Cortical connections of the second somatosensory area and the parietal ventral area in macaque monkeys

Abstract

To gain insight into how cortical fields process somatic inputs and ultimately contribute to complex abilities such as tactile object perception, we examined the pattern of connections of two areas in the lateral sulcus of macaque monkeys: the second somatosensory area (S2), and the parietal ventral area (PV). Neuroanatomical tracers were injected into electrophysiologically and/or architectonically defined locations, and labeled cell bodies were identified in cortex ipsilateral and contralateral to the injection site. Transported tracer was related to architectonically defined boundaries so that the full complement of connections of S2 and PV could be appreciated. Our results indicate that S2 is densely interconnected with the primary somatosensory area (3b), PV, and area 7b of the ipsilateral hemisphere, and with S2, 7b, and 3b in the opposite hemisphere. PV is interconnected with areas 3b and 7b, with the parietal rostroventral area, premotor cortex, posterior parietal cortex, and with the medial auditory belt areas. Contralateral connections were restricted to PV in the opposite hemisphere. These data indicate that S2 and PV have unique and overlapping patterns of connections, and that they comprise part of a network that processes both cutaneous and proprioceptive inputs necessary for tactile discrimination and recognition. Although more data are needed, these patterns of interconnections of cortical fields and thalamic nuclei suggest that the somatosensory system may not be segregated into two separate streams of information processing, as has been hypothesized for the visual system. Rather, some fields may be involved in a variety of functions that require motor and sensory integration.

Projection from Visual Areas V2 and Prostriata to Caudal Auditory Cortex in the Monkey

“…However, only the very superficial layers of auditory areas were involved, and lack of label in visual cortex may not be representative of their connections. Labeled cells were found in the parietal areas of the postcentral gyrus, intraparietal sulcus, and inferior parietal gyrus, consistent with the known connections of SII (Disbrow et al 2003).…”

Cortical Folding Abnormalities in Autism Revealed by Surface-Based Morphometry

“…In individuals with autism, the core deficit in social communication often includes flat affect and lack of appropriate use of facial expressions (Yirmiya et al, 1989;American Psychiatric Association, 1994). The parietal operculum, or secondary somatosensory cortex (SII), is implicated in numerous complex functions related to multimodal sensory and motor integration (Caselli, 1993;Bremmer et al, 2001;Disbrow et al, 2003). The shape abnormality in this region may be related to the unusual responses to sensory stimuli that are commonly observed in individuals with autism (Rogers and Ozonoff, 2005;Iarocci and McDonald, 2006).…”

Multimodal Convergence within the Intraparietal Sulcus of the Macaque Monkey

“…1C) stimulations, while fixating a central point, in independent time series. Based on prior studies, we used large field visual stimuli (expanding and contracting optic flow stimuli and moving bars) (Bremmer et al, 2002b), tactile stimuli to the face and upper body (Duhamel et al, 1998), and rich auditory stimuli moving in space (complex sounds have been shown to produce more robust cortical activations outside the primary auditory cortex, Blauert, 1997; than pure tones as used by Schlack et al, 2005). These stimulations were effective in activating the primary areas involved in their processing: all the visual stimuli activated the primary visual areas, and coherent movement specifically activated areas MT and MST (Fig.…”

“…These neurons can have a preference for large field dynamic visual stimuli, such as expanding or contracting optic flow patterns or moving bars (Schaafsma and Duysens, 1996;Bremmer et al, 2002a;Zhang et al, 2004), or smaller moving visual stimuli (Vanduffel et al, 2001). The parietal cortex also receives monosynaptic afferents from the somatosensory cortex (Seltzer and Pandya, 1980;Disbrow et al, 2003). Accordingly, tactile neuronal responses have been documented in this region (Duhamel et al, 1998;Avillac et al, 2005).…”

“…The parietal cortex also receives monosynaptic afferents from the somatosensory cortex (Seltzer and Pandya, 1980;Disbrow et al, 2003). Accordingly, tactile neuronal responses have been documented in this region (Duhamel et al, 1998;Avillac et al, 2005). A light auditory input to the parietal cortex has also been described from the caudomedial auditory belt (Lewis and Van Essen, 2000a), corroborating the description of parietal neurons responsive to auditory stimulations Grunewald et al, 1999;Schlack et al, 2005).…”