cognitive neuroscience Flashcards
phinneas gauge
- survived an explosion and recovered fairly well
- despite severed optic nerve, had a strange lack of injury and cognitive damage
- however, his behaviour and personality changed extremely after the injury
- he went from being quiet, responsible and well liked - to erratic and unreliable
what is EEG and how to do it
place electrodes on scalp and record changes in electrical potentials caused by neural firing in brain - potentials are only around 2-10 microvolts
to generate a measurable response, a very large number of neurons would have to fire at the same time
cause a temporary deficit in a healthy brain which is used to measure the differences in performance of a cognitive task before and after the deficit
has poor spatial resolution - typically use 32 or 64 electrodes, because signals are conducted through the skulls so hard to determine where the neural activity is happening
good for knowing when neural activity takes place
signals are noisy - measures tiny signal that have to compete with many sources of noise (like random neural firing and activity for eye movements and facial muscles, interference from equipment) - signal to noise ration for single experimental event trail is poor (studies average measurements over number of trials)
why should we study the brain
psych - study of mental processes and behaviour
knowing when and where cognitive processes take place in the brain helps us to understand the nature of these processes
can be important for treating and understanding neurological disorders
cognitive neuroscience in theories of cognition
knowing when and where effects occur in the brain can constrain cognitive theories of those effects
e.g. the n400 is an electrophysiological signal that occurs when we hear an unexpected word (widely used to study how and when prediction occurs in language - the brain process the strange word roughly 400 ms after it has been said
cognitive neuroscience in clinical practice
understanding of the neural basis of behaviour allows us to understand cognitive disorders and predict the effects of damage on the brain
sometimes basic understanding of neural processes can have unanticipated applications
e.g. using EEG or fMRI to evaluate patient’s awareness/consciousness or even communicate with them
what are the 2 ways if investigating neural activity and cognitive functions
- change the behaviour and measure the effect on the brain
- change the state of the brain and measure the behaviour
what is a recording study - example
give the brain a stimulus (like a word) and look at where is activated in the brain as a response to the stimulus
for example if you read an action word (verb) there may be greater activity in the motor cortex when patients read this word so you could argue there is a correlation between the motor cortex and reading action words
an inference of this - when people process an action word, they simulate the action to help them understand the word
- but we don’t know is the simulation is necessary to understanding the word
what is an interference study - example
they are better for finding causal relationships
looking at a damaged brain to see if an impaired activity (like word understanding) is related or associated with the part of the brain that is damaged
for example, if patients have damage to their motor cortex, they may have an impaired understanding of action words
an inference of this - activation of the motor cortex is necessary to understand action words
- you must then assume there are no other difference between the 2 groups that could have cause the effect
recording methods
IV - conditions that manipulate behaviour/cognitive processes
DV - brain activity (EEG/MEG, blood flow fMRI)
causality - correlational technique
interference methods
IV - lesion and brain stimulation (conditions manipulating behaviour as validity check)
DV- behaviour or cognitive processes
causality - permits causal inference
are interference studies better
they do allow stronger inference about necessity of a brain region/causality
but they have limitations such as plasticity and reorganisation of function
are recording studies better
can allow for greater flexibility in experimental design and often richer sources of data
- you can sample across multiple brain regions with high spatial/temporal resolution
- sample at a very high temporal resolution
but cannot make causal inferences
converging evidence
comparing results from different techniques can reveal limitations in a theory
- can also reveal areas for improvement in applying analytical techniques to recorded data
what famous cases are most widely used in develop theories about brain and cognition and what areas did they supplement
phineas gauge - behaviour and planning
broca - language
hm - memory
df - vision
classical neuropsychology
mapping brain areas to cognitive functions
typically performed at group level
good at answering clinical questions
cognitive neuropsychology
determining which functions dissociate under damage - evidence for distinct cognitive processes
often relies on single case studies
focus on cognitive processes
doesn’t require information on location of damage
single dissociation - reading example
patient x has reading impairment
ability to read irregular words is impaired (like aisle) but ability to read non words is spared
how to draw inferences from single dissociations - reading example
x had damage to a neural system that is important for reading irregular words but not non words
reading irregular words require different cognitive/neural system than reading non words do
but what if reading irregular words is just harder than reading non words - well if this were the case, both types of reading would rely on the same system and damage to system would affect irregular words more
