cognitive neuroscience Flashcards
phrenology
marie jean pierre flourens
john hughlings jackson
f - lesioned pigeons brains to debunk and create aggregate field theory as he could not find specific behavioural deficits - thought behaviour is mediated by interactions across whole brain
jj - epilepsy patients had ordered jerks, lead to topographical organisation theory (in homunculus) and localisation
when was the neuron doctrine and what happened
1906 - golgi and cajal argued that NS has discrete individual cells , rather than one large united unit. Golgi created the black reaction - silver staining technique to visualise. ramon y cajal was the first to identify the unitary nature of neurons - also recognised dendrite→ axon movement
main signalling units in the NS
neurons
types of glial cells
oligodendrocytes - myelinate axons in CNS
schwann cells - myelinate axons in PNS
astrocytes - large cells that surround neurons, contect blood vessels and moderate neuron activity
key parts of a neuron and its charge
soma (body), dendrites (before body, receives info and branched) and axon (passes info on at synapse on axon terminal)
charged -> electrical potential from the neuronal membrane - Na2+ is pumped out and K+ pumped in
action potential description
70mv is the resting potential and neurons surrounded by physiological solution that contains ions: Na+, Cl-, K+. membranes have selective permeability for the individual ions and APs occur when permeability changes, NA+ flows inside membrane and K+ flows out - through gated channels and reaches +40mv and cell depolarises, Na+ channels close and cell repolarises.
synaptic transmission process
AP arrives at axon terminal, causing the membrane to depolarise. Ca2+ channels open and small vesicles containing neurotransmitters fuse with synapse membrane. it is released into the cleft and diffuses across onto postsynaptic membrane
grey vs white matter
grey - has neuronal cell bodies and dendrites
white - axons and glial cells, has nerve fibers
subdivisions of the frontal cortex
prefrontal cortex -higher order associations
motor cortex - in front of the central sulcus. receives input from cerebellum and basal ganglia via thalamus and premotor area
what is the central sulcus
groove that separates frontal and parietal
(and motor and sensory cortex)
mental processes vs mental representations
representation is anything that means something to the individual
mental processes are the cognitive function that transform our thoughts/behaviours/experiences such as sensation/perception/attention/language
(translation of representation)
info processing depends on mental reps (even simple stimuli have several reps such as image, linguistic, description formula)
sternberg’s task and inportance
- to identify mental operations and differentiate between processes and representations
task: presented with letters on screen which dissapear. ps must identify when there are new or old letters that flash up
Mental operations can be subdivided into encoding, comparing, deciding and responding to a task. And reaction times increase in a linear pattern as target sizes increase.
early vs late selection theories of attention
early -> pre perceptual analysis
evidence: stronger response in cats brainstem when attention (not controlled - cat moves). fmri shows field maps 20-50ms after onset, and mri in helschls gyri in auditory cortex
late selection -> equal perceptual analysis, then high order to determine what stimuli is given access to awareness
exogenous vs endogenous attention, and how to quantify spatial attention
exo - bottom up, automatic
endo - sustained by us, top-down and voluntary
posners cueing task - screen when valid and invalid (misleading) cues are given. when cueing: high ERPs when the stimuli occurs compared to uncued - endogenous attention. exo - automatically captures due to flash
inhibition of return
initially, enhances detection of attended object for approximately 100–300 milliseconds, but later it impairs bc of relative suppression of stimuli that was recently the focus.
