3.3 neural processes: brain regions and neural mechanisms Flashcards
what are 4 research methods to determine brain regions involved in WM?
- lesion studies
- functional neuroimagin studies (fMRI, PET, EEG)
- neurophiosological studies (extracellular recording of neurons)
- neuromodulatory studies (reversible inactivation or electrical stimulation of brain regions)
how is a sensory representation built?
sensory receptors
early processing stations
thalamus
primary sensory corticies
association cortex
role of PFC in WM?
central executive (focuses attention, ordering, inhibiting)
does not store content of WM
reciprocally connected to more posterior sensory regions of the brain
role of dorsolateral PFC in WM?
focuses spatial attention
role of ventrolateral PFC in WM?
left = phonological loop
right = visuospatial sketchpad
role of parietal cortex in WM?
spatial WM
holds the contents of WM, connects with PFC which controls these contents
right side = spatial info of objects in left visual field
left side = processes verbal info
role of temporal cortex in WM?
lateral temporal cortex = verbal WM
temporal cortex = visual WM
role of temporal cortex in WM?
verbal and visual WM
no spatial WM
role of hippocampus in WM?
HM had no hippocampus but had unimpaired WM
medial temporal lobe (MTL) may be involved when task demands exceed WM capacity
how has the neural mechanism of WM been elucidated throughout history?
history: higher mental functions belong to psychology and philosophy
discoveries: place theory, persistent activity in PFC in subject with no sensory stimulus, and later, state theory
what is PA?
persistent activity
- continuous firing of neurons during a delay period in the absence of a sensory stimulus
- first found in the PFC, now in other areas too
2 conditions for PA?
- PA must be stimulus-specific
- PA must be able to predict WM errors (PA interference should affect WM)
3 methods that provide evidence for PA?
- neurophysiology: continued spiking in neurons
- EEG: signal obserrved above certain brain regions
- fMRI: increased blood flow to regions of WM
who first recorded PA? how?
fuster & alexander, 1971
behavioural task
- rhesus monkeys were single-unit recorded during a delayed response task (cue, delay, response)
observations
- sustained firing of neurons in PFC into the delay period
- PA observed in some neurons that didn’t respond to the cue
implications
- persistent stimuli-specific firing = sensory info is still being coded in its absense
what did EEG studies reveal about PA?
EEG = global electrical activity
after presentation of an event, an event-related potential (ERP) can be visualized
visualize ERP by averaging activity across several trials to minimize noise.
EEG signals show synchronized activity of large populations of neurons = indicates level of alertness (commonly gamma rhythms in demanding tasks)
