Cog Neuro Exam 3

1/3

how much of your life you spend asleep

cognitive impairment

what happens when you don’t sleep for 8-10 hours or more

circadian rhythms

a group of systems that fluctuate throughout the day such as sleep, body temperature, etc. - there are many different types of this thing

light

what our circadian rhythm is cued by

superchiasmatic nucleus

a brain region at the bottom left of the hypothalamus - above optic nerves - some of the axons that leave the retina go to this portion of the brain - sensitive to light and is very involved in sleep - tells the brain whether there is a lot of light or not as much light - cooler light activates it more than warmer light - can trigger arousal

pineal gland

place in the brain that produces melatonin - a bump underneath the thalamus

melatonin

a chemical released in the brain that produces sleepiness - production follows a cycle - tends to rise when the sun goes down and goes down when the sun starts coming up

nap strategies

the idea that you don’t technically have to sleep all at once - some people take naps throughout the day instead of sleeping all at once - regularly spaced interval naps?? - not good for you - it can be forced but its not natural

ventrolateral preoptic nucleus

region in the hypothalamus - responsible for the secretion of GABA (the main inhibitory neurotransmitter) - helps with sleep induction - lowering excitation - doesn’t make you feel groggy - it literally lowers your metabolic brain activity - inhibits the three arousal areas

locus coeruleos

involved in arousal - secretes norepinephrine (strongest excitatory neurotransmitter) - adrenaline neurotransmitter

raphe nucleus

involved in arousal - secrete serotonin

Tuberomammillary nucleus

involved in arousal - secrete histamine - histamine is not as strong as norepinephrine but they are excitatory

EEG

the way we study the activity that happens in your brain during sleep - your brain is active during sleep

gamma waves

the frequency that exists when you are awake and concentrating and thinking about stuff - fastest waves

beta waves

the frequency that exists during most activities when you’re awake, but not like stuff where you need to be super locked in - this is what stage 1 sleep looks like on an EEG

alpha waves

the frequency that exists while you are relaxed or sleepy - waves are starting to get slower

theta waves

the frequency that exists during stage 1 and stage 2 sleep - light sleep

delta waves

the frequency that exists during stage 3 sleep (deep sleep) - slowest waves

stage 1 sleep

when you aren’t fully unconscious but you are getting there - waves are like a mix of alpha and theta - edge of consciousness - only accounts for about 5% of the time you are asleep - slowed respiration and heart rate - decrease muscle tension and body temp -

stage 2 sleep

when you’ve slipped into the warm happiness - starting to relax - body temperature is starting to lower a bit - accounts for about 50% of the time you are asleep - body temp and heart rate drop - theta waves + sleep spindle + k complex - memory consolidation may happen here

stage 3 sleep

when you are fully gone and very difficult to wake up - deepest state of bodily relaxation - accounts for about 25% of sleep - mostly delta waves - where the body heals itself (repairing tissue, flushing junk, etc.)

rapid eye movement sleep

accounts for about 20% of the time you are asleep - longest you are in this stage is like 5-10 minutes - heart rate and respiration speed up - you have dreams - increased neural activity (30-70hz)

90 minutes

the amount of time you spend in each stage of sleep - not exact but its a solid estimate - happens 4-5 times per person in an average night

sleep spindle

little bits of waves that look like gamma waves embedded into a slower cycle - may be important for unpacking memories - tied to moments when the cortex and hippocampus are talking

k complex

a big jagged wave that looks like a delta wave happening out of nowhere

restoration

the theory that we sleep in order to reboot the body and brain - what does that reboot look like? - the brain is active so we aren’t fully rebooting

survival advantage

the theory that sleep is to protect organisms with poor night vision - but then why didn’t we evolve night vision?

simulating rare situations in dreams

the theory that sleep is meant to test our strategies for later use - no real evidence for this and the theory got thrown out

aiding info processing

the theory that sleep is meant to aid learning and memory - there is evidence for this

astrocytes

clears waste from the brain by pumping cerebrospinal fluid (CSF) between neurons - this process is more effective when sleeping - glial cells - the space between the neurons increase when we sleep which allows the CSF to flow more smoothly

interstitial volume

the space between our cells

beta amyloid

a protein involved in Alzheimers - being awake causes this stuff to accumulate - this gets flushed out when you sleep - not great for you

