Decoding visual object categories in early somatosensory cortex.
Bottom Line: We further show that this decoding is observed for familiar but not unfamiliar visual objects in S1.In addition, whole-brain searchlight decoding analyses revealed several areas in the parietal lobe that could mediate the observed context effects between vision and somatosensation.These results demonstrate that even the first cortical stages of somatosensory processing carry information about the category of visually presented familiar objects.
Affiliation: School of Psychology, University of East Anglia, Norwich NR4 7TJ, UK The Brain and Mind Institute, University of Western Ontario, London, ON, Canada N6A 5B7.Show MeSH
Mentions: We defined anatomical masks of the bilateral postcentral gyrus (PCG) in each individual participant (see Fig. 2 and Materials and Methods). Figure 3A shows the cross-validated performance of the linear classifier (linear SVM) in decoding visual object category (3AFC) from the PCG. Remarkably, decoding of visual object category significantly exceeded chance in each case: right PCG mean decoding accuracy 40%, t(7) = 3.68, P = 0.004 (chance 1/3); left PCG 36.8%, t(7) = 2.18, P = 0.03 (chance 1/3); and pooled 37.5%, t(7) = 2.71, P = 0.015 (chance 1/3). Decoding accuracy was significantly higher in the right as opposed to the left PCG (t(7) = 2.61, P = 0.035). Thus, the earliest stages of somatosensory cortex, that is, the PCG, carry information about different categories of visual object presented to participants. The full confusion matrices underlying this performance can be seen in Supplementary Figure 2. Crucially, univariate signal changes did not differ across the 3 object categories in the PCG (Supplementary Fig. 3 and Supplementary Text).Figure 3.
Affiliation: School of Psychology, University of East Anglia, Norwich NR4 7TJ, UK The Brain and Mind Institute, University of Western Ontario, London, ON, Canada N6A 5B7.