Cognitin in clinical context Flashcards
cognition
“refers to all processes by which the sensory input is transformed, reduced, elaborated, stored, recovered and used” Neisser 1967
used in everything humans do
information processing metaphor
looking at brain doesnt reveal its functions, needs a metaphor
processes between presentation of stimulus and response
information -> input -> processor -> storage -> processor -> output -> information
whys scientific metaphor needed for cogition
scientific theories aim to be refutable
can’t look inside mind to see cognition
cognitive psychology relies on analogy
models of cognition evaluated against data
methodological approaches
- experimental psychology: healthy humans tested, large sample sizes, small budget
- computational modelling: computer stimulations of cognitive processes, parallel distributed processing
- cognitive neuropsychology: consequences of brian damage, associations and dissociations
- cognitive neuroscience: brain implements cognitive functions using neuroimaging technology
top down processing
processing influenced by individual goals, expectations, desires, plans, intentions rather than stimulus by itself
bottom down processing
processing directly influenced by stimulus, input proceeds through series of processing stages until required output is produced
perception
refers to ability to extract meaning from sensory input
includes audition, taste, touch, olfaction but is dominated by vision
vision alone accounts for over 50% of neurons in cortex
perception is constructive process
visual system
image -> retina -> cognitive system constructs perception
distal stimulus-object “out there” in environment
proximal stimulus-info registered on sensory receptors
misleading impression of simplicity
tootel 1982-support notion that near perfect representation of eternal world is projected onto primary visual cortex
monkeys unconscious, eyes pinned open, stimulus displayed for 25 mins to eyes, eyes in glucose solution, activity of brain detected, image in visual cortex, not what stimulus was
processing streams
ventral-‘what’ pathway, facts/objects you see
dorsal-‘where’ pathway, sensory inputs/location
-ventral stream; visual memory, specialised for object perception and recognition, determines what you’re looking at, V1 to temporal lobe
-dorsal stream; no visual memory, determines where object is using spatial configurations between objects, V1 to posterior regions of parietal lobe
-no colour at peripheral vision, brain assumes it
object recognition; 3 stage model
- image->local features ->shape representation ->object recognition
- image -> edge detection/contrast -> gestalt principles/feature integration -> stored representation/knowledge
- if object recognition goes wrong can tell when
gestalt principles
- whole visual perception more than sum of parts
- perceptual system try impose organisation on inputs
- components of image grouped together on basis of certain visual properties
- laws ‘good continuation’ and ‘closure’ = illusory contours
- see patterns rather than random arrangement
- proximity/similarity/continuation/closure
shape perception
- primarily bottom up processes produce primitive sketch
- sketch contains primitives eg edges/orientations/positions
- top down processes used to group collections of primitives into “lines, curves, blobs, groups and small patches” known as symbolic primitves
object recognition 3 models
- template matching
- feature analysis
- recognition
how do we do facial recognition so well
- challenge of individuating faces made apparent by fact they share basic configuration
- first order relations: two eyes, nose, mouth
- features are ample for rendering percept of face, but inadequate in rendering percept of ‘that’ face
- some instances where features are distinctive and accurate in signalling identity of individual
- second order relational properties
early model of facial recognition-modular model
Bruce and Young 1986
modular model with sub functions whihc are processed independently
distinctive pathways: recognising familiar faces vs recognising expressions
parallel pathways: facial expression, facial speech, visually derived semantic information
familiar face recognition-fru&pins
serial process
- face recognition units-stored descriptions of previously encountered faces, seen it before?
- personal identity nodes-identity specific info, their job, where they are from
- name generation-input from PINs generate name of identified individual
other routes for face recognition
parallel
expression analysis-computing facial emotion as happy, fearful etc
-facial speech analysis-lip reading regardless of hearing loss or not
-directed visual processing-when looking for information from a face
early evidence for bruce and young model-memory loss diary
memory loss diary study
-person not recognised
-feeling familiarity without identity
-person recognised, name not retrieved
-person misidentified
-repetition priming-recognise it quicker next time
familiarity not influence gender decision, expression analysis
humans selectively attend to identity or emotion in sorting tasks
brain support for Bruce and Young model
parallism: double dissociation between processing of facial expression and face recognition, some have deficits in identity but not expression and vice versa
double dissociation: two related processes function independently
different cortical sites active in processing of identity vs emotion, lateral fusiform gyri and inferior occipital
challenge of semantic priming
semantic-meaning/content/facts
face responded to faster if follows a closer related face than unrelated face
response to target is faster when proceeded by semantically related prime
interactive activation and competition (IAC model)
-built in as basic models/processes
-semantic information/knowledge is ‘pooled’
relationships between different bits of knowledge are represented in connections between the pools
-connections wihtin pools are mutually inhibitory
-connections between pools are mutually facilitatory
-if info from a pool is recollected, it inhibits any other info from pool being remembered but info from other pools that is linked is remembered
face selective neurons
- signal face familiarity, PINs are modality free gateways to semantic info
- no separate node for names; part of semantic information
- inferior temporal cortex-only neurons in cortex fire when hands or face are seen, but dont fire when fruit or genitalia are seen
- superior temporal sulcus used in social interactions, social perception and speech
logic of gnostic units
cells in inferior temporal cortex are selective to complex stimuli, giving credence to hierarchal theories of object perception
- early visual cortex codes elementary features such as line orientation and colour
- cells at highest level in hierarchy code specifically to shapes such as hands or faces
grandmother cells
hypothetical neuron
idea that single neuron will detect and represent a single object
linked to sparseness in neural coding
early stages object codes are distributed broadly, later stages become selective for combinations with code becoming more sparse