criticality

a point when the brain is at peak computational power

oscillations

when your brain is doing long slow waves (minus the hippocampus and hypothalamus) - you get sleep spindles from the thalamus during certain parts of this - happens during stage 2 or 3 sleep

sharp waves ripples

happens at the same time as sleep spindles - comes from the hippocampus - moments when the cortex, thalamus and hippocampus are all lining up - happens during stage 2 or 3 sleep - aids in memory consolidation

neocortex

when information goes when sleeping in order to store memories in the long term memory - moves from the hippocampus to this place

hippocampal place cells

replay real world trajectories during sleep - and also rest that is like sleepy but awake - happens during sharp wave ripples - also important for spatial navigation - they fire when a “rat” is in a specific space - recorded neurons in this place in free moving rats - each one of these fires for a different area - sparse representations of space - these are static

info rehearsal

the idea that we rehearse info during sleep - study done with objects placed on checkerboard with an accompanying sound - rate of mistake was equal for the cued and uncued sounds before sleeping - then people took a nap and researchers waited for stage 2 sleep and then cued half of the sounds - after sleeping, the change in error rate (how much worse did u do than before the nap) for the cued sounds was much lower then the error rate in uncued sounds - uncued got 20% worse - the cued people didn’t get worse at all

insights

the idea that sleep can lead to eureka moments - sleep is somewhat thought to drive out bad connections or associations - not a lot of scientific evidence behind this, but there is a little

boosting the recall of studied words

the idea that when someone stimulates certain brain waves (like theta), and then gives people a test to see how much they can recall - the stimulated people remembered much more than the unstimulated

dreams

we don’t really know what these are - maybe our brains are replaying information while our hippocampus consolidates info - these typically happen during REM (the more fantastical stuff happens here) - can happen during stage 2 sleep (but these are more boring) -

hippocampus, cingulate gyrus, striatum, amygdala, parietal association cortex

the places that show increased activated in REM and activate during dreams

interactive lucid dreaming

we are sometimes able to communicate with people in dreams - people were asked to make a certain number of eye movements to answer a math problem - electrodes on their head and on their eyes (EMG) - allows you to see the eye muscle movement - the researchers were able to get responses

precuneus

area that are active particularly during lucid dreaming as opposed to non lucid dreaming (consciousness area)

phoneme

perceptually distinct unit of sound - Kuh + ah + t

grapheme

the smallest meaningful unit of a writing system - cat = c + a + t - smallest unit of whatever the writing system is

syntax

the structured arrangement of words and phrases - how a language is structured - that actual grammar

semantics

the meaning of words and groups and words - actual meaning

primary auditory cortex

a part of the brain that can break continuous streams into chunks - this evolutionary ability kind of came out of nowhere - responses to sounds at different frequencies and different time scales - the burst duration of the neuron in this cortex can be modulated by language - capable of morphing its own action potentials to keep track of someone talking to you

speech waveform

the way to plot speech pattern based on frequencies and tone of voice

syllable edges

tracked by theta waves in the auditory cortex - splits the acoustic stream into syllables

phonemic features

tracked by gamma waves in the auditory cortex - low or high pitch - voice rising or falling? - the fine tuned details

aphasia

the loss of language - two kinda of this - both speech and writing are affected by this

broca’s aphasia

results from damage to Broca’s area of the frontal lobe (left lateral frontal) - expressive aphasia - effects the syntax and structure of language - doesn’t effect comprehension of language - can flip to right hemisphere damage if you are left handed - meaning is intact but the speech itself doesn’t make grammatical sense - activation in brain area is scaled to the complexity of sentence - this is associated with word generation

wernicke’s aphasia

results from damage to wernicke’s area of the frontal lobe (left lateral temporal) - just behind primary auditory cortex - receptive aphasia - effects the semantics of language - speech is meaningless - this brain area responds to simple sentences when trying to place meaning

angular gyrus

place in the brain that does a lot - involved in aspects of language - parietal area involved in processing context - helps assign meaning and significance to language - in posterior medial brain network - monitoring the language process

arcuate fasciculus

white matter bundle connecting broca’s and wernicke’s areas - passes through the angular gyrus - shows that there is a connection between the language areas

visual word form area

place in the brain that responds more to larger words compared to consonants or meaningless streams of consonants - regardless of visual field - responds more to letters than psuedoletters (responds less to language that you don’t know too) - exists in the left hemisphere - response ramps down if you see the same letter many times in a row, including if you switch between upper and lower case - responds to braile in blind people

