Direction‐specific adaptation of motion‐onset auditory evoked potentials

Auditory evoked potentials ( AEP s) to motion onset in humans are dominated by a fronto‐central complex, with a change‐negative deflection 1 ( cN 1) and a change‐positive deflection 2 ( cP 2) component. Here the contribution of veridical motion detectors to motion‐onset AEP s was investigated with the hypothesis that direction‐specific adaptation effects would indicate the contribution of such motion detectors. AEP s were recorded from 33 electroencephalographic channels to the test stimulus, i.e. motion onset of horizontal virtual auditory motion (60° per s) from straight ahead to the left. AEP s were compared in two experiments for three conditions, which differed in their history prior to the motion‐onset test stimulus: (i) without motion history ( B aseline), (ii) with motion history in the same direction as the test stimulus ( A daptation S ame), and (iii) a reference condition with auditory history. For E xperiment 1, condition (iii) comprised motion in the opposite direction ( A daptation O pposite). For E xperiment 2, a noise in the absence of coherent motion ( M atched N oise) was used as the reference condition. In E xperiment 1, the amplitude difference c P 2 −  cN 1 obtained for A daptation S ame was significantly smaller than for B aseline and A daptation O pposite. In E xperiment 2, it was significantly smaller than for M atched N oise. A daptation effects were absent for c N 1 and c P 2 latencies. These findings demonstrate direction‐specific adaptation of the motion‐onset AEP . This suggests that veridical auditory motion detectors contribute to the motion‐onset AEP .