Multisensory Interplay Within Human Auditory Cortex: New Evidence from Intraoperative Optical Imaging of Intrinsic Signal.

BACKGROUND

The primary auditory cortex, which was previously considered to be unisensory, has been shown to be multisensory. However, the temporal details of processing nonauditory stimuli in the human auditory cortex remain unclear, owing to the low temporal and spatial resolution of the adopted imaging techniques.

METHODS

Using intraoperative optical imaging of intrinsic signals recording techniques, detailed cortical activations within the auditory cortex in response to auditory and somatosensory stimulation were recorded from 3 intraoperative anesthetized patients with brain tumors located in the superior temporal gyrus.

RESULTS

At both green-light (545 nm ± 13) and red-light (610 nm ± 10) illumination, the primary and secondary auditory cortices responded significantly to the somatosensory stimulation. As induced by the somatosensory stimulus, the average overlapping rate of the activated region was 74.51% ± 0.15, and the peak responding time occurred at poststimulus 7-8 seconds. There was no significant difference in the peak responding time between auditory and somatosensory stimuli (P < 0.01, paired t test).

CONCLUSIONS

These findings provide novel evidence for multisensory interplay within human auditory cortex at an early stage of cortical processing, which extends the understanding of multisensory mechanisms of human brain functions.