Ventral tegmental area (VTA) activation induces the shift of place field center of mass (COM).

(A) Atlas schematic shows E123T/T159C virus injection and optic fiber implantation in the VTA of TH::Cre rats and tetrodes position in the hippocampal CA1. (B) Baseline recordings of 2 sample place cells. The upper group of panels shows the first baseline, while the lower group of panels shows the second baseline. Top left panels represent the animal trajectory with spikes (red dots), top middle panels show the coordinates of the laser application (blue dashed lines), and top right panels show color-coded Bhattacharyya distance metric (bhatt) overlap between the distribution of spikes and the applied light pulses from the subsequent photostimulation session (lower bhatt values mean higher overlap of both distributions). Bottom images show 3D color-coded firing rate maps. (C) First (channelrhodopsin 2 [ChR2], upper panel groups) and second (ChR2 2, lower panel groups) photostimulation sessions of the same place cells. Top middle panels show the location of the applied laser light pulses (red dots). (D) Center of mass shift (ΔCOM) between the baseline and the first photostimulation; second baseline (base 2), 2-tailed independent t test, t(31) = 3.291, **p = 0.002; second photostimulation, t(31) = 3.449, **p = 0.002 for control group (yellow fluorescent protein [YFP], n = 16 cells) and ChR2 group (n = 17 cells). Error bars, mean ± SEM; **p < 0.01. (E) Ratio of bhatt values of the baseline relative to the first photostimulation session; second baseline, 2-tailed independent t test, t(31) = 3.423, **p = 0.002; second photostimulation session, t test, t(31) = 3.289, **p = 0.003 for YFP (n = 16) and ChR2 (n = 17) groups. Error bars, mean ± SEM. (F) Correlation between bhatt and ΔCOM for the ChR2 group, n = 34, Pearson’s r = 0.360, p = 0.036. Files dataset is available at Figshare public repository in Tsanov 2016 data / Open arena spatial stimulation folder