adaptive as it biases attention to novel areas after a critical period
how to map visual areas with fmri
retinotopic mapping
this is the orderly representation of retinal image in brain and helps us know which areas in the human visual cortex are modulated by attention
biased competition theory of attention
each object in the visual field competes for cortical representation and cognitive processing. it can also be biased by top-down and bottom-up processes
seen in single cell responses where non-preferred stimuli is suppressed. results mirrored in fmri
attentional modulation of single cell responses - monkeys
mcadams and reid
rained monkeys to fixate on a central point and covertly attend to other flashing stimuli - found that spatial attention enhanced the responses of simple cells . studies show that attention affects processing at multiple stages in the cortical visual pathways from v1
attentional network theory
- concept of alerting (change in state), orientating (allocation of attention in space) and executive functions (conflict resolution, control, decision making, error detect and habit) working together
what pathways are in the attention network
top down: fronto-parietal system is dorsal network for voluntary attentional control (IPS and FEF), bottom up: ventral network for novelty and attentional reorientating ((TPJ and VFC)
midbrains role in the attention network
spatial attention with the superior colliculus - it directs out eyes to look at what is relevant
superior colliculus is active when monkey makes a saccade from a fixation point to a stimulus
this is subcortical
How does the attentional network influence sensory processing
spatial cuing paradigm - the pathway used dictates what is paid attention - such as whether bottom up or top down processes are used
evidence that the attention network influences sensory processing
spatial cueing paradigm - posners task
participant fixates on a cross, a cue is shows, then delay and then a stimulus is shown
spatial cuing paradigm and fmri evidence for brain areas
Control Network - DLF, IPL, STS and PC, MF
Target processing - Pre/Post CS, SPL, VLF and SMA, AC, VC
monkey attentional network
posterior parietal cortex and frontal eye fields
what pathways do voluntary and novelty attention have
dorsal network for voluntary and ventral for novelty
extinction vs neglect in attention
neglect: when there is a lesion or damage in one hemisphere which biases patient to one side, other side does not exist -
seen in drawings, dinner plates and nails painted etc. the patients are not blind though
extinction: attentional deficit where the presence
of a competing stimulus (stimuli shown at the same time on the side of/opposite side of lesion) in the ipsilateral hemifield prevents the patient from detecting the contralesional (opposing)
stimulus. however the patient can detect the stimulus on the injured side in isolation without distraction
how to understand strength of neglect in patients
line cancellation test (patients with neglect will have a biased midpoint - evidence of neglect at the level of object representations/line and the visual space/paper) and copying objects/scenes (will neglect one/the left side, even with the knowledge of what a clock looks like. cannot draw it from memory either)
spatial vs object centred neglect
S - person unable to recognize stimuli on one side of their body - the IPL (inferior parietal lobule) is most sensitive to lesions resulting in spatial neglect, but the stg (superior temporal gyrus)is also involved but needs larger lesions for the same affect.
O - blind to half of every object, half of everything is drawn and exists in mind - bc of STG - neglect the contra-lesional side of each object, do not detect the gap if on the left, and categorize the item as a no-gap item.
attentional memory deficits
neglect also affects imagination and memory → patients with unilateral right hem damage describe images as they see it (neglecting the left)
mismatch field brain response and how we know length of auditory (echoic) memory
mismatch field elicited by deviant tones in comparison to standard tones. amplitude of mmf declines as time between deviant and standard
lasts 9-12seconds
up to 9s is surprise, different at 12
(comparison - visual is only 1-2s)
hierarchical modal model
atkinson and shiffrin
sensory inputs go into the sensory register, attention allows it to enter short term storage and rehearsal allows for long term storage
is serial -predicts that no STM = no LTM
discrete stages of memory
brain structure for procedural memory on motor tasks (and how we know)
basal ganglia, NOT mtl
seen in serial reaction time task - copying flashing lights
can increase rt to repeating sequences without realising
working memory model - baddeley and hitch
the central executive controlling the phonological loop (which information can be phonologically (acoustically) coded in working memory) and the visuospatial sketch pad (information is visually coded in working memory)
areas operate independently at the same time
information loop flows in left hemisphere between ba44 and supramarginal gyrus ba40
what is the word fragment task for
to show priming
12 months later -> can fill in the black without consciously knowing
- ffects are even seen in patients like hm with damaged medial temporal lobe. had no episodic memory but could be primed - had new implicit knowledge
- medial temporal lobe cannot be responsible for priming → must be an independent memory structure
neural underpinnings of episodic memory
what - path to perirhinal cortex
where - info enters parahippocampal cortex
hippocampus bings info into cortices
then combined into association areas and entorhinal cortex
hippocampal function in monkeys
delayed non match to sample test
replication of HMs MTL lesion
monkey must choose novel item after a delay for food reward
longer delay = more incorrect reponses - monkeys with lesions of the hippocampal formation, parahippocampal cortex, and perirhinal cortex (HPP) performed worst
korsakoff syndrome
can recall facts about external world, but not the self
caused by damage of dorsomedial nucleus of the thalamus and the mammillary bodies
patient EE
had selective short term memory deficit (digit span of 1-2) due to a tumor and surgery in the left angular gyrus affecting left superior temporal and left inferior parietal cortex. BUT retained sig long term memory
does MTL damage cause anterograde amnesia for all forms of memory?
no -
HM had no episodic but residual factual memory
could draw floor plan of living space post surgery, despite no memories of living there
also - familiarity not affected by hippocampal damage
could recognise items they had previously made colour/animacy judgments on the next day -> entorhinal cortex responsible
what are the two structures critically involved in episodic memory encoding?
mamillary bodies and MTL
mammillary bodies are a pair of small round brainstem nuclei. they work with the hippocampus and seen their effects in korsakoff syndrome (mammillary bodies are destroyed and therefore no new episodic memories can be made)
which forms of memory are at least partly spared in hippocampal damage
procedural learning, familiarity and semantic memory (knowledge of the world)
what brain areas are seen in declarative vs nondeclarative memory?