semantic memory

conceptual knowledge that leads to word meaning - leverages the meaning of words to understand concepts - highly integrative, bridges memory, perception and language - traditionally assumed to be amodal (abstract and ungrounded), but this is questioned in contemporary theories - can understand concepts without knowing exactly how it feels - some concepts may be grounded

hub and spoke model

some evidence for grounding of semantic featured - but we also have abstract semantic knowledge - how do we make these two coexist? - the theory is that we have an amodal hub - many spokes connected to the hub - spokes are where the grounded concepts live - some concepts only live in the spokes, which exist in other areas in the brain - ex. action related semantics live in the motor and premotor areas

amodal hub

categorized broad concepts - damage to this area causes general issues with semantics - in the anterior temporal lobe - can cause semantic dementia - where semantics live in our brain

factual info

the brain is rapidly signaling whether the language is representing this type of information - word and world knowledge are used when determining this

negative 400 milliseconds; n400

particular component of an EEG signal - comes from an electrical waveform recorded at the scalp - a red flag signal in the brain when looking at factual info - happens this number of milliseconds after a word is presented - spike gets more negative when looking at an EEG at this number of milliseconds as sentences get less coherent - coherent and true is the lowest followed by coherent and false followed by incoherent - all signals gets a spike, but the amount of spike depends on the coherence of the sentence

dyslexia

disorder affecting reading - can by developmental or aquired - not due to a sensory or intellectual deficit (not like a visual or intelligence issue) - very complicated phenomenon, because not all dyslexic brains look the same - generally see reduced activity in wernicke’s area but more activity in Broca’s area (maybe to compensate??, but don’t fully understand why)

phonological dyslexia

problems with the sound structure of language - not about the meaning - just sounds and pieces of language - more common developmental variant - reliant on lexical semantic route - the grapheme phoneme pathway is impaired

surface dyslexia

problems with the appearance of language - the more reading affected type of dyslexia - relies more heavily on grapheme phoneme conversion - the lexical semantic route is impaired - more commonly due to acute damage - regularity (does a word look how it sounds?) and frequency of use of words helps - regular words are consistent across frequency - as frequency gets higher (especially with irregular words) reading it gets more consistent

standard dual route model

the idea that there are two branches of language processing that lead to speech production - one goes through visual analysis, letter recognition, visual lexicon, semantic memory, phonological lexicon and then speech production (this bypasses sounding it out and relies on semantic memory)- the other starts at visual analysis to letter recognition and then goes straight to grapheme and phoneme conversion (sounding out the word) and then to speech production

lexicon

bank of stored sounds that you can remember

lexical semantic route

the faster route of the dual route model - can gloss over familiar words that you can anticipate processing - using semantic memory - starts with the visual word form area then tends to engage parietal areas (angular gyrus) - eventual goal is to get to Broca’s area

grapheme - phoneme route

the slower route of the dual route model - sounding out the sounds - starts with the visual word form area - goes to temporal pole which is capable of pulling out semantics - eventual goal is to get to Broca’s area

critical period

the point in your brain’s development where exposure to language is absolutely key to your development - happens in the first 2 years of life - language is the strongest evidence we have for this - 6-8 months is when we see syllables start to emerge - then by 18 months they have a small vocabulary - missing this has long lasting effects - children can miss this and be almost unable to learn language - “feral children”

universal grammar

the idea that you are born with a predisposition for language - your brain is set up to learn the grammar of languages - cross cultural - we can’t really explain how children even learn language (it shouldn’t happen??) so this is our explanation

cognitive map

map that lives in your mind - did an experiment with rats in a maze making it from one end to the other - they learned the space and then he blocked their path but they were actually able to use untrained routes really quickly - rats must have had some representation of the space?? - doesn’t have to be solely spatial - we map out many things like decision trees and semantic knowledge and relationships - can apply to conceptual spaces

hippocampus

one of the main places involved in making spacial maps - lesion to this part of the brain make spatial navigation very difficult

morris water maze

rats get dropped into a pool filled with opaque water in order to hide a platform - rats are motivated to find the hidden platform because they hate water - they have to rely on spatial navigation to get there because they can’t see it - they reliably learned where the platform was and were able to beeline there - hippocampal lesions caused them to swim around for a lot longer and made it very difficult to find the hidden platform

place field

hippocampal place cells tend to fire for a specific environment, which is what this is called - can be cell populations that fire for these

