Cortical thickness of supratemporal plane predicts auditory N1 amplitude

The auditory-evoked potential's N1 component of the scalp electroencephalogram is a well-established measure of electrical brain activity. The N1 reflects basic auditory processing and is modulated by auditory experience, for instance, by musical training. Here, we explore a possible correlation between the auditory N1 amplitude and cortical architecture in the supratemporal plane. We hypothesize that individual differences in N1 amplitude reflect differential acuity, which might also be reflected by differences in auditory cortex anatomy. Auditory potentials evoked by sine wave tones and structural MRI were collected from 27 healthy volunteers. The thickness and surface area of the cortex were calculated using a surface-based morphometry approach. Cortical thickness, rather than surface area, in a cluster on the posterior supratemporal plane, predominantly located on Heschl's sulcus and lateral aspects of Heschl's gyrus, correlated with the N1 amplitude. In particular, lower cortical thickness was associated with larger N1 amplitudes. This is well in agreement with previous functional magnetic resonance studies reporting a thinner cortex to be related to a larger functional response.