- declarative : medial temporal, middle diencephalon and neocortex
- nondeclarative: basal ganglia and skeletal muscle, perceptual and association neocortex, cerebellum and reflex pathways
double dissociation between STM and LTM?
EE vs HM
- may argue yes because of the memory abilities and anatomy → left perisylvian cortex vs medial temporal lobes
- however EE had not lost entire STM, which leads to alternate explanations
summary of hippocampal involvement of memory
hippocampus is in mtl
cannot function with damaged connections to parahippocampal area (where) and perihinal cortex (what)
hm - no episodic, anterograde amnesia
studies in rats: hippocampus not involved instimulus-response behaviours but was involeved in spatial navigational learning
what brain area encodes familiarity
entorhinal cortex - in and around
fmri activations are correlated with confidence ratings
what does the hippocampus mainly support in memory?
source based recollection
not familiarity
stronger activation for those sucessfully recollected
which part of the medial temporal lobe supports recollection-based recognition
posterior hippocampus
what is long term potentiation
- long term strengthening - confirming hebbs law of cells that fire together wire together
- high stimulation in a pathway leads to a larger magnitude of ESPs (excitatory post synaptic potentials) create greater synaptic strength so that when simulated later there becomes larger postsynaptic responses
process of synaptic transmission
action potentials reach the synaptic cleft and vesicles containing NTs bind with the presynaptic membrane. this allows for them to be released into the cleft and the NTs bind with receptors in the post synaptic membrane
process of LTP and role of NMDA receptors
- NMDA mediates LTP and is activated upon glutamate binding to NMDA receptors in the dendritic spines of the post synaptic neuron.
- LTP is prevented when NMDA receptors are blocked in the CA1 region of the hippocampus.
- NMDA receptors are central to producing LTP.
- NMDA is gated - because it is naturally blocked by Mg2+ and only unblocked by glutamate which allows depolarisation.
- CA2+ floods into post synaptic cell and changes enzyme activity which increases synaptic strength
morris water maze and importance
- using mice with no NMDA receptors
- when LTP is induced will go back to base quick bc of no NMDA
- wild mice are able to learn the maze and find the platform over the water much faster than the mutant
- mutant mice struggle to space map and have disrupted space cell activity
- mutant are distracted by faux cues
Which factor most likely contributes to variations in brain activation during memory retrieval?
salience and activity coordination
double dissociation for episodic memory vs familiarity
MTL in encoding diff forms of memory: one medial temporal lobe mechanism involving the perirhinal cortex that supports familiarity -based recognition memory, and a second system involving the hippocampus and posterior parahippocampal cortex that supports recognition based on the recollection of source (episodic) information
where are explicit memories stored and evidence
long term → the cortex. this is because although new long term memories cannot be formed without the hippocampus and mamillary bodies patients such as HM still retain memories after their injury
role of frontal cortex in memory encoding and retrieval
semantic and encoding retrievel in the left hemisphere such as brocas areas for linguistic representations. right frontal cortex more involved in object and spatial memory informatio
MTL and short term memory
- patients with lesions perform normally
- perirhinal cortex in mtl may play role in stm for complex and novel visual objects
- seen in patients with severe mtl lesions
- monkey with mtl lesions - when including the perirhinal cortex there are severe deficits for novel objects
- single cell recordings in monkeys - perirhinal and entorhinal neurons has persistent object delay activity during retention delays in stm tasks
do patients with perisylvian cortex lesions show selective stm deficits
must test for info that is difficult to encode
- patients with phonological stm deficits have severly impaired ltm for menaingless nonwords
- patients with perisylvian lesions can exhibit normal LTM for information that can be encoded visually or semantically, but they clearly have deficiencies in phonological STMandLTM. Accordingly, there is no reason to believe that these patients exhibit a dissociation between STM and LTM.
