principles of neuroscience and neuroimaging Flashcards
Descarte
separate res cogitates ( soul ) to res extent ( body )
res extensa works based on impulse , no need for cogitates
influenced behaviourism
Wundt
first school of psychology at leipzig 1879
supported to stop of subjectivism
used objective measures ( chronoscope)
Titchener
exported psychology to USA
structuralism : mind is the sum of its component and need to be dissected ( according to objective criteria) into components to be understood–> elementist criterion
William James
functionalism : mind processes need to be understood in relation to each other, no structuralism
Weber and fechner
weber fechner law
weber: just noticeable difference= minimum amount of change to start to percieve stimulus 50 % of the times ( varied with initial stimulus )
fechenr :generalised and found constant for this JND for different sensory modalities
Empiricist
Wundt
titchner
weber fechner
william james
Helmholtz
donders
helmholtz
measured reaction times of neural activity on frog legs
speed depended on diameter of axon and presence of myelin
donders
used mental chronometry ( abandoned since wundt )
cognitive subtraction (can subtract reaction times of different component of a process) based on pure insertion assumption ( adding a cognitive task woudl not change the performance on the already present task
Thomas willis
conned the term neurology
studied blood supply to the brain ( circle of willis )
understood gyri = more cognitive complexity
listed the crania nerve
studied many diseases like epilepsy
cortex is the basis of cognition
Localizationism
Gall
bouillon
dax
aubertine
munk
gazzaniga and spray
john jackson
cognitive neuropsychology
gall and co
phrenology –> premises : brian seem to look alike , so could be that same areas on different brains have the same function ( localizationist view)
also people with more prominent or less prominent areas could have respectively enhanced or diminished capacity in the function of that area
flourens: opposed –> performed localised lesion on animal who did not report specific damaged areas SO functions are not specific and could move
bouilland supported–> found replicated impairment in speech after frontal lesion?
dax
localised speech in left hem
the great brian debate
gratiolet : supported function to be distributed in networks
VS
aubertine ( localizationist view due to speech impairment replicated with lesion in same areas
munk
discovered role of occipital lobe in vision ( dogs with lesioned occipital could not recognise object )
gazzaniga and sparry
supported jackson role of right hem –>block test after callosotomy : right hand ( left hem for language without help of right hem for visual task ) could not perform
john jackson
recognised role fo right hem , so far not deemed important : let for language and rights for visual task )
types dissociation o cognitive neuropsychology
single : impairment in task a but normal in task y
strong : impairment in both but one task better than the other
double :lesion in areas for a cause impairment in task a but not taking b , and lesion in b causes impairment in task b but not task a
vogt
6 layer cortex
huber and wiesel
organization of V1
broadmann
Penfield
homunculus
in vivo brian stimulation to spare functional areas in cortex removal
limitation of localizatinism
not explain how it work when functions require network
no one to one correspondence between areas and function
milner
found that HM impaired memory but had intact ability to learn-> differentiate episodic form from porcedural memory
wernike
link between connectionist and localzationism : taught some areas where more important than other but function could require still a network like f or speech( realized lesion in areas in outside the focal areas for speech could still cause impairment )
connectionist
steno
newton
meynert
reil
von monakov
lichteim
liepman
lissauer
dejerine
paper
Goodale and milner
ramon y cajal
steno and newton
recognised the functional importance of white matter
reil
described the arcuate fascicles, the connection between broca and wernike
meynert
classification in three categories of white matter tracts
if wm has been kept by evolution it means it has fuction
von monakov
diaschisis
diaschis and the different types
defintion= impairment in the function of one area due to damage to a connected area
types:
commissural : impairment in homologous area
associative : damage in ipsilateral hem
thalamic cortical : cortex impairment due to thalamus
cerebrospinal : spinale impairment due to damage in cortex
crossed cerebellar : impairment in cerebellum due to cortex damage
characteristics:
can regress even completely
impairment in the target area is not due to inhibition form the connected area but due to firing cessation
diaschisis can spread to the whole networks of connected areas
lichteim
modified the model of wernike for language including different types of aphasia depending not he location on the conceptual network
liepman and lisseaur
first case of apraxia ( then found that different types corresponded to different locations )and first cases of agnosia ( lesion on connection between visual and semantic ares , object recognised but not named)
dejerine
case of Alexia without agraphia ,
papez
found a circuit of connected area participating in the same function ( initially emotion and then memory )
goodale milner
differentiated dorsal and ventral pathway of visual processing
ramon y cajal
neurons are single and separated entities
conservation laws: spur system aims at minimising the expense of resources by minimising neuronal distance and the length the the signal needs to travel
