Fig. 2: Effects of the NMDA NR2B antagonist TCN237 on delay firing of dlPFC cells.

(A) A single neuron example of the dose-dependent effects of TCN237 on delay-related firing. Raster and histograms for the neuron’s preferred and non-preferred directions are shown. TCN237 produced a dose-dependent decrease in delay-related firing selectively for the neuron’s preferred direction. Activity was partially recovered after drug application was terminated. (B) Population spike density functions for the average of 14 delay cells showing firing for their preferred vs. nonpreferred directions under control condition (blue) and following iontophoresis of TCN237 (red). Results represent mean ± SEM. (C) Histograms showing the mean firing rate (± SEM) of the 14 delay cells during the delay epochs of the task for their preferred vs. nonpreferred directions under control condition (blue) and following iontophoresis of TCN237 (red). Statistical analysis shows that TCN237 significantly reduced the delay firing, especially for neurons’ preferred direction (p < 0.001). (D) Spatial tuning index (d’) is calculated by comparing each neuron’s delay firing for its preferred vs. nonpreferred directions. Greater d’ value indicates greater directional selectivity, i.t., greater spatial tuning. Iontophoresis of TCN237 significantly reduced the spatial tuning of the 14 delay cells. **p < 0.01, ***p < 0.001, compared with control condition; paired t-test.