Figure 4. vmPFC neurons were strongly and weakly modulated during reward and shock cues, respectively, and very few are modulated by both. A, Location of recording sites based on histology (Paxinos and Watson, 2007); PL, Prelimbic cortex, DP, dorsopeduncular region. Each symbol represents the location of neurons that showed differential firing (Wilcoxon; p < 0.05) in the analyses described in the text (see Results) and shown in the table in B. Dark blue indicates reward > neutral; light blue, neutral > reward; dark red, shock > neutral; light red = neutral > shock; -, decreasing-type cells; +, increasing-type cells. B, Table quantifying numbers and percentages of cells that were reward > neutral, neutral > reward, shock > neutral, neutral > reward, or none of the above. C–F, Histograms depicting average normalized firing rate (spikes/s) for cells in which reward < neutral (n = 40; C), reward > neutral (n = 30; D), shock < neutral (n = 5; E), and shock > neutral (n = 12; F) within the overall population (N = 289 cells) across trial time for reward (blue), neutral (orange), and shock (red) trial types. Cue onset is depicted with a gray dashed line aligned to time = 0. Insets show scatter plots depicting each cell within each subpopulation (reward < neutral, reward > neutral, shock > neutral, shock > neutral) along computed reward (reward − neutral; x-axis) and shock (shock − neutral; y-axis) indices. Indices were calculated by subtracting average firing rates during the cue epoch on neutral press trials from reward press and shock press (i.e., avoid) trials.