Fig. 1: Ketamine alters the coding features of MEC neurons in navigating mice.

a Schematic of Neuropixels probe recording and VR setup. Left: side view. Right: top view. Animals received visual cues from three monitors and received rewards from a front facing lick port. Left panel was published in Low et al.⁴⁷, Copyright Elsevier. b Schematic of the 400 cm linear VR hallway. Five virtual towers spaced 80 cm apart served as landmarks. One traversal through the hallway is equivalent to one trial. The mouse received a water reward for completing the trial before seamlessly teleporting back to the beginning of the hallway. c Animals ran 50 baseline trials (gray), 50 trials following a control needle insertion (pink), and 190 trials following a 25 mg/kg ketamine injection (green). d Example sagittal slice of a mouse brain showing 3 dye color (DiI, DiD, DiO) tracks of Neuropixels probe recording insertions in MEC. Up to 6 recording sessions were conducted on each mouse (3 insertions per brain hemisphere). e Spatial raster plots (top row) and spatial firing rate maps (bottom) of example cells. Raster plots indicate individual spikes (black dots). Bottom panels are color coded for minimum (black) and maximum (red) firing rate values. Each cells’ maximum firing rate is labeled on the top of the cell’s spatial firing rate maps. The panel shows data from the control session in which an empty needle was inserted intraperitoneally after trial 50 and again after trial 100. f As in (e), for data from the experimental condition of a control injection after trial 50 and a 25 mg/kg ketamine injection after trial 100.