Figure 5. Mephenesin strongly reduces the magnitude of the vestibular-mediated responses and blockade of GABAA receptors reveals an inhibitory component in the iMMC response of C2 and the iLMC response of L2.
A, responses evoked during electrical stimulation of the VIII nerve with a 5 s train at 5 Hz (2T) in the iMMC of C2 and T7 and the iLMC of L2 before (traces on the left) and after (traces on the right) application of mephenesin to a split-bath compartment containing the cervico-thoraco-lumbar or thoraco-lumbar regions of the spinal cord. B, graph showing the magnitudes of the responses during mephenesin application, normalized to the control response. Each point shows the average response in a single preparation and the horizontal lines indicate the grand mean. C, left traces, responses evoked during electrical stimulation of the VIII nerve with a 5 s train at 5 Hz (2T) in the iMMC of C2 and the iLMC of L2. Middle and right traces, effects of 20 μm biccuculine and 40 μm PTX on these responses. D, graph showing the magnitudes of the responses during application of each drug, normalized to the control response. Each point shows the average response in a single preparation and the horizontal lines indicate the grand mean.