Abstract
The posterior parietal cortex (PPC) serves as a sensorimotor interface by integrating multisensory signals with motor related information for generating and updating body representations and movement plans. Using retrograde transneuronal transfer of rabies virus combined with a conventional tracer, we identified direct and polysynaptic pathways to two PPC areas, the rostral medial intraparietal area (MIP) and the ventral part of the lateral intraparietal area (LIPv) in macaque monkeys. We found that rostral MIP and LIPv receive ascending vestibular pathways, and putative efference copy inputs disynaptically from the medullary medial reticular formation (MRF) where reticulospinal pathways to neck and arm motoneurons originate. LIPv receives minor disynaptic vestibular inputs, and substantial projections from the head movement-related rostral MRF, consistent with head gain modulation of LIPv activity and a role in planning gaze shifts. Rostral MIP is the target of prominent disynaptic pathways from reaching- and head movement-related MRF domains, and major ascending vestibular pathways trisynaptically from both labyrinths, explaining prominent vestibular responses and discrimination between active and passive movements demonstrated in rostral MIP and in the neighboring ventral intraparietal area, which are heavily interconnected. The findings that rostral MIP (belonging to the 'parietal reach region'), receives vestibular inputs as directly as classical vestibular areas, via a parallel channel, and efference copy signals pathways from MRF reticulospinal domains that belong to reach and head movement networks have important implications for the understanding of the role of the PPC in updating body representations and internal models for online guidance of movement.
Highlights
The posterior parietal cortex (PPC), which is part of the visual dorsal stream and has reciprocal connections with frontal lobe motor areas, is a major sensorimotor interface, which maintains dynamic representations of internal and extrapersonal space and participates in planning and execution of sensory-guided goal-directed movements (Andersen, 1997; Rushworth et al, 1997; Grefkes et al, 2004; Buneo & Andersen, 2006; Filimon et al, 2009)
In keeping with reports of reciprocal interconnections of medial intraparietal area (MIP) and LIPv with ventral intraparietal area (VIP) (Lewis & Van Essen, 2000b; Bakola et al, 2017), the cholera toxin B (CTB) results showed that direct projections to the injected rostral MIP originate from dorsal VIP (Fig. 3C and E); by comparison, projections to LIPv are derived from wider VIP portions, especially from ventral VIP, and are much heavier (Fig. 3A)
The present study provides the first description of ascending polysynaptic pathways that convey vestibular signals to rostral MIP and LIPv
Summary
The posterior parietal cortex (PPC), which is part of the visual dorsal stream and has reciprocal connections with frontal lobe motor areas, is a major sensorimotor interface, which maintains dynamic representations of internal and extrapersonal space and participates in planning and execution of sensory-guided goal-directed movements (Andersen, 1997; Rushworth et al, 1997; Grefkes et al, 2004; Buneo & Andersen, 2006; Filimon et al, 2009). Integration of internal information (proprioceptive, vestibular, motor) and external signals (visual, tactile, auditory) is crucial for these functions. Cortical integration of vestibular signals evoked by self-motion is important for a variety of self-related perceptual and cognitive functions (Andersen, 1997; Lopez et al, 2008; Blanke et al, 2015). Evidence has been provided that the human IPS uses vestibular signals for fast online adjustment of goal-directed arm movements (Reichenbach et al, 2016). Vestibular responses in the IPS have been recorded in the ventral intraparietal area (VIP) and in the rostral medial intraparietal area (MIP) (Bremmer et al, 2001, 2002; Schlack et al, 2002; Klam & Graf, 2003, 2006; Chen et al, 2011)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
