Multisensory responses in a belt region of the dorsal auditory cortical pathway

A basic function of the cerebral cortex is to receive and integrate information from different sensory modalities into a comprehensive percept of the environment. Neurons that demonstrate multisensory convergence occur across the necortex but are especially prevalent in higher order association areas. However, a recent study of a cat higher order auditory area, the dorsal zone (DZ) of auditory cortex, did not observe any multisensory features. Therefore, the goal of the present investigation was to address this conflict using recording and testing methodologies that are established for exposing and studying multisensory neuronal processing. Among the 482 neurons studied, we found that 76.6% were influenced by non‐auditory stimuli. Of these neurons, 99% were affected by visual stimulation, but only 11% by somatosensory. Furthermore, a large proportion of the multisensory neurons showed integrated responses to multisensory stimulation, constituted a majority of the excitatory and inhibitory neurons encountered (as identified by the duration of their waveshape) and exhibited a distinct spatial distribution within DZ. These findings demonstrate that the DZ of auditory cortex robustly exhibits multisensory properties and that the proportions of multisensory neurons encountered are consistent with those identified in other higher order cortices. Multiple single‐unit recordings in auditory area DZ were made, whereas auditory, visual and somatosensory stimuli (and their combinations) were presented. As expected, almost all DZ neurons responded to auditory stimulation, but a substantial portion (>76%) were also responsive to non‐auditory inputs. This high proportion of multisensory neurons is consistent with the hierarchical status of DZ as a higher order cortical region.