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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 ...
The synaptic cleft—also called synaptic gap—is a gap between the pre- and postsynaptic cells that is about 20 nm (0.02 μ) wide. [12] The small volume of the cleft allows neurotransmitter concentration to be raised and lowered rapidly.
Synaptic tags mark where synaptic plasticity has occurred and can thus provide information on synaptic strength and potential for long-term plastic changes. [8] The tag is temporary and involves a large number of proteins, activated by the influx of Ca 2+ into the postsynaptic cell. [ 8 ]
The ability of a motoneuron to branch at the neuromuscular junction represents the pre-synaptic plasticity of the motor unit. The ability of acetylcholine receptors to increase and decrease in number on the motor end plate of the effector muscle represents the post-synaptic plasticity of the motor unit. Studies have shown that with increased ...
The number of such connections made by the axon to the dendrites, How well the signal propagates and integrates in the postsynaptic cell. The changes in synaptic weight that occur is known as synaptic plasticity, and the process behind long-term changes (long-term potentiation and depression) is still poorly understood. Hebb's original learning ...
The change in synaptic strength is responsible for motor learning and is dependent on the simultaneous activation of glutamatergic corticostriatal and dopaminergic nigrostriatal pathways. These are the same pathways affected in Parkinson's disease , and the degeneration of synapses within this disorder may be responsible for the loss of some ...
Chemical and electrical synapses are two ways of synaptic transmission. In a chemical synapse , electrical activity in the presynaptic neuron is converted (via the activation of voltage-gated calcium channels ) into the release of a chemical called a neurotransmitter that binds to receptors located in the plasma membrane of the postsynaptic cell.
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.