scholarly journals Realistic modeling of ephaptic fields in the human brain

2019 ◽  
Author(s):  
Giulio Ruffini ◽  
Ricardo Salvador ◽  
Ehsan Tadayon ◽  
Roser Sanchez-Todo ◽  
Alvaro Pascual-Leone ◽  
...  
Keyword(s):  
Human Brain ◽  
Electric Fields ◽  
Neuronal Activity ◽  
Direct Interaction ◽  
Pyramidal Cells ◽  
Brain Structures ◽  
Relative Orientation ◽  
Transcranial Brain Stimulation ◽  
Potential Perturbation ◽  
Human Function

AbstractSeveral decades of research suggest that weak electric fields may influence neural processing, including those induced by neuronal activity and recently proposed as substrate for a potential new cellular communication system, i.e., ephaptic transmission. Here we aim to map ephaptic activity in the human brain and explore its trajectory during aging by characterizing the macroscopic electric field generated by cortical dipoles using realistic finite element modeling. We find that modeled endogenous field magnitudes are comparable to those in measurements of weak but functionally relevant endogenous fields and to those generated by noninvasive transcranial brain stimulation, therefore possibly able to modulate neuronal activity. Then, to evaluate the role of self-generated ephaptic fields in the human cortex, we adapt an interaction approximation that considers the relative orientation of neuron and field to derive the membrane potential perturbation in pyramidal cells. Building on this, we define a simplified metric (EMOD1) that weights dipole coupling as a function of distance and relative orientation between emitter and receiver and evaluate it in a sample of 401 realistic human brain models from subjects aged 16-83. Results reveal that ephaptic modulation follows gyrification patterns in the human brain, and significantly decreases with age, with higher involvement of sensorimotor regions and medial brain structures. By providing the means for fast and direct interaction between neurons, ephaptic modulation likely contributes to the complexity of human function for cognition and behavior, and its modification across the lifespan and in response to pathology.

scholarly journals Transcranial Electrical Stimulation generates electric fields in deep human brain structures

2021 ◽  
Author(s):  
Samuel Louviot ◽  
Louise Tyvaert ◽  
Louis G. Maillard ◽  
Sophie Colnat-Coulbois ◽  
Jacek Dmochowski ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Human Brain ◽  
Electric Fields ◽  
Brain Structures ◽  
Transcranial Electrical Stimulation

scholarly journals Homologous laminar organization of the mouse and human subiculum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michael S. Bienkowski ◽  
Farshid Sepehrband ◽  
Nyoman D. Kurniawan ◽  
Jim Stanis ◽  
Laura Korobkova ◽  
...  
Keyword(s):  
Gene Expression ◽  
Hippocampal Formation ◽  
Expression Patterns ◽  
Pyramidal Cells ◽  
Brain Structures ◽  
Longitudinal Axis ◽  
Brain Atlas ◽  
Fiber Density ◽  
Laminar Organization ◽  
Hybridization Data

AbstractThe subiculum is the major output component of the hippocampal formation and one of the major brain structures most affected by Alzheimer’s disease. Our previous work revealed a hidden laminar architecture within the mouse subiculum. However, the rotation of the hippocampal longitudinal axis across species makes it unclear how the laminar organization is represented in human subiculum. Using in situ hybridization data from the Allen Human Brain Atlas, we demonstrate that the human subiculum also contains complementary laminar gene expression patterns similar to the mouse. In addition, we provide evidence that the molecular domain boundaries in human subiculum correspond to microstructural differences observed in high resolution MRI and fiber density imaging. Finally, we show both similarities and differences in the gene expression profile of subiculum pyramidal cells within homologous lamina. Overall, we present a new 3D model of the anatomical organization of human subiculum and its evolution from the mouse.

Kinetic images of neuronal activity of the human brain based on the spatio-temporal MNLS inverse: A theoretical study

1995 ◽  
Vol 7 (3) ◽  
pp. 193-200 ◽  
Author(s):  
Jia -Zhu Wang ◽  
Samuel J. Williamson ◽  
Lloyd Kaufman
Keyword(s):  
Human Brain ◽  
Neuronal Activity ◽  
Theoretical Study ◽  
Spatio Temporal

scholarly journals First evidence of long-term effects of transcranial pulse stimulation (TPS) on the human brain

2022 ◽  
Vol 20 (1) ◽  
Author(s):  
Eva Matt ◽  
Lisa Kaindl ◽  
Saskia Tenk ◽  
Anicca Egger ◽  
Teodora Kolarova ◽  
...  
Keyword(s):  
Human Brain ◽  
Brain Stimulation ◽  
Longitudinal Design ◽  
Brain Structures ◽  
Brain Network ◽  
Long Term Effects ◽  
Sensorimotor Network ◽  
Functional Brain Network ◽  
Pulse Stimulation

