Differences in superficial and deep source contributions to middle latency auditory evoked potential Pa component in...

Multichannel brain-mapped middle latency auditory evoked potential (MLAEP) data obtained from 15 normal subjects and three neurologically impaired subjects using the common average reference (CAR) were converted off-line to source current density (SCD). This technique is sensitive to activity generated in the superficial cerebral cortex. The SCD maps were subtracted from the CAR maps (CAR-SD). The derived CAR-SD maps are believed to represent the proportion of scalp-recorded activity that is generated deep to the cerebral cortex. Topographic analysis of this data manipulation technique supports the hypothesis that Pa originated from within the temporal lobes bilaterally as well as from a deeper subcortical system.