prefrontal cortex contributions to STM
- several neocortex areas have persistent stimulus-specific activity in short retention delays
- lateral prefrontal cortex is not a critical site for ltm as studies do not show consistent effects on retention of object/verbal info across short delays. effects attributed were due to issues in task learning, attention/response selection instead
- STM in patients with unilateral prefrontal lesions - digit span normal even when faced with distraction
- pfc may not be needed for verbal short term storage
- instead prefrontal lesions may affect LTM performance when asked to initiate strategies to actively encode information or when given tests that require strategic processing during retrieval
- evidence presents pfc as not a stm buffer but necessary for implementing control processes which contribute to LTM and STM
alternatives to memory that is not multi store view (DD between short and long term memory)
- may be neural circuits that differentially support STM and LTM within the same cortical area
- or distinctions between neural mechanisms of STM and LTM, where memory is supported by reactivation of neocortical networks. crucial differences among neocortical memory stores or systems is not their contribution to memory at different retention intervals, but rather the types of information they process and represent. creates assumption that there are multiple memory stores
patient SM - emotion (and compare these issues with monkeys)
bilateral amygdala damage, brain tissue replaced by cerebrospinal fluid
could not identify or draw fearful face
esions to the amygdala in monkeys cause loss of innate fear, becoming hyperoral, hypersexual, and docile. Lesions in humans have more subtle effects. They affect emotional fear processing
limbic system model
maclean, old model
- hippocampus as seahorse shaping centrepiece which would receive external sensation inputs, internal inputs and from the visceral environment. was believed to be the basis for emotional experience. he created the limbic system (forming a ring around corpus callosum)
- errors with maclean’s limbic system - many brainstem nuclei that are connected to the hypothalamus are not part of the LS and some brainstem nuclei are part of autonomic reactions (not part of model). also, some areas of the system are important for non emotional areas (hippocampus and memory)
circumplex model of emotion
circular ranging from pleasant-unpleasant and activation/deactivation and both basic and complex emotions can be placed on this scale
evidence for james lange vs cannon bard emotion
- JL - believed that physiological response informed emotion
- CB - emotion informs response removed all sympathetic visceral feedback in cats by brain/midbrain stem sectioning. these cats still expressed emotions - argument against feedback from visceral system as trigger. process it thalamus informs cortex (fear) and hypothalamus which activates sympathic NS for physiological response and action
- dentist example → russel goes to the dentist, given adrenaline - faster HR should indicate fear, but russel said he was not scared
damasio’s card game
somatic marker hypothesis
-2 stacks of cards - left is big yield and risk, right is moderate
- left = anxious state- physical reaction precedes emotion
- why? processing is estimation of value.
- in the orbitofrontal cortex and the amygdala. orbitofrontal cortex lesion - cannot estimate value anymore → would stick with left stack and will make risky decisions. these people focus only on short term gains than long term goal. do not know what is good/bad for them
high vs low road of emotional processing
- high road - slower, cog analysis is more thorough . sensory information projects to the thalamus, which then sends the information to sensory cortex for a finer analysis. this projects the results of this analysis to the amygdala
- low road - signal sent rapidly. thalamus to amygdala without being filtered through cognition or consciousness. cortex is bypassed
how to measure emotions
physiological response - skin conductance due to sweat/moisture on fingers. more activation = more moisture = more conductance
implicit and explicit learning and fear
- implicit learning - fear conditioning has been experienced (saw blue box then shocked)
- explicit learning - fear hald been expressed to individual but they haven’t experienced it (told you will be shocked after seeing blue box)
role of the hippocampus and amygdala in emotional learning
- patient SP - bilateral lesions - the right amygdala and a large section of the right temporal lobe including the hippocampus was removed. found that they could not be conditioned explicitly or implicitly → understand that they will be shocked after seeing blue square but will not show fear response
- Hippocampus mediates learning by awareness (declarative memory system).
- Amygdala mediates conditioned autonomic responses. also, activation aids the retention of hippocampus dependent memories (emotional events are much better remembered)
how to detect fear
- fear → we have very wide eyes
- S.M. could only identify fear when told to look at eyes. would usually focus on nose and centre of face
- size of eye whites alone is sufficient to induce differential amygdala response to fearful expressions. more eye whites = more fear
- Activity in the left ventral amygdala in response to eye whites and eye blacks relative to fixation demonstrate that fearful eye whites alone induce increased response above baseline. Eye blacks were control stimuli
elizabeth phelps and implicit attitude response
found that more amygdala response was found then more bias were in implicit attitudes - reponse is stronger negative implicit attitudes
- right amygdala is more active for black versus white faces when faces are presented for 30 ms.
