Structural connectivity and functional properties of the macaque superior parietal lobule

Abstract

Despite the consolidated belief that the macaque superior parietal lobule (SPL) is entirely occupied by Brodmann's area 5, recent data show that macaque SPL also hosts a large cortical region with structural and functional features similar to that of Brodmann's area 7. According to these data, the anterior part of SPL is occupied by a somatosensory-dominated cortical region that hosts three architectural and functional distinct regions (PE, PEci, PEip), and the caudal half of SPL by a bimodal somato-visual region that hosts four areas: PEc, MIP, PGm, V6A.To date, the most studied areas of SPL are PE, PEc, and V6A. PE is essentially a high-order somatomotor area, while PEc and V6A are bimodal somatomotor-visuomotor areas, the former with predominant somatosensory input, the latter with predominant visual input. The functional properties of these areas and their anatomical connectivity strongly suggest their involvement in the control of limb movements. PE is suggested to be involved in the preparation/execution of limb movements, in particular the movements of the upper limb; PEc in the control of movements of both upper and lower limbs, as well as in their interaction with the visual environment; V6A in the control of reach-to-grasp movements performed with the upper limb.In humans, SPL is traditionally considered to have a different organization with respect to macaques. Here, we review several lines of evidence suggesting that this is not the case, showing a similar structure for human and nonhuman primate SPLs.

Receptor-driven, multimodal mapping of cortical areas in the macaque monkey intraparietal sulcus

“…According to the studies from Lewis and Van Essen, 2000a and Bakola, Passarelli ( Bakola et al, 2017 ), three areas occupied the medial wall of the IPS: area PO is located in the junction with POS, and the remaining rostral part consists of two distinct areas. The middle area was named MIP ( Lewis and Van Essen, 2000a ; Bakola et al, 2017 ), whereas the rostralmost area was identified as area 5V ( Lewis and Van Essen, 2000a ) or as area PEip ( Bakola et al, 2017 ; Gamberini et al, 2020a ). The present partitioning scheme was able to confirm the existence of these two areas, their location and extent are more similar to the scheme charted by Bakola et al, 2017 , so we followed their nomenclature.…”

“…Interestingly, this shift in functional systems, from a caudo-lateral visual domain to a rostro-medial sensorimotor domain ( Grefkes and Fink, 2005 ; Lewis and Van Essen, 2000b ; Gamberini et al, 2020a ; Guipponi et al, 2013 ), is also the most significant trend reflected by changes in the shape and/or size of the fingerprints. From an overall perspective, the rostralmost areas (i.e.…”

A Sensorimotor Numerosity System

“…Like the macaque VIP, area NCP1 is located posterior to a region of visual tactile convergence ( Figure 2B [33]). This region may correspond to area 5 [40], which in monkeys hosts neurons involved in the sensorimotor control of limb action [41], including numerosity [25,26].…”

Mixed Selectivity in Macaque Medial Parietal Cortex during Eye-Hand Reaching

“…The associative cortices, like the posterior parietal cortex (PPC), include a variety of multimodal associative areas whose neurons are modulated by a plethora of different factors ( Binkofski and Buccino, 2018 , Galletti and Fattori, 2018 , Gamberini et al., 2020 ). Within macaque PPC area V6A, located in the anterior bank of parieto-occipital sulcus, ( Galletti et al., 1999 ), is a higher-order visuomotor area modulated by visual signals coming from the whole visual field and somatic signals coming from the upper limbs ( Gamberini et al., 2011 , 2018 ), as well as by oculomotor signals related to gaze position and eye movement ( Galletti et al., 1995 ; Kutz et al., 2003 Breveglieri et al., 2012 ).…”