Fig. 2

Firing types and synaptic responses of IC neurons. a Illustration of representative discharge patterns of IC neurons in response to current. Upper and lower traces are responses to depolarizing and hyperpolarizing current (gray traces), respectively. These traces were modeled by MATLAB (Mathworks, Natick, MA, USA). Scale bars, 20 mV, 50 ms. b–e Synaptic responses of mouse IC neurons to sound. Adapted, with permission, from Refs. [53, 54]. These are recordings are from different neurons. b The synaptic responses of an IC neuron to contralateral (left) and ipsilateral (right) sound. Gray boxes indicate the timing of sound presentation. Red and blue traces are excitatory and inhibitory conductance, respectively. The excitatory and inhibitory conductances were separated under the voltage clamp by recording the sound-evoked currents at the reversal potentials of the inhibitory and excitatory inputs, respectively. The responses to different sound intensities ranging from 0 to 80 dB sound pressure level (SPL) are presented. c, d Spike (upper black traces) and synaptic responses to contralateral sound of IC neurons. The spike responses were recorded in gigaseal condition before break-in. Note that the time courses of the excitatory conductance are different. e Spike and synaptic responses of an IC neuron to binaural sound of which the interaural level differences (ILD) were varied. The ILD value is shown as negative when contralateral sound was stronger. The spike trace was the response to the sound with ILD of −40 dB (asterisks). The ILD tuning curve (right panel) of spike responses was more sharply tuned to contralateral side than to that of excitatory inputs (color figure online)