Neurons in the cortical taste area receive nociceptive inputs from the whole body as well as the oral cavity in the rat

Abstract

Almost all mechanoreceptive neurons in the cortical taste area (CTA) of the rat had receptive fields (RFs) in the oral cavity, except for a few neurons at the border with the primary somatosensory area that had RFs on the contralateral rhinarium or upper lip. About one-third of the mechanoreceptive neurons with RFs in the oral cavity had additional RFs on the tips of limbs, earflaps or tail, i.e. the glabrous skin or skin with sparse hairs of the external surface of the body (whole body type). Most of these neurons received both innocuous and noxious inputs (wide dynamic range type), but some had either type of input (low threshold mechanoreceptive or nociceptive specific type). Some nociceptive neurons were responsive to taste, as previously found. Nociceptive neurons with the whole body type of RFs were diffusely distributed across the CTA without clustering. The corticocortical afferents, probably originating from the visceral part of the insula, may code body condition to modulate the taste responsiveness of the cortical taste neurons.