Fig. 5 S2

Timescales of reticulospinal, ARTR and turn state correlations.

(A) Ventromedial cells (vSPNs) in the hindbrain reticulospinal system (identified via spinal backfills, white) are correlated with turning behavior. Cyan and magenta show GCaMP6 voxels with laterality indices to the left and right, respectively. N = 4; one fish shown. Scale bar, 100 µm. (B) Example traces from 10 vSPNs (middle) and 10 ARTR neurons (bottom) during fictive swimming. ARTR neurons are active on longer timescales than vSPNs. (C) Quantification of ARTR (red) and vSPN (blue) response dynamics triggered on turns (gray). Only turns that were not followed by another turn in the same direction for at least 5 s were included to isolate ARTR dynamics from correlation in behavior. The ARTR signals are slower than the vSPN signals (as measured with the calcium indicator), and peak about 1.5-2 s after a turn, compared to a near-instantaneous peak in the vSPN signals, suggesting feedback from (peripheral) motor circuits to the ARTR. ARTR analyses use pooled data from both medial and lateral clusters (shown separately in Figure 2-figure supplement 3). (D) Normalized autocorrelation of ARTR signals (red), convolved turn laterality (gray), and convolved turn laterality after shuffling turn identity (dotted). ARTR activity and turning is correlated on similarly slow timescales. The length of the shuffled correlation reflects the width of the convolution kernel. (E) Convolved turning behavior (gray) matches the instantaneous difference between left and right ARTR fluorescence. ARTR analyses use pooled data from both medial and lateral clusters.