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Hypobaric Hypoxia: Adaptation and Acclimatization
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
John H. Coote, James S. Milledge
Such reactions are involved in learning and memory which involve the neocortex and structures in the medial temporal lobe including the hippocampus. In the hippocampus, transmission has been shown to be enhanced for a long time following a brief burst of stimuli in a process termed long-term potentiation (LTP). Long-term potentiation is thought to be a neural process underlying learning and memory, and such an event at the synapse includes activation of a type of glutamate receptor known as the N-methyl-D-aspartate (NMDA) receptor on the post-synaptic membrane. After activation by a neurotransmitter, this receptor only allows a limited amount of calcium entry into the post-synaptic cell, initially causing a small membrane depolarization that then leads to activation of a second class of glutamate receptor, the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor. As a consequence, more calcium channels open and there is a large increase in calcium-dependent post-synaptic currents, a strong depolarization of the membrane and action potential generation.
Neurophysiological and molecular approaches to understanding the mechanisms of learning and memory
Published in Journal of the Royal Society of New Zealand, 2021
Shruthi Sateesh, Wickliffe C. Abraham
LTP can be generated through several intracellular signal transduction pathways, triggered by both ionotropic and metabotropic receptor activation at the relevant synapses. The major excitatory neurotransmitter in the hippocampus is glutamate, which binds to three types of ionotropic receptors: α-amino-3-hyroxy-5-methyl-isoxazole-propionic acid receptors (AMPAR), kainate receptors, and N-methyl-D-aspartate receptors (NMDAR), as well as a range of metabotropic glutamate receptors (mGluR). AMPA receptors mediate the majority of the fast excitatory synaptic transmission, while NMDA receptors are critical for the induction of most forms of LTP and LTD, expressed as changes in the AMPA receptor-mediated transmission.