Imaging Flashcards
classical cognitive approach involves 3 things
- measuring observable behavior
- making inferences about underlying cognitive activity
- consider what the behavior says about how the mind works
what does imaging introduce
whole range of objectively measurable things that we can now incorporate into our investigations
Cognitive neuroscience approach involves 3 things
- measuring neural activity (and/or observable behavior)
- making inferences about underlying cognitive activity
- consider what the neural activity (and or behavior says about how the mind works
3 important considerations relevant for conducting/interpreting imaging work?
- Theoretically meaningful interpretations can be complicated
- Analyses often rely on subtractive logic, which may obscure meaningful information (e.g. what’s happening with the default network)
- Localization of function is often assumed but may sometimes be an oversimplification
within Theoretically meaningful interpretations something emerges
- Many confounds can emerge (e.g. false positive, which can become much more likely if you don’t adequately correct for multiple comparisons)
false positives can sometimes occur when
there is a large volume of data
statistical problem of multiple comparisons (what type of error)
, the more comparisons you make between various data points, the more likely you are to find a statistically significant result purely by chance (type 1)
Subtractive logic (mental chronometry) is used
used to make inferences about the differing time courses of various cognitive processes
Subtractive logic in neuro imaging (3 steps)
- measure activity at rest (baseline activation)
- measure brain activity during task (task activation)
- subtract baseline from activation
potential problem with subtractive logic
our brains are constantly active and that baseline activity may actually reflect processes that you don’t fully understand… if so, you may be ‘subtracting the background’, which doesn’t always make sense to do
default mode network (DMN)
a network of brain regions that are active at rest
properties of default mode network
Evidence for some form in many different mammals, Associated with mind wandering in humans, May have other adaptive functions (e.g. memory consolidation
localization of function
the idea that we have specific brain regions (or networks) that are specialized for certain kinds of processes
Phrenology
A belief system that attempted to relate variation in the shape of different parts of the skull with behaviour and cognition
mass action
proposed that specific functions were in fact not localized to particular parts of the brain
equipotentiality
which assumes any chunk of cortical tissue has the potential to support any brain function
plasticity
tissue in different parts of the brain can ‘take over’ for other damaged parts and effectively relocate functions, albeit there are limitations
pioneers who used EEG
Herbert Jasper
imaging methods with high spatial resolution
fMRI, PET
imaging methods with high temporal resolution
EEG/ERP, MEG
Electroencephalogram (EEG)
provides an overall measure of electrical activity emanating from the brain on the basis of the signal that reaches electrodes placed on the scalp
human brainwaves (5) from highest frequency to lowest
gamma, beta, alpha, theta, delta
application for EEG
screening for seizure activity
Event-Related Potentials (ERPs)
using EEG to measure average characteristic changes in electrical activity associated with particular psychological events (e.g. a stimulus presentation)
