L9 - Techniques Flashcards
Temporal resolution
the precision of measurement of brain activity in time
Spatial
the precision of measurement of brain activity with respect to space
Invasiveness
the degree to which the brain is directly and physically affected
Macroscopic
visible to the naked eye
meters & centimeters
Mesoscopic
On a scale between microscopic and macroscopic
millimetres
Microscopic
so small as to be visible only with a microscope
micrometers & nanometers
The scientific method
~ observations (data) ~ explanation of model/theory ~ predictions ~ experiment ~ repeat
Active experimental conditions
subject performs a cognitive task while brain activity is being measured
e.g. detection
Passive experimental conditions
subject sits passively and performs no task
e.g. sleep
Use of lesions
~ to localise different brain functions
~ dame to brain = cognitive impairment
LIMITATION: other areas may also be vital for function in question
Name imprecise origins of lesions
Degenerative disease
stroke
traumatic brain injury
~ poor spatial resolution
Name precise origins of lesions
artificial legions
temporal legions (cooling techniques)
~ good spatial resolution
Single dissociation
~ test for impairment on task with damage to one brain region e.g. temporal
~ compare to controls
Double dissociation
~ test for impairment on task on patients with different types of brain damage e.g. temporal and frontal lobe
~ compare to controls
Name four methods of invasive perturbations
(invasive brain interruptions) cooling pharmacology electrical stimulation optogenetics
Cooling
~ deactivates brain regions
~ specially precise
~ fully reversible
~ animals can be their own controls (much better than separate control group)
Pharmacology
~ psychoactive substances cross the blood brain barrier + act on synaptic transmission
~ can be agonist or antagonist
Electrical stimulation
~ implantation of electrode via neurosurgery
~ stimulate neural activity
~ deep-brain stimulation in basal ganglia alleviates Parkinson’s disease
Optogenetics
~ genetic modification allows expression of protein (ChR-2) which forms light-gated ion channels
~ action potentials can be turned on and off with light
~ behaviour changes = possibility of clinical applications
Lesion studios pros
~ unequivocal evidence that damaged area participates in certain cognitive function
~ artificial ablations are precise
Lesion studies cons
~ spatially imprecise when cause by injury or disease
~ LIMITED - does not reveal fully how or where function takes place, only shows necessary parts not all parts involved
Invasive perturbations pros
~ excellent spacial and temporal resolution (electrical stimulation. & optogenetics)
~ subjects are their own controls
~ clinical applications
Invasive perturbations cons
~ poor resolution (pharmacology)
~ invasiveness - risk of infection + discomfort