- activity in the dorsolateral prefrontal cortex, anterior cingulate cortex, and ventrolateral prefrontal cortex was greater for black faces
Implicit attitudes correlate with amygdala activation, even in the absence of explicit attitudes (e.g. racial bias/stereotyping). The amygdala is involved in implicit learning of emotional information and implicit coding of information.
better than average effect and neural correlate
rate yourself as better than others
ps rating self-descriptiveness of diff traits
less deactivation in Ventral anterior cingulate cortex (vACC) when rating positive personality traits vs negative - allows us to differentiate between diff worldviews
Which brain region tracks the intention behind eye gaze shifts in social cognition tasks
eye gaze tasks where character moved eyes congruently in incongruently
superior temporal sulcus tracked intention, not just all shifts
incongruent tasks - do not know what ps are looking at
empathy responses and perceived fairness
brain activation in revenge
trust game task - with fair and unfair players
in scanner -> own, fair or unfair player hand shocks
anterior insula cortex reflect own/fair players pain
revenge - nucleaus accumbens (reward centre)
neural region responding to disgust
insula -> more disgust increases in computer morphing method
fusiform gyrus is equal across emotions
role of orbital frontal cortex social cognition
lhermittes utilisation behaviours - insight (phineas gage)
and controls what is appropriate in social context
would not be able to judge social situations in the moment but feel embarrassed when watching in 3rd person
theory of mind tests social cognition
false belief and false photograph (landscape changes post pic)
needs temporoparietal junction
social isolation in rats vs humans
rata - more impulsive and less sensitive to dopamine
humans - HPA system overactivation due to high cortisol - under-expression of anti inflammatory genes, cognitive decline, worsening depression etc
self referential processing
more knowledge about the self - more elaborate coding
more strongly associated with MPFC function than is the
processing of information about people we do not know
personally
where am I in my brain
system of connected brain areas that show increased activity when a person is not focused on external tasks (includes self reflection, memories, daydreaming and social evaluations. mostly spread around ventromedial PFC, dorsomedial PFC and posterior cingulate cortex and adjacent areas) decreased activity in external tasks, increased activity in internal (the self)
resting state brasin network
other (non-resting state) areas deactivate during self referential processing, but the resting state network does not
more active when people are at rest (daydreaming, idling)
It largely consists of areas of the medial frontal and parietal cortex and the lateral parietal cortex
medial prefrontal cortex
needed for self perception and
and judgement/perception of other people.
two theories of action understanding
visual understanding where recognition is dependent of the activity in higher order visual areas and superior temporal sulcus, or empathetic understanding where observations activate in analogous motor representation and this motor knowledge informs.
monkeys and empathetic understanding mirror neurons
in ventrall premotor cortex - fire selectively when watching and hearing paper being ripped
empathetic understanding
mirror neurons and evolution
monkeys posses mirror mechanism for understanding but not imitations
developed later in evolution
mirror system in humans - MEG and TMS
MEG - desynchronization of motor cortex in active movements also seen in observation of action done by others
TMS - observation of actions by others determines increase in corticospinal excitability → increase were in specific muscles that individuals would use for imitating the movement
inferior parietal lobule involvement mirror neurons
core of system with posterior inferior frontal gyrus
fmri - watching biting or communication (speech reading, lip smacking or barking). same activation of inferior parietal lobule seen in biting when man/monkey/dog but barking showed no mirror system activation
intention understanding - inferior parietal lobule
majority of these grasping neurons (65%) were influenced by action where grasping was embedded - more for eating than moving/placing
goal of action determines the motor selectivity of ipl neurons in given motor act , rather than factors related to movement kinetics
in monkeys - selection activation for eating/non-eating conditions
chain actions and IPL
IPL mirror neurons discriminate one motor act from another, thus activating a motor act chain that codes the final goal of the action. Here, observing individual may re-enact internally the observed action and thus predict the goal of the observed action.
disgust and action understanding
non-cold action (emotion)
disgust seen in amygdala and insula
The right anterior insula mediates both the recognition and experience of disgust, showing humans most likely understand this, and other emotions through a direct mapping mechanism
altruism theory and mirror neurons
mirror mechanism transforms what others do and feel in the observer’s own experience. The disappearance of unhappiness in others means the disappearance of unhappiness in us, therefore we act altruistically to make others happy for our own egoistic happiness.
posner’s letter match task
reaction times differ for different conditions in accordance with the amount of processing required for the task. When this task is extended and intervals are added, phonetic identity is reduced. This shows how mental representations are transformed into a more abstract code
advantages of fmri and tms
both non invasive
fmri has good temporal and spatial res
used together - for example in tactile perception we know that the extra striate and striate cortex is used - impaired in tms
disadvantages of tms and fmri
tms - 1cm radius, superficial
fmri - expensive and sensitive to movement
