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Na + channels both open and close more quickly than K + channels, producing an influx of positive charge (Na +) toward the beginning of the action potential and an efflux (K +) toward the end. Ligand-gated sodium channels, on the other hand, create the change in the membrane potential in the first place, in response to the binding of a ligand ...
The reward system (the mesocorticolimbic circuit) is a group of neural structures responsible for incentive salience (i.e., "wanting"; desire or craving for a reward and motivation), associative learning (primarily positive reinforcement and classical conditioning), and positively-valenced emotions, particularly ones involving pleasure as a core component (e.g., joy, euphoria and ecstasy).
Because all brain areas are bidirectionally coupled, these connections between brain areas form feedback loops. Positive feedback loops tend to cause oscillatory activity where frequency is inversely related to the delay time. An example of such a feedback loop is the connections between the thalamus and cortex – the thalamocortical radiations.
Positive feedback occurs when a gene activates itself directly or indirectly via a double negative feedback loop. Genetic engineers have constructed and tested simple positive feedback networks in bacteria to demonstrate the concept of bistability. [28] A classic example of positive feedback is the lac operon in E. coli. Positive feedback plays ...
In membrane biology, the Hodgkin cycle is a key component of membrane physiology that describes bioelectrical impulses, especially prevalent in neural and muscle tissues. It was identified by British physiologist and biophysicist Sir Alan Lloyd Hodgkin.
The main dopaminergic pathways of the human brain. Dopaminergic pathways (dopamine pathways, dopaminergic projections) in the human brain are involved in both physiological and behavioral processes including movement, cognition, executive functions, reward, motivation, and neuroendocrine control. [1]
Low-T3 syndrome and high-T3 syndrome: Consequences of step-up hypodeiodination, e.g. in critical illness as an example for type 1 allostasis, [20] or hyperdeiodination, as in type 2 allostasis, including posttraumatic stress disorder. [12] Resistance to thyroid hormone: Feedback loop interrupted on the level of pituitary thyroid hormone receptors.
Gross anatomy (also called topographical anatomy, regional anatomy, or anthropotomy) is the study of anatomical structures that can be seen by the naked eye. [1] Microscopic anatomy is the study of minute anatomical structures assisted with microscopes , which includes histology (the study of the organization of tissues), [ 1 ] and cytology ...