Vision for action: thalamic and cortical inputs to the macaque superior parietal lobule.

The dorsal visual stream, the cortical circuit that in the primate brain is mainly dedicated to the visual control of actions, is split into two routes, a lateral and a medial one, both involved in coding different aspects of sensorimotor control of actions. The lateral route, named "lateral grasping network", is mainly involved in the control of the distal part of prehension, namely grasping and manipulation. The medial route, named "reach-to-grasp network", is involved in the control of the full deployment of prehension act, from the direction of arm movement to the shaping of the hand according to the object to be grasped.

Claustral Input to the Macaque Medial Posterior Parietal Cortex (Superior Parietal Lobule and Adjacent Areas).

The projections from the claustrum to cortical areas within and adjacent to the superior parietal lobule were studied in 10 macaque monkeys, using retrograde tracers, computerized reconstructions, and quantitative methods. In contrast with the classical view that posterior parietal areas receive afferents primarily from the dorsal and posterior regions of the claustrum, we found that these areas receive more extensive projections, including substantial afferents from the anterior and ventral regions of the claustrum. Moreover, our findings uncover a previously unsuspected variability in the precise regions of the claustrum that originate the projections, according to the target areas.

The superior parietal lobule of primates: a sensory-motor hub for interaction with the environment.

The superior parietal lobule of the macaque monkey occupies the postero-medial part of the parietal lobe and plays a crucial role in the integration of different sources of information (from visual, motor and somatosensory brain regions) for the purpose of high-level cognitive functions, as perception for action. This region encompasses the intraparietal sulcus and the parieto-occipital sulcus and includes also the precuneate cortex in the mesial surface of the hemisphere. It hosts several areas extensively studied in the macaque: PE, PEip, PEci anteriorly and PEc, MIP, PGm and V6A posteriorly.

Open access resource for cellular-resolution analyses of corticocortical connectivity in the marmoset monkey.

Understanding the principles of neuronal connectivity requires tools for efficient quantification and visualization of large datasets. The primate cortex is particularly challenging due to its complex mosaic of areas, which in many cases lack clear boundaries. Here, we introduce a resource that allows exploration of results of 143 retrograde tracer injections in the marmoset neocortex.

Thalamic afferents emphasize the different functions of macaque precuneate areas.

We studied the thalamic afferents to cortical areas in the precuneus using injections of retrograde fluorescent neuronal tracers in four male macaques (Macaca fascicularis). Six injections were within the limits of cytoarchitectural area PGm, one in area 31 and one in area PEci. Precuneate areas shared strong input from the posterior thalamus (lateral posterior nucleus and pulvinar complex) and moderate input from the medial, lateral, and intralaminar thalamic regions.

Structural connectivity and functional properties of the macaque superior parietal lobule.

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.

Anterior Intraparietal Area: A Hub in the Observed Manipulative Action Network.

Current knowledge regarding the processing of observed manipulative actions (OMAs) (e.g., grasping, dragging, or dropping) is limited to grasping and underlying neural circuitry remains controversial.

Cortical Afferents and Myeloarchitecture Distinguish the Medial Intraparietal Area (MIP) from Neighboring Subdivisions of the Macaque Cortex.

The parietal reach region (PRR) in the medial bank of the macaque intraparietal sulcus has been a subject of considerable interest in research aimed at the development of brain-controlled prosthetic arms, but its anatomical organization remains poorly characterized. We examined the anatomical organization of the putative PRR territory based on myeloarchitecture and retrograde tracer injections. We found that the medial bank includes three areas: an extension of the dorsal subdivision of V6A (V6Ad), the medial intraparietal area (MIP), and a subdivision of area PE (PEip).

Thalamo-cortical projections to the macaque superior parietal lobule areas PEc and PE.

The exposed surface of the superior parietal lobule in macaque brain contains two architectonically defined areas named PEc and PE. The aim of the present study is the characterization of thalamic afferents of these two areas. For this purpose, retrograde neuronal tracers were injected, or placed in crystal form, in areas PEc and PE.

Sensory properties of the caudal aspect of the macaque's superior parietal lobule.

In the superior parietal lobule (SPL), the anterior part (area PE) is known to process somatosensory information, while the caudalmost part (areas V6Av and V6) processes visual information. Here we studied the visual and somatosensory properties of the areas PEc and V6Ad located in between the somatosensory and visual domains of SPL. About 1500 neurons were extracellularly recorded in 19 hemispheres of 12 monkeys (Macaca fascicularis).