-ultimate spareness leads to single neurone mapping single object
what is agnosia
when object recognition fails
damage to occipital or inferior temporal cortex
different types of agnosia reveal clues about processes involved with object recognition
visual agnosia
unable to recognise everyday objects
normal visual acuity, memory, language function and intelligence
move around without bumping into things
reach and pick up objects they dont recognise
apperceptive agnosia
unable to recognise objects due to inability to percieve form
move about and negotiate obstacles without difficulty
low level binding of feature is absent
unable to perform basic copying and matching tasks
in object recognition model it occurs at stage 2: shape representation
associative agnosia
copying and matching skills unimpaired
unable to name object even with intact perception of it
could draw it but still be unable to recognise
involves failure in accessing knowledge about object
in object recognition model it occurs at stage 3: object representation
what is prosopagnosia
profound loss in ability to recognise faces
due to damage in right inferior temporal, ventral stream
unable to recognise familiar faces via visual input, recognition by other modalities; such as being identified by voice remain
face blindness
covert recognition
looked at skin conductance in response to a face
peak amplitudes to familiar faces compared to unfamiliar faces
similar pattern for prosopagnosia patients
capgras
recognition without feeling
recognise a face but not identity of individual
delusion that friend, spouse or close family member has been replaced by imposter that looks like them
can recognise someone by voice or characteristic behaviour
damage to dorsal stream
delusional misidentification
mulit-sensory perception
process where information from each sense is brought together
advantages: efficiency, establihs single coherent perspective of world
vision affects sound, colour influences taste and sound influences hardness
McGurk illusion
what you see clashes with what you hear
‘ba’ presented to ears, ‘Ga’ presented to eyes, subject perceives ‘da’
fmri shows looking at moving lips activate auditory part of brain
what is synaesthesia
neurological, automatic process
one sensory/cognitive pathway is stimulated leading to involuntary experiences in second sensory/cognitive pathway
concrete perception experiences elicited by stimuli in external environment or by internal thoughts
each person has different experiences of it
developmental synaesthesia
- genetics; runs in family
- present throughout life time
- equally present in males and females
- triggered by linguistic stimuli
- some regions of brain more connected in some people than others
- exuberant connectivity across brain, not just in regions related to synaesthesia
acquired synaesthesia
sensory deprivation
pharmacologically triggered eg LSD
effects temporary
how does synaesthesia link to normal cognition
links between vision and touch
blakemore 2005- watch someone being touched activates own somatosensory cortex, but when watching object being touched there’s no activation
number - space synaesthesia
see numbers in spatial array
small numbers on left, big numbers on right
faster responding to small numbers with left hand and faster responding to big numbers with right hand
culturally independent
what is attention
“taking possession from mind, in clear and vivid form, one out of what seem several simultaneously possible objects or trains of thought. Focualisation, concentration of consciousness.
attention as a process
selective attention: ability to preferentially process a subset of all available information
sustained attention: ability to maintain state of high alertness/arousal/vigilance
attention as resource
set of limited resources for cognitive processing
divided attention: ability to distribute attention over range of competing inputs
selective auditory attention
shadowing/dichotic listening
cocktail party phenomenon
cherry 1953-participants say very little about non-shadowed ear, participants unable to remember contents of message or tell if language changed, participants could tell if voice was male or female and detect sudden tone change
early perception model
perception -> sensory buffer -> selective filter -> limited capacity processor
filter selects information on basis of it’s gross physical properties
evidence that info beyond physical is processed:
-SCRs to words associated with shock despite not hearing word
-shadow meaningful words if channel switched
-debate over whether selection occurs early or late in processing stream
-triesman attenuation model, name is heard in attenuated channels (cocktail effect)
attentuation model
perception -> sensory buffer -> attenuator -> attentuated channel/selected channel -> semantic analysis
selective visual attention
- selectively process subset of visual input
- small area of retina capable of processing visual info with high degree acuity
- compensated for by moving eyes 2-3 times a second
- eye movement adn attention linked
- phenomenon of attentional blindness reveals how little info taken in from surroundings
- visual attention explored with parallel processing
parallel vs serial processing
parallel searches have flat, set size functions and will always spot red dot same time regardless of how many green dots around it
serial search have positive set size function
FEATURE INTEGRATION
visual search
basic feature analysis: colour/orientation/intensity, occur in parallel, targets defined by single feature will pop out instantly
figure integration: attention is visual glue, allows different features to be combined to form coherent percept
conjoint searches: positive set size function, each stimulus processed one at time in order to bind together
attention and automacy
what happens when attention not required
automacy results from extensive practice eg reading or driving familair routes
source of action slips eg taking unusual route home
automatic processing in inevitable and once activated runs to completion
divided attention
refers to doing more than one thing at a time
three factors influence extent to which two tasks can be successfully carried out simultaneously, how similar, how practised, how difficult task
never really multitasking as one task always have decreased performance
anxiety
trait anxiety: individuals differences related to tendency to present anxiety
state anxiety: psychological and physiological reactions directly to situations in moment
emotional stroop test
name colour that threat related word is written in
increased anxiety found in those with PTSD, panic disorder, OCD, social phobia, specific phobia
visual attention tasks
dot probe task
words and pictures
visual search
attention to faces in anxiety
- Bradley, Mogg, Millar 2000
- dot probe task to look at attention to different levels of face
- student sample
- self-reported state of anxiety/depression
- avoidance score for happy face decreased as state anxiety increased
- avoidance score for threat face increased as state anxiety increased
theoretical issues of biases
are biases unconditional?