problems with connectionist assumption in simulated networks
do not replicate mechanism of the brian ( ex hormones are not taken into account )
not good for replicating high level complex processing
do not include different types of neurone
assume the mechanism of the brain are the same as the simulated ones ( like back propagation)
the time and number of learning cycles in a simulation is unrealistic for a brain
holism pros and cons
pros: lashley , webb, duncan ,
cons : sperry
general fundamentals of holism
- brain is a whole -> impairment in one area means impairment in the whole brain ( difference with connectionist )
- critics connectionist to be localizationist but for networks instead of brain areas
- functional recovery after lesion
hebb
repetitive firing of neuron a to neuron b will make the connection more efficient thought physical and metabolic change
Laschley
coined neuropsychology
law of integration: brain is more than the sum of its parts
law of mass action: Amount of cortical tissue removed is proportional to deficits in memory. Therefore, memory is not localized to one area but distributed across the cortex.
law of equipotentiality: a small part of a brain area cna take the fucntion of the whole brian area
law of equipotentiality
a part of a brain area can carry out the function of the whole brain area
good: explain recovery of function
bad : could just be plasticity , not everyone recovers function
law of mass action
memory impairment extent depends on the amount of cortical tissue removed
but after big removal task could be impossible due to removal of other functional areas like attention
duncan
discovered a frontoparietal network, Multiple Demand System, involved in many different task that could adapt to changes in task requirement on the fly
supported that a process sis formed by many different subtask that could be individually solved -_> the task should then be not only the sum of the subtask but also the organisation of the subtask carry out
sperry
many commissurotomie–> found that some areas are strictly localised in one hemisphere ( after lesion , some function are lost due to loss of connection between hem)
connectom definition
a matrix that represent all possible connection between brain structures,
Watts and Strogatz
concepts of graph theory :
nodal degree: how many nodes
clustering coefficient: how probable for two nodes connected to a common node to also be connected between each other
characteristic length path : average minimum numebr of edges to connect two nodes ( integrative capacity )
betweenness centrality : how many shortest path does a node have –> capacity tot influence the network
three class of graphs
regular . long path high clustering
random. : short path low clustering
small world: e.g. brain–< good balance
problems with graph theory
no standar pipeline
convergence of data coming from different sources can alter result
generally not demonstrate
phylogeny and ontogeny
phylogeny : the tduy of brian evloiution
ontogeny : the study of brin development in single individual ( form embryo on )
haeckel
ontogeny replicates phylogeny–> brian development si a fast version of brian evolution
hourglass model : all species reach a common stage form where they depart with development in adults form
how to study brain evolution
brain volume: first we have to determine at what period a skull is dated ( carbon 14 ) and then we use enbocast to recreate what a brian would have been in that skull
genome phylogeny : compare genome section to those of other species–> the more genes in common the closer the species to human in evolution
different paths of brian evolution
concerted: brai structures develop coherently at same pace indecent of the function
allometric: brain develops as a whole but some structure after than other depending on their function base don evolutionary pression
mosaic: one area or network could evolve on its one while the rest of the brain does not, again based on evolutionary selection of function
hypothesis regarding what makes human brain different from primate brian
prefrontal cortex : the biggest increase along evolution BUT proportion is the same as monkey s comapared to the rest of the brian
connectivity : human have more white matter than primates
slow brain development : woudl allow for more experience shaping the connection , so more complex functions
variability grey and white matter : based on the assumption n that the more variable and areas is the newer in the evolutionary terms is
gradient and hierarchy
gradient : vector along which the faction changes on a continuum
ex–> sensory cortex
hierarchy : vector along with the function increment in complexity
ex: visual cortex
possible organisation fo prefrontal cortex
fuster
miller
badre
fuster
cortex divided in fontal areas for executive function , temporo Parieto and occipital for sensory , both work together for integration
evidence: delayed response to cue task showed activation of both frontal and posterior areas , showing both are involved and cooperating
Milner
pcf role is to extract rule from stimuli
evidence : most lateral PFC neurons reflect the association between a cue and reward
badre
anterior are to more distant representaitonin time, posterior to more temporally close representation
problems : tf sequential actions can be represented simultaneously in a single layer neural network
problem with hierarchies
representation might hood but function might not be actually happening in hierarchies
