4 - Investigating the Brain Flashcards
describe structural brain imaging
knowing the physical components in the brain, where they are to describe structure in detail
disadvantage of structural imaging
may not know what the component is for
what does structural imaging help to localise
changes in white (myelinated axons) matter and grey (neurons)
describe functional brain imaging
knowing the roles of brain regions and how areas work together
define direct measurement
directly measuring electrical activity or consequences of the activity in the brain
examples of electrical activity measured
post synaptic potentials
action potentials
how does the cap in EEG collect electrical activity data
macroelectrodes detect minute electrical changes across scalp’s surface then eephalogram created
what do EEGs show about electrical activity
frequency (divided into EEG correlates) and location
what does alpha data represent
visual and mental effort
what does beta data represent
motor control changes, alertness, wakefulness, anxious thinking
what does gamma data represent
cognitions, neurons linking cognition and motor function
what does delta data represent
sleep
what does theta data represent
alertness
mental activity
advantages of EEGs
relatively cheaper
good temporal resolution as neurons firing detected instantly
non-invasive, comfortable for children to use
portable
disadvantages of EEGs
can’t measure deep-brain electrical activity
poor spatial resolution so can’t pinpoint areas
describe magnetoencephalography
SQUID sensor detects weak magnetic field of current produced by APs in axons of cortical surface of the brain to map active regions
direct methods
EEG
MEG
indirect methods
fMRI
PET
DTI
advantages of MEG
good temporal resolution
good spatial resolution for sperficial brain parts i.e. cortex
what are the general disadvantages of MEG
poor spatial resolution for deep brain
not portable
v expensive
have to put head in machine so uncomfortable
specific disadvantage for MEG
if sensor and magnetic field aligned incorrectly then info can be missed
define indirect methods
picking up signals indirectly related to action potentials
how do fMRIs work
go into a tunnel to measure changes in local blood flow, volume, O2 consumption
describe the haemodynamic response
o2 flooding to area where neurons fired to support it and levels dropping below baseline when neuronal firing stops