Fig. 7: Feedback CS activity driven by FN^E–IO–cortical loop is essential for precise motor control.

a, Schematics showing simultaneous photoactivation of ChrimsonR-expressing FN^E–IO neurons (FN^A, 50 Hz, 50% duty cycle and 3.0 mW) and photoinhibition of stGtACR2-expressing mcMAO neurons (IO^I, 50 Hz, 50% duty cycle and 2.4 mW). See detailed optogenetic protocols in ‘Methods’. b–d, Comparison of FN^A-evoked CS probability, saccadic movement and upper body movement, with and without mcMAO inhibition (two-sided Wilcoxon matched-pairs signed rank test). b, Vermal PC recordings showing decreased FN^A-evoked CS activity by mcMAO inhibition. Left: evoked CS activity of an example PC. Right: maximum spike rates of FN^A-evoked CS for all PCs (n = 18 cells from three mice, P = 7.6 × 10⁻⁶). Dots and bars represent mean ± s.e.m. c, Left: example FN^A-driven saccade before and after mcMAO inhibition. Traces are plotted as mean ± s.e.m. Right: group summary showing increased saccadic amplitude and velocity after mcMAO inhibition (n = 9 mice, P = 0.0078 and 0.027). Dots and bars represent mean ± s.e.m. d, Same as c, but for the FN^A-evoked upper body movements before and after mcMAO inhibition (n = 9 mice, P = 0.027 for both comparisons). e, Schematics of long-term inhibition of FN^E terminals on mcMAO during spontaneous saccades (lasting inhibition, 50 Hz, 50% duty cycle and 2.5 mW). f, Raw traces of spontaneous saccadic movements from an example mouse following FN^E–IO terminal inhibition (green) and control (black) conditions. An asterisk indicates nasal saccades. g, Average trace and accumulative distribution of saccade amplitude and velocity from the same mouse in f. h, Effects of FN^E–IO terminal inhibition on spontaneous saccade frequency, amplitude, amplitude deviation, velocity and velocity deviation (n = 5, two-sided paired t-test, P = 0.209, 0.025, 0.041, 0.0010 and 0.010). Gray dots represent individual mice, and black dots and bars represent mean ± s.e.m. i, Summary of the excitatory and inhibitory cerebellar nucleo-olivo-cortical motifs for motor control. Excitatory projections are indicated by arrows and inhibitory projections are indicated by flat-end lines.

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