Figure 3. Whole-Face-Selective Neurons.

(A) Mean response of all whole-face (WF)-selective units that increased their spike rate for WFs compared to bubble trials (n = 32 units, ±SEM, normalized to average response to WFs for each unit separately). Asterisk indicates a significant difference between the response to WFs and bubble trials (p < 0.05, two-tailed t test, Bonferroni-corrected for 14 comparisons). The response to eye and mouth regions of interest (ROIs) that was used for selecting the units is shown but not used for statistics.

(B) Histogram of firing rates before and after scramble onset as well as for WFs (n = 32 units). Mean rates were 1.4 ± 0.24 Hz, 1.7 ± 0.3 Hz, and 2.2 ± 0.4 Hz, respectively.

(C) Histogram of the whole-face index (WFI) for all recorded units (n = 185), according to whether the unit was classified as a non-WF-selective (top) or WF-selective (bottom) unit. The WFI was calculated as the baseline-normalized difference in response to whole faces compared to bubbles (which was independent of how we classified units as WF selective or non-WF selective).

(D) Distributions (plotted as cumulative distributions) of the WFI across the entire population for both WF- and non-WF-selective units (n = 36 and n = 149, respectively), calculated for both ROI trials (bold lines) and bubble trials (dashed lines). The two WFI populations for bubble trials were significantly different (p < 1e-9, two-tailed Kolmogorov-Smirnov test). Note the similarity of the distributions for cutouts (bold lines) and bubble trials (dashed), indicating that the response to both is very similar.