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

Abstract

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. For comparison, the patterns of claustral label that resulted from injections involving neighboring cytoarchitectonic areas were analyzed. We found that the claustral territories sending projections to areas PE and PEc partially overlapped zones previously shown to form projections to the posterior parietal, somatosensory, visual, and motor cortex. The projection zones to the PE and PEc overlapped extensively, and consisted of multiple patches separated by label-free zones. Most of the labeled neurons were located in the posterior-ventral part of the claustrum. Area PE received additional inputs from a posterior-dorsal part of the claustrum, which has been previously reported to project to the somatosensory cortex, while the PEc receives additional input from an anterior-ventral region of the claustrum, which has been reported to project to the visual association cortex. These observations reflect the known functional properties of the PE and PEc, with the former containing neurons that are predominantly involved in somatosensory processing, and the latter including both somatosensory and visual neurons. The present results suggest that the claustrum projections may help coordinate the activity of an extensive neural circuit involved in sensory and motor processing for movement execution. J. Comp. Neurol. 525:1475-1488, 2017. © 2016 Wiley Periodicals, Inc.

The relationship between the claustrum and endopiriform nucleus: A perspective towards consensus on cross‐species homology

“…Regionalization of CLA connections is also evident following tracer injections in prefrontal (Burman et al, 2011;Reser et al, 2014Reser et al, , 2017Selemon & Goldman-Rakic, 1988), inferior temporal (Baizer et al, 1993), posterior parietal (Baizer et al, 1993;Gamberini et al, 2017;Selemon & Goldman-Rakic, 1988), and orbitofrontal cortex (Morecraft, Geula, & Mesulam, 1992; also shown by fiber degeneration staining, Leichnetz & Astruc, 1975). Finally, there has been a long-standing assertion that the En components of the CLA complex project selectively to the "limbic" areas of cortex, especially the orbitofrontal, ventromedial prefrontal, and anterior cingulate areas, while the insular CLA projects more to higherorder sensory and association areas.…”

“…Additional work has shown that there are some modality‐specific characteristics of CLA connectivity, including localization of visual connections to the ventral and caudal aspects of the CLA, with somatomotor projections concentrated in the dorsal regions (Baizer et al, ; Pearson et al, ). Regionalization of CLA connections is also evident following tracer injections in prefrontal (Burman et al, ; Reser et al, , ; Selemon & Goldman‐Rakic, ), inferior temporal (Baizer et al, ), posterior parietal (Baizer et al, ; Gamberini et al, ; Selemon & Goldman‐Rakic, ), and orbitofrontal cortex (Morecraft, Geula, & Mesulam, ; also shown by fiber degeneration staining, Leichnetz & Astruc, ). Finally, there has been a long‐standing assertion that the En components of the CLA complex project selectively to the “limbic” areas of cortex, especially the orbitofrontal, ventromedial prefrontal, and anterior cingulate areas, while the insular CLA projects more to higher‐order sensory and association areas.…”

“…In area 9 of the dorsal prefrontal cortex in Cebus , the predominant input is from a region corresponding to DEnI and DEnV, even though area 9 is recognized as a prefrontal area involved in attention in New World monkeys (Dias, Robbins, & Roberts, ). Similarly, prestriate (prelunate gyrus) and posterior parietal injections in macaque monkeys label regions that are likely to include all subdivisions of DEn, based on their morphological similarity to the structure of the CLA complex in New World species (Baizer et al, ; Gamberini et al, ). However, that similarity must be viewed with some skepticism, as the equivalent myeloarchitecture‐based parcellation has not yet been performed on macaques.…”

“…A key feature of these newer studies is the combination of detailed connectional analysis of CLA projections with cytoarchitectural and topographical organizational analysis of the cortical origins of these projections. Thus, we are now aware of a topographical organization of projections to the CLA complex originating from various levels of the parallel distributed hierarchy of visual cortex areas of the macaque (Baizer, Desimone, & Ungerleider, 1993;Baizer, Lock, & Youakim, 1997;Gattass et al, 2014), between adjacent areas of the mPFC and anterior cingulate cortex of the marmoset (Reser et al, 2017), and between the closely related parietal areas PE and PEc in the macaque (Gamberini et al, 2017). On a more granular level, differential connectivity to the CLA has been described for connections arising within the medial and lateral portions of a single cytoarchitecturally defined area of prefrontal cortex, the frontal polar Area 10 (Burman et al, 2011;Reser et al, 2014).…”

“…The CLA portion of the claustrum complex is outlined in blue, while the DEn is marked in yellow. (Baizer et al, 1997;Gamberini et al, 2017). However, that similarity must be viewed with some skepticism, as the equivalent myeloarchitecture-based parcellation has not yet been performed on macaques.…”