Lecture 1: The Brain

Sentient meat, Dualism, Materialism, Descartes, Consciousness

Phineas Gage

Phineas Gage

tamping iron to head, changed personality/temperament, frontal lobe (control inhibitions, treatment of others, deliberate behaviour)

What can we learn from Phineas Gage

Disproves dualism, brain has big impact on our personality/self (previously though to be mind)

Greg F. (monk dude)

tumour in his head affecting frontal and temporal lobes (lost vision, memory, ability to make memories, docile temperament)

Darwin & Crick Hypothesis

Astonishing Hypothesis: brain makes thought,

"You" are just behaviour of a vast assembly of nerves

Materialism

brain = mind = only physical

Materialism; drawback

how do we distinguish between mental and physical events then

Leibniz

look inside brain and no room for mind

Dualism

brain is physical and mind/soul is separate in some nonphysical way

Descartes; 2 dualism arguments

1. Machines are unfeeling and programmed to do things, but humans choose to do things (creativity and spontaneity)

2. I think therefore I am: don’t know if dreaming and don’t have a body, but can still think, thus minds are immaterial

Reasons why dualism is appealing (5)

1. Language (my brain, my leg, my arm = all physical)

2. personal identity 1: still same mind after bodily transformation (13 going on 30)

3. personal identity 2: multiple people in 1 body (DID)

4. intelligent beings without bodies (God)

5. survival of self after destruction of body (reincarnation, heaven)

Why Descartes is wrong (2 reasons)

1. machine theory: now have computers doing complex things (i.e. chess). complexity of actions =/= proof

2. can doubt you have a body, but doesn’t make it true (can imagine many things that don’t exist)

Why dualism is wrong (3 reasons)

1. Pinker: immaterial can’t interact with material

2. evidence for role of the brain (physical change of Phineas Gage = personality change, caffeine/drugs/dementia all affect brain)

3. new technologies (MRI to see parts of brain light up)

Brain (1/4 of energy): glial cells

1/2 of brain

nourish/support/cleanup after neurons

mental life = result of

neurons

Dendrites

receive info

if strong enough/right input, then neuron will fire and electrical signal will pass through axon

Axon

covered in myelin shealth

signal runs through to other dendrites or out to muscles,etc

Myelin sheath

fatty shield over axon like insulation on wire

helps communication go more efficiently

Flow of info in neurons

dendrites > cell body > axon > dendrites of other neurons

3 types of neurons

1. Sensory: take in info from world (pull back from pain)

2. Motor: out to external world (movement to grab smth)

3. Interneurons: don’t connect to world but others (thinking)

How neurons fire

all or nothing, either do or dont

How neurons represent intensity (2)

1. number that fire (10000 or 100)

2. frequency of individual firing (bang………bang or bangbangbang)

Soups or sparks

soups: neurotransmitters

Synapses

gaps between neurons bc neurons dont touch

when neurons fire, neurotransmitters cross synapses (Cajal)

Excitatory/agonist

increase likelihood of firing

drugs: encourages

Inhibitatory/antagonist

decrease likelihood of firing

drugs: prevents neurotransmitter from binding

How neurons fire

calculate sum of excitatory/inhibitatory neurotransmitter inputs and see if enough to fire

Are brains simultaneous/parallel or serial

brains = parallel

computers = serial

Intelligence arises from unintelligence

1s and 0s, fire or not fire

Creation of false memories

recollection of memories are changed through current discussion (false retrieval cue)

Clean-up crew that cleans up neurotransmitters, sometimes ________ by drugs = more dopamine

inhibited

Don’t need brain for

• vomiting

• suckling in newborn

• erection

• Limb flexion in withdrawal from pain

Gall: school of phrenology

Good idea: different parts of brain responsible for different functions

Bad idea: brain bloats up the more they are used and make bumps (rub heads to learn about them)

Broca's area

part of frontal lobe

Could understand language/what is heard, but could only produce "tan"

Wernicke's area

Back of temporal lobe Couldn’t understand speech, but could talk rapidly/fluently even if was gibberish

Cortex (why so folded?)

surface of brain. most important stuff is subcortical

folded to maximize surface area

Medulla

autonomic functions (heart rate, breathing)

Cerebellum

movement, posture, motor learning, some language

Hypothalamus

sleep, thirst, hunger, sex

Limbic system

emotions

Hippocampus

long-term memory storage, locations & things in space

Pituitary gland

secretes hormones involved in sex, reproduction, etc.

Lobes of brain

• frontal

• parietal

• occipital

• temporal

Isomorphic

parts of brain responsible for right pointer finger is close to right thumb, which is close to right wrist area, etc.

Division of labour in brain

1/4 movement, rest is language/memory/perception/etc.

Apraxia

not paralysis, unable to do fine/complicated things/tasks/behaviours

Agnosia (visual)

not unable to see, just cant recognize things (cant tell it’s a piano)

Agnosia (prosopagnosia)

problems identifying faces (ie cant identify husband)

Sensory neglect

Think world contains only left or right sides

Aphasia

Can’t produce or understand language

Acquired psychopathy

obvious

Left hemisphere

language, reason, logic

Right hemisphere

social processes, imagination, music

Corpus Callosum

connection between hemispheres (network of neurons)

• If cut: halves cant readily communicate (Alien hand syndrome). Seen as 2 individuals fighting for 1 body

Eisenberger (loneliness)

computers leave out human in virtual ball game. pain of rejection akin to physical pain

Since we cant understand others’ consciousness, how can we walk in their shoes

1. infer mental state of others

2. use our experiences as stand-ins

(but can often be wrong, practice empathy)

Gopnik: attention

attention is willful. not focusing but still notice if someone calls our name

babies lack willful control

time passage may be different for species

CFF: light flickering until it doesn’t

How EEGs reveal consciousness

track oscillations in brain:

Frequency reveals how conscious you are

• Alpha: 8-15hz = relaxation

• Theta: <4hz = sleep

• Beta: 16-31hz = agitation

Monti: how used MRIs to communicate with vegetative patients

different areas of brains light up for thinking of different things (i.e. playing tennis or walking in house)

Global Workspace Theory

unconsciously, sensory areas of brain light up from outside stimulus, but have to direct focus on something for it to be conscious

Chalmers: Performance of cognitive and behavioural functions is from experience

Easy question: categorize something as red (recognize)

Hard question: understand experience of how the brain sees red

(Block) Phenomenal consciousness

(hard) feeling/experience of what it’s like to be in that state

(Block) Access consciousness

(easy) availability of experience for use in reason/rationality in speech/communication

Limitations of access consciousness

can’t experience both at once, focus flips back and forth

Shadowing (access conscious)

forced to focus on one input (i.e. language in one ear)

Cocktail party effect

involved in a convo with someone, dont focus on background noise until you hear your name or taboo words

(only a small fraction of input comes in, most is lost)

When you do something habitually, it becomes ___________

unconscious

Stroop effect

if you have a list of words in different colours, its easy to name the colours, but when the words are colour names = harder

Spotlight effect (Gilovich)

If wearing something embarrassing or cool, tend to overestimate how much others focus on you

How to move attention away from self (3)

• (Le Bon) Being in a group setting shifts consciousness away from self. Could be good (concert) or bad (bystander apathy)

• being drunk

• pain

Trivers: how to keep information secret

deceive yourself

Generalizations of consciousness (5)

1. Repetition and practice makes things unconscious (driving a car)

2. Consciousness is limited (only focus of faces or vase at once)

3. Consciousness can be effortless (but not always)

4. Consciousness can be involuntary (ie dont read the letters)

5. We are not conscious of most of what we experience (switching out people asking directions)