalance theory of anger

Triple imbalance theory of anger

Anger is the result of an imbalance of three things

Testosterone

Leads to aggression (fighting over mates)

Vary over the course of the day (pretty common for many hormones)

Cortisol

Released by stress

Increases fear and inhibition

Reduction leads to aggression (you are uninhibited)

Serotonin

High levels inhibit aggression

[High levels inhibit lots of behaviors]

Serotonin

Vary depending on what we consume

Made from tryptophan

Tryptophan enters the brain through active transport

Other amino acids can compete for ‘space’ on the transporter (like people lining up for the bus; if lots of people are lining up, not everyone will get on)

Give men a drink made of lots of amino acids (makes space for lots of tryptophan)

Tell them someone is stealing their money

Measure their aggression towards that (fictitious) person

Their aggression increases

Effect lasts for hours!

Fear

No clear location in the brain but closely related to the amygdala

Involved in:

Fear response generally

Learning to fear things

Using learned information to enhance/suppress the fear response

Directing attention to surprising/scary stimuli

Toxoplasmosis

Infects cats; released in their faces

Damages rat amygdala -> fearless -> eaten by cat

Can also infect humans. Not (usually) dangerous except for compromised immune systems or fetuses (pregnant women: don't eat raw meat; avoid litter boxes)

Stress

Response of the body to any threat

External dangers

Disease, injury

Three stages (Selye)

Alarm

Initial emotion (fear, anger)

Activation of the sympathetic nervous system

Short-lived (a couple minutes to a couple of hours)

Resistance

Long-term rise in immune activity (shuts down immune system and digestive system)

Sympathetic system stands down

Lots of cortisol (has massive effects)

Exhaustion

After long time in resistance

Nervous and immune systems ‘crash’

People in first-world countries spend a lot more time in the resistance phase than usual (not healthy)

Physiology of stress

Activation of the HPA axis

Hypothalamus releases CRH

Pituitary releases ACTH

Locus coeruleus (in pons) releases norepinephrine

Adrenal glands release cortisol

Increases/decreases immune function

Increases available glucose (reduces fat reserves)

Improves/impairs memory

Reduces protein synthesis

Complex relationship, still not well understood

Evolution of stress

Why would we need such a response?

For external threats

Dangers come in groups

Being ‘primed’ increases speed of response

For disease

Combating disease requires that the body not interfere

Body has limited resources and must prioritize

External threats are usually more immediate

Activation of the sympathetic system inhibits immune response

Disease responses reduce body activity

Anxiolytic drugs (reduces anxiety)

Amygdala projects to hypothalamus

Mediates physiological response to fear

Inhibited by GABA

Increasing GABA activity (everywhere) decreases fear activation

E.g., benzodiazepines (Valium, Xanax, Lactium…)

Bind to (one subunit of ) GABAa receptors and sensitize them

Drink warm milk before bed

Alcohol also increases GABA

And is also anxiolytic

Memory and Navigation

Basics of memory

Once information is learned, it must be stored in the brain: memory

There are many different kinds of memory

We devise a hierarchy

This is not necessarily how the brain does it!

Working memory -> attention, only holds a certain amount of things (approx. 7)

Reference memory -> no capacity limit (as far as we know)

Procedural memory -> ability to do stuff (like riding a bike), unconscious

Declarative memory -. All the stuff you know (knowing all 50 states), conscious

From episodic to semantic

Episodic memories are autobiographical

Yesterday i saw the sunset

Semantic memories are rules about the world

The sun sets in the evening

Always derived from personal experience

Even if someone tells you the rule or you read it, that is an experience

How are episodic memories turned into semantic memories?

Involves the hippocampus

Involves repeated exposures to relevant events

Basic processes of memory

Events happen in the world and are perceived

The brain does some processing

E.g.: optical illusions [and entire class so far]

The information is stored (in working memory?)

The memory is consolidated into reference memory

And stored there (forever?)

When using it, it must be retrieved

Where in the brain?

Where does learning happen?

Different types of learning happen in different places

E.g.: cerebellum is important for some types of simple association

Where is memory stored?

The memory trace itself is called an engram (a little drawing on your brain)

Hard to locate

Memories are (probably) stored all over the cortex

Important brain areas

Basal ganglia

Important for habit formation, implicit learning

E.g.: learning a new skill

Tracing a shape in the mirror

Anterior temporal lobe

Important for semantic memory

Knowing facts about the world

Prefrontal cortex

Lots of things: values, complex concepts

Amygdala

Emotional memories, memory consolidation

Hippocampus

Episodic, spatial, consolidation, relational learning

The hippocampus

Very important for memory

Precise function is debated

Involved in:

Turning working memories into reference memories

Acquiring relational memories

Where the important feature of the learning is a relationship between two or more objects

Episodic memories

Turning episodic memories into semantic memories

Learning spatial things

Which tend to be relational

Other (seemingly random things)

e.g.: Olfactory memory

Damage to the hippocampus

Patient HM had (both) his hippocampi removed

Had severe memory deficits, including:

Anterograde amnesia (forward in time)

Not able to form new long-term memories

[Retrograde amnesia: loss of previous memories]

Loss of episodic memory and conversion to semantic

Never learned to recognize Milner

Intact working memory

Good implicit (e.g., skill) learning

Became better at the mirror-tracing task

Could not remember ever having done it before

March 21st

Basics of learning

Animals learn to associate events that reliably happen after each other with each other

Every time you hear “cookie”, you get a cookie

Usually one neutral event (the word) and one innately positive/negative event (cookies)

Animals begin to respond to the neutral event (the conditioned stimulus) not just the innately positive one (unconditioned stimulus)

You start salivating when you hear the word

The conditioned response doesn’t have to be the same as the unconditioned response

The animals have associated the two events with each other

Pavlov’s dog:

Buzzer followed by food, several times

Eventually, the dog salivates to the buzzer alone

Hebbian synapses

Brain is made of neurons

Memories have to consist in (long-term) changes to neurons

Changes happen at the synapse

Donald Hebb proposed:

“Neurons that fire together, wire together”

Every time two connected neurons fire together (at about the same time), the synapse between them gets stronger

Learning consists of strengthening and weakening synapses

Associations are strong (easily excitable) synapses

Long-term potentiation

After repeated bursts of stimulation, synapses become easier to excite

Mostly occurs in glutamate synapses (excitatory)

2 kinds of glutamate receptors:

AMPA: ionotropic, allows Na+ in

NMDA: ionotropic, allows Na+, Ca+ in; blocked by Mg+

Step 1:

Glutamate released

AMPA-R opens, Na+ enters

NMDA-R blocked (by Mg+)

Step 2:

Strong stimulation (e.g., from 2 neurons)

Lots of glutamate

AMPA-R opens, lots of Na+ enters

Na+ depolarizes cell

Depolarization removes Mg+ from NMDA-R

NMDA-R opens, Ca+ (and more Na+) enters

Ca+ goes to work inside the cell

Step 3:

Ca+ activates CaMKII

CaMKII activates CREB

CREB regulates gene expression

Step 4:

CREB changes the expression of genes which:

Increase the number of NMDA and AMPA receptors at that dendrite

AMPA receptors become easier to open

More dendrites form onto the same axon branch

Postsynaptic cell will receive more EPSPs from the same presynaptic neuron

Retrograde messenger change the presynaptic terminal

Cell is more likely to fire

Releases more transmitter (glutamate) per event

These changes can last for years!

Inhibition

If synapses just had LTP, they would (all) get stronger and stronger

Need a way to also inhibit firing

Long-term depression (LTD)

Involves excitatory glutamate receptors (AMPA, NMDA)

Occurs in hippocampus and cerebellum (and probably other places)

Results from low frequency repeated stimulation

Stimulation opens NMDA-R, but slowly

Ca+ levels rise, slowly

If levels rise slower than threshold → LTD

Threshold depends on previous experience and LTP

Cell reduces density of AMPA-R (and phosphorylates them)

Probably other mechanisms as well

Navigation

Animals (and humans) need to find their way

To food, to work, back home...

Need a cognitive map of their space

The map must allow:

Navigation between any two points (shortcuts)

How do I get home from here?

Using different landmarks

I don’t see the tower – but I do see the church

The map needs to be:

Unified: all the info in one representation

Allocentric: not dependent on where I am

Flexible: allowing calculations of vectors between points

Spatial information is relational:

My house is 3 blocks north of the church

The map is (most likely) in the hippocampus

Hippocampal connections

Sensory cortex -> entorhinal cortex

Entorhinal cortex -> dentate gyrus trisynaptic circuit

Dentate gyrus -> CA3 trisynaptic circuit

CA3 -> CA1 trisynaptic circuit

CA1 -> subiculum

Cells of the Hippocampal Formation

Cells in the HF represent aspects of the environment

Place cells (CA1): always fire at the same place (only fire when you're in a particular location)

Head direction cells (EC): fire when facing a direction (the head specifically, not the whole body)

Boundary cells (EC & Sub.): fire close to walls

Grid cells (EC): fire on a grid

Remapping

When in a new space, need a new map

Cells can remap when the space changes

Completely, partially, not at all, rate, stop firing…

New places, grid realignment…

Coordination

Events in the brain need to be coordinated:

Firing of cells related to CS and US

Brain has global rhythms of subthreshold stimulation

E.g.: hippocampal theta rhythm

Probably generated by the trisynaptic circuit

About 3-10 Hz

Rhythm raises (and lowers) membrane potential

Like an EPSP for all the cells at once

Makes it easier (or harder) to fire

Causes firing to synchronize

Evolution of languages

The adaptive benefits are obvious

Communication, cooperation, coordination, culture...

Physiological requirements:

Language requires a wide range of sounds

Adaptations to the larynx

May predispose us to choking

Also requires social adaptations:

Language depends on conventions

Language needs to be learned (from a teacher)

Is language uniquely human?