is attentional bias cause or effect?
does anxiety cause attentional bias?
are attentional biases specific to anxiety
Purkis, Lester, Field 2011
- spider phobic participant found spider images distracting but not Dr who
- dr who expert didnt find spiders distracting but found DR who distracting
are attentional biases a cause
-training biases: probes consistently presented in location of threat or nonthreat items according to training groups, novel material items test for induced bias
after training avoidance for neutral threat was -5 and vigilance was 25
neuropsychology
“reverse engineering” of brain
infer cognitive functions b measuring effect on rest of system when it’s removed
neglect background
"failure to report, respond or orient to meaningful contralesional stimuli" patients often: -shave/make up one side of face -eat off one side of plate -read text on one side of page -bump into walls/ignore people on their left -unaware of difficulties "agnosognosia"
causes of neglect
stroke affecting right side of brain-parietal lobe
area most associated with neglect in sample of 20 was right side parietal lobe
tests for neglect
line bisection: mark midpoint, patients with neglect draw midpoint to the right side
picture copying: flower, patients with neglect only draw right half of flower
cancellation: circle all symbol, patients with neglect not circle symbol on left side
recovery from neglect
usually recovers spontaneously within a few weeks/months
self portrait drawings at progressive stages after stroke show recovery-draw more of left side each time
what frames of reference foes neglect operate on
egocentric reference frame; things to left of oneself
object centred reference frame; tells us how objects are processed in absence of awareness
intrinsic axis; neglect patients extract dominant axis and ignore whats on left even if not egocentric left
task: identify the gap in line image, harder to identify if left of intrinsic axis
blind sight in neglect
task: picture of house, picture of same house on fire
asked if pictures same or different, asked which house preferred
-if have neglect say pictures the same, but preferred house not on fire
-suggests unconscious processing can influence action/decision making
does neglect affect ‘mental representaton’
patients asked to draw object from memory
if have neglect tend to draw only half the numbers on clock
neglect and visual imagery
Bisiachs Milan Square experiment Italian participants asked t imagine square asked whats on the left if suffer from neglect, won't remember what was on left of square
extinction
mild form of neglect
only occurs when two or more objects presented at same time
therapist hold up two hands, if one hand is fist and other has fingers up patient can see both hands
if therapist holds up exactly same number fingers neglect patient cant see hand on left
Rees 2000
patient correctly scores 58/60 when presented in left visual field alone
patient scores 2/60 when presented in left visual field aswell as stimulus in right visual field
extinguished items still activated visual cortex despite lack of awareness
neglect is impairment of attention not perception
episodic memory
reference is to oneself organised temporally events recalled 'consciously' susceptible to forgetting context dependent
semantic memory
reference to knowledge only not organised temporally events are known relatively permanent context independent
evidence for episodic-semantic distinction
interdependence of systems makes distinction unclear
some evidence from different pathologies eg semantic dementia
evidence from semantic dementia
neuropathology: non alzheimer type degenerative pathology of polar and inferolateral temporal cortex, sparing of hippocampus in early stages
symptoms: progressive selective deterioration in semantic memory, reasonably preserved episodic memory
knowledge and language
- informs many aspects of language processing
- much more than a store of word meanings or grammar rules
- we read or listen to spoken language, use knowledge to make inferences
- ability to make correct inferences underlies language comprehension
structure of semantic memory
feature comparison model
prototype model
exemplar model
network model
feature comparison model
concepts are stored as lists of defining or characteristic features
sentence verification task: reaction time taken to verify sentence, is carrot veg, is artichoke veg? quicker to answer carrot question
limitations: few concepts can be reduced to list of defining characteristics, features not independent
prototype model
category membership not clear cut
define ‘centre’ of category not the boundary
prototypicality effect: defining characteristic
categories have graded structure, some members more prototypical than others
key claims: differ from non prototypes, examples of category most often generated are those rated most prototypical, prototypes share most features with other category members
objects categorised at 3 levels; subordinate, basic, subordinate
prototypes change with context, lose information
exemplar models
specific exemplars rather than averaged prototypes drive typicality effects easy to find specific memories of common objects compared to uncommon ones
benefit: don’t require abstraction, preserve info about variability
limitations: apply to complex more than simple categories, infer store every single example of category
network models-hierarchal nets
emphasise relationship between concepts
related to feature comparison models
key concepts: concepts represented by nodes, nodes connected by links, semantic relatedness
network models-semantic nets
key concepts: semantic distance, spreading activation, link strength or weight
evidence: semantic priming greater for ‘closer’ items, false memory effect: DRM paradigm
network model: ACT-R
theory of all cognition
