Figure 1.

Uni- versus bimodal evoked responses in primary sensory cortices and corresponding first-order thalamic nuclei. (a) Schematic drawing displaying the sensory stimulation via light flashes and whisker deflections as well as the position of recording electrodes in S1, VPM, V1, and dLGN of a Brown Norway rat. (b) (i) Schematic drawing displaying the location of all recording sites in VPM (n = 18) that were used for the analysis of the LFP and SUA. (ii) Same as (i) for dLGN. (c) (i) Nissl stained coronal section displaying the location of the custom-made DiI-labelled multi-site recording electrode in the S1 of a Brown Norway rat. Note that the silicon probe is inserted angularly to target both S1 and VPM. (ii) Same as (i) for VPM. (iii) Nissl stained coronal section displaying the position of recording sites in the VPM in (ii) when displayed at higher magnification. (d) Same as (c) for V1 and dLGN. (e) Positive (P1) and negative (N1) peaks of EPs averaged across animals after visual (red), tactile (orange) and bimodal visual-tactile (blue) stimulation in granular layers of S1 (top) and VPM (bottom). Inset displays the EP in VPM at larger magnification. Black arrow marks the stimulation. (f) (i) Bar diagrams displaying the maximum amplitude of P1 and N1 across animals after visual (red), tactile (orange) and bimodal visual-tactile (blue) stimulation in VPM. (ii) Bar diagrams displaying the latency of the maximum amplitude of P1 (left) and N1 (right) after tactile (orange) and bimodal visual-tactile (blue) stimulation in VPM. (g) Same as (e) for granular layers of V1 and dLGN. (h) Same as (f) for dLGN. A1 = primary auditory cortex, PtCx = parietal cortex, RSC = retrosplenial cortex. (^*p < 0.05, ^**p < 0.01, ^***p < 0.001; paired sample t-test). The schematic drawing in (a) was obtained and modified from Bieler et al⁸⁰. Visual-tactile processing in primary somatosensory cortex emerges before cross-modal experience. Synapse. 2017 Jun;71(6). John Wiley & Sons, Inc., Hoboken, NJ, USA.