measuring brain activity and artificial modification

Electroencephalography EEG

main diagnostic test for epilepsy

EEQ strengths

• good temporal resolution

• relatively cheap

• portable

• safe and well-tolerated by participants

EEG limitations

• poor spatial resolutions - difficult determine precise brain signal location

• detects activity on surface of cortex - harder find central reasons

electrophysiology

• single neurons

• much of sensory and motor cortex mapped using these methods in animal studies

electrophysiology strengths

• direct from individual neurons good to know specifically what neurons are doing

electrophysiology limitations

• high risk infection - invasive

• only record small network activity

MRI

• exploits magnetic properties of brain tissue

• magnetic fields get hydrogen atoms to align

• radio frequency waves cause signal detected by machine - converts signal into images

fMRI

• cognitive processes use energy

• oxygenated blood doesn’t distort surrounding magnetic field

• deoxygenated blood distorts around mag - blood vessel more visible

(f)MRI strengths

• high spatial resolution

• can identify specific structural and functional properties

(f)MRI limitations

• very expensive

• large equipment - specialist facility and staff needed

• safety risks of large magnet

PET

radioactive substances/tracers to visualise glucose metabolism or neurotransmitter function

• diagnostic tool for alzheimers

pet strengths

can detect diff chemicals associated with metabolism or specific neurotransmitter levels or receptors

limitations

expensive, specialist facilities + staff

low spatial reso compared to MRI

tracers in blood safe but risks must be managed

ablation studies

deliberate lesions

• surgically used linked to frontal lobe

leucotomy

• leucotome inserted into a hole drilled in skull, whire extended and leucotome rotated to remove core of tissue

• or implemented above eyelid and rocked side to side to slice frontal

electrical brain stimulation

• originally reveal precise location of cortical function

non-invasive electrical brain stimulation - electroconvulsive therapy - italy 1930’s

• treated rang eof mental illnesses - now just severe depression

• must be enough to cause seizure

transcranial direct current stimulation

coil carrying electrical current generates brief pulses - temporarily disrupt tissues

drugs

impact every stage of neurotransmitter function