 Dear students, in this topic we shall discuss the neuronal plasticity. The neuronal plasticity is the capacity of the nervous system to change with experience. You know that the basic architecture or anatomy of the nervous system is established during embryonic development. However, the behavioral patterns modify with time, age and experience. This modification is known as neural plasticity and is of premier importance for the fitness and survival of an animal in its environment. Dear students, the neural plasticity is the basis of learning, memory, development of motor skills and habits. It is also the basis of ability to respond to stimuli in diverse ways which are different from fixed programmed reflexes. The neural plasticity also lies behind human intelligence. Dear students, now we shall discuss the mechanism of neural plasticity. The reshaping of the nervous system that is plasticity occurs at synapses. The reason is that it is usually called synaptic plasticity. The synaptic plasticity is a hot topic for research by the neurophysiologists. Dear students, the synaptic plasticity involves modification of synapses over the course of lifetime due to various developmental events. The synaptic connections are basically established in embryos. But during plasticity or modification, these synaptic connections are refined into adult patterns. As a result, they become mature synapses. These mature synapses have the capacity to learn and memorize events. The changes for learning and memory actually depend on a mechanism which is