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Frontiers in Neuroendocrinology Jan 2019Sex plays a role in the incidence and outcome of neurological illnesses, also influencing the response to treatments. Despite sexual differentiation of the brain has... (Review)
Review
Sex plays a role in the incidence and outcome of neurological illnesses, also influencing the response to treatments. Despite sexual differentiation of the brain has been extensively investigated, the study of sex differences in microglia, the brain's resident immune cells, has been largely neglected until recently. To fulfill this gap, our laboratory developed several tools, including cellular and animal models, which bolstered in-depth studies on sexual differentiation of microglia and its impact on brain physiology, as well as on the onset and progression of neurological disorders. Here, we summarize the current status of knowledge on the sex-dependent function of microglia, and report recent evidence linking these cells to the sexual bias in the susceptibility to neurological brain diseases.
Topics: Animals; Brain; Brain Diseases; Humans; Microglia; Sex Characteristics; Sex Differentiation
PubMed: 30481522
DOI: 10.1016/j.yfrne.2018.11.003 -
Stroke Jun 2021We propose a new evolutionary interpretation of the brain's circulation that has physiological, pathophysiological, and clinical implications. We review the evidence for... (Review)
Review
We propose a new evolutionary interpretation of the brain's circulation that has physiological, pathophysiological, and clinical implications. We review the evidence for the concept, discuss clinical implications, and suggest techniques to address outstanding questions. We conclude that the brain circulation contains complementary low-pressure and high-pressure system that must be kept in balance for optimal brain health.
Topics: Amyloid beta-Peptides; Animals; Brain; Cerebral Hemorrhage; Cerebrovascular Circulation; Humans; Hypertension
PubMed: 33940956
DOI: 10.1161/STROKEAHA.120.033492 -
Brain Connectivity 2011The pressing need to better understand human brain organization is appreciated by all who have labored to explain the uniqueness of human behavior in health and disease.... (Review)
Review
The pressing need to better understand human brain organization is appreciated by all who have labored to explain the uniqueness of human behavior in health and disease. Early work on the cytoarchitectonics of the human brain by Brodmann and others accompanied by several centuries of lesion behavior work, although valuable, has left us far short of what we need. Fortunately, modern brain imaging techniques have, over the past 40 years, substantially changed the situation by permitting the safe appraisal of both anatomical and functional relationships within the living human brain. An unexpected feature of this work is the critical importance of ongoing, intrinsic activity, which accounts for the majority of brain's energy consumption and exhibits a surprising level of organization that emerges with dimensions of both space and time. In this essay, some of the unique features of intrinsic activity are reviewed, as it relates to our understanding of brain organization.
Topics: Animals; Brain; Brain Mapping; Energy Metabolism; Humans; Magnetic Resonance Imaging; Nerve Net
PubMed: 22432951
DOI: 10.1089/brain.2011.0019 -
Journal of Cerebral Blood Flow and... Dec 2020
Topics: Brain; Humans; Microglia
PubMed: 33208002
DOI: 10.1177/0271678X20968993 -
Journal of Integrative Neuroscience Oct 2023This article presents evidence indicating that intracranial pressure (ICP) pulsatility, associated with the heartbeat and breathing, is not just a source of mechanical... (Review)
Review
This article presents evidence indicating that intracranial pressure (ICP) pulsatility, associated with the heartbeat and breathing, is not just a source of mechanical artefact in electrical recordings, but is "sensed" and plays a role in the brain's information processing. Patch-clamp recording of pressure-activated channels, and detection of Piezo2-protein channel expression in brain neurons, suggest that these channels provide neurons with an intrinsic resonance to ICP pulsatility, which acts to synchronize remote neural networks. Direct measurements in human patients indicate that heartbeat and breathing rhythms generate intracranial forces of tens of millinewtons, exceeding by orders of magnitude the localized forces shown by atomic force microscopy and optical tweezers to activate Piezo channels in isolated neocortical and hippocampal neurons. Additionally, many human touch and proprioceptors, which are also transduced by Piezo channels, show spiking that is phase-locked to heartbeat- and breathing-induced extracranial pressure pulsations. Finally, based on the observation that low-frequency oscillations modulate the phase and amplitude of high-frequency oscillations, body and brain oscillations are proposed to form a single hierarchical system in which the heartbeat is the basic frequency and scaling factor for all other oscillations. Together, these results support the idea that ICP pulsatility may be elemental in modulating the brain's electrical rhythmicity.
