[The role of the temporal cortex in long-latency auditory evoked potentials]

There is no definite agreement on the localization of the PEAL generators. However, some authors have claimed that the temporal auditive cortex plays a role. Based on these assumptions we searched for the eventual changes developing in PEALs in patients who applied for temporal epilepsy, where the temporal cortex activity is somehow impaired. Altogether 19 patients were explored. The results were compared with 17 matched healthy controls and 4 patients with focal epilepsy who, at the time of the study, received the same treatment as the temporal epileptic subjects. In every case PEATs and PEALs were studied. One thousand Hz less than time monoaural stimulation, 50 db and 50 ms duration was employed for evoking PEALs. Recording was done with surface electrodes located at Cz, F3 and F4 coupled with an electrode placed at the contralateral mastoid; 500 ms sweep were averaged. Band-pass was set up between 1 and 125 Hz and latencies and amplitudes were studied for both types of evoked responses, PEATs and PEALs. No statistical difference was found between patients and both control groups when PEATs mean parameters were analyzed. For further PEALs results, patients were divided into 3 groups; a) Those with right temporal epilepsy (n = 6) (R); b) Those with left temporal epilepsy (n = 7) (L); c) Those in whom the affected side could not be determined (n = 7) (N). In R it was observed, when stimulating the left ear, a delay in the arrival of P1 (F4 mea 87 +/- 10.4 ms) and N1 (F4 mean 122.33 +/- 6.1 ms; Cz mean 170.75 +/- 18.8 ms) waves.(ABSTRACT TRUNCATED AT 250 WORDS)