Magnetoencephalography (MEG): a non-invasive tool for studying cortical effects in psychopharmacology.

Magnetoencephalography (MEG) is a non-invasive method for studying magnetic fields generated by simultaneously firing neurons outside the skull. The skull, scalp and brain tissue do not distort magnetic fields, so the cortical activity can be easily measured. MEG is starting to be used to explore the effects of various psychopharmacological agents on resting brain, sensory and cognitive processing. Scopolamine and agents enhancing GABA functions have shown differential effects on cortical neural oscillations. Further, with GABA, serotonin, dopamine and acetylcholine transmissions have differential effects on early cortical and pre-attentional processing in the auditory and frontal cortices. Monoamines also differently regulate the activity of the somatosensory cortex. Taken together, MEG with a resolution of milliseconds allows exploration of focal cortical effects of psychopharmacological agents giving information different from other brain-imaging modalities.