Thermosensory perceptual learning is associated with structural brain changes in parietal-opercular (SII) cortex

The location of a sensory cortex for temperature perception remains a topic of substantial debate. Both parietal-opercular (SII) and posterior insula have been consistently implicated in thermosensory processing, but neither region has yet been identified as the locus of fine temperature discrimination. Using a perceptual learning paradigm in male and female humans, we show improvement in discrimination accuracy for sub-degree changes in both warmth and cool detection over 5 days of repetitive training. We found that increases in discriminative accuracy were specific to the temperature (cold or warm) being trained. Using structural imaging to look for plastic changes associated with perceptual learning, we identified symmetrical increases in grey matter density in parietal-opercular (SII) cortex. Furthermore, we observed distinct, adjacent regions for cold and warm discrimination, with cold discrimination having a more anterior locus than warm. The results suggest that thermosensory discrimination is supported by functionally and anatomically distinct temperature-specific modules in parietal-opercular SII cortex. SIGNIFICANCE STATEMENT We provide behavioural and neuroanatomical evidence that perceptual learning is possible within the temperature system. We show that structural plasticity localizes to SII, and not posterior insula, providing the best evidence to date resolving a longstanding debate about the location of putative ‘temperature cortex’. Furthermore, we show that cold and warm pathways are behaviourally and anatomically dissociable, suggesting that the temperature system has distinct temperature-dependent processing modules.