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Neuropeptide Regulation of Ion Channels and Food Intake
Published in Tian-Le Xu, Long-Jun Wu, Nonclassical Ion Channels in the Nervous System, 2021
Ion channels tightly control the neuronal activity through transmembrane ion flux for depolarization or hyperpolarization. Changes in the protein structure of ion channels can drastically change how the neuron responds to extracellular signals such as neuropeptides. For instance, dysfunctional KATP channels, possibly from high-fat diets, would be unable to close under elevated glucose levels, resulting in constitutively active inhibition of the anorexigenic POMC neurons, leading to the development of obesity (Parton et al. 2007). Mutations in KATP channels are also associated with congenital diabetes and hyperinsulinism (Tinker et al. 2018). Tonically elevated PIP3, a signaling molecule naturally activated by insulin, acts as a sexually dimorphic inhibitor of POMC neurons via stimulation of KATP channels. Female mice have a larger weight gain than males when PIP3 is perpetually elevated (Plum et al. 2006). Kir6.2 is a key pore-forming subunit of KATP channels (Miki et al. 2001). The defective Kir6.2 prevents ATP blockade of KATP channels, which results in increased food intake and obesity due to loss of glucose sensitivity of Kir6.2-expressing hypothalamic neurons (Sohn 2013; Miki et al. 2001). Kir6.2 knockout mice also showed a blunted hypothalamic response to glucose loading and elevated hypothalamic NPY expression accompanied by hyperphagia, while they are resistant to obesity (Park et al. 2011).
Functional Neurology
Published in James Crossley, Functional Exercise and Rehabilitation, 2021
The action of neurons is altered at various points throughout the nervous system, a process referred to as neuromodulation. Modulation can either excite (increase) or inhibit (decrease) levels of transmission between neurons. Both stable changes in neuronal activity and the formation of new neurons, known as neurogenesis, are considered the foundations for learning and memory.
Pharmacotherapy of Neurochemical Imbalances
Published in Sahab Uddin, Rashid Mamunur, Advances in Neuropharmacology, 2020
Rupali Patil, Aman Upaganlawar, Suvarna Ingale
Like neurotransmitters, a substance should fulfill following standards to qualify as a neuromodulator: The substance must not act as a neurotransmitter.The substance must be distributed in biological fluids and must reach the modulatory site in substantial amount.Alterations in concentrations of the substance in body must modify the neuronal activity almost certainly and constantly.Direct administration of the substance must produce the same effect as with increase in its endogenous concentrations.The substance must act through precise targets of action with which it can modulate neuronal activity.There must be inactivating mechanisms which will determine its duration of neuronal effects produced with changes in concentrations of the substance endogenously or exogenously.Interference of the neuronal effects of increased endogenous concentrations or exogenous administration of the substance must be equal (Barchas et al., 1978).
Inter-organ regulation by the brain in Drosophila development and physiology
Published in Journal of Neurogenetics, 2023
Sunggyu Yoon, Mingyu Shin, Jiwon Shim
The brain is composed of two specialized cell types: glial cells that maintain, nourish, and protect neurons and neurons that transmit electrochemical signals to induce neuronal activity (Jessen, 2004; Tsodyks & Gilbert, 2004; von Bartheld et al., 2016). It has been extensively reported that neuroactivity in the brain determines mental or behavioral characteristics. As a well-known example, dopaminergic neurons found in the substantia nigra pars compacta play a critical role in controlling mood, reward, and stress response, and serotonin neurons located in the raphe nuclei of the brainstem control emotional conditions, such as depression, anxiety, and sadness (Berger et al., 2009; Chinta & Andersen, 2005; Meneses & Liy-Salmeron, 2012). With the view that obvious consequences of neuronal function are changes in animal behavior, previous research in neurobiology has largely focused on animals’ external, emotional, and behavioral phenotypes.
Consciousness in a Rotor? Science and Ethics of Potentially Conscious Human Cerebral Organoids
Published in AJOB Neuroscience, 2023
Federico Zilio, Andrea Lavazza
The intrinsic activity of the brain is crucial before, during, and after the stimulus, integrating different neuronal activities—neural prerequisites, predispositions, correlates, and consequences—along with various timescales (from milliseconds to hours) (Northoff and Zilio 2022b). In other words, normal neural activity associated with a normal state of consciousness is characterized by free-scale spontaneous brain activity (e.g., faster frequencies nested within slower ones) that stochastically aligns with the outside, exerting an influence before and after stimulus processing, and, at the same time, is shaped by the interaction with the stimuli from outside (Northoff 2018). The “nestedness” and “alignment” of spontaneous brain activity are necessary prerequisites and predispositions for possible consciousness. Thus, consciousness does not simply emerge from the firing activity of neurons: the (externally or internally generated) input, if it is not encoded into the spatiotemporal structure of spontaneous brain activity, is not likely to be consciously processed in the subsequent post-stimulus activity (e.g., in altered states of consciousness, where abnormally long timescales of neuronal activity prevent the segregation and processing of inputs; Northoff and Zilio 2022b).
Ellen R. Grass Lecture: The Future of Neurodiagnostics and Emergence of a New Science
Published in The Neurodiagnostic Journal, 2023
Electroencephalography (EEG) is the original and oldest functional brain measurement technology. Although many seemingly more advanced brain imaging technologies have emerged as powerful research tools for neuroscience, EEG remains the most direct measurement of neural activity that we have. Some have even referred to EEG as a window into the mind itself (Nunez and Srinivasan 2006). Interpretation and analysis of EEG data is essentially an information processing exercise. Traditionally, electrical potentials generated by groups of pyramidal neurons in the cortex are measured by sensors on the scalp. The voltages are converted to traces on a moving strip of paper or now to digital numbers that represent the value of the voltage. In either case, human eyes review and analyze the time series traces for patterns that are indicative of specific brain states or pathological function. Increasingly, computer algorithms are supplementing human analysis by screening for certain features, such as artifacts, or other patterns that humans may then review. Several trends are accelerating the evolution of computer analysis of EEG recordings.