CGS 2301 Exam 1

cognitive science defintion

problems solved with brains and minds; interdisciplinary

sensation and perception

internalizing the physical world

-light: electromagnetic radiation- vision

-sound: sound pressure level- audition

-chemical: olfaction, gustatory, trigeminal: senses toxic chemicals

-mechanical: touch

-temperatures

-gravity, acceleration: vestibular sense

-infrared, echolocation, magnetic

4 things

1) understanding, thought, planning/imagining, solving, attention, learning, memory

2) communication- speech, language, gesture, body lang, posture, gait

3) action- manipulating the nevironment; actively exploring, navigation

4) emotion- drive system

psychology

mind and behavior, hypothesis testing, clinical, analytic, introspective

neuroscience

neural basis of perception, cognition, action

neuroanatomy

structure- neurons and neural tracts, staining, brain injury

neurophysiology

functions of neurons, recording from single neurons (w/stimulation), neuroimaging

neuropsychology

global functions of brain areas, lesions, electrical stimulation

computer science, engineering, and robotics

build machines that stimulate the functions of perception (vision, audition, etc.), cognition (thought, speech understanding), communication (language, task interface), action (manipulation of objects - robots)

philosophy

reason based approach to understanding the mind, predates psychology (scientific method)

cognitive science is a:

reverse engineering problem, the solution is the human brain

Who said "What can the senses tell us?"

Locke, Hume, Berkeley

Who said "What is consciousness?"

Descartes

recursion problem

you are the machine that you study

When was the first written mention of the brain?

1700 BCE

What was the copy of a surgical treatise about? (3000-2500 BCE)

how to treat a skull injury

egyptian view

the heart is the seat of mind and intellect

Alcemeaon

Sicily, 450 BCE

-first neuroscientist

-brain is seat of perception and cognition, anatomical dissection because of optic nerve eye/brain, light bearing paths- rubbing your eyes- phospheres

Hippocrates

Mediterranean, 452 BCE

-philosopher, leading biologist, founder of comparative anatomy, embryology, studied animal behavior, dissected 49 different animals but never a human

-blunder: heart not brain controls sensation

Galen

Pergamon (129-199 AD)

-1st detailed anatomy of brain, ox vs. human

-lesion experiments: laryngeal nerve, pigs' vocalization

-mistake (long lasting)- soul/mind in ventricles of brain- psychic pneuma (animal spirits)

-soul- should not be material substance

Medieval Cell Doctrine

199-1200 AD

ventricles-

cell 1: lateral, common sense, multimodality

cell 2: middle, reason, thought

cell 3: memory

early church

thought nature of the soul was nonmaterialistic

A. du Laurens

(1597) professor of medicine

Andreas Vesalius of Padua

(16th Cent)

greatest Renaissance anatomist- dissection (human body+brain)

-claimed ventricles are not seat of soul and mind because animals have them too

Thomas Willis

(1664)

founder of clinical neuroscience

wrote Cerebri Anatomie

Christopher Wren

drew detailed drawing of the brain

Descartes

(1662)

mind-body problem- soul is in the pineal gland (only thing in the brain that is truly central)

phrenology

founders- Gall and Spurzheim

-cortex: set of 35 intellectual-affective faculties, detectable by bumps on the skull

-compared skulls of criminals and smart people

Broca

(1800s)

confirms localization of function

-had a patient that could only say "Tan"

Broca's aphasia

cannot speak but can understand language

Wernicke's area

for understanding language

Phineas Gage

(1848)

railroad worker that had an iron bar pass thru his head

remained conscious, Dr. Harlow

-coordination, movement, senses, hearing and language were normal

-had a negative personality change

lesions

can happen through accidents, surgeries (intended, for epilepsy)

-corpus collosum: connects hemispheres, can be severed to prevent seizures

-hippocampus, frontal lobe disconnect

strokes

clots in blood supply to brain, selective impairments

seelenblindhat

Munk- soul blindness

Dogs with lesions of the occipital cortex had:

good navigation but poor recognition

(level 1 controlled lesion)

What/Where pathways of vision

(level 2 controlled lesion) Mishkin, Ungerlleder

with monkeys:

"where"- respond if anything appears at locus

"what"- respond if circle appears anywhere

results:

lesion in parietal lobe impairs "where" but not "what"

lesion in temporal lobe impairs "what" but not "where"

transcranial magnetic stimulation (TMS)

electromagnetic induction to induce weak electrical currents in a target brain region; causes temporary disruptions in neural firing; clinical and experimental regions; can be used for extreme cases of depression, diagnostic- connectivity tests

1950's Direct Brain Stimulation

somatosensory system is behind the central sulcus, motor cortex is in front

-controlled stimulation

-Wilder Penfield- during brain surgery

-Parietal cortex- contains map of the body in the brain

-rough topography, homunculus, cortical magnification

neurophysiology (more)

recording activity from single neurons while stimulating

1959 Letvin et. all experiment

looked at what a frog's eye tells its brain

recorded cells in retinae, responded to small moving spots of light

1962 Hubel and Wiesal experiment

recorded from cells in cat's occipital (visual) cortex

-found highly oriented edges; cells responsive to orientated lines, orientations changed systematically; binocular dominance columns

**topographic representation of space in visual cortex; cortical magnification - center (??)

neuroanatomy (more)

staining and tracer dyes

- anterograde: trace forward projections

- retrograde: trace backward projections

level 1: structure

level 2: function

glucose based dyes

EEG

electroencephalogram

-surface electrodes on scalp detect electrical current

-synchronous activity of millions of neurons

-source localization calculations

-clinical and experimental uses: excellent time resolution, less good spatial resolution

-evoked potentials - VEP ex: binocular system

MEG

magnetoencephalography

-source signal, same as EEG but magnetic fields form electrical currents

-SQUID: superconducting quantum interface devices

-data similar in form to EEG

-clinical and experimental uses: excellent time resolution, less good spatial resolution

PET

positron emission tomography

-inject radioactive isotope with glucose, neural firing is fueled by glucose

-subject engages in a task or activity

-imaging of brain

-advantage: good spatial resolution, bad temporal resolution

MRI

magnetic resonance imaging

-aligns spins of nuclei of atoms in brain with BIG magnet

-spins "realign" with big magnet at different rates

-looks at white/gray matter, CSF, bone, fat, blood, skin

adv: good spatial resolution

fMRI

functional magnetic resonance imaging

-same as MRI but subject engages in a task, neurons active

-hemodynamic response: extra blood flow

-BOLD: blood oxygenation level dependent response

-oxygenated blood in, deoxy. out

- MR properties of the blood

adv: excellent spatial resolution, reasonable temporal: 1 brain image every 2 seconds, noninvasive

DTI

diffusion tensor imaging

-MRI technique: directionality and magnitude of H2O diffusion at exact locations in the brain

- fractional anisotropy: shape of diffusion tensor at each voxel

-clinical and anatomical uses: post stroke and accident imaging

telencephalon

neocortex

diencephalon

limbic system

mesencephelon

midbrain

metencephelon

brain stem, cerebellum

myenlencephalon

spinal cord

neocortex

cerebrum - 2 hemispheres, tied by corpus collosum, 4 lobes

occipital lobe

visual cortex

parietal lobe

somatosensory, spatial orientation

temporal lobe

auditory cortex, speech understanding, visual object/face recognition, autobiographical/episodic memory

frontal lobe

prefrontal lobe is the frontal part of frontal lobe (?), Broca's area is located here, working memory (short term), planning, cognitive assessment and regulation/assessment of emotion, personality, judgement- decision making, motor- premotor.....

most recently evolved part of the brain

limbic system (mammalian brain)

-hippocampus: memory

-cingulate gyrus: brain wrapped around the cingulate cortex

- entorhinal cortex: memory, navigation, perception of time

-thalamus: sensory relay, "Grand Central Station"

-amygdala- emotion, esp. fear

midbrain & brain stem (reptilian brain)

-oldest parts of brain (500 mil+ years old)

-subcortical sensory systems: super colliculus, optic tectum (?), inferior colliculus, mid brain structures in auditory system?

