Neuroscience Flashcards
what did psychologists learn from the case of phinneas gage
damage to frontal lobe lead to major selective changes
showed psychologists specific areas = specific functions
why do we study the brain
knowing when + where cognitive processes occur helps us understand them
understanding and treating neurological disorders
create therapies
how do we measure language when and where
event related potential info in graph
e.g hear unexpected word 400 ms later get the N400 which helps us understand how prediction works in language.
what is the aim of cognitive neuroscience in clinical practice
understand neural basis of behaviour = understanding cognitive disorders and predict effects of damage in brain
basic understanding of neural processes can have unanticipated applications
how can vegetative state patients use fmri
they are not thought to be able to respond to their environment, are they conscious? The idea is they cant respond to their environment. But this study asked them to do tasks such as imagining walking around their house, they recorded activated regions of the brain similar to those of healthy objects. They got them to do different tasks as a response for yes or no. showed using fmri can communicate with patients in a vegetative state, not all patients responding this way but some responded reliably. Revolutionary study allowed them to communicate when they couldn’t through physical action. Clinical application that came out of this science.
when designing an experiment to investigate neural activity how can we do it
change behaviour and measure effect on brain - stroop test ask them to read the word then to say the colour
change state of the brain and measure the effect on behaviour - make temporary lesion then look at effect on behaviour
describe a recording study
manipulate the brain and record whats goin on in the brain. Does it get activated in the same way as when you actually do the action as to when you process the word. Desing exp give people some action words to process in some way and make a decision about it, then compare to some non action words that are similarly sounfing. Go in Fmri scanner and measure brain activation in the brain when process both types, compare the activation in the two conditions, motor cortex activated when presented with action words
what are the results from the recording study on action words
reading action words is correlated with greater activity in motor cortex
inference when people process an action word they simulate the action and this helps them understand the word
how do we determine if the activation is necessary for the comprehension of the words.
an interference study
determine if activity is optional or part of the comprehension process. Manipulate the status of the brain compare people with damage to motor cortex to people without damage to the motor cortex as controls. Observe behaviour of patients performing the task, same paradigm same material, might find the results above. Control for alternative explanations, make sure its action words not all words. etc
what can we conclude from an interference study
damage to the motor cortex is associated with impaired action word understanding
inference = activation of the motor cortex is necessary to understand action words
if we assume no other diff between groups that could have caused it
IV, DV causality for recording vs interference methods
Recording:
Iv = behaviour or cog process
DV = brain activity - EEG/MEG blood flow
causality = correlational
Inference:
IV = brain damage lesion or brain stimulation
DV = behaviour or cog process
permits causal interference
strength and limitation of interference studies
strengths = allow stronger inference about necessity of a brain region
limitations = plasticity and reorganisation
strengths and weaknesses of recording studies
greater flexibility in experimental design often richer source of data
sample across whole brain with high spatial resolution
sample at high temporal resolution
is converging evidence from different types of measurement viable
strong theories are supported by converging evidence from multiple techniques
comparing results from diff types can also reveal limitations in the theory
or in the method being used
causes of brain damage from selective to diffuse
surgery brain tumour stroke traumatic brain injury neurodegeneration
describe in more detail the causes of brain damage
surgery - remove specific part of the cortex to prevent seizures.
tumour - grows and damages the tissue around it.
stroke - damages the blood supply to the brain blocked or haemorrhagic stroke where the wall of the blood vessel bursts and leaks so blood doesnt get to the brain and therefore cells die
traumatic brain injury - cu = initial place of impact and contra cu is the site of impact after the brain has moved in the skull.
neurodegeneration = diseases e.g alzheimers slowly damage brain functioning
what are the two approaches to neuropsychology
classical - mapping brain areas to cog functions
performed at group level typically
good at answering clinical questions
cognitive neuropsychology = determining whether functions dissociate under damage - evidence for distinct cognitive processes
rely heavily on single case studies
focus on cog processes
doesnt require info about where the damage is
difference between reading non words and irregular words
Read non words due to knowledge of alphabet sounds. Irregular don’t follow usual letter sound rules but are real words. Does brain use two diff systems whne reading diff types of words. Look at a dissociation in a single patient to start with.
