MEG is a noninvasive imaging method that measures magnetic fields produced by electrical activity in the brain. Several recent studies using MEG have reported brain activity differences in FASD during sensory processing. During auditory stimulus presentation, young children with FASD displayed an approximate 10ms delay in cortical auditory processing (M100 and M200 latencies) compared to controls [40]. On a prosaccade task, adolescents with FASD exhibited a delay in visual cortex activation (M100 peak latency). Furthermore, during this visual task gamma-band oscillations differed between FASD and controls. Gamma oscillations are periodic fluctuations in the local field potential, driven by synchronized interactions between a network of inhibitory interneurons and excitatory principle neurons in the cortex. Gamma oscillations tend to increase in magnitude in the presence of a cognitive or perceptual stimulus. This magnitude escalation may reflect increases in local field potential synchrony, amplitude (power) or both [41]. In FASD, relative increases in gamma oscillations were seen in right frontal clusters, while relative decreases occurred in right parietal and left temporal/occipital clusters [42]. These gamma-band power changes occurred despite a lack of difference