neuron

soma, dendrites, axon; purpose- conduct axon, potentials, transmit info from one place to another in the brain, 10^11 in brain, 10k diff kinds

synapse

end of axon, synaptic vesicles filled with neurotransmitter, fuse with side of membrane, spill contents into synaptic cleft

time course of action potential

refractory period- 1 ms; 800-900 times per sec

soma & dendrites

graded potential; decremental conduction; temporal and spatial summation

axons

non-graded potential (all or none); non-decremental; threshold; more intense firing--> more spikes per second

summary of neurons

parts: soma, dendrites, axon

stats: 10^11 of them, 10k diff kinds

physiology: conduction of nerve impulse, action potential

function: transmits a signal, intensity of signal related to firing rate

receptive field

part/aspect of world that can cause change in firing rate of neuron

-inhibit decreases firing rate and exciting increases it

-no direct link to sensory world "hand/face cells"- whole object stimuli

-mechanoreceptor: under skin, most peripheral, receptor connected to neuron

-inferiortemporal cortex

-vision: spatial quality, line orientations, motion, hue

-audition: frequency, spatial location

-touch, chemical senses

-MLD in inferior colliculus in owl

-to hear: intensity, louder in left or right ear, speed of sound

neuron

compute a threshold function of a spatial and temporal (time of refractory period) integration which dendrites, extension, director

theoretical model of a neuron (1943)

McCollach & Pitts

-logical calculus of ideas in nervous activity

1) neuron - binary device with binary inputs

2) fixed threshold

3) binary output

effect- by combining logical propositions in networks, any finite logical exp. can be realized; small- neuroscience, large- C.S. --> binary

John von Neumann

father of computer science

difference between neurons

anatomically (hardware) and physiologically (software)

synaptic efficacy

how easy it is for input from a dendrite to excite a neuron

inhibition w

tweak: friend that tells you to do something but they give bad advice

3 questions - need to know for exam!!

1) What can a neuron do?

2) What can a neuron know?

3) What can a neuron learn?

Perception- Rosenblatt

(1958) neural model: input from retina, output neuron "pattern detector" retinal units, input signal- light?

Hebb (1949)

organization of behavior, modification of synaptic efficacy of dendrites, changes in values of w; values of the model

simple operation rules

-set w1's to random values

-a set of targets "goals" (set of input patterns to classify categories of output

-apply first input pattern and compute output

-0=sum of w1x1

-threshold function

-if correct: do nothing= 3x3 array example

-if incorrect: too high

w

neural network/perception

categorizes input, detects instances of a category

limits- linearly separably

2 hemispheres

right-emotional, holistic, intuitive side

left- logical, calculating, linguistic side

effects of a stroke in right hemisphere

optimistic, unemotional , un-noticing of serious injury+disability

effects of a stroke in left hemisphere

pessimistic, overemotional, overnoticing

anosognosia

A condition in which a person with an illness seems unaware of the existence of his or her illness; semiconscious

lateralized function

one hemisphere controls "task processing"

language

left (Broca's and Wernicke's), left handers- some times right

right hemisphere

faces, visual motor tasks

localized function

contiguous portion of brain controls task

amnesia

selective memory, patient GR who forgets identity for years, recovers it on operating table (Schacter)

apperceptive agnosia

good vision, no ability to recognize shapes/forms

associative agnosia

good vision, good shape, object recognition problems

man mistook his wife for a hat (Sacks)

-recognition of a glove

dyscalculia

cannot do simple calculations; left angular gyrus (Ramachandran)

aphasia

Broca's- cannot speak, left frontal lobe

Wernicke's- can't understand, left temporal

alexia

can't read

agraphia

can't write

prospagnosia

selective memory loss, can't recognize faces

Capgras syndrome

think someone you love has been replaced by an imposter; no other signs of dementia

side note

you have an emotional response when you recognize people

how info moves

-cerebral hemispheres: corpus callosum

-vision: optic chiasm

-audition: a subcortical mess!

-sensory motor: spinal cord

-emotion: anterior commissure

corpus callosum

bridge of 80 million fibers; for split brain patients with epilepsy

vision

optic chiasm

-right hemifield: left hemisphere

-left hemifield: right hemisphere

**each eye goes to both hemisphere

sensory motor

pain, temperature, touch, vibration