Figure 3.

Average in vivo data for the 24-whiskers array. The multi-whisker functional representation (MWFR) for the 24-whiskers array was assessed in vivo using intrinsic signal optical imaging (n = 10; A–C) and supra- and sub-threshold neuronal recordings from an 8-electrode array (n = 12; D,E). The single whisker functional representation (SWFR) for whisker C2 was also assessed in the same rats for reference. (A–C) The average in vivo-MWFR for the 24-whiskers as assessed with imaging for the same 6 × 6 mm field-of-view can be plotted in 2D with barrel cortex topography superimposed (A) or in 3D (B). It can also be plotted as a line plot for the rostral-caudal slice through the center of whisker C2 barrel and hence through the center of the 24-whiskers' MWFR and C2 whisker's SWFR (C; mean ± SE as solid line and shading, respectively). Scale bar = 1 mm in (A); colorscale is the same in (A,B). (D,E) The average in vivo-MWFR as assessed with neuronal recordings. Plotted is the mean ± SE of sub- (D) and supra- (E) threshold neuronal activity of the MWFR for 24-whiskers (magenta trace) vs. the SWFR for whisker C2 (black trace). Whisker stimulation consisted of 5 back-and-forth whisker deflections in the rostral-caudal direction delivered at 5 Hz; parent panels contain data averaged across the five stimulus whisker deflections whereas panel insets contain data separated according to stimulus deflection. For both imaging (A–C) and neuronal recording (D,E) data, note that the MWFR for the 24-whiskers array consists of a single peak located centrally within a large activation spread, thus resembling a relatively symmetrical activity mountain with one peak. Also note that, compared to the single whisker C2, the 24-whiskers' MWFR exhibited no shift in location of peak activity, no (C,E) or modest (14%; D) increase in peak magnitude, and relatively moderate increases in the tangential spread of activity and thus a broader shape of the activity mountain.