how do we build a single dissociation for non words and irregular words
patient x reading impairment of irregular words, can read non words
inferences - x has damaged a neural system responsible for reading irregular words but not nonwords
reading irregular words requires a different cognitive system to reading non words
what is the problem with a single dissociation
what if they are in the same cognitive system but reading irregular words is just harder
how to tackle the problem with a single dissociation
do a double dissociation - compare x with y who has impaired non words reading but intact irregular word reading
rule out task demand as an explanation
damage to diff neural systems can selectively impair either irregular word or non word reading
does finding patients that are equally bad at non words as they are irregular words does this undermine the double dissociation
not necessarily because these patients may have damaged another neural system that is necessary for both types
or damaged two different systems that are close to each other in the brain
what are the assumptions applied to a single case research
fractionation - brain damage can selectively affect different cog/neural systems
transparency - brain lesions can affect existing cognitive systems but do not create new systems
universality - all cognitive systems are basically rhe same
what are the issues with the assumptions
fractionation - neural specialisation can occur and is a basic principle in cognitive neuroscience
transparency - existing systems can be reconfigure due to neural plasticity
universality - individual differences in how people perform different cognitive operations
how are individual differneces applied to neuroscience
people vary in cog abilities and the strategies they use to solve problems
same brain damage can affect people differently
what have psychologists interested in the reading domain investigated for years
non words - use knowledge of orthography - rules of english
irregular words this doesnt work - how do we read irregular words is debated
what are the two models of reading that have developed from the debate about irregular words
connectionist triangle model
dual route cascaded model
describe the connectionist triangle model
to read irregular words correctly we have to activate their meanings for the correct pronunciation meanings are semantic
describe the dual route cascaded model
to read irregular words we dont have to activate meaning we use lexical representations instead. this means a mental dictionary remembers that the letter form is pronounced a certain way and is separate from meaning
is there evidence against the connectionist model
there is a single dissociation between irregular reading and semantic knowledge -patient EM impaired semantic knowledge spared irregular word reading suggests semantics not necessary but is this enough
what is the alternative explanation to the evidence against the connectionist model
woollams et al. argued that occasional single cases did not invalidate theory
claimed that although semantic knowledge is needed in irregular words there were ind diff in how much people rely on the semantic route
some are skilled at reading dont need semantic system
em could be one of them as she was a secretary
is there evidence for the connectionist model
woollams et al - discovered strong association between irregular reading and semantic knowledge
100 obs in semantic dementia
poor irregular word reading
suggests semantics needed
but what if patients have damage to separate semantic and lexical systems that are close to each other
who criticised woollams explanation for the single dissociation
coltheart et al argued it was a post hoc explanation applied to patients who dont fit the semantic model
not good enough - theory needs to predict in advance who will show an association and who will show a dissociation
illustrates issue with single case studies \individual diff clouding the view, cant see how exactly the cognitive system has changed.
if a patient has a cog deficit and damage in a particular brain area can we infer that region is the only one necessary for the cognitive def
no - two problems with this
specificity of behaviour and specificity of the lesion
explain the problem of specificity of the behaviour
rarely a 1:1 mapping between cognitive abilities and brain areas most abilities involve multiple processes supported by a network of brain regions
to link damage to a particular cognitive process we need to assess how specific the behavioural deficit is
explain the problem of specificity of the lesion
Brain lesions not always very specific can include multiple areas and need to map the brain lesions.
are lesions specific or random
neither - Stroke and middle cerebral artery results in interruption of blood supply which supplies a lot of areas in the frontal and temporal lobe, lots of damage in diff areas. Set of areas compromised, referred to as perisylvian cortex as its near the perisylvian fissure. how do we tackle this - Move away from single case to larger groups of patients so can study relationships between them and look at statistical significance between the damage and behaviour.
how do we tackle lesions being neither specific nor random
Move away from single case to larger groups of patients so can study relationships between them and look at statistical significance between the damage and behaviour.
how do we map lesion symptoms
acquire structural scans of patients - 50 or more, identify areas and then combine them to make the lesions overlap. Automated algorithms can look over the scans and identify the areas of damage. Individual brain lesions over the top of each other on a brain map. can then identify areas of high overlap red = more overlap
what area were lesions mapped to study reading
poor irregular word reading correlated with amount of damage to the anterior temporal lobe
