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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Available from: Justin L Vincent, Oct 08, 2015
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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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    ABSTRACT: Resting state fMRI (RSfMRI) and arterial spin labeling (ASL) provide the field of pharmacological Neuroimaging tools for investigating states of brain activity in terms of functional connectivity or cerebral blood flow (CBF). Functional connectivity reflects the degree of synchrony or correlation of spontaneous fluctuations-mostly in the blood oxygen level dependent (BOLD) signal-across brain networks; but CBF reflects mean delivery of arterial blood to the brain tissue over time. The BOLD and CBF signals are linked to common neurovascular and hemodynamic mechanisms that necessitate increased oxygen transportation to the site of neuronal activation; however, the scale and the sources of variation in static CBF and spatiotemporal BOLD correlations are likely different. We tested this hypothesis by examining the relation between CBF and resting-state-network consistency (RSNC)-representing average intranetwork connectivity, determined from dual regression analysis with eight standard networks of interest (NOIs)-in a crossover placebo-controlled study of morphine and alcohol. Overall, we observed spatially heterogeneous relations between RSNC and CBF, and between the experimental factors (drug-by-time, time, drug and physiological rates) and each of these metrics. The drug-by-time effects on CBF were significant in all networks, but significant RSNC changes were limited to the sensorimotor, the executive/salience and the working memory networks. The post-hoc voxel-wise statistics revealed similar dissociations, perhaps suggesting differential sensitivity of RSNC and CBF to neuronal and vascular endpoints of drug actions. The spatial heterogeneity of RSNC/CBF relations encourages further investigation into the role of neuroreceptor distribution and cerebrovascular anatomy in predicting spontaneous fluctuations under drugs. Hum Brain Mapp, 2012. © 2012 Wiley Periodicals, Inc.
    Human Brain Mapping 03/2014; 35(3). DOI:10.1002/hbm.22224 · 5.97 Impact Factor
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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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    ABSTRACT: Resting-state investigations based on the evaluation of intrinsic low-frequency fluctuations of the BOLD fMRI signal have been extensively utilized to map the structure and dynamics of large-scale functional network organization in humans. In addition to increasing our knowledge of normal brain connectivity, disruptions of the spontaneous hemodynamic fluctuations have been suggested as possible diagnostic indicators of neurological and psychiatric disease states. Though the non-invasive technique has been received with much acclamation, open questions remain regarding the origin, organization, phylogenesis, as well as the basis of disease-related alterations underlying the signal patterns. Experimental work utilizing animal models, including the use of neurophysiological recordings and pharmacological manipulations, therefore, represents a critical component in the understanding and successful application of resting-state analysis, as it affords a range of experimental manipulations not possible in human subjects. In this article, we review recent rodent and non-human primate studies and based on the examination of the homologous brain architecture propose the latter to be the best-suited model for exploring these unresolved resting-state concerns. Ongoing work examining the correspondence of functional and structural connectivity, state-dependency and the neuronal correlates of the hemodynamic oscillations are discussed. We then consider the potential experiments that will allow insight into different brain states and disease-related network disruptions that can extend the clinical applications of resting-state fMRI (RS-fMRI).
    Frontiers in Neuroanatomy 07/2012; 6:29. DOI:10.3389/fnana.2012.00029 · 3.54 Impact Factor
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    • "Spatially smoothing greatly improves the signal-to-noise ratio of data while minimizing the effects of functional anatomical variability at the cost of reducing spatial precision. Smoothing is a standard preprocessing step in both human and animal fMRI experiments including previous resting-state investigations of the macaque (Vincent et al. 2007, 2010; Margulies et al. 2009) that, like the current study, used a smoothing kernel of 3 mm FWHM. By definition, smoothing will cause blurring, often into white matter tracts. "
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    ABSTRACT: Subregions of the cingulate cortex represent prominent intersections in the structural networks of the primate brain. The relevance of the cingulate to the structure and dynamics of large-scale networks ultimately requires a link to functional connectivity. Here, we map fine-grained functional connectivity across the complete extent of the macaque (Macaca fascicularis) cingulate cortex and delineate subdivisions pertaining to distinct identifiable networks. In particular, we identified 4 primary networks representing the functional spectrum of the cingulate: somatomotor, attention-orienting, executive, and limbic. The cingulate nodes of these networks originated from separable subfields along the rostral-to-caudal axis and were characterized by positive and negative correlations of spontaneous blood oxygen level-dependent activity. These findings represent a critical component for understanding how the anterior and midcingulate cortices integrate and shape information processing during task performance. The connectivity patterns also suggest future electrophysiological targets that may reveal new functional representations including those involved in conflict monitoring.
    Cerebral Cortex 08/2011; 22(6):1294-308. DOI:10.1093/cercor/bhr181 · 8.67 Impact Factor
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