Memory Structure #4

Presynaptic mechanisms of synapse changes.

Presynaptic mechanisms include changes in the release of a mediator from the presynaptic process due to previous synaptic activity. The same type of thinking demonstrates a decrease in mediator release, whereas sensitization and associative training demonstrate an increase in mediator release. In both cases, changes in the amount of mediator released lead to a change in the entry of Ca2+ into the presynaptic terminal and to the mobilization of synaptic vesicles into active zones.

Postsynaptic mechanisms of synapse changes.

Postsynaptic mechanisms of synapse changes are associated with changes in the sensitivity and number of postsynaptic receptors. These mechanisms, which are best studied, are glutamatergic synapses and are involved in long-term potentiation in the hippocampus and long-term depression in the cerebellum. Long-term potentiation is a continuous increase in synaptic response over several hours. Extremely important in this phenomenon are postsynaptic NMDA glutamate receptors, which play the role of coincidence detectors, since they are activated only by a combination of two phenomena - the binding of glutamate to them and at the same time a sufficiently large depolarization. Activation of NMDA receptors leads to increased absorption of calcium ions, which activate several types of kinases - protein kinase A, tyrosine kinase, protein kinase C. These kinases phosphorylate various proteins, which leads to an increase in their sensitivity to glutamate and an increase in their number. This is followed by an increase in excitatory postsynaptic potentials. Prolonged potentiation is characteristic not only of the hippocampus, but also of the cerebellum, neocortex, and amygdala. The lack of long-term potentiation leads to impaired spatial training and memory.

Long-term depression is a prolonged decrease in the efficiency of synaptic transmission. It has been best studied in Purkinje cells, which receive excitatory glutamatergic information from parallel fibers. Reactivation of some fibers ending in the same Purkinje cell causes suppression of synaptic transmission. Long-term depression is observed in the hippocampus and neocortex.

Structural changes in synapses.

Structural changes in synapses are caused by long-term forms of learning and memory resulting from the synthesis of new proteins. Major structural changes:

- an increase in the number of nuclei in the presynaptic terminal membrane;

- an increase in the number of synaptic vesicles;

- an increase in the number of presynaptic and postsynaptic endings and the formation of new synapses.

These changes increase the ability of synapses to transmit signals during the creation of long-term memory. Starting your betting experience on a trusted international platform has never been more rewarding. New players are actively searching for verified promo codes that provide the highest possible welcome bonus. If you love sports betting on football, tennis, basketball, or esports, beginning with extra funds gives you a significant advantage. At the heart of the best current offer stands the powerful melbet promo code during registration and making your first deposit, you unlock an enhanced 130% welcome bonus up to $130. This extra balance allows you to place more bets, explore live potential right from the start.