-attention/visual cognition/memory/action
-declarative memory consist of propositions-smallest units of info that can be declared true or false
-more often links are activated, stronger they become
-fan effect: time to make decision increases with number of items of info associated with person or location
ACT-R assumes finite amount of activation
network models-parallel distribution
key features: neuron like nodes connected by links, concept represented by pattern of activity distributed across many nodes, links have different ‘weights’, informatin processing periods, pattern spreading activation occur at same time, PDP model allows fro spontaneous generalisation and graceful degeneration
schemas and scripts
semantic memory stores more than just concepts
schemas-generic information about situations/general rules that are typically accurate
scripts-structured, ordered sequences of events, can be prototype-abstraction
schema research highlights interplay between top down and bottom up process
thinking and reasoning
judgement: calculating the likelihood of certain events
decision making: selecting one out of number of potential options
problem solving: cognitive processes go from recognising there’s problem through developing solution
reasoning: determining what conclusion can be drawn given various statements are assumed to be true
judgement
- not wired to understand percentages/fractions
- rephrasing problems in terms of frequencies may make easier
- due to cognitive/time limitations we employ heuristics when making judgements: availability, representativeness, anchoring/adjustment
availability heuristic
used when estimate frequency/probability on basis of ease with which examples come to mind when evaluating topic
why we think we do more washing up than others
mental shortcut: rely on examples coming to mind
representative heuristic
used when events that are representative or typical of a class are assigned a higher probability of occurrence easy computation assessing similarity of objects and organising based on category prototype
anchoring and adjustment heuristic
influences way people intuitively assess probabilities
start with implicity suggested reference point and make adjustments to it in order to reach estimate
decision making
- utility theory: eliciting judgements about preference of choice based on greatest utility
- prospect theory: decision making depend on choosing among options that may rest on biased judgements
- ‘loss averse’ : pay more attention to potential loss than potential pain
- framing effect: cognitive bias-decide on options based on if presented with positive or negative connotations
- somatic marker: emotional processes guide behaviour
problem solving
- three aspects: goal directed, immediate solution not available, involves conscious cognitive processes
- three parts of problems: problem itself, things might do, solution
- insight: solution presents itself quickly and without warning
- functional fixedness: mental block against using object in a new way that’s required to solve problem
early approaches to problem solving
behaviourism: using previous knowledge to solve problem, rely on old habits
gestalt: success in problem solving influenced by how its represented in persons mind
reasoning
- deductive: conclusion based on ideas assumed to be true
- inductive: making decisions after observing repeated instances
- syllogistic: one proposition in inferred from two others
- conditional: draw conclusion based on conditional (if..then)
- valid inferences: modus ponens(made by assertion), modus tollens(made by denial)
- invalid inferences: affirming consequent, denying antecedent
- hypothesis testing: exhibit confirmation bias-seek info to confirm theory not falsify it
early distinctions of memory
primary: portion of present space of time, linked to conscious experience, retrieval is effortless
secondary: genuine past, unconscious-permanent, retrieval is effortful
atkinson and shiffrin-modal model
stimuli->sensory memory->short term memory->long term memory
sensory memory
- sensations persist after stimulus has disappeared
- subject to very rapid decay
- stores exist for visual (iconic) and auditory (echoic) sensory information
- sperlings experiments:matrix letters presented ofr 1/20th second, report as many letters as poss, only recalled 5, then played low,med,high tone wiht each row, when one tone played recall is almost perfect
short term memory: coding
- verbal info
- 3 encoding dimensions for words: orthographic (shape/pattern), phonological (sounds of words), semantic (meaning of words)
phonological similarity effect
-Baddeley 1966
-lists of 5 words
-2 control lists
-1 phonological list
-1 semantic list
more word sequences recalled correctly with phonological similarity, no effect for semantic similarity
short term store: selective damage
damage to left hemisphere; parietal and temporal lobe reduced verbal memory spans normal performance on verbal tasks intact word perception no problem with speech
working memory
- work space for solving problems
- Baddeley suggested STM has limited capacity and filling will make difficult to do tasks that depend on STM
- evidence against claim: participants could hold short string numbers in memory and carry out other tasks eg reading
definition short term memory
store fro information over short durations
definition working memory
mental workspace for holding and manipulating information ‘in the mind’
Baddeley and Hitch 1974-working memory model
working memory model
visual spatial sketch pad central executive -> phonological store
phonological store
word length effect
list of 5 words
each list increases in syllables
correct recall related to syllables
higher recall correct with fewer syllables
to remember words/number people repeat under breath
done via articulately loop