Botvinick & Plaut (2004) demonstrated that goals and subgoal representations of sequential actions can be represented simultaneously in a single layer neural network
hierarchies putting front poplar cortex at teh top
domain generality
relational complexity
cascade model by koechlin
badre additi0on to koechlin
domain generality
caudal to rostral axis where info about stimulus become from content based to domain independent
relational complexity
caudal to rostral axis in pfc where the function goes from
1 step : concrete features = recognise rules about the stimulus properties
2 step : first order relation= evaluating since relationisp
3 step : second order relation = comparison among relationship
cascade model by koechlin
4 step caudal to rostral axis :
1): sensory control = simple motor response
2 ) contextual control = in different cortex to modify or withhold motor response
3) episodic control : use previous info form memory to adapt new response
4) branching : integration of all previous steps
evidence : in a branching task ( where a dual task and delayed task instruction and both to be followed at th same time ) the only active area was the fronto polar cortex
badre additions to koechglin
pfc is in charge of making a decision between competing repossess ( like in koechlin ) but the hierarchy os more a continuum than a fixed step by step process, and the implying of one areas is dictated by demand of the situation
mesulam
we have independents modality specifci hierarchies working in parallel ( ex , auditory , motor , etc) , that then coverage in a multimodal hierarchy for complex processing
mergulis
corroborated mesulam theory of lower level domain specific hierarchies and a higher integrative hierarchy he called the Default mode network
anatomical brain asymmetries
brian torque
Sylvia fissure symmetry longer on the left
arcuate fasciuclus more volume on left –> predict speech recovery form stroke
planum temporale–> volume lateralisation prediccts language dominance
opercular area–> more lower level dendrites in right , and more higher level dendrites in left
right functional asymmetries ( lateralisation)
- episodic memory retrieval ( HERA model )
emotion ( chimeric faces more emotional on left visual field ) –> generally rich hem involved in initiation withdrawal maybe residue of evolutionary perception of danger
- non verbal stimuli ( compared to content of verbal stimuli that is not lateralised
- spatial attention: the dorsal stream is not lateralised, the ventral is –> neglect area can be isolated form everything else in right hem (posterior parietal )
- monitoring (ROBBIA model ) –> task performance , error correction
left lateralisation
episodic memory encoding ( HERA model )
criterion setting ( robbia model )
language : chose one with each hand , coherent picture for another image presented on two opposite hemeifield ( ex they see an egg and chose a chicken ) –> split brain patient could not answer why their left hand ( right hem without connection to left hem for language )
evidence of left PFC on criterion setting
vallesi 2015. : so far monitoring was tested only on verbal task –> so they tested with non verbal task that changed criterion–> left PFC was active when task switching ( so monitoring new rule )
diffusion model: the bigger teh distance between the upper and lower limit ( “difficulty” in decision making) the more the left Pfc was active
brain tumour: people with left hem affected had difficulty in task criterion switching
Langdon and Warrinton ( 2000 ), Vallesi, Arbula, Capizzi et al., (2015)
and Babcock & Vallesi, (2015): left PFC was involved both in spatial and verbal tasks but right PFC in spatial only –> confirm role of left PFC in criterion setting independently of the modality
evidence of right lateralisation for monitoring
(Woodrow, 1914): in people showing fore period effect ( preparing for an upcoming stimulus the more time passes form a cue ) had higher right PFC activation for the cases in the foreperiod paradigm had higher preparation for upcoming stimulus so long fixed period and short variable period
people showed hiegrh right activation pin PFC for degraded verbal marie rial compared to integer one , reflecting higher need for monitoring in degraded
domain independecw : both in retrieval o verbal cues and visual proportion estimation higher right PFC activation correlated to lower confidence that could ,had to higher monitoring
modes of interhemisheric interaction
insualtion
inhibition
cooperation
interhemisperic cooperation
the high the task demand the more beneficial cooperation is because :
can use more resources and allow parallel processing
insolation
= the connection between hemisphere acts a s a barrier to prevent interference
having contrasting task presented in opposite field has lower error rates than when they are presented in same hemifield
inhibition
connection causes interference
there is evidence of more metabolic activity in unilateral condition than bilateral –> should be the opposite since in bilateral activity we should have more metabolitc activity , but since they inhibit each other two side active are actually less active than one
roland
found that after callorsotomy there was still some interhemispoehric activation in homologous sensory areas –> less dependent on higher processing connection
ALSO
frontal areas ( of higher processing ) showed still some activation in partial callososvomy whcih still involved removal of frontal part of cc–> there must be other tracts supporting these regions
does lateralizations in different function happen together ?