Uniformity and Diversity of Cortical Projections to Precuneate Areas in the Macaque Monkey: What Defines Area PGm?

We report on the corticocortical connections of areas on the mesial surface of the macaque posterior parietal cortex, based on 10 retrograde tracer injections targeting different parts of the precuneate gyrus. Analysis of afferent connections supported the existence of two areas: PGm (also known as 7 m) and area 31. Both areas received major afferents from the V6A complex and from the external subdivision of area 23, but they differed in most other aspects.

Neural activity in the medial parietal area V6A while grasping with or without visual feedback.

Recent works have reported that grasping movements are controlled not only by the dorsolateral visual stream, as generally thought, but also by the dorsomedial visual stream, and in particular by the medial posterior parietal area V6A. To date, the grasping activity of V6A neurons has been studied only in darkness. Here we studied the effect of visual feedback on grasp-related discharges of V6A neurons while the monkey was preparing and executing the grasping of a handle.

Claustral afferents of superior parietal areas PEc and PE in the macaque.

The exposed surface of the primate superior parietal cortex includes two cytoarchitectonically defined areas, the PEc and PE. In the present study we describe the distribution of neurons projecting from the claustrum to these areas. Retrograde neuronal tracers were injected by direct visualization of regions of interest, and the location of injection sites was reconstructed relative to cytoarchitectural borders.

Thalamic projections to visual and visuomotor areas (V6 and V6A) in the Rostral Bank of the parieto-occipital sulcus of the Macaque.

The medial posterior parietal cortex of the primate brain includes different functional areas, which have been defined based on the functional properties, cyto- and myeloarchitectural criteria, and cortico-cortical connections. Here, we describe the thalamic projections to two of these areas (V6 and V6A), based on 14 retrograde neuronal tracer injections in 11 hemispheres of 9 Macaca fascicularis. The injections were placed either by direct visualisation or using electrophysiological guidance, and the location of injection sites was determined post mortem based on cyto- and myeloarchitectural criteria.

Cortical connectivity suggests a role in limb coordination for macaque area PE of the superior parietal cortex.

In macaques, superior parietal lobule area 5 has been described as occupying an extensive region, which includes the caudal half of the postcentral convexity as well as the medial bank of the intraparietal sulcus. Modern neuroanatomical methods have allowed the identification of various areas within this region. In the present study, we investigated the corticocortical afferent projections of one of these subdivisions, area PE.

Cortical connections of area V6Av in the macaque: a visual-input node to the eye/hand coordination system.

The goal of the present study was to elucidate the corticocortical afferent connections of area V6Av, the ventral subregion of area V6A, using retrograde neuronal tracers combined with physiological and cytoarchitectonic analyses in the macaque monkey. The results revealed that V6Av receives many of its afferents from extrastriate area V6, and from regions of areas V2, V3, and V4 subserving peripheral vision. Additional extrastriate visual projections originate in dorsal stream areas MT and MST.

Cortical connections of parietal field PEc in the macaque: linking vision and somatic sensation for the control of limb action.

The cortical projections to the caudal part of the superior parietal lobule (area PEc) were studied in 6 cynomolgus monkeys using fluorescence tracers. Significant numbers of labeled cells were found in a restricted network of parietal, mesial, and frontal areas. Quantitative analysis demonstrated that approximately 30% of the total projection neurons originated in the adjacent areas of the dorsocaudal part of the superior parietal lobule (areas PE and V6A).

Cortical connections of the visuomotor parietooccipital area V6Ad of the macaque monkey.

Area V6A, a functionally defined region in the anterior bank of the parietooccipital sulcus, has been subdivided into dorsal and ventral cytoarchitectonic fields (V6Ad and V6Av). The aim of this study was to define the cortical connections of the cytoarchitectonic field V6Ad. Retrograde and bidirectional neuronal tracers were injected into the dorsal part of the anterior bank of parietooccipital sulcus of seven macaque monkeys (Macaca fascicularis).

Somatosensory cells in area PEc of macaque posterior parietal cortex.

PEc is an area defined on cytoarchitectural grounds, located in the posterior part of the superior parietal lobule of macaque brain (Pandya and Seltzer, 1982). The aim of this work was to assess whether passive somatosensory stimulation elicited responses in PEc neurons. Extracellular recordings were performed in three awake Macaca fascicularis.