Functional Connectivity of the Macaque Posterior Parahippocampal Cortex

1Department of Psychology and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA.
Journal of Neurophysiology (Impact Factor: 2.89). 12/2009; 103(2):793-800. DOI: 10.1152/jn.00546.2009
Source: PubMed


Neuroimaging experiments in humans suggest that regions in parietal cortex and along the posterior midline are functionally connected to the medial temporal lobe and are active during memory retrieval. It is unknown whether macaques have a similar network. We examined functional connectivity in isoflurane-anesthetized macaques to identify a network associated with posterior parahippocampal cortex (PPHC). Functional connectivity was observed between the PPHC and retrosplenial, posterior cingulate, superior temporal gyrus, and inferior parietal cortex. PPHC correlations were distinct from regions in parietal and temporal cortex activated by an oculomotor task. Comparison of macaque and human PPHC correlations revealed similarities that suggest the temporal-parietal region identified in the macaque may share a common lineage with human Brodmann area 39, a region thought to be involved in recollection. These results suggest that macaques and humans may have homologous PPHC-parietal pathways. By specifying the location of the putative macaque homologue in parietal cortex, we provide a target for future physiological exploration of this area's role in mnemonic or alternative processes.

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    • "In recent years, development of task-independent functional neuroimaging has made important strides in neuropharmacology research as it avoids the difficulties of controlling for intersubject variations in task perception and performance under drug and placebo conditions. Importantly, estimating the ''resting-state'' brain activity facilitates translational research across different species [Margulies et al., 2009; Vincent et al., 2010], making it an appropriate tool in preclinical stages of drug development. Two particular approaches, arterial spin labeling (ASL) and resting-state functional MRI (RSfMRI), have proven applicable in pharmacological neuroimaging [Becerra et al., 2006, 2009; Khalili-Mahani et al., 2011a,b; MacIntosh et al., 2008; Pattinson et al., 2009; Pendse et al., 2010; Rack-Gomer et al., 2009; Wise et al., 2002]. "
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    • "Their results also advanced the idea that the PGm is not in fact a component of the DMN (Buckner et al., 2008). A third study of the same isoflurane anesthetized monkeys using a PCC/Rsp seed defined from a PPHC connectivity map revealed a combination of areas from the previous studies albeit with limited dlPFC connectivity (Vincent et al., 2010; Figure 3C). A separate seed-region based investigation of three isoflurane anesthetized macaques did not corroborate the potential homologous cortical areas as medial frontal, dorsal frontal, and hippocampal regions were absent when using a posteromedial cortex seed (Teichert et al., 2010; Figure 3D). "
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