visuospatial sketch pad
evidence for separable working memory ‘buffers’
can investigate using spatial span tasks
brain damage: impairment in visuospatial memory bu not verbal memory
capacity for 7 items
necessary for holding sequence of visually guided actions
necessary for ‘seeing in minds eye’
central executive
complex, least understood
co-ordinates activities of memory buffers
no storage capacity of it’s own
supervisory attentional system
serial position curves
free recall task: list of words presented at fixed pace, subjects recall words in any order, recall plotted as function of word position
recency effect: items from end of list recalled well, filled delay at end of test abolishes this effect
primary effect: items from beginning of list recalled well
long term memory
3 processes: encoding, storage, retrieval
forgetting happen at any process
-storage failure typically result from brain damage/head injuries
-most everyday forgetting is likely to be due to encoding or retrieval failures
encoding
-repeated exposure not enough
mere exposure not enough
type of processing and level
orthographic-shallow level, poor retention
phonological-moderate level and retention
semantic-deep level and good retention
levels of processing
participants asked to make judgements about words
-words upper and lower case, rhyme with ‘plate’ fit in sentence “the … was on the road”
-given surprise memory test
-encoding as independent process, processing leading to durable memories
-deep encoding or elaboration best way to learn new material
reasoning is circular, better memory >deeper processing
encoding and retrieval
Morris 1977
- 2 acquisition conditions, semantic or rhyme
- 2 test conditions, standard recognition, or rhyme
- processing goal directed
- shallow processing task better if retrieval uses same type of processing
- transfer appropriate processing
- godden and baddeley: learn list of words on land or under sea, tested for words on land or under sea, context dependent memory
retrieval
occurs with cue
more cues there are, easier it is to remember something
recall is different depending on cue: harder when asked to describe, easier if asked ‘is this what …’
types of memory
episodic memory-events that occur at particular place or time
semantic memory-general facts and knowledge
procedural memory-skills and habits
anatomy of memory
episodic memory in hippocampus and medial temporal lobes
semantic memory in lateral temporal lobe
procedural memory in basal ganglia
types of memory:episodic and procedural
-pre training familiarise yourself with VR town or repeatedly follow same route
test: navigate to new location (episodic) or go to next place in sequence (procedural)
condition 1 activated hippocampus
condition 2 activated basal ganglia
episodic memory
long term episodic memory based on meaning
extract ‘gist’ of whats happenign and often have poor memory for specifics
memory not like video recorder
false memories
- 2 groups, ‘crashed’ and ‘contacted’
- asked 2 weeks later if saw glass
- 32% from smashed said yes
- 14% from contacted said no
Patihis and Loftus 2016
- session 1: individual differences measure
- session 2: random assignment to either suggestion group or no suggestion group
- session 3: interview
- 13.4% had false memory
- memories change over time, are fallible
- when recall information, re-construct what we think has happened
- faked information or leading questions can distort or change memories
what is amnesia
- ability to take in new information is severely and permanently affected
- intelligence and attentional span are intact
- personality is unaffected
- HM: underwent surgery for treatment of severe epilepsy, completely lost his memory or events after surgery, not recall ever having met the specialists he had been talking to after they left the room for few minutes
anatomy of amnesia
HM’s surgery involved bilateral removal of medial temporal lobe including hippocampus
amnesia normally caused by damage to medial temporal lobe or anatomically connected regions
occur in head injuries, Alzheimer’s, epilepsy
new learning
anterograde amnesia-after brain injury
HM had anterograde amnesia: severely impaired no matter what kind of memory test given, modality, regardless of test format
tests for amnesia
recognition memory test-pairs of faces and have to identify face seen before
recall test-test of visual memory, copy image, then after delay, recall from memory
typically test both verbal and visual memory
which memory systems not affected by amnesia
verbal and visual short term memory
digit span-repeating numbers
spatial span-tap same blocks as researcher
procedural memory-learn new skills, mirror tracing
priming-visually degraded images can be recognised quicker over time and practise
declarative memory theory
- long term memory splits into declarative (conscious) and implicit (unconscious) memory
- declarative memory splits into priming effects and procedural memory
- Tulving: proposed episodic memory and semantic memory is different, early research associated amnesia with episodic memory
semantic memory
- conceptual knowledge about world
- includes knowledge of meaning of words, objects and other stimuli perceived through senses, facts and associated info
- tests of semantic memory: palm tree adn pyramids
semantic dementia
- difficulty in remembering the meaning of words or concepts
- profound naming difficulties and making semantic related errors
- semantic deficits not defined to single modality
- associated with lateral temporal cortex
can amnesics acquire new semantic memories
yes:
-Jon, Kate, Beth sustained damage to hippocampus soon after birth, grossly impaired episodic memory however normal schooling, good vocab and knowledge of world
no:
-Bayley 2003
-tested new vocab in 2 adult amnesics
-each test contained one target word snd eight fail words
