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Brain Insulin Action in the Control of Metabolism in Humans
Published in André Kleinridders, Physiological Consequences of Brain Insulin Action, 2023
Besides investigating localized brain activity, fMRI can be used to study connected processes. Regions in the brain, with similar functional properties such as, for example, the left and right somatosensory cortices (60), exhibit a consistent pattern of synchronous activity. They are thus considered to be highly functionally connected, reflecting the presence of a functional network (61, 62). Functional connectivity is used for the characterization of brain networks in health and disease, especially under resting-state conditions. Hence, insulin-induced neural activity and changes in insulin-induced functional connectivity can be detected non-invasively using fMRI.
ENZOGENOL Pine Bark Extract
Published in Dilip Ghosh, Pulok K. Mukherjee, Natural Medicines, 2019
To investigate whether ENZOGENOL may influence brain activities directly, the study also examined effects on brain functional connectivity during the performance of a recognition memory task (Pipingas and Silberstein 2007). Functional connectivity is a term that describes how different brain regions interact or interfere with each other. The hypothesis was that the ENZOGENOL formula would improve functional connectivity by reducing cortical coupling between certain neural regions. In this test, a constant 50 Hz light flicker is projected onto the retina, which results in a constant EEG signal that was detected over 64 electrodes across the scalp, referred to as steady-state visually evoked potential (SSVEP). This signal is influenced and modified by the brain’s own electrical activities during task performance. Measuring this signal over the course of the task allows the calculation of event-related partial coherence (ERPC), which is a measure of functional connections between brain regions. These functional connections are referred to as cortical couplings. One could think of this as more coupling equates to more noise across the brain and less coupling indicates less noise.
Customized DNA–directed precision nutrition to balance the brain reward circuitry and reduce addictive behaviors
Published in Debmalya Barh, Precision Medicine in Cancers and Non-Communicable Diseases, 2018
Kenneth Blum, Marcelo Febo, Eric R. Braverman, Mona Li, Lyle Fried, Roger Waite, Zsolt Demotrovics, William B. Downs, Debmalya Barh, Bruce Steinberg, Thomas McLaughlin, Rajendra D. Badgaiyan
The integrity of resting state functional connectivity is crucial for normal homeostatic function. Zhang et al. (2015) showed that heroin addicts exhibit reduced connectivity between the dorsal anterior cingulate cortex (dACC) and rostral anterior cingulate cortex (rACC), as well as reduced connectivity between the subcallosal anterior cingulate cortex (sACC) and dACC. The heroin addicts’ variations in functional connectivity of three subregions of the ACC indicate that these three subregions, along with other key brain areas (such as the dorsal striatum, putamen, orbital frontal cortex, dorsal striatum, cerebellum, amygdala) potentially modulate heroin addiction. Blum's laboratory and Zhang's group (Blum et al., 2015b) showed that in abstinent heroin addicts, KB220Z™ (a putative dopamine D2 agonist) increased BOLD activation in caudate-accumbens-dopaminergic pathways, compared to a placebo following one-hour acute administration. In addition, KB220Z™ also induced the reduction of resting state activity in the putamen. In the second phase of this pilot study, all 10 abstinent heroin-dependent subjects had three brain regions of interest (ROIs), which were shown to be significantly activated from the resting state by KB220Z™ compared to the placebo (P < 0.05). Increased functional connectivity was also observed in a system involving the dorsal anterior cingulate, medial frontal gyrus, nucleus accumbens, posterior cingulate, occipital cortical areas, and cerebellum.
Erythritol and xylitol differentially impact brain networks involved in appetite regulation in healthy volunteers
Published in Nutritional Neuroscience, 2022
Anne Christin Meyer-Gerspach, Jed O. Wingrove, Christoph Beglinger, Jens F. Rehfeld, Carel W. Le Roux, Ralph Peterli, Patrick Dupont, Owen O’Daly, Lukas Van Oudenhove, Bettina K. Wölnerhanssen
Therefore, this study’s overall aim was to examine the effects of these two naturally occurring, low-calorie sweeteners compared to the caloric sweetener glucose and tap water on two measures of brain function, resting cerebral blood flow (rCBF) [12] and resting functional connectivity in a network of homeostatic and reward-related regions involved in appetite regulation, and to test whether these effects are related to the release of gut hormones. These measures are based on arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) sequences, respectively. They represent highly complementary measures of brain function, as the latter taps into temporal fluctuation in coordinated activity patterns between regions in a network, whereas the former measures neural activity within each region (or voxel), in our case of the same network. Hence, functional connectivity analyses of resting neuroimaging data are based on the concept of synchrony between the signal responses in spatially distinct brain regions. In addition to functional connectivity between specific regions, the functional properties of an entire brain network can be analyzed using a graph theoretical approach. Graph theory provides a theoretical framework in which the topology of complex networks can be examined, and can reveal important information about both the local and global organization of functional brain networks [13].
What have we learned from past failures of investigational drugs for Alzheimer’s disease?
Published in Expert Opinion on Investigational Drugs, 2021
Bruno P. Imbimbo, Mark Watling
Functional magnetic resonance imaging (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. Functional connectivity is defined as the temporal dependency of neuronal activation patterns in anatomically separated brain regions. Cognitive tasks are performed not by individual brain regions working in isolation but by networks consisting of different brain regions that are functionally connected [64]. Large-scale brain networks are collections of widespread brain regions showing functional connectivity [65]. fMRI studies in subjects with mild cognitive impairment (MCI) and in AD patients have revealed abnormalities in large-scale memory and cognitive brain networks. A number of fMRI studies have focused on the medial temporal lobe (MTL), a site of very early pathology in AD [66]. Other fMRI studies have identified abnormalities early in AD in the frontal, temporal, and parietal cortices. Functional hypoactivation has been documented in brain regions with marked pathology and atrophy. However, there are also areas of hyperactivation in brain memory and cognitive circuits, possibly representing compensatory responses. Resting state functional connectivity has been shown to be impaired in cognitively normal subjects with preclinical ADAD [67] and may be of value in the near future to monitor ‘global’ effects of therapeutic candidates in both early and late stages of AD.
Transcranial magnetic stimulation and neuroimaging for cocaine use disorder: Review and future directions
Published in The American Journal of Drug and Alcohol Abuse, 2021
Yong Shen, Heather Burrell Ward
There is a large body of literature describing the brain regions responsible for substance use disorders, including the mesolimbic pathway (7,8), prefrontal cortex (9,10), and insula (11–13). Brain regions are organized into functional networks that interact to perform tasks (14,15). These large-scale brain networks can be identified by measuring changes in blood-oxygen-level-dependent (BOLD) signal using functional MRI (fMRI). The intrinsic connectivity of these networks can be measured when the brain is at rest without any interference from the external environment (16). Functional connectivity refers to the temporal coherence of the BOLD signal within or between networks at rest and is the degree to which the brain regions in networks function synchronously. The salience network has been extensively implicated in substance use disorders and other psychiatric disorders (17). This network comprises the dorsal anterior cingulate cortex (dACC), bilateral anterior insula, dorsolateral prefrontal cortex (DLPFC), inferior parietal lobule, head of the caudate nucleus, mediodorsal nucleus of the thalamus, and dopaminergic brainstem nuclei (18).