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Changes in postsynaptic signaling are most commonly associated with a N-methyl-d-aspartic acid receptor (NMDAR)-dependent LTP and long-term depression (LTD) due to the influx of calcium into the post-synaptic cell, which are the most analyzed forms of plasticity at excitatory synapses.
Autocrine signaling is a special case of paracrine signaling where the secreting cell has the ability to respond to the secreted signaling molecule. [9] Synaptic signaling is a special case of paracrine signaling (for chemical synapses) or juxtacrine signaling (for electrical synapses) between neurons and target cells.
Each gap junction (sometimes called a nexus) contains numerous gap junction channels that cross the plasma membranes of both cells. [11] With a lumen diameter of about 1.2 to 2.0 nm, [2] [12] the pore of a gap junction channel is wide enough to allow ions and even medium-size molecules like signaling molecules to flow from one cell to the next, [2] [13] thereby connecting the two cells' cytoplasm.
The presynaptic axon terminal, or synaptic bouton, is a specialized area within the axon of the presynaptic cell that contains neurotransmitters enclosed in small membrane-bound spheres called synaptic vesicles (as well as a number of other supporting structures and organelles, such as mitochondria and endoplasmic reticulum).
Synaptic signaling during synaptogenesis is not only activity-dependent, but is also dependent on the environment in which the neurons are located. For instance, brain-derived neurotrophic factor (BDNF) is produced by the brain and regulates several functions within the developing synapse, including enhancement of transmitter release, increased ...
Two molecular mechanisms for synaptic plasticity involve the NMDA and AMPA glutamate receptors. Opening of NMDA channels (which relates to the level of cellular depolarization) leads to a rise in post-synaptic Ca 2+ concentration and this has been linked to long-term potentiation, LTP (as well as to protein kinase activation); strong depolarization of the post-synaptic cell completely ...
An example of a Bipolar junction transistor which can be used as a model for synaptic gating. B would represent the gatekeeper neuron that regulates the transmission of the signal from C to E. The model for gated synapses was originally derived from the model electronic circuit, in which the gatekeeper serves as a transistor in a circuit. In a ...
The existence and observations of synaptic fatigue are accepted universally, although the exact mechanisms underlying the phenomenon are not completely understood. It is generally seen in mature cells at high frequencies of stimuli (>1 Hz). One specific example is that the gill withdrawal reflex of the Aplysia is caused by homosynaptic ...