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Brain Wave Generation And The Astrocytes

 Jul 27, 2022

Brain wave generation and The Astrocytes

Astrocytes are the cells of the central nervous system (CNS), which are active and dynamic signalling players. Over a couple of decades, it has become obvious that astrocytes participate in the healthy brain's essential physiological processes. Apart from providing structural support to the neurons, astrocytes play a crucial active and dynamic elements of circuit of the brain. Astrocytes participate in maturation and formation of synapses, control of the homeostasis of ions, energy metabolites, receptor trafficking and clearance of neurotransmitters. Along with this, astrocytes also modulate the moment-to-moment synaptic plasticity and regulate the extracellular space volume (Dr. Rouach). Multiple research based studies have shown an association between information processing and memory formation in the brain. Also it is pointing to a role of astrocytes in higher integrated functions of the brain. Data shows that such reciprocal signalling also occurs in the human brain. Astrocytes from the tissue of the human brain exhibit Ca2+-based “intrinsic excitability” and can also respond to released neurotransmitters.

 

Furthermore, human astrocytes display specific characteristics compared to their rodent counterparts as revealed by genomic, morphological and functional studies and also remarkable morphological diversity. They also exhibit a high protein expression involved in Ca2+ signalling. These studies and findings support the role of astrocytes in higher cognitive functions. Alterations in the physiological roles of astrocytes have been associated with contributing to cerebral pathology. Several Neuro-pathologists such as Alzheimer, Fromman and Nissl, envisioned a role for glial in brain conditions and diseases. Such brain diseases still remain the most complicated ones to treat and understand. CNS pathologies indicate that astroglial dysfunctions majorly contribute to the pathogenesis of several psychiatric and neurological disorders (Dr. Buzsaki).

 

 

In the nervous system of central region (CNS), neurons communicate via electrochemical signals and current flows through synaptic contacts. The synchronization of electrical activity of the neurons produces rhythmic voltage fluctuations which travel across various brain regions, called brain waves or neuronal oscillations. Brain waves can be modulated in time & space and are affected by the dynamic interplay between cellular membrane properties, neuronal connectivity patterns, intrinsic circuitry, synaptic delays and speed of axonal conduction.  At the cellular level, fluctuation in these synchronous oscillations create “up states” and “down states” refer to membrane hyper-polarization and resting activity whereas Up states are associated with firing bursts of action potentials and neuronal depolarization (Dr. Cossart). This network coherence seems to be essential for several motor and sensory processes as well as for cognitive flexibility showing to play a role in the basic functions of the brain.

 

Many physiological brain functions, including synaptogenesis, metabolic coupling, nitrosative regulation of synaptic release, synaptic transmission, network oscillations, and plasticity are essentially linked to astrocytes. Astrocytes express receptors, pumps, ion channels, and cotransporters and allow them to interact with neurons through various mechanisms. Astrocytes communicate with other astrocytes and neurons mainly through Ca2+ signals. Astrocytic Ca2+ signaling and glutamate clearance by astrocytes play a crucial role in the K+ homeostasis and regulation of the network activity, which finally affects the neuronal excitability. So it was found that Neuromodulators can process signal through the astrocytes and by affecting their Ca2+ oscillations (Dr. Ding).

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