THE SPECTRAL SHAPING OF NEURAL DISCHARGES BY REFRACTORY EFFECTS

It has previously been shown that post-stimulus time (PST) histograms have autoregressive properties, which implies that the neural firings have spectral components that are determined by these properties. The expected power spectral density of neural discharges is derived when t he process is firing at a constant rate (similar to tonal stimulation at CF with no phase locking). Although the unconditional intensity of the process is not time varying, the spectrum exhibits prominent spect ral peaks. The effect of histogram bin size, stimulus intensity, and r efractory effects are examined with respect to spectral shape and it i s shown that stimulus intensity determines the magnitude of spectral p eaks while refractory duration determines the peak locations. The effe ctiveness of predicting the spectrum is demonstrated with eight-nerve data and point process simulations.