Human auditory primary and association cortex have differing lifetimes for activation traces.

The magnetic field pattern over the temporal area of the scalp 100 ms following the onset of a tone burst stimulus provides evidence for neuronal activity in auditory primary and association cortices that overlap in time. Habituation studies indicate that onset and offset features of a tone produce activation traces in primary cortex that are at least partially common, but only the onset produces an appreciable trace in association cortex. The characteristic time constant for the decay of the latter's activation trace is several seconds longer than for the former.