Fig 1.
Differential biomechanical characteristics of different whiskers arcs.
(A) Experimental design. The whiskers are contacting a rotating cylinder covered with textured sandpaper and an edge. (B) Example of 2 outermost whiskers’ vibrations in response to texture (P220) and edges. On the right, a magnified segment from the left panel showing whiskers’ motion while colliding with an edge and the resultant resonant movements (arrows). (C). Heat map of whiskers’ response movement SD to all textures across all whiskers. Each pixel denotes the normalized whisker vibrations’ SD to the highest value in the map. (D) The upper panel shows the recorded whiskers. The lower panel shows the mean and SD of each of the arcs in C. The inequality sign indicates a statistically significant difference between the various arcs. The underlying data for this Figure can be found in S1 Data.
Fig 2.
Rostral whiskers exhibit higher responses range to different texture grain.
(A). Example of 2 outermost whiskers’ (C4, γ) vibrations in response to textures (P120, P600, P1200). (B) The panel shows the quantification of 3 whiskers’ vibrations’ SD in response to different textures. (C) Power spectra of movements of the same whiskers across different textures is shown color coded. (D) The panel shows the quantification of 3 whiskers’ vibrations’ cumulative power in the 5–250 Hz range in response to different textures. (D) The intrinsic curvature of 2 outermost whiskers in response to the same textures as in A. (E) The panel shows the quantification of 3 whiskers’ curvature SD in response to different textures. These examples show a higher sensitivity to the different textures in rostral whiskers in all of these parameters. The underlying data for this Figure can be found in S1 Data.
Fig 3.
Rostral whiskers exhibit higher response sensitivity to texture grain.
(A, C, E) Linear regression fit of the normalized SD (A), power (C), and curvature (E) of whisker vibrations in response to several textures (n = 5; each texture is represented by the mean particle size). (B, D, F) Normalized slopes (normalized to the slope of arc 4 whiskers of each session) of the linear regression fit for all whiskers. The numbers indicate the different arcs. The inequality sign indicates a statistically significant difference between the various arcs. The underlying data for this Figure can be found in S1 Data.
Fig 4.
Rostral whiskers exhibit greater texture discrimination.
Average AUC for texture discrimination as a function of the different arcs. Whisker position SD (panel A), power (panel B), and curvature (panel C). (D–E) Combining tactile signal from multiple whiskers increased texture discrimination for γ whisker but not for C4. (F) A measure of linearity of summation of signals from multiple whiskers (see text for details). In most cases, summation in supralinear. The numbers indicate the different arcs. The inequality sign indicates a statistically significant difference between the various arcs. The underlying data for this Figure can be found in S1 Data. AUC, area under the receiver operating characteristic curve.
Fig 5.
Changes in surface distance does not alter the gradient of tactile inputs across the pad.
(A) Experimental design. The whiskers are contacting a rotating cylinder covered with textured sandpaper at the same distance. Example of 2 outermost whiskers’ (C3 and γ) vibrations and curvature in response to texture (P220). (B–C). The mean SD of each of the arcs in panel A. Normalized SD mean and SD of each arc in all animals (n = 5). (D–E) The same as in panels B–C for curvature. The inequality sign indicates a statistically significant difference between the various arcs. The underlying data for this Figure can be found in S1 Data.
Fig 6.
TG neurons innervating rostral whiskers exhibit higher response range to different texture grain.
(A) Typical examples of raster plots and PSTHs from different arcs aligned to edge contact shown from caudal (right) to rostral (left). The red transparent square demarcates edge-related responses. The middle and lower panels show the responses of the neurons at different distances of texture wheel from the pad. (B) Normalized firing rate ratio (the ratio between firing rates in response to edges and responses to textures normalized to the highest value across arcs) from the different arcs and at different conditions. (C) Normalized firing rate ratio (the ratio between firing rates in response to edges and responses to textures normalized to the highest value across rows) from 2 different rows. Scale bar of the PSTHs refers to firing probability at a given bin. The underlying data for this Figure can be found in S1 Data. PSTH, peri stimulus time histogram; TG, trigeminal ganglion.
Table 1.
Distribution of neuronal types across all whiskers.
Fig 7.
TG neurons innervating rostral whiskers exhibit higher response sensitivity to texture grain.
(A) The relationship between texture coarseness and TG firing rates in 2 arcs. (B) Normalized firing rates (normalized to the maximal firing rates) for all neurons innervating Greek and arc 3 whiskers in response to the different textures. (C) Normalized slopes of the linear regression fit for normalized firing rates versus texture surface coarseness. (D) AUC for texture discrimination (blue bars) and texture-edge discrimination (red bars) for the different arcs. The numbers indicate the different arcs. The inequality sign indicates a statistically significant difference between the various arcs. The underlying data for this Figure can be found in S1 Data. AUC, area under the receiver operating characteristic curve; TG, trigeminal ganglion.