Spatial organization of neurons in the superior temporal sulcus.

摘要

How are neurons with different modality preferences spatially distributed in multisensory cortical regions? Although spatial patterns of neurons have been well documented in the primary cortices (e.g., tonotopic maps in the auditory cortex, columnar structures in the visual cortex), data are lacking as to whether neurons in multimodal regions are organized in some way.One functional magnetic resonance imaging (fMRI) study (Beauchamp et al, 2004) has suggested an orderly layout of neuron clusters sensitive to auditory and visual stimuli in the human superior temporal sulcus (STS), in which a putative multisensory area [the homolog of monkey superior temporal polysensory cortex-also known as TPO in the study by Seltzer and Pandya (1978)] (Fig. 1) is located. Consistent with this, an anatomical tracer injection study showed that afferent projections from cortical unisensory auditory and visual regions target nonover-lapping vertical modules within the upper bank of the STS (uSTS) (Seltzer et al., 1996). However, given the limited spatial resolution of fMRI and the lack of explicit functional information yielded by tracer injection techniques, the existence of functionally organized clusters in this multisensory region remains speculative without neurophysiological studies directly assessing spatial organizations of neuronal responses to sensory stimuli.