Apes can be taught sign language:

Only learn 100-250 words or signs over years of training

Rarely make spontaneous utterances of more than one sign

Mostly just request items (usually food)

Humans:

Children learn thousands of words a year for many years (about 60,000 by the end of high-school)

Construct complex sentences spontaneously

Spontaneously imitate others’ speech

Every [known] society has a language, with a grammar

Deaf children not taught sign language make up their own

Children learn a second language much better than adults

Human sensitive periods

Do we have a sensitive period for language learning?

Test subjects with no language learning at a young age

Feral children (Mowgli, Tarzan, real examples)

All have trouble with language for whole life

Combined with many other problems (social, mental)

Kaspar-Hauser

[This story is doubted by many]

Raised with no human language until the age of about 13

Had difficulty learning language even with lots of help

Language in the brain

In most people, language skills are in the left hemisphere

Unless you are left-handed

Unless you are bilingual from a young age

Language consists of 2 skills:

Production (speaking)

Relies on motor skills

Broca’s area

Comprehension (listening)

Relies on auditory skills

Wernicke’s area

Broca’s area

Damage causes Broca’s (non-fluent) aphasia

Inability to speak or write (or sign)

Incorrect stress patterns

Lack of grammar

Not related to motoric problems

Can be severe:

Broca’s patient was nicknamed “Tan”, his only word

Also some deficits in comprehension

Especially of complex sentences

Speech actually activates most of the cortex, not just Broca’s area

Wernicke’s area

Damage causes Wernicke’s (fluent) aphasia

Inability to comprehend language

Whether heard or read (or seen: sign language)

Trouble remembering or recognizing names of objects

Can speak with normal grammar but not make sense

Have lost the nouns and verbs

(Broca’s patients lose prepositions)

Use random or invented words

“Thingamajig”

Consciousness

Lots of questions; few (or no?) answers

Difficult to even define the problem

Much of the debate is philosophical, not biological

Possibly there is no answer

“Trying to turn up the gas quickly enough to see how the darkness looks” – William James

“Cogito ergo sum”

Descartes suggested that only internal subjective experience is direct; everything else is inferred

We know that we are conscious

We infer that others are also conscious. Problem!

Also proposed dualism: mental states are not physical

How can non-physical things interact with (be created by) physical processes? [Descartes said: pineal gland]

Flavors of consciousness

There may be several types of consciousness:

Perceptual consciousness

Detecting things in the world and constructing a model of the world from them

[most people don’t consider this enough]

Phenomenal consciousness (sentience)

What it feels like to be conscious

Having valenced internal states

[e.g., not sleep]

Access consciousness

Availability of information for use in cognition

[e.g., not unconscious priming]

What is consciousness?

We all recognize the subjective experience of (phenomenal) consciousness

Being conscious involves feeling like something. This experience is called qualia (singular: quale)

Can we find qualia in the brain?

Hard problem: why is there anything that it feels like?

What does consciousness look like from the outside, objectively?

Can we define a behavior that is a sign of consciousness?

Turing test:

Have a conversation over text with another ‘being’

Determine if your interlocutor is human (conscious) or not

ChatGPT, Siri: are they conscious?

The Chinese Room

Can any complex system (computer) that behaves “conscious- like” be said to have mind or consciousness?

i.e.: can you pass the Turing test without ‘really’ being conscious?

Searle’s argument (that it CANNOT):

Place you in a room; you speak no Chinese

Give a list of rules (in English) that correlate any English symbol (words, sentences, arguments) into a set of Chinese symbols

Can respond, in Chinese, to a set of questions written in Chinese

Chinese speakers will think you ‘understand’ Chinese

But you don’t

What does consciousness do?

We (and animals) can do a lot of things without consciousness

Sleepwalking (sleep conversing)

Anything robots can do: drive, answer questions, play chess...

Parietal cortex activates before we are aware of having decided on an action

Is consciousness an epiphenomenon?

A side-effect of very complex systems

Would any complex system have some degree of it?

What is the adaptive function of consciousness?

Who is conscious?

We assume that beings that behave as we do when conscious are also conscious

Do animals that solve similar tasks to us use consciousness to do it?

We can ask people if they are conscious of something

Binocular rivalry

Requires language: Excludes babies, brain-damaged patients, animals...

People often give wrong answers

E.g., blindsight

Neural correlates of consciousness

Global workspace theory:

(Phenomenally) conscious information is spread across the cortex

Integrates perceptual, affective, memory

“Broadcast” by the prefrontal cortex

Gamma waves

Synchronize firing across large regions of cortex

Like theta in the hippocampus

Possibly involved in the binding problem

Ensuring all the stimuli are perceived as one scene

Maybe help to broadcast some representations?

P300

EEG signal correlated with decision-making

Exists in some non-conscious patients

Split-brain patients have two working consciousnesses

We are not conscious in deep sleep, yet there is lots of (global) brain activity