l3- methods for studying teh brain Flashcards
1
Q
particpant population
clinical populations
A
- ppts w brain injuries or nuerological disorders
- eg parkinsons disease affecting basal ganglia
2
Q
ppt populations
neurologically intact ppl
A
- ppts w no brain damage; used to study how the brain functions under normal conditions using non invasive methods
3
Q
ppt population
animal models
A
- non-human subjects used in neuroscience
- allow for invasive techniques n more control
- ethical issues+ limit study of complex cognition
4
Q
lesion method
lesion method
A
studying brain function by observing deficits after damage to specific brain regions
5
Q
lesion method
brocas area lesion example
A
- damage to brocas area (BA 37) in Left hemisphere impairs speech production but not comprehension
- suggests brocas area is necessary for speech production (reverse inference)
6
Q
lesion method
lesion causes
A
- can be accidental (eg stroke/trauma) or surgical (eg epilepsy treatment)
7
Q
lesion method
lesion localisation methods
A
- autoposy (limited by brain reorganisation)
- known neurosurgery
- brian imaging (eg MRI,CT)
8
Q
lesion method
single case vs group studies
A
- single case: in depth, hard to generlise
- group: confirms brain behvaiour links, variability in lesion locations=challenge
9
Q
lesion method
strengths
A
- shows casual links between brain regions n specific functions
10
Q
lesion method
limitations
A
- identifies only 1 region
- variability in lesion location
- brain reogranisation or compensation may occur
11
Q
animal lesion studies
animal lesion studies
A
- surgical removal of brain regions in trained animals to assess behavioural changes
12
Q
animal lesion studies
advantages
A
- controlled lesion location
- compare before vs after, or to sham group
13
Q
animal lesion studies
disadvantages
A
- ethical concerns
- animal human brain differences
14
Q
anatomical imaging
anatomical imaging
A
- originally for locating lesions; now also used to correlate anatomy w behaviour
- eg brain size w traits
15
Q
anatomical imaging
computerized tomography (CT)
A
- uses xrays- creates 3d images
- measures tissue density- diff in skull, brain n blood but little diff in white n grey matter
- spatial resolution ~ 1cm per voxel
- invasive (ionising radiation)
16
Q
anatomical imaging
magnetic resonance imaging MRI
A
- uses radiofrequcny waves to excite hydrogen atoms
- captures emitted signals to create images
- fine spatial resoltion (~1mm)
- non-invasive
17
Q
anatomical imaging
diffusion weighted MRI
A
- measures water diffusion direction
- it diffuses along axon in white matter
- used to map white matter structure
18
Q
anatomical imaging
diffusion tractography
A
- maps white matter connections by following water diffusion paths
- identifies brain fascicles between regions
19
Q
functional techniques
functional techniques
A
- measure brain activity during tasks either elctrophysiological (direct) or neuroimaging (indirect) methods
20
Q
functional techniques
electrophysiological techniques
(EP)
A
- record electrical activity like APs or PSPs
21
Q
functional techniques
neuroimaging techniques
A
- measure metabolic activity (blood flow, glucose/oxygen use) linked to neural activity
22
Q
functional techniques- EP methods
single-neuron recordings
A
- microelectrodes record electrical activity from individual neurons
- highly invasive, mainly in animals
- reveals receptive fields n stimulus preferences
23
Q
functional techniques- EP methods
EEG
A
- records electrical potentials from scalp
- measure PSPs from neuron populations
- good temporal but poor spatial resolution
24
Q
functional techniques- EP methods
event related potentials (ERPs)
A
- averaged EEG responses to repeated stimuli
- reveal stages of sensory n cognitive processing
- eg emotional pictures elicit stronger erp 400 ms after stimulus
25
ERP example study
schupp et al 2000
- ppts presented w neautral, pleasant n unpleasant pictures
- erps r more positive for pleasant n unpleasant pics then neutral pics, 400ms post stimulus
26
# functional techniques- ep methods
MEG (magnetoencephalography)
- measures magnetic fields from brain activity
- uses squid sensors
- slightly better spatial resolution than EEG
- still non-invasive
27
# functional techniques- NI methods
PET
- inject radioactive tracer
- measures blood flow, glucose or NT use
- invasive n poor temporal resolution (~1min)
- spatial resolution ~1cm per voxel
28
# functional techniques -NI methods
fMRI
- measures oxygenated vs deoxygenetaed blood
- reflects hemodynamic reponse not direct activity
- good spatial (~3mm) poor temporal (1-10s)
- eg memory encoding activites LIFG n temporal regions
29
fMRI eg study
wagner et al 1998
- ltm n brain areas study
- ppts lie in mri scanner
- shown words to remember
- asked to recall later
- some regions respond more to words that were later remembered:
- the LIFG and parahippocampal n fusiform gyri (in temp lobe)
30
# functional techniques- NI methods
Functional near-infared spectroscopy
- NRI light measures blood flow in superficial cortex
- also reflects hemodynamic response not neuronal activity directly
- non-invasive, portable, but limited to outer brain regions
- temporal resolution ~ 1-10s
- spatial res= few cms, only records from superficial cortex between light source n sensor
31
# non- invasive brain stimulation methods
why use brain stimulation?
- recording shows correlation
- stimulation shows causation (if altering activity changes behaviour)
32
# non- invasive brain stimulation methods
example study
- letters presented on screen
- TMS applied to visual cortex at diff times before/after presentation
- ppt reports letter presented
- result: accuracy decreases if TMS applied 80 to 120 ms after letter
33
# non- invasive brain stimulation methods
transcranial direct current stimulation
- applies weak electrical current between electrodes
- anode+: excess (depolarises); cathode-: inhibts (hyperpolarises)
- poor spatial resolution
- superfical cortical regions
34
# non- invasive brain stimulation methods
transcranial ultrasound stimulation
- uses ultrasound pressure waves to affect deep brain activity
- more precise than TMS/TDCS
- very new method w unknown mechanisms
35
# non- invasive brain stimulation methods
transcranial magnetic stimulation
- magnetic pulses disrupt activity in specific brain areas
- eg visual cortex TMS affects letter recognition if applied 80-120 ms after stimulus
