Figure 9: BF Shift of Fast Spiking Neurons.

(A) Tonal receptive field of single fast spiking neurons. Left, spike tonal receptive field composed of 568 traces in response to tones at different frequencies and intensities. (B) Peristimulus time histogram. The bar represents the sound stimulation. Right corner, 50 randomly chosen superimposed spike waveforms and the reconstructed morphology of a L4 fast-spiking neuron. (C) Color map of the TRF. The color represents the number of spikes. The white stars represent the BF at each intensity. The horizontal arrow indicates the difference between the BF at 70 dB SPL and the intensity threshold level. (D) Difference between the BF at the threshold level and 70 dB SPL. Inh, inhibitory synaptic input; FS, fast spiking neurons. Bar, S.D. (E) Schematic model representing the co-shifting of the excitatory and inhibitory synaptic inputs, which supports the feedforward inhibitory synaptic circuit in L4 of A1 and suggests that the BF’s dependence on the intensity is inherited from the early stages in auditory processing, including the basal membrane response properties.