-not remember target word
implications for declarative memory
- evidence can acquire semantic memory provide evidence against it
- memory processes in jon, kate different as brain damage occurred early in life
old memories
retrograde means before brain injury
some retrograde memory loss almost always present in amnesia
HM retrograde for famous people generally good
test for NT-amnesic patients impaired on all retention intervals
standard theory of consolidation
coretx -> hippocampus ->cortex
overtime cortex -> cortex -> cortex
multiple trace theory
every time a memory is retrieved, it is re-encoded and new set of connections between hippocampus and cortex made
multiple connections between
standard theory of consolidation vs multiple trace theory
- no consensus about who is right
- evidence to support both theories from functional mri
- patient studies
- memories transformed over time
memory and executive function
frontal lobes are important fro straight aspects of memory
searching for right memory, checking and verifying memory is correct
confabulation
- “erroneous memories, false in themselves or resulting from ‘true’ memories misplaced in context and inappropriately retrieved or interpreted”
- provoked-normal response to a demand for info which isnt available
- spontaneous-person acts on their erroneous memories, damage to frontal lobe, breakdown in memory executive processes such as monitoring if memory relevant to now
what is dementia
describes set of symptoms that may include memory loss, difficulties with thinking, problem solving or language
- all symptoms impact behaviour
- syndrome with multiple variants with different causes
alzheimer type dementia
irreversible, progressive brain disease that slwoly destroys memory and thinking skills, eventually destroys ability to carry out simple tasks
AD, DAT, ATD, SDAT
progression of AD
symptoms typically after age 60
experience varies fro each individual and depends on factors such as genes, emotional resilience, , physical health medication and support to rely on
pathology: changes in brain
brain atrophy:
- significant tissue loss in frontal and temporal lobes and hippocampus
- 5% brain cells die each year wiht AD
- neurotransmitter production and function impaired
- major loss of cell bodies for cholinergic system in basal forebrain bundle
- abnormalities develop in proteins required for maintenance and repair
what are the abnormalities in proteins in AD
senile plaques:
-excess beta-amyloid protein, occur without clinical signs
neurofibrillary tangles
-abnormal tau protein
-density of NFT correlated better with memory loss than beta-amyloid deposition
behavioural changes of AD
AD everyday memory loss occurs in mainly omissions
- omissions (fail use milk)
- sequence (add milk to kettle)
- substitution (stir cup with fork)
- additions (blend two routines)
- spatial (wrong end of spoon)
- other (quantity errors)
recall of patients with AD
- instructed to give instructions on hwo to make cup of tea exactly how they do it themselves
- performed recall had 30 actions
- instructed recall had 15 actions
- verbal recall had 5 actions
- with interventions, number of actions from instructed recall increased to 20+ actions
risk factors for AD
- age: over age 80, 20% impairment
- genetic risk:chromosome 21,14+,19, e4/e4 alleles increase risk of AD
- most people develop AD no family history
- psychological: depression increases risk of AD, high neuroticism and low conscientiousness increase AD risk more
protective factors of AD
higher education antihypertensive drugs rich social network mental activities diet
psychobiological view of appetite
eating is consequence of physiological processes monitoring nutrient status
models can’t explain overeating and rise in obesity or eating disorders
cognitive processes implicated in eating
memory:food food recently eaten, and for foods liked
attention: responsiveness for food cues, awareness of physiological appetite signals, distraction while eating
decision making: what/when to eat. healthy choices
learning:liking of food, expectations of fillingness
perception: taste/smell, food liking, portion size
cognitive theories fro susceptibility to over eat
externality theory
restraint theory
emotional eating
externality theory
- susceptibility to weight gain in dependent on extent to whcih internal and external signals motivate person to eat
- predicted obese people be more responsive to external signals rather than physiological appetite signals
restraint theory
individuals use cognitive processes to restrict their intake due to weight concerns
cognitive restrictions of food intake predicted to lead to overeating when dietary restraint breaks down
emotional eating
in response to negative emotions, attempt to distract attention from or alleviate feelings
measure food-related attention
- food dot probe task, paired stimuli one food one control, shown fixed time, measure RT to probe, attentional bias for food cues
- food stroop task: attentional bias for food cues, slower naming colour of food related words
cognitive biological interactions and appetite
food related attentional bias stronger when healthy volunteers tested when hungry
hunger enhanced food bias found in normal weight but NOT obese participants
abberrant attention in obesity
preferential allocation of attention to food cues even when not hungry
heightened emotional response to food cues
stronger approach tendencies
overating and obesity
attentional bias for food related cues found in obese adults/children
causal factor in overeating
attentional biases for food cues in healthy people susceptible to overeating: adults with dietary restrictive, emotional eaters, external eaters
attentional biases for healthy people not susceptible to over eating: bulimic and anorexic
reducing eating by modifying attention
