Fig. 3: In vivo DBS activates somatostatin interneurons in mice.

a In vivo experimental setup. A bipolar electrode is lowered into the STN and an optical fiber is placed over M1, while recording from neurons in M1. b, Top: electrophysiological traces of representative opto-identified pyramidal, SST, and PV neurons recorded in M1. SST and PV neurons are opto-activated by brief flashes of light (shown in blue). c Photomicrographs of juxtacellularly labeled and immuhistologically identified pyramidal, SST and PV neurons (n = 10, 6, and 3 independent experiments with similar results for pyramidal, SST, and PV cells, respectively) (bar scale = 30 µm). Bottom: Raster plots representing the activity of the neurons described above in response to 2-min DBS at 120 µA. Spikes occurring during the DBS are represented in red. d Heatmaps of individual pyramidal, PV and SST neuron activity (normalized by the maximal firing rate of each neuron), before, during and after DBS (10s bins) (only non-silent neurons are represented). e Averaged time course of DBS-induced modulation of pyramidal, PV and SST neuron activity (bars: mean ± SEM of all non-silent neurons, and the mean ± 2 × SD of the baseline is superimposed). Boxplots indicate the firing rates before, during and after DBS of pyramidal (Off vs DBS: p = 0.0297, and DBS vs Post: p = 0.0085, n = 28, two-tailed Wilcoxon signed-rank test), PV (p = 0.0074 and p = 0.0495, n = 27) and SST (p = 0.0040 and p = 0.0019, n = 26) neurons (including silent neurons). Box plots: the center is the median; box: 25% and 75% quartiles; whiskers extend to the last data point within 1.5* the interquartile range outside of the box range (data outside the whisker range are not shown, but are included in the statistical analysis). f Proportion of pyramidal, PV, and SST neurons activated (white), inhibited (black), non-modulated (gray) during DBS or silent (hatched) throughout the recording. The number of neurons is indicated for each category. *p < 0.05; **p < 0.01.