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要旨:
Sensory properties of cells in the upper bank polysensory area (STP) of the superior temporal sulcus (STS) were systematically investigated using recordings of single unit and population responses. STP (also referred to as TPO) receives convergent projections from the ventral as well as the dorsal pathway, including visual, auditory and somatosensory areas. Moreover, there is evidence for motion sensitivity, including the analysis of optic flow, and for facial and body movements in this region. However, only little is known about the structural organization of STP with respect to the various modalities being integrated. While recent imaging studies suggest that modality specific responses are clustered in spatially segregated patches [Beauchamp et al Nature Neurosci. 7, 2004], physiological evidence for this is limited.
Activity was recorded in two Macaque monkeys performing a visual fixation task. Stimuli included conspecific communication signals, natural scenes and artificial motion patterns. Somatosensory stimulation consisted of air-puffs applied to the back of the head. Stimuli were presented either in isolation or as multimodal combinations.
Single and multi unit activities suggest two types of functional representation: At some recording sites, responses can be elicited by stimulation of several modalities in isolation, and responses to different modalities show interactions when presented together. Other sites show a very specific representation and respond to only one dominant modality, preferentially visual or auditory. The spatial pattern suggests that neighboring sites (within 1.5mm) often show similar response patterns.
Altogether, our results show that the multimodal area in the superior temporal sulcus shows a patchy organization into modality specific domains, albeit this is only evident at a small spatial scale.
