Techniques for studying brain function Flashcards
Which are direct vs indirect?
Direct: Lesion, single cell recording
Indirect: EEG, ERP, MEG, PET, fMRI, Optical imaging, TMS
Lesions
for humans- only natural/experiments of nature such as Broca’s area, neurological/psychiatric patients, or TMS
for animals- chemical or thermal lesions
single cell recording
micro-electrode inserted into brain; records activity from a single neuron.
more fine grained than any other technique.
not used in humans except for maybe epilepsy.
highly invasive/expensive/not good for higher cognitive activities
ERP- event related potentials
EEG segments are averaged together to produce a single waveform- produces ERPs.
Electrical activity on scalp is recorded during repeated events.
Cons: can’t study most complex forms of cognition like problem solving, limited spacial resolution
PET- Positron Emission Topography
Water with radioactive tracer emits positrons- when brain region becomes active the water rushes there. Detector measures positrons emitted.
Limitations: poor temporal resolution; invasive-can’t do too many because the substance is radioactive
fMRI
Placing subject in magnetic field aligns most protons; RF pulses disrupt alignment; measures relaxation.
BOLD signal- blood oxygen level-dependent contrast
MEG
Uses superconducting quantum interference device (SQUID). Measures magnetic fields produced by brain’s electrical activity. High temporal resolution and moderate spacial resolution.
Limitations: expensive, requires participants maintain a potentially uncomfortable body position for long duration. technology is newer
TMS
Produces a brief “lesion” by pulses into the skull. Produces a magnetic field that can disrupt brain activity and reveals a causative rather than correlational brain-behavior link.
Limitations: not clear how it changes activity; can only target cortex; may be painful
