[Analysis of field potentials in the postcruciate dimple evoked by stimulation of the ampullary nerve of the posterior semicircular canal in cats].

Field potentials evoked by stimulation of the posterior semicircular canal nerve (PCN) were studied in the postcruciate dimple (PCD) in anesthetized cats. When weak stimulation was provided, field potentials composed of 3 components of small positive, large positive and large negative waves were observed on the surface of the PCD. The field potentials could be observed at the stimulus intensity weaker than 1.5 x N1T. The latencies of initiation of the 3 components were 2.32 +/- 0.75 (mean +/- S.D.; n = 37), 3.75 +/- 0.92 (mean +/- S.D.; n = 99) and 9.34 +/- 2.81 (mean +/- S.D.; n = 101), respectively. The large positive wave of the maximum amplitude was recorded in the lateral part of the PCD. In this point, the large and small positive waves reversed their polarity at the layer III and V, respectively, which located about 500 microns and 1000 microns deep from the surface. Stimulations of the whole vestibular nerve (WVN) and the deep radial nerve (DR) shared response areas of field potentials. These findings agreed with the previous results as to a neuronal convergence of the somatic and vestibular inputs in the cat.