Wide-field retinotopy reveals a new visuotopic cluster in macaque posterior parietal cortex
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ORIGINAL ARTICLE
Wide‑field retinotopy reveals a new visuotopic cluster in macaque posterior parietal cortex Samy Rima1,2 · Benoit R. Cottereau1,2 · Yseut Héjja‑Brichard1,2 · Yves Trotter1,2 · Jean‑Baptiste Durand1,2 Received: 6 August 2019 / Accepted: 22 August 2020 © The Author(s) 2020
Abstract We investigated the visuotopic organization of macaque posterior parietal cortex (PPC) by combining functional imaging (fMRI) and wide-field retinotopic mapping in two macaque monkeys. Whole brain blood-oxygen-level-dependent (BOLD) signal was recorded while monkeys maintained central fixation during the presentation of large rotating wedges and expending/contracting annulus of a “shaking” fruit basket, designed to maximize the recruitment of PPC neurons. Results of the surface-based population receptive field (pRF) analysis reveal a new cluster of four visuotopic areas at the confluence of the parieto-occipital and intra-parietal sulci, in a location previously defined histologically and anatomically as the posterior intra-parietal (PIP) region. This PIP cluster groups together two recently described areas (CIP1/2) laterally and two newly identified ones (PIP1/2) medially, whose foveal representations merge in the fundus of the intra-parietal sulcus. The cluster shares borders with other visuotopic areas: V3d posteriorly, V3A/DP laterally, V6/V6A medially and LIP anteriorly. Together, these results show that monkey PPC is endowed with a dense set of visuotopic areas, as its human counterpart. The fact that fMRI and wide-field stimulation allows a functional parsing of monkey PPC offers a new framework for studying functional homologies with human PPC. Keywords Visuotopy · Dorsal · Primates · fMRI · PIP · CIP
Introduction In primates, the posterior parietal cortex (PPC) constitutes the end stage of the dorsal visual pathway and as such, it is notably involved in visuospatial and visuomotor functions (Buneo and Andersen 2006; Freedman and Ibos 2018; Hadjidimitrakis et al. 2019a, b). Most of what we know about how those functions are implemented in the PPC emanates from invasive (anatomical and electrophysiological) studies Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00429-020-02134-2) contains supplementary material, which is available to authorized users. * Samy Rima [email protected] * Jean‑Baptiste Durand [email protected] 1
Centre de Recherche Cerveau et Cognition, Université de Toulouse, Toulouse, France
Centre National de la Recherche Scientifique, Toulouse Cedex, France
2
performed in macaque monkeys. They have notably demonstrated the existence of a myriad of structurally and/or functionally distinct areas (Pandya and Seltzer 1982; Colby et al. 1988; Andersen et al. 1990; Lewis and Van Essen 2000), although their precise number and boundaries remain debated (Van Essen 2004). Such invasive studies have led to the view that monkey PPC is only marginally visuotopic, with coarse topographic representations of visual space restricted to the lateral intr
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