11. Behavioural Neuroscience: Measuring Brain Activity Flashcards
EEG refers to both ___ and ___
- Electroencephalography (the equipment/method)
- Electroencephalogram (the data output - “writings of electricity from the head”)
how do EEGs work?
- put electrodes on head (sometimes in skull)
- electrodes detect electrical charges (change in action potential)
- graph: 1 row = 1 electrode
4 strengths of EEGs, desc them
- good temporal resolution (can discriminate v brief events in time)
- relatively CHEAP
- Portable, possible to record when ppl are moving around (wear EEG cap)
- Safe & well tolerated by participants (no real risk, mild discomf)
2 limitations of EEG, desc them
- POOR SPATIAL RESOLUTION: diff to determine precisely from WHICH AREA the brain signal came from
- usually will only detect activity on SURFACE OF CORTEX: hard to detect activity from more central regions of brain (DEEP w/in)
what is electrophysiology
study of electrical properties of single neurons
strength of electrophysiology - single neurons
records DIRECTLY from indv neuron so BEST method to use to understand WHAT the neurons are DOING
2 limitations of electrophysiology - single neurons
- high risks of INFECTION - tech is invasive, penetrates brain (cut hole into skull)
- only possible to record from a few (up to ~ 100) neurons @ a time, can only record inv neuron/small network of activity
MRI stands for?
Magnetic Resonance Imaging
MRI exploits ___ of brain tissue
magnetic properties
how do MRI work
- MRI coil generates VERY strong magnetic field
- this will pass thru persons head, causing H atoms in blood to align w/ magnetic field & tissue
- also radio freq waves that’ll distrust the alignment, causes signal that’s detected
- diff prop of H2O in diff types of tissue, each emit diff signals
- convert signals > detailed images of brain
DTI stands for
Diffusion Tensor Imaging
how does DTI work
- use same MRI equipment
- detect large axon tracts (white matter in corpus callosum, F.A around axons)
- F.A cause fluid in these regions to be V CONSTRAINED (in terms of direc of move)
- Will move in direc of F.A layers
- DTI sees WHAT direc molecules vibrate in, DET WHERE the big axon bundles are
fMRI stands for…
functional Magnetic Resonance Imaging
cognitive processes use ___
- energy
- prod of energy uses Oxygen from haemoglobin (blood)
oxygenated blood ___ ___surrounding magnetic field
doesn’t distort
deoxygenated blood ____ surrounding magnetic field
distorts
blood vessels become ____ visible as blood oxygen ____
MORE, DECREASED
BOLD stands for ____ & it …
- Blood oxygen level dependent signal
- Tracks the ratio of oxygenated vs deoxygenated blood
- use BOLD to see what parts of brain are active during diff activities
2 strengths of MRI
- very HIGH SPATIAL res, can identify EXACTLY WHERE in the brain diff structures are/diff func is occurring
- can identify specific ANATOMICAL/STRUCTURAL & FUNC properties of diff brain regions
what would you use to learn about structural damage to the brain? & WHY
- USE MRI
- wouldn’t use EEG because it has a LOW SPATIAL RES, cannot see specific area where signal comes from
4 limitations of MRI & desc
- Very Expensive
- Very large, req specialist facility
- Safety risks, no metal in room
- Req specialist staff
PET stands for …
Positron Emissions Tomography
How does PET work
- AIM: look at changes in chem elements of brain
- create artificial ver of chem (glucose, serotonin) & add radioactive component
- inject into blood
- see where the chemicals are binding, its conc
strength of PET
can detect DIFF CHEM in brain associated w metabolism or specific neurotransmitter lvls or receptors
3 limitations of PET
- expensive, req specialist facilities & staff
- relatively LOW spatial res (compared to MRI)
- req radioactive tracers to be injected into blood, risks need to be managed
what can brain modification do? (3)
- permanently remove/destroy regions
- decrease brain activity temporarily
- stimulate areas to enhance/increase activity in that region
what are the 3 reasons why you’d modify brain?
- medical treatment
- enhancement
- scientific research
brain modification for medical treatment to…
- target ABNORMAL brain processes/func
e.x epilepsy, tumor
what does ENHANCEMENT - brain mod refer to
improvement of healthy func to ABOVE or BETTER THAN NORMAL
brain modulation provides information about ___ & …
- causation
- whether a given brain region is NECESSARY for a particular task
ablation means to _____
carry away
what did Egas Moniz introduce & what did it relief
- prefrontal leucotomy (remove sections of brain)
- psychiatric disorders
what is electrical brain stimulation done for
- reveal precise localisation of cortical func (var cognitive processes)
what was Non-invasive electrical brain stimulation ECT used to treat & what it does
- range of mental illnesses (now depression)
- induce seizures into patients
- unclear HOW it works, but effects are clear
what are the non-invasive electrical brain stimulation methods called
- ECT
- tDCS : transcranial direct current stimulation
- TMS : transcranial magnetic stimulation
desc transcranial magnetic stimulation (TMS)
- opposite of MRI
- coil carries electrical current, generates brief, focal magnetic pulse > activated small region of brain
- temporarily disrupt tissue
- treat depressive disorder
