01828nas a2200169   4500008004100000022001400041245006100055210006000116260001200176300001300188490000700201520134800208653001801556100002101574700001801595856004501613       1977                        eng d  a0013-469400aHemispheric differences in the auditory evoked response.0 aHemispheric differences in the auditory evoked response  c07/1977  a99–1020 v433 aThe separation of the 80-250 msec portion of the AER to click stimulation into N1P2, produced by large areas of cortex, and the T complex, probably produced by secondary auditory cortex, was recently described (Wolpaw and Penry 1975). The present study investigated the ipsilateral vs. contralateral and right vs. left hemispheric differences in N1P2 and T complex latencies and amplitudes. One msec clicks at 60 dB above threshold were presented at 4.7 sec intervals monaurally to 32 normal adults and binaurally to 13 of the 32. AERs were recorded from vertex and temporal referred to a balanced non-cephalic reference electrode. For monaural stimulation, N1P2 and T complex amplitudes were significantly greater and T complex latency was significantly less over the contralateral and right hemispheres. The ipsilateral vs. contralateral and right vs. left hemispheric amplitude differences were significanlty greater for the T complex than for N1P2. Binaural results, which provided in additional measure of right vs. left hemispheric differences, were in agreement with the monaural findings. The results are consistent with neurophysiologic and behavioral findings in regard to ipsilateral vs. contralateral and right vs. left hemispheric differences and support the hypothesis that the T complex is produced by secondary auditory cortex.10aReaction Time1 aWolpaw, Jonathan1 aPenry, J., K.  uhttp://www.ncbi.nlm.nih.gov/pubmed/68878