Synaptic plasticity

Memory and learning are essential properties of the nervous system : They allow on the one hand, to distinguish among the new elements familiar elements, and, secondly, integrate spent a decision experiences. Synaptic plasticity probably plays a fundamental role in the processes of memory and learning. It corresponds to the change more or less durable effectiveness of a synapse, that is to say the amplitude of the depolarization or hyperpolarization it produces on its target cell. By changing the relative effectiveness of two synapses, a neuron changes the relative weight given to the information passing through. The same effect is also obtained the connection between two neurons through training or removal of synaptic contacts.Synaptic plasticity offers neuron another way to implement the principle of Convergence of synchronous activities (see supra "Alterations"). Convergence is not done then by the change in the number of synapses, but by changing their efficiency. Instead of forming new connections, the neuron will increase the efficiency of active synapses simultaneously.     Experimentally, it is possible to simulate the synchronous activation of several excitatory synapses onthe depolarizing a neuron. Following the above, the stimulation of a synapse associated with this singledepolarization should lead to increased efficiency. This phenomenon has been observed for examplein the hippo campus, a brain region involved in memory processes. The association Experimental depolarization of a pyramidal neuron of the hippocampus and a high stimulation a frequency synaptic terminal from another pyramidal neuron causes a doubling the efficiency of synaptic transmission between neurons. This change can take several hours, even several days (this is called LTP [ long-term potentiation]). We did not observe if the neuron is hyperpolarized.There is probably no universal mechanism for modulation of synaptic transmission and probably several principles governing the different types of synapse according to the specific needs of nervous system. Changes in synaptic efficacy are considered a basic form learning, which likely contributes to the storage in the nervous system.