Abstract Background With the high spatial resolution and the potential to reach deep brain structures, ultrasound-based brain stimulation techniques offer new opportunities to non-invasively treat neurological and psychiatric disorders. However, little is known about long-term effects of ultrasound-based brain stimulation. Applying a longitudinal design, we comprehensively investigated neuromodulation induced by ultrasound brain stimulation to provide first sham-controlled evidence of long-term effects on the human brain and behavior. Methods Twelve healthy participants received three sham and three verum sessions with transcranial pulse stimulation (TPS) focused on the cortical somatosensory representation of the right hand. One week before and after the sham and verum TPS applications, comprehensive structural and functional resting state MRI investigations and behavioral tests targeting tactile spatial discrimination and sensorimotor dexterity were performed. Results Compared to sham, global efficiency significantly increased within the cortical sensorimotor network after verum TPS, indicating an upregulation of the stimulated functional brain network. Axial diffusivity in left sensorimotor areas decreased after verum TPS, demonstrating an improved axonal status in the stimulated area. Conclusions TPS increased the functional and structural coupling within the stimulated left primary somatosensory cortex and adjacent sensorimotor areas up to one week after the last stimulation. These findings suggest that TPS induces neuroplastic changes that go beyond the spatial and temporal stimulation settings encouraging further clinical applications.

scholarly journals Cellular resolution anatomical and molecular atlases for prenatal human brains

2021 ◽  
Author(s):  
Song-Lin Ding ◽  
Joshua J. Royall ◽  
Phil Lesnar ◽  
Benjamin A.C. Facer ◽  
Kimberly A. Smith ◽  
...  
Keyword(s):  
Human Brain ◽  
Hippocampal Formation ◽  
Marker Gene ◽  
Brain Structures ◽  
Marker Genes ◽  
Subcortical Structures ◽  
Cellular Resolution ◽  
Reliable Marker ◽  
Human Brains ◽  
Developmental Features

Increasing interest in studies of prenatal human brain development, particularly using new single-cell genomics and anatomical technologies to create cell atlases, creates a strong need for accurate and detailed anatomical reference atlases. In this study, we present two cellular-resolution digital anatomical atlases for prenatal human brain at post-conceptional weeks (PCW) 15 and 21. Both atlases were annotated on sequential Nissl-stained sections covering brain-wide structures on the basis of combined analysis of cytoarchitecture, acetylcholinesterase staining and an extensive marker gene expression dataset. This high information content dataset allowed reliable and accurate demarcation of developing cortical and subcortical structures and their subdivisions. Furthermore, using the anatomical atlases as a guide, spatial expression of 37 and 5 genes from the brains respectively at PCW 15 and 21 was annotated, illustrating reliable marker genes for many developing brain structures. Finally, the present study uncovered several novel developmental features, such as the lack of an outer subventricular zone in the hippocampal formation and entorhinal cortex, and the apparent extension of both cortical (excitatory) and subcortical (inhibitory) progenitors into the prenatal olfactory bulb. These comprehensive atlases provide useful tools for visualization, targeting, imaging and interpretation of brain structures of prenatal human brain, and for guiding and interpreting the next generation of cell census and connectome studies.

scholarly journals Volitional Control of Individual Neurons in the Human Brain

2020 ◽  
Author(s):  
Kramay Patel ◽  
Chaim N. Katz ◽  
Suneil K. Kalia ◽  
Milos R. Popovic ◽  
Taufik A. Valiante
Keyword(s):  
Human Brain ◽  
Firing Rate ◽  
Phase Locking ◽  
Brain Structures ◽  
Human Memory ◽  
Skill Learning ◽  
Oscillation Phase ◽  
Improved Performance ◽  
Beta Frequency ◽  
Interconnected Structure

AbstractCan the human brain, a complex interconnected structure of over 80 billion neurons learn to control itself at the most elemental scale – a single neuron. We directly linked the firing rate of a single (direct) neuron to the position of a box on a screen, which participants tried to control. Remarkably, all subjects upregulated the firing rate of the direct neuron in memory structures of their brain. Learning was accompanied by improved performance over trials, simultaneous decorrelation of the direct neuron to local neurons, and direct neuron to beta frequency oscillation phase-locking. Such previously unexplored neuroprosthetic skill learning within memory related brain structures, and associated beta frequency phase-locking implicates the ventral striatum. Our demonstration that humans can volitionally control neuronal activity in mnemonic structures, may provide new ways of probing the function and plasticity of human memory without exogenous stimulation.

Analysis of human brain exposure to low-frequency magnetic fields: A numerical assessment of spatially averaged electric fields and exposure limits

2013 ◽  
Vol 34 (5) ◽  
pp. 375-384 ◽  
Author(s):  
Xi-Lin Chen ◽  
Stefan Benkler ◽  
Nicholas Chavannes ◽  
Valerio De Santis ◽  
Jurriaan Bakker ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Human Brain ◽  
Electric Fields ◽  
Low Frequency ◽  
Exposure Limits ◽  
Numerical Assessment ◽  
Brain Exposure

Mind and Matter

Mind Shift ◽  
2021 ◽  
pp. 19-31
Author(s):  
John Parrington
Keyword(s):  
Human Brain ◽  
Rene Descartes ◽  
Brain Structures ◽  
Human Mind ◽  
Black Box ◽  
Human Consciousness ◽  
Common Thread ◽  
René Descartes

This chapter discusses different views on the basis of human consciousness. A major problem with much popular speculation about the biological roots of consciousness is that those who advocate a gene-based view of consciousness often appear to have little understanding of modern genetics, while speculation about how brain structures shape that consciousness often bear little resemblance to emerging knowledge about the complexity of an actual human brain. There is a common thread here, which is that idealised genes and brains have been substituted for real ones. Unfortunately, because of this tendency, it is not clear how much we have really advanced forwards from René Descartes and his belief that the human mind was an unknowable entity, or for that matter, the behaviourists with their view that the human mind could be treated as a black box. In contrast, to understand human consciousness, there is a need to understand real genes, real brains, and how these have evolved in humans compared to other species.

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