Fig. S6.

Analysis of putative DLM-projecting pallidal neuron activity. (A) Scatter plot of pallidal neuron activity showing the mean FR during the nonsinging state (resting FR) and mean Fano factor during singing. Putative DLM-projecting pallidal activity (diamonds) and non–DLM-projecting pallidal activity (triangles) from control (black) and mHTT birds (red) could be segregated with a mean Fano factor of 1.0 (horizontal dashed line) (29). The Fano factor was calculated for the first 500 ms of the dominant motif as variance divided by mean (σ²/μ) of a 20-ms binned spike count (a sliding step size of 1 ms) across 30 iterations. Quantification of precise temporal modulation of putative DLM-projecting pallidal neuron activity in control and mHTT birds (same dataset as in Fig. 4) shows a reduction in the CV of the mean FR (B), trial-to-trial correlation (C), and timing information (D) in mHTT birds [CV of mean FR: t(8) = 2.649, P = 0.029; correlation: t(8) = 2.498, P = 0.037; timing information: t(8) = 5.294, P < 0.001]. Error bars indicate SEM. *P < 0.050.