Population analysis of discharge-rate and modulation spectral spatiotemporal RF profiles.

<p>Comparison of mean optimal TF (A), optimal SF (B), optimal velocity (C), TF normalized bandwidths (D) SF normalized bandwidths and (E) mean normalized variability of the fundamental Fourier component (F) for discharge-rate responses in subpopulations of neurons with unmodulated (R_um) and modulated (R_mod) responses, and for modulations (zF1_mod) in a subpopulation with modulated responses. Short grey lines with error bars indicate mean <b>±</b> SEM. Thick black lines mark median values, boxes cover values from first to third quartiles, and black dashed lines show the ranges of all obtained values. In A, notice that for Sg neurons optimal TF for the modulation component was significantly higher than optimal TF for the discharge rate. In B, the only significant difference in optimal SFs was found between zF1 and the discharge rate in SCi. The optimal stimulus velocity for modulation was significantly higher than the optimal velocity for discharge rate for SCi and AES (C). In D, note that in all structures, the mean TF normalized bandwidth was lower for modulation RFs than for discharge rate RFs (significant in all structures). No significant differences were found for SF normalized bandwidths (E). With the exception of the AES, the normalized variability of the fundamental Fourier component in responses maximizing zF1 did not differ significantly from the variability of responses maximizing F0 (F), suggesting that modulations, if they occur, are stable and do not cause an increase in the variability of the responses. The only significant difference in discharge rates between modulated and unmodulated subpopulations was found in the variability of the fundamental Fourier component in the Sg – this was due to the occurrence of bursts in the activity of modulated Sg neurons.