Figure 5. Complex stimuli reveal dramatically sharpened receptive fields relative to conventional stimuli.

Population averaged STRFs were calculated for neurons of the same cell type. a, Population STRFs based on complex multi-whisker stimuli. b, Population STRFs simple single-whisker stimulation for the same neurons as in A. c – h, Receptive field properties for complex (black) versus simple (gray) stimuli (* p < 0.05; ** p < 0.01; *** p < 0.001; TL, p < 0.1; all tests were non-parametric two sided rank-sum test). Bars, means ± SEM. c, Adapted STRFs had significantly fewer responsive whiskers than unadapted STRFs. d, For adapted STRFs the total fraction of the response power contained in the surround receptive field was significantly less than in unadapted neurons. e, Onset latency of the receptive field (usually, but not always, the onset of the PW response) was unchanged between groups. f, The average latency between the onset of the PW response and the mean onset of the SW responses was shortened for adapted STRFs, and was significant in L2 (p<0.05, t-test). g, The vector strength, a measure of coherence or directional similarity between significantly responsive whiskers, was highest in infra and supra-granular layers but was unchanged between simple stimuli and complex stimuli (0 anti-coherent, 1 perfectly coherent). h, Directional tuning of the PW, defined as strength of response to the preferred direction divided by the summed response to all directions, was always higher during complex stimuli but results were not significant (0.125 = no tuning preference; 1.0 = tuned to a single direction).