Fig. 5.

Thalamic neurons discharge at high, fixed rates within pallidal ISIs. A and B: the distribution of p-t interval durations from a pair recorded during singing (A) and nonsinging (B) (solid lines, pair 4). Also plotted are the interval distributions computed after thalamic spike times were randomized (dotted lines; randomized p-t intervals smaller than δ were eliminated). C and D: distribution of t-t interval durations from the same pair during singing and nonsinging periods, plotted as in A and B. E: average t-t interval duration as a function of the interval number within the HTD (defined as multiple thalamic spikes that occur within a single pallidal ISI). F: the average firing rate within an HTD as a function of the number of spikes in the HTD. Data are means ± SE across 6 pairs during singing and nonsinging periods (solid and dotted lines, respectively).