|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1998 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1997 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1996 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Responses of layer 2/3 pyramidal neurons to sound stimuli were recorded intracellularly. Under a light Nembutal anaesthesia, pure tones, clicks, white noises, and noises with a defined band width were applied to cats' external meatus under monaural and/or binaural conditions. In many neurons, biocytin was injected after the recording to trace the courses of axons of the recorted neurons.
Excitatory postsynaptic potentials (EPSPs) were induced with best or nearbest frequencies. EPSPs, often associated with action potentials, were followed by hyperpolarizing deflection of the membrane potential (IPSP), which was more conspicous in layer 3 neurons than in layer 2 neurons. In some neurons, if sound intensity was increased, IPSP deflection was increased together with the decreased number of action potentials, revealing the non-monotonic response properties. In some deep layer 3 neurons, binaural stimulation with the best or near-best frequencies or with noise induced less spikes than monaural stimulation of either ear, revealing the EI response properties. Then stronger IPSPs were associated with the binaural stimulation than monaural stimulaiton, and seem to reduce the number of binaurally-induced spikes.
In order to compare axonal trajectories of the neurons with IPSP and without IPSP, some of the recorded and then biocytin-injected neurons have been reconstructed.
These results and some related data have been published in abstract forms and/or in full papers.