Fig. 1. Effects of subanesthetic ketamine on the activity of pyramidal neurons and SST interneurons in vivo.

a Schematic and timeline of the experiments. b Coronal histological section, showing the extent of AAV-mediated expression of GCaMP6f in the mouse medial prefrontal cortex. Cg1, cingulate cortex. M2, secondary motor cortex. PrL, prelimbic cortex. c Example motion traces from a head-fixed animal during a two-photon imaging session before and after saline injection (black), and another session before and after ketamine (10 mg/kg) injection (red). Gray shading denotes the 5 min during which the injection was made and imaging was done to verify that the field of view had not shifted. d Time-averaged motion (mean ± s.e.m.) for epochs including pre-injection, 5–30 min post-injection, and 30–60 min post-injection for saline (left) and ketamine (right). For saline injection (black), there were no detectable differences between epochs (pre-injection vs. 5–30 min post-injection: P = 0.6; pre-injection vs. 30–60 min post-injection: P = 0.1; Wilcoxon signed rank test). For ketamine (red), hyperlocomotion was detected transiently following injection (pre-injection vs. 5–30 min post-injection: P = 0.06; pre-injection vs. 30–60 min post-injection: P = 1; Wilcoxon signed rank test). Each point is an imaging session. n = 5 animals each for saline and ketamine. e Schematic of imaging location, and an in vivo two-photon image of GCaMP6s-expressing pyramidal neurons in Cg1/M2. Inset, magnified view of neuronal cell bodies. f The normalized difference in the rate of spontaneous calcium events of pyramidal neurons. Normalized difference was calculated as post-injection minus pre-injection values normalized by the pre-injection value (ketamine (10 mg/kg): 23.7 ± 2.1%, saline: 9.4 ± 1.9%, mean ± s.e.m.; P = 3 × 10⁻⁸, two-sample t-test). For ketamine, n = 613 cells from 5 animals. For saline, n = 681 cells from 5 animals. g Each row shows time-lapse fluorescence transients from the same pyramidal cell in the pre-injectiion (left) and post-injection (right) periods. Two example cells were plotted for saline injection (black), and two other examples were plotted for ketamine (10 mg/kg) injection (pre-injection: black; post-injection: red). h–j Same as (e–g) for GCaMP6s-expressing SST interneurons in Cg1/M2 of SST-IRES-Cre animals (ketamine (10 mg/kg): −12 ± 3%, saline: 13 ± 6%, mean ± s.e.m.; P = 1 × 10⁻⁴, two-sample t-test). For ketamine, n = 198 cells from 5 animals. For saline, n = 179 cells from 5 animals. *P < 0.05; **P < 0.01; ***P < 0.001; n.s., not significant.