A common representation of the left and right fingers

The left and right hands, beyond being physically identical structures, have a number of functional connections. Their representations are both morphologically similar and highly integrated, in primary somatosensory cortex as well as higher cortical areas. Previous studies have shown that there is a highly consistent pattern of tactile confusions made between fingers of the left and right hand, but none have directly compared the patterns on the two hands. Here, we investigated the similarity of patterns of confusions across the fingers of the left and right hands. We also investigated whether there are individual differences in response patterns that are shared across the two hands. We obtained confusions matrices showing the pattern of tactile mislocalisations on the hairy skin surfaces of the fingers of the left and right hands, and show that these patterns are similar. Using a decoding approach, we show that there are idiosyncratic differences in individual participants' patterns of confusions that are shared across the fingers of both hands, despite the overall patterns of confusions being highly consistent across participants. These results demonstrate that there is a common high-level representation of the hands that does not distinguish body-side, as has been suggested in previous studies.