INTRACELLULAR-RECORDINGS IN RESPONSE TO MONAURAL AND BINAURAL STIMULATION OF NEURONS IN THE INFERIOR COLLICULUS OF THE CAT

The inferior colliculus (IC) is a major auditory structure that integr ates synaptic inputs from ascending, descending, and intrinsic sources . Intracellular recording in situ allows direct examination of synapti c inputs to the IC in response to acoustic stimulation. Using this tec hnique and monaural or binaural stimulation, responses in the IC that reflect input from a lower center can be distinguished from responses that reflect synaptic integration within the IC. Our results indicate that many IC neurons receive synaptic inputs from multiple sources. Fe w, if any, IC neurons acted as simple relay cells. Responses often dis played complex interactions between excitatory and inhibitory sources, such that different synaptic mechanisms could underlie similar respon se patterns. Thus, it may be an oversimplification to classify the res ponses of IC neurons as simply excitatory or inhibitory, as is done in many studies. In addition, inhibition and intrinsic membrane properti es appeared to play key roles in creating de novo temporal response pa tterns in the IC.