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Neural connections of the posteromedial cortex in the macaque - PubMed

  • ️Sun Jan 01 2006

Neural connections of the posteromedial cortex in the macaque

Josef Parvizi et al. Proc Natl Acad Sci U S A. 2006.

Abstract

The posterior cingulate and the medial parietal cortices constitute an ensemble known as the posteromedial cortex (PMC), which consists of Brodmann areas 23, 29, 30, 31, and 7m. To understand the neural relationship of the PMC with the rest of the brain, we injected its component areas with four different anterograde and retrograde tracers in the cynomolgus monkey and found that all PMC areas are interconnected with each other and with the anterior cingulate, the mid-dorsolateral prefrontal, the lateral parietal cortices, and area TPO, as well as the thalamus, where projections from some of the PMC areas traverse in an uninterrupted bar-like manner, the dorsum of this structure from the posteriormost nuclei to its rostralmost tip. All PMC regions also receive projections from the claustrum and the basal forebrain and project to the caudate, the basis pontis, and the zona incerta. Moreover, the posterior cingulate areas are interconnected with the parahippocampal regions, whereas the medial parietal cortex projects only sparsely to the presubiculum. Although local interconnections and shared remote connections of all PMC components suggest a functional relationship among them, the distinct connections of each area with different neural structures suggests that distinct functional modules may be operating within the PMC. Our study provides a large-scale map of the PMC connections with the rest of the brain, which may serve as a useful tool for future studies of this cortical region and may contribute to elucidating its intriguing pattern of activity seen in recent functional imaging studies.

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Figures

Fig. 1.
Fig. 1.

Tracing the neural connections of the PMC. The PMC (highlighted in red in a and b) includes the posterior cingulate areas 23 a, b, and c, area 31, the retrosplenial areas 29 and 30, and the mesial parietal area 7m (i.e., the precuneus). These cortices are located dorsal to the corpus callosum (cc) and confined between the parietooccipital sulcus (poms), cingulate sulcus (cgs), and its marginal branch (mb). The macaque PMC (b) contains the same Brodmann areas and sulci (c). (c) The injection sites are shown in the anterograde (red) and retrograde (blue) experiments, respectively. Numbers correspond to the Exp column listed in Table 1. (d) The photomicrograph shows axonal terminals labeled for anterograde tracers, BDA (black) and FR (brown). The axonal varicosities or boutons are indicative of synaptic terminals, suggesting that these projections are not bypassing but terminal projections. (e) The photomicrograph is in a section of the brain visualized under fluorescent microscope showing cells that are labeled retrogradely with DY or FB or both (DY + FB).

Fig. 2.
Fig. 2.

Overview of the neural connections of the PMC. This cartoon illustrates that distinct areas of the PMC are interconnected with each other and share connections with some of the same brain structures. The interconnections among PMC components are not equally reciprocal. Note that the arrows within the green box have different thicknesses or some are absent. Colored arrows outside this box indicate connections between a specific PMC component and a given brain region. The direction of the arrows denotes whether a given brain region projects to or receives projection from a PMC component. For example, amygdala (Amy) only projects to the retrosplenial areas 29/30 but does not receive projections from it, whereas TPO is reciprocally interconnected with all of the PMC components. Acc, accumbens; Amy, amygdala; BF, basal forebrain; BP, basis pontis (relay to the cerebellum); Cd/Pu, caudate and putamen; Cl, claustrum; EC, entorhinal cortex; PAG, periaquaductal gray matter; PE, superior parietal lobule; PG, posterior inferior parietal lobule; PO, opercular lateral parietal area; Th, thalamus; TPO, cortex buried in the superior temporal sulcus; ZI, zona incerta.

Fig. 3.
Fig. 3.

Corticothalamic projections of the PMC. Fourteen consecutive coronal sections of the brain from anterior (a) to the posterior (n) levels of the thalamus show the anterograde corticothalamic projections from two different areas of the PMC in the same monkey (M3) by using the dual tracing method. Each section is 50-μm thick and 500 μm apart from the next. As shown in a′, areas 30/29 and a small segment of area 23a absorbed the injected anterograde tracer BDA (red), whereas area 31 in the contralateral side was injected with Fluoro-Ruby (blue). The black lines in a-n indicate the floor of the ventricle (the green highlighted space in a). (a″) A coronal section of the brain at the level of anterior thalamus processed with double immunohistochemistry by using antibodies against calbindin (light brown) and parvalbumin (dark blue). Terminal labeling in the nucleus reuniens (Re) is shown in a, and bilateral projections to the anterior medial thalamic nucleus are shown in a and pictured in a‴. Note how close the corticothalamic projections are to the floor of the ventricle. This approximity means that these projections target the dorsum (toward the top) of the thalamus. Also note how continuous these projections are. We have referred to this continuous pattern as the bar-like pattern of projections because they traverse the thalamic nuclei from the anterior most (a) to the posterior most (n) tip of the thalamus. (o) This drawing shows how the bar of corticothalamic projections traverses the dorsal nuclei of the thalamus in its entire extent and cross the midline in the anterior medial nucleus.

Fig. 4.
Fig. 4.

Thalamocortical connections of the PMC. Red dots represent retrogradely labeled cells in the thalamus (highlighted in gray) in case M3-FB-30/23a. Although the labeled cells are seen in every coronal section, their number differs significantly along the anterioposterior axis of the thalamus (see Fig. 5).

Fig. 5.
Fig. 5.

Relative number of thalamic neurons projecting to different components of the PMC. The anterior-posterior gradient in thalamic projections is illustrated in different cytoarchitectonic areas of the PMC. For instance, when areas 29 and 30 were injected with a retrograde tracer, labeled thalamic neurons were predominantly found in the very anterior or posterior nuclei. By comparison, when area 31 was injected, only a few neurons were labeled in the anterior thalamic nuclei, but a much larger number of neurons were labeled in the pulvinar.

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References

    1. Maquet, P. (1997) J. Neurol. 244, S23-S28. - PubMed
    1. Fiset, P., Paus, T., Daloze, T., Plourde, G., Meuret, P., Bonhomme, V., Hajj-Ali, N., Backman, S. B. & Evans, A. C. (1999) J. Neurosci. 19, 5506-5513. - PMC - PubMed
    1. Laureys, S., Goldman, S., Phillips, C., Van Bogaert, P., Aerts, J., Luxen, A., Franck, G. & Maquet, P. (1999) NeuroImage 9, 377-382. - PubMed
    1. Raichle, M. E. & Gusnard, D. A. (2002) Proc. Natl. Acad. Sci. USA 99, 10237-10239. - PMC - PubMed
    1. Raichle, M. E., MacLeod, A. M., Snyder, A. Z., Powers, W. J., Gusnard, D. A. & Shulman, G. L. (2001) Proc. Natl. Acad. Sci. USA 98, 676-682. - PMC - PubMed

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