mindfulness: attention to food need, training mindful approach help those susceptible to impulsive responses
decision making: portion size selection, increasing portion size makes us eat 70-80% more
expectations: expected fillingness
learning: development of likes and dislikes
-born with innate liking for sweet and disliking for bitter, all other likes/dislikes learnt
flavour preferences in childhood track into adulthood-important for healthy eating
assimilation theory
contrast effect
variety influence
assimilation theory
expected and sensed sensory experience combine so actual evaluation of food closer to expectations than is seenw hen food evaluated wihtout prior expectations
contrast effect
occurs when expected and sensed sensory experience very different resulting in decrease in rated quality of food
variety influence
sensory specific satiety-decrease in palatability of recently eaten food
due to habituation to sensory properties of eaten food
decrease in desire for food just eaten while still desiring more of other foods
sensory specific satiety and obesity
evidence obese peopel show no within meal decrease in palatability for eaten foods whioe still desiring other foods
obesegenic environment full of different types of foods keeps renewing desire for food
modifying perceptions to reduce obesity
establish healthy eating in childhood
change eating environment
increase expectations that foods will be filling so small portions selected
regulate advertising high fat sugar foods
decrease variety
make all food taste same
memory and eating: healthy participants
series of studies by higgs using healthy participants
asked to think about their lunch today, yesterday or asked random non food related question
measure snack intake
-those thinking about recently eaten food reduces intake at next eating episode
memory and eating: amnesiac patients
-often eat multiple meals, memory of recent eating important factor in how much is consumed at next meal
amnesiac patients can differentiate between foods of different sweetness, memory not involved
liking of food decreased in both control particiapnts and amnesiacs
memory and over eating
disrupting encoding of memories while eating results in overeatin at next meal
memory of previous meal not accurate leads to incresed intake at next meal
sedentary activities associated with obesity
reducing intake of food by enhancing memories
focus on taste/smell/texture (food focus) leads to reduced food eaten
reading food article (food thoughts) increases food eaten
no task (control) increased food but not as much as food thoughts
obesity interventions: increase attention to experience of eating, slowing down eating rate, discouraging distractions while eating
philosophical background of volition
- concern about metaphysical constraint of determinism
- metaphysical libertarianism: claim determinism is false and hence free will exists
- hard determination: claim determinism is true and hence that free will does not exist
- incompatibilitists: choose between determinism or freewill, can’t mutually exist
- compatibilists: determinism and freewill can mutually exist without being logically inconsistent
Libet 1983 and experimental approaches
- participants watch dot rotating on clock face
- at time of their choosing they spontaneously press a button
- report where dot was when first ‘felt urge to move’
- electrodes on prefrontal motor areas record readiness potential (negative shift in electrode potential occurring before action)
- RP began some 350ms before reported ‘will’ to move
implications of Libet 1983
appears to demonstrate unconscious brain processes precede conscious decisions to act, incompatibilist might take as evidence against free will
criticisms of Libet 1983
action is trivial real ‘decision’ was to join study
time of ‘will’ is subjectively reported and may vary depending on division of attention
makes assumption about nature of RP, specifically that it reflects preconscious decision process
assess only choice of time not choice of action
EEG has limited spatial resolution so it provides only limited insight into specific brain regions involved
challenges basis of readiness potential
assumed that readiness potential reflects some form of planning or preparation for movement
stimulations recreate characteristic patterns and successfully make new novel predictions-RP may not reflect a preconscious decision process
experimental approaches Soon 2008
- participants watch stream of letters presented at half second intervals
- at time of choosing spontaneously press left or right button
- indicate which letter was present when decided to press button
- pattern classification algorithm identified areas of prefrontal cortex predicting which hand 7 seconds before decision
- represent an earlier stage in causal chain-RP also have antecedent causes
limitations of Soon
electroencephalography has limited spatial resolution but good temporal resolution
- fMRI has good spatial resolution but very poor temporal resolution
- intracranial electrodes used for evaluation prior to neurosurgery, when clinical needs coincide with those of scientific enquiry they can provide rich source of data
experimental approaches Fried 2011
- 12 epileptic patients with intracranial electrodes in medial frontal areas
- replicate ramp like increase before movement for subset of medial-frontal neurons
- time of conscious intention could be predicted by small sub populations of these
- difficult to separate prediction of intention and prediction of action
- previously pre-SMA implicated in planning and volition and SMA for execution
- SMA not pre-SMA contained more active neurons before feeling of intention
- suggest feeling of intention may correspond to moment when unconscious plan enacted-volition as ‘intention in action’
is free will and free won’t separate?