Topics: Humans; Brain; Intracranial Pressure; Hippocampus; Cognition; Heart Rate
PubMed: 38176935
DOI: 10.31083/j.jin2206143 -
Biological Psychiatry Feb 2020Human brain development is optimized to learn from environmental cues. The protracted development of the cortex and its connections with subcortical targets has been... (Review)
Review
Human brain development is optimized to learn from environmental cues. The protracted development of the cortex and its connections with subcortical targets has been argued to permit more opportunity for acquiring complex behaviors. This review uses the example of amygdala-medial prefrontal cortex circuitry development to illustrate a principle of human development-namely, that the extension of the brain's developmental timeline allows for the (species-expected) collaboration between child and parent in co-construction of the human brain. The neurobiology underlying affective learning capitalizes on this protracted timeline to develop a rich affective repertoire in adulthood. Humans are afforded this luxuriously slow development in part by the extended period of caregiving provided by parents, and parents aid in scaffolding the process of maturation during childhood. Just as adequate caregiving is a potent effector of brain development, so is adverse caregiving, which is the largest environmental risk factor for adult mental illness. There are large individual differences in neurobiological outcomes following caregiving adversity, indicating that these pathways are probabilistic, rather than deterministic, and prolonged plasticity in human brain development may also allow for subsequent amelioration by positive experiences. The extant research indicates that the development of mental health cannot be considered without consideration of children in the context of their families.
Topics: Adult; Amygdala; Brain; Child; Humans; Neurobiology; Parents; Prefrontal Cortex
PubMed: 31399257
DOI: 10.1016/j.biopsych.2019.06.018 -
Developmental Neurobiology Jun 2018The proverbial role of microglia during brain development is shifting from passive members of the brain's immune system to active participants that are able to dictate... (Review)
Review
The proverbial role of microglia during brain development is shifting from passive members of the brain's immune system to active participants that are able to dictate enduring outcomes. Despite these advances, little attention has been paid to one of the most critical components of early brain development-sexual differentiation. Mounting evidence suggests that the normal developmental functions microglia perform-cell number regulation and synaptic connectivity-may be involved in the sex-specific patterning of the brain during these early sensitive periods, and may have lasting sex-dependent and sex-independent effects on behavior. In this review, we outline the known functions of microglia during developmental sensitive periods, and highlight the role they play in the establishment of sex differences in brain and behavior. We also propose a framework for how researchers can incorporate microglia in their study of sex differences and vice versa. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 580-592, 2018.
Topics: Animals; Brain; Humans; Microglia; Sex Characteristics
PubMed: 29243403
DOI: 10.1002/dneu.22569 -
Communications Biology Dec 2022How global and local activity interact with each other is a common question in complex systems like climate and economy. Analogously, the brain too displays 'global'... (Review)
Review
How global and local activity interact with each other is a common question in complex systems like climate and economy. Analogously, the brain too displays 'global' activity that interacts with local-regional activity and modulates behavior. The brain's global activity, investigated as global signal in fMRI, so far, has mainly been conceived as non-neuronal noise. We here review the findings from healthy and clinical populations to demonstrate the neural basis and functions of global signal to brain and behavior. We show that global signal (i) is closely coupled with physiological signals and modulates the arousal level; and (ii) organizes an elaborated dynamic topography and coordinates the different forms of cognition. We also postulate a Dual-Layer Model including both background and surface layers. Together, the latest evidence strongly suggests the need to go beyond the view of global signal as noise by embracing a dual-layer model with background and surface layer.
Topics: Health Status; Brain
PubMed: 36481785
DOI: 10.1038/s42003-022-04297-6 -
Current Opinion in Neurobiology Feb 2023How have animals managed to maintain metabolically expensive brains given the volatile and fleeting availability of calories in the natural world? Here we review studies... (Review)
Review
How have animals managed to maintain metabolically expensive brains given the volatile and fleeting availability of calories in the natural world? Here we review studies in support of three strategies that involve: 1) a reallocation of energy from peripheral tissues and functions to cover the costs of the brain, 2) an implementation of energy-efficient neural coding, enabling the brain to operate at reduced energy costs, and 3) efficient use of costly neural resources during food scarcity. Collectively, these studies reveal a heterogeneous set of energy-saving mechanisms that make energy-costly brains fit for survival.
Topics: Animals; Brain; Head
PubMed: 36571958
DOI: 10.1016/j.conb.2022.102668 -
NeuroImage Jul 2021It is shown how the brain's linear transfer function provides a means to systematically analyze brain connectivity and dynamics, and to infer connectivity, eigenmodes,...
It is shown how the brain's linear transfer function provides a means to systematically analyze brain connectivity and dynamics, and to infer connectivity, eigenmodes, and activity measures such as spectra, evoked responses, coherence, and causality, all of which are widely used in brain monitoring. In particular, the Wilson spectral factorization algorithm is outlined and used to efficiently obtain linear transfer functions from experimental two-point correlation functions. The algorithm is tested on a series of brain-like structures of increasing complexity which include time delays, asymmetry, two-dimensionality, and complex network connectivity. These tests are used to verify the algorithm is suitable for application to brain dynamics, specify sampling requirements for experimental time series, and to verify that its runtime is short enough to obtain accurate results for systems of similar size to current experiments. The results can equally well be applied to inference of the transfer function in complex linear systems other than brains.
Topics: Algorithms; Brain; Electroencephalography; Evoked Potentials; Humans; Magnetic Resonance Imaging; Models, Theoretical; Neuroimaging
PubMed: 33819612
DOI: 10.1016/j.neuroimage.2021.117989