cognitive map theory

the hippocampus stores spatial maps of the environment - it codes for the structure that you are in - maps are thought to be allocentric, but there are so egocentric codes in them too - space is the thing that other things are built on to

allocentric

a map that is independent of an animal’s personal viewpoint - objectively true map

egocentric

the map as someone experiences it - dependent on human experience

grid cells

arranged in a hexagonal (honeycomb) type shape - this is the pattern of the cells firing - different entorhinal cells have different ones of these - if you put all of these cells together then you can have a general layout of space - different scaling for these cells - small and tight in dorsal entorhinal cortex, but as you move ventrally, the get further apart - scaling allows you to code fine grain or larger scale information

entorhinal cortex

the place in the brain that is getting info into the hippocampus - known to have place fields that looked very odd and fired in multiple locations - takes info from the periorhinal cortex (object info) and parahippocampal gyrus (spatial info) - integrates this info and then sends it to the hippocampus

head direction cells

cells that fire to your facing direction - change how they fire depending on which way you face

boundary vector cells

fire when you are close to a boundary in the room (walls, etc.)

conjunctive cells

combine a bunch of different types of signals

london taxi driver study

looked at the size of the hippocampus in experienced london taxi drivers - tended to be larger with more time spent as a driver - evidence for hippocampus as spatial navigation in humans

patient TGA

adapted the morris water maze experiment into VR for humans - humans had to find the target in VR - controls were pretty good at getting to the target platform - however this patient was pretty bad at learning to find the platform - he could beeline to the target when he could see it - he has a hippocampal lesion - when they moved the platform, the controls went to where it used to be and just stood there - this patient continued wandering

parahippocampal cortex, retrosplenial cortex, occipital palce area, parietal regions

other really active parts of the brain during spatial navigation

retrosplenial cortex

place in the brain behind the very back of the corpus collosum - active during spatial tasks

posterior and dorsal

the general regions in the brain where there is more activity during spatial navigation

multivoxel pattern analysis

used to look at pattern similarity - looking at the pattern of activation associated with different stimuli - how similarly are things that are represented

hippocampal scaling

the idea that as the distance between two objects that we are thinking about get further apart, the activation in our hippocampus rises - farther apart = more activation - closer items were represented more similarly than farther apart landmarks

grid code

if you lay out the honeycomb shape of grid cells, certain linear paths through the environment will intersect more with the active spots in that grid - linear paths hit more nodes - linear is aligned to the grid while nonlinear is misaligned - this doesn’t necessarily matter functionally - data comes from fMRI, which means we only know that the area is active and needs more oxygenated blood - each people have different ideas of aligned and misaligned so you have to figure it out for each person

entorhinal + hippocampus navigation

the first gives you a new goal while the second gives you a descion point, new entries and travel - the first gives you a basic map of the space - the second is responsible for actually moving around the space and specific locations / planning out paths

directional coding

happens in the retrosplenial cortex - participants learned a virtual environment with alcoves with paintings - people had to learn where the paintings were - they found that retrosplenial cortex was sensitive to the direction that people were facing - signal was consistent with facing direction - gives you a sense of direction

conceptual space

can grid cells code this? - ex. plotting the similarities between vehicles on a grid - can grid cells map onto the two dimensional abstract space - what does traveling a space look like when its this space? aligned? misaligned?

bird space paper

plotting the neck length and the leg length of birds on a two dimensional grid - objects associated with the birds then also associate with the grid - people traveled a mental path between objects associated with the birds - could travel aligned and misaligned

social space

people played a video game where they learned about characters and their power dynamics in the game - activity in the hippocampus seemed to track the social changes in the characters - helps you understand how people fit together in the social hierarchies in the world - we see grid coding of social concepts

memory space

episodic memory and spatial cognition both represent relationships between things - the place in space vs. who, what where - maybe the hippocampus is just about putting context together - episodic memory is still temporal but it is binding - basically that it is all about relationships

event cognition

our experiences are continuous, dynamic and fleeting - but we tend to perceive and remember discrete organized chunks of experience - afield of study that describes the mechanisms of the way we think about and represent events

event

a segment of time at a given location that is perceived by an observer to have a beginning and end - constantly chunking continuous experience into this - the way we divide our experience into our life and frames the way we experience the world and talk about it - all stories have a natural starting and end point - components are ordered and hierarchical