is ‘urge to move’ a simple correlate of action
sub populations of neurons decreased in activity in pre-SMA providing evidence for inhibitory component, implies supression of action and its voluntary initiation are closely linked
Fried-when applying stimulation to perfrontal areas patients report experiencing urge to move without movement being made
Desmuget-show urge to move can be created by stimulating parietal areas
demonstartes urge can exist independently of action
emerging picture
- motor cortex receives two broad categories of inputs driving voluntary and stimulus driven activity
- voluntary driven: in voluntary action the loop through the basal ganglia integrates range of cortical signals to drive appropriate actions, dopaminergic inputs from substantial nigra to striatrum provide modulation based on reward, voluntary action can be seen as flexible intelligent interaction with current and historical context
- stimulus driven: information from sensory cortices is relayed to intermediate-level representations in parietal cortex, relayed to lateral part of pre-motor cortex and ultimately onto motor cortex, guides object orientated actions such as grapsing
disorders of volition
anarchic hand
- condition where person reports that one of their hands has will of its own
- some mix terms with alien hand and anarchic hand- alien hand where they dissociate themselves from hand, anarchic refers to situation where know hand is their own
explanations of anarchic hand
- initially thought to be due to disconnection of hemispheres as some patients who have callosotomy exhibit symptom
- logically fails as it would need to result from separation between right hemisphere motor cortex and left hemisphere areas for planning and execution - anarchic hand would always be left hand in right dominant but not the case
- review of 39 anarchic hand patients by Della Sala, found that most lesions are centred on SMA on contralateral side to anarchic hand
explanations of anarchic hand
- initially thought to be due to disconnection of hemispheres as some patients who have callosotomy exhibit symptom
- logically it fails as it would need to result from reparation between right hemisphere motor cortex and left hemisphere areas for planning and execution - anarchic hand should always be on left but it not
- notion that damage to SMA impairs voluntary circuit leaving actions guided primarily by exernal stimulus cues on that side
- actions not result of second ‘will’ but rather result of stimulus driven actions that cannot be inhibited
utilisation behaviour
- damage to SMA bilaterally can result in utilisation behaviour
- utilisation behaviour is where patients show compulsive urge to use objects that are insight in automatic fashion
- symptom can be observed in dementia
- environment triggers utilisation behaviour such as anarchic hand
- those with utilisation behaviour are often not aware their behaviour is inappropriate
- don’t exhibit conflict and embarrassment that those with anarchic hand suffer
birth of psychosurgery
- introduction of antipsychotic thorazine
- lobotomies used to treat mental ilness
- after lobotomies people became vegetables, or held responsible jobs r became impulsive and childish
- lobotomies were crude and resulted in damage to parts of brain
function of frontal cortex
when given a choice of two things the ‘frontal cortex is what makes you do the harder option’
myopic discounting after medial orbitofrontal damage
- patients with brain damage to other regions have higher subjective value than those with damage to prefrontal cortex
- those with damage to prefrontal cortex change to easier option sooner than those with damage to other regions
- the more damage to area 11, the quicker you change to easy option
iowa gambling task
- subjects choose from 4 decks
- total of 100 choices
- two decks have large short term gain and long term loss cards (non-advantageous)
- two decks have smaller short term gains and long term gain (advantageous)
- subjects were patients who had sustained unilateral focal damage to frontal lobes and healthy controls
- frontal lesion subjects showed impaired decision making compared to control subjects, persist with disadvantageous decks
main substances of abuse
alcohol nicotine heroin, morphine, codeine, opioid agonists thc cocaine and other psychostimulants hallucinogens sedatives inhalants
reasons to take drugs
experimentation: novelty seeking
pleasure: drugs as desired rewards
medication: to relieve unpleasant states
peer pressure: to be cool
addiction
- latin word addictus which means “bound” or “devoted to”
- 3 characteristics: compulsive drug taking and seeking, inability to stop and high rates of relapse after cessation, why drugs more wanted and less liked
- few become addicted but many try them
what is not an addictin
experimental use
recreational use
circumstantial use
diagnostic criteria fro substance use disorders
mild disorder: 2 symptoms
moderate disorder: 4/5 symptoms
severe: 6+ symptoms
-substance often taken in larger amounts or over longer period than intended
-persistent desire or unsuccessful efforts to cut down
-craving or strong desire to use
-continued use despite social or interpersonal problems
-tolerance
-withdrawal
-recurrent use in situations in which physically dangerous
frontal function in drug users
- smaller volume of prefrontal lobe in polysubstance abusers
- PET scan of glucose metabolism, reduced OFC function in cocaine users compared to control subjects during protracted withdrawal
- iowa task: always showed impaired decision making in spite of obvious failure
- abstinent drug users and control subjects asked to perform delay discounting, drug users had to indicate which option they would or wouldnt want, controls asked to designate sooner or larger reward
- delay discounting in meth subjects: choose smaller immediate reward quicker
drugs changes in brain
-amphetamine self administartion produced structural changes lasting longer than month in limbic forebrain regions of rats
long term drug use lead to increased impulsive behaviour/loss inhibitory control due to changes in prefrontal cortex, relationship could exist in opposite direction
prefrontal model on addiction
-impulsive control -> increased likelihood of taking drugs -> drug intake -> drug induced structural in functional changes in prefrontal regions
what is template matching
internal representation, memory against visual input is matched, intuitively plausible-object recognition involves contact with ‘comparable internal form’
whats feature analysis
assume lower level features analysed first, perceptual system searches for simple but characteristic features of object, neurological evidence supports
model of object recognition: recognition by components
feature analysis in 3D
any view of object can be represented as arrangement of simple 3D shapes-geons
geons-view point invariant from 2D retinal image, invariant properties include cotermination
object recognition impaired if geons made ‘non recoverable’ by removing termination
