The limbic system

Rajmohan,; Mohandas, E.

doi:10.4103/0019-5545.33264

Cited by 275 publications

(219 citation statements)

References 19 publications

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“…Thus, the radiation-induced white matter damage described in our study has a potential role in radiation-induced cognitive dysfunction. The fornix and cingulum bundle are elements of the limbic system, an interconnected circuit including the hippocampus which regulate emotion, memory and learning, behavior, and attention [45]. Implicated in a range of disorders featuring cognitive dysfunction from MCI to Alzheimer’s and major depression to schizophrenia [46,47], the limbic system has been investigated as a specifically sensitive structure in whole-brain RT studies [13,44].…”

Section: Discussionmentioning

confidence: 99%

Regional susceptibility to dose-dependent white matter damage after brain radiotherapy

Connor

Karunamuni

McDonald

et al. 2017

Radiotherapy and Oncology

103

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Background and Purpose Regional differences in sensitivity to white matter damage after brain radiotherapy (RT) are not well-described. We characterized the spatial heterogeneity of dose-response across white matter tracts using diffusion tensor imaging (DTI). Materials and Methods Forty-nine patients with primary brain tumors underwent MRI with DTI before and 9–12 months after partial-brain RT. Maps of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were generated. Atlas-based white matter tracts were identified. A secondary analysis using skeletonized tracts was also performed. Linear mixed-model analysis of the relationship between mean and max dose and percent change in DTI metrics was performed. Results Tracts with the strongest correlation of FA change with mean dose were the fornix (−0.46 percent/Gy), cingulum bundle (−0.44 percent/Gy), and body of corpus callosum (−0.23 percent/Gy), p<.001. These tracts also showed dose-sensitive changes in MD and RD. In the skeletonized analysis, the fornix and cingulum bundle remained highly dose-sensitive. Maximum and mean dose were similarly predictive of DTI change. Conclusions The corpus callosum, cingulum bundle, and fornix show the most prominent dose-dependent changes following RT. Future studies examining correlation with cognitive functioning and potential avoidance of critical white matter regions are warranted.

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Section: Discussionmentioning

confidence: 99%

Regional susceptibility to dose-dependent white matter damage after brain radiotherapy

Connor

Karunamuni

McDonald

et al. 2017

Radiotherapy and Oncology

103

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“…The medial limbic circuit is one of the major pathways primarily involved in the cortical control of emotions and memory function (Rajmohan and Mohandas, 2007). This circuit includes the hippocampus (HP), fornix, mammillary body, anterior nucleus of the thalamus, cingulate cortex, parahippocampal gyrus, and entorhinal cortex (Mesulam, 2000).…”

Section: Introductionmentioning

confidence: 99%

Fornix deep brain stimulation circuit effect is dependent on major excitatory transmission via the nucleus accumbens

et al. 2016

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Introduction Deep brain stimulation (DBS) is a circuit-based treatment shown to relieve symptoms from multiple neurologic and neuropsychiatric disorders. In order to treat the memory deficit associated with Alzheimer's disease (AD), several clinical trials have tested the efficacy of DBS near the fornix. Early results from these studies indicated that patients who received fornix DBS experienced an improvement in memory and quality of life, yet the mechanisms behind this effect remain controversial. It is known that transmission between the medial limbic and corticolimbic circuits plays an integral role in declarative memory, and dysfunction at the circuit level results in various forms of dementia, including AD. Here, we aimed to determine the potential underlying mechanism of fornix DBS by examining the functional circuitry and brain structures engaged by fornix DBS. Methods A multimodal approach was employed to examine global and local temporal changes that occur in an anesthetized swine model of fornix DBS. Changes in global functional activity were measured by functional MRI (fMRI), and local neurochemical changes were monitored by fast scan cyclic voltammetry (FSCV) during electrical stimulation of the fornix. Additionally, intracranial microinfusions into the nucleus accumbens (NAc) were performed to investigate the global activity changes that occur with dopamine and glutamate receptor-specific antagonism. Results Hemodynamic responses in both medial limbic and corticolimbic circuits measured by fMRI were induced by fornix DBS. Additionally, fornix DBS resulted in increases in dopamine oxidation current (corresponding to dopamine efflux) monitored by FSCV in the NAc. Finally, fornix DBS-evoked hemodynamic responses in the amygdala and hippocampus decreased following dopamine and glutamate receptor antagonism in the NAc. Conclusions The present findings suggest that fornix DBS modulates dopamine release on presynaptic dopaminergic terminals in the NAc, involving excitatory glutamatergic input, and that the medial limbic and corticolimbic circuits interact in a functional loop.

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“…Another major component of the fornix is the axonal projections from the septal area to the hippocampus. The fornix constitutes an integral part of the classical circuit of Papez, a major pathway of the limbic system, primarily involved in memory function [16].…”

Section: Introductionmentioning

confidence: 99%

Rapid Modulation of Protein Expression in the Rat Hippocampus Following Deep Brain Stimulation of the Fornix

et al. 2015

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The limbic system

Cited by 275 publications

References 19 publications

Regional susceptibility to dose-dependent white matter damage after brain radiotherapy

Regional susceptibility to dose-dependent white matter damage after brain radiotherapy

Fornix deep brain stimulation circuit effect is dependent on major excitatory transmission via the nucleus accumbens

Rapid Modulation of Protein Expression in the Rat Hippocampus Following Deep Brain Stimulation of the Fornix

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