Auditory-visual interaction in single cells in the cortex of the superior temporal sulcus and the orbital frontal cortex of the macaque monkey

Previous anatomical studies show that the cortex of the superior temporal sulcus and the orbital frontal cortex receive convergent corticocortical and thalamocortical projections which represent different sensory modalities. In the present experiments both intracellular and extracellular recordings were made in these cortical regions to determine if the individual cells receive polysensory information and if interactions between different medalities are a result of local convergence at the cortical cell. The results show that many neurons have visual receptive fields which are bilateral, include the fovea, and are sensitive to moving stimuli. Many of these neurons are also excited or inhibited by auditory stimuli. For both modalities a variety of ON or OFF excitatory and inhibitory effects was seen. The results further indicate that neurons in both regions show auditory-visual interactions and that at least some of these interactions are due to convergence at the cortical cell. For example, we found that auditory stimuli of a specific frequency had a powerful inhibitory effect on many of the neurons and that this inhibitory effect could negate the excitation caused by a visual stimulus. These types of interactions are related to the anatomical inputs and may be possible mechanism implicating each of these regions in attention and discrimination.