does not seem so-_> ex language seem left lateralised but in left and right handed people
why is lateralisation evolutionarily useful
could optimise resources of space ( more areas taking care of some function is a waste of space )
could have been necessary to have specialized areas to support diversity and richness of human cognition
neuroplasticity
the change in anatomical or functional change in organization fa brain area due to experience or riadaptation after brain insult
rosezweig
found that rat sin enriched environment had increased brain weight–> later found that human increase in dendrite lengths and number of synapses
ambiome : the set of environmental et of physical, psychological and cultural factors that change the biochemistry, anatomy, and physiology of the brain during the lifespan of an individual or can determine the clinical expression of a disease
kendel
studied long term changes in neuronal organisation
habituation eld to almost disappearnce of neuronal connection
sensitisation instead produced physical streghtenign of the connection by increasing the number of terminal so that synaptic transmissions more efficient and causing long term memory of the stimulus
structural neuroplscticity effect
increasiin grey matter due to learning a new skill or due to increasing the experience with that skill ( hippocampus in taxi drivers )
better white matter integrity in language areas after learning new grammar rules
types of functional neuropalsticirty
homologous area adaptation: eh fuctnion of damaged areas is adopted but its omologous , diminishing the activity of the homologous area–> child with language parietal damage had the areas for number adopt the lost function but it developed discalulia
cross modal reassignment: united area due to body damage adopt different function-_> in blind people the visual areas start to adopt tactile function ( reading braille )
map extension : a function enlarges its cortical area due to learning and when new skill is absorbed the critical map readjust to original size
compensatory masquerade : no damage , a brain region simply takes on another function –> the posterior to anterior shift in old age
maladaptive plasticity
plasticity cause wrong rewiring could cause
slowing recovery of lost function
reorganisation of somatotopic maps ( face sensation function invading hadn’t sensation function if hand not used )
development unwanted symptoms
ex: tinnitus =hearing a sound not present when people have impaired hearing ( due to other frequencies invading the area for lost one ) —> can be fixed with plasticity filtering out the lost frequency to sound stipulations that cortex reorganised correctly
what we witness in aging
decrees fluid intelligence
maintained crystallised intelligence
higher variability between subject on same task
cognitive dedifferentiation: higher correlation between performances in different task
possible mechanism that explain cognitive decline with age
lower processing speed: by the time people carry out the higher level of processing the lower level products of processing are not available anymore
loss of inhibitory control : older are less efficient to filter out irrelevant information –> ex pay as much attention irrelevant images in active task than to general image in passive viewing
decreased sensory perception–> this leaf to worst prformance in working memory
worse sensory perception.–> age explains all of sensory perception decrease with in turn would eb a better predictor for all cognitive decline
neurological physical problems :
- atrophy
- lack of dopamine due to dysregualtion of receptors –> can cause impaired reward association problem and impact working memory
possibilities of how hearing loss could explain dementia
plain common cause
higher activity go brain due to compensation could spread the problem at molecular level
diminished sensory input could affect cognitive reserve directly ( other than through dimished sociality )
compensatory high activity could occupy resources needed
how is impaired inhibition an advantage for older people
