Fig. 3: Different neuronal populations in the NAc shell show distinct firing preference before and during exploration of anxiogentic environments.

a Scatter plot of the firing rate and peak-to-peak width for 98 units from 9 mice. Inset, representative waveforms from an identified Non-FS (blue) and FS (red) neuron; ISVD, initial slope of valley decay; HDT, valley half decay time. b Left, mean firing rates of FS and Non-FS neurons (Mann–Whitney rank sum test, n of FS = 5, n of Non-FS = 28, P <= 0.0001); right, burst number of FS and Non-FS neurons (Mann–Whitney rank sum test, n = 5 (FS), n = 28 (Non-FS), P <= 0.001). c Scatter plot showing the firing rate of FS neurons between closed and open arms (Paired t test, n = 5, t = 2.135, one-tailed P = 0.0498). d Z-scores of FS neurons during movement from the closed to open arms (nonparametric Kolmogorov–Smirnov test, n = 5, P = 0.0301); inset, horizontal and vertical arms represent closed and open arms, respectively. e Correlation between locomotion and firing rates of the FS neurons. f Scatter plot showing the firing rates of Non-FS neurons in closed and open EPM arms (Paired t test, n = 28, t = 0.64, one-tailed P = 0.2619). g There was no difference in individual Non-FS neuron firing rates between closed and open arms. h Schematic showing fiber photometry recording strategy. i–k Left, normalized NAc Ca²⁺ activity maps from different neuron populations in the EPM (warm colors, high activity), binned by time (s) from the EPM crossing point (inset, red point); inset, horizontal and vertical arms represent open and closed arms, respectively; right, normalized NAc Ca²⁺ transients of different neuron populations in the EPM open arms compared with closed arms (Wilcoxon test, n = 250, *P < 0.05). l Mean activity traces from different NAc neuron populations during the EPM. m Comparison of the time to peak between PV and D2 cells when mice were approaching the crossing point in the EPM (n = 19 trials, t = 2.149, one-tailed P = 0.0261). n Normalized Ca²⁺ transients in NAc PV neurons was correlated with anxiety state (Open arm exploration time) (linear regression, F (1, 248) = 316.4, R² = 0.56, P < 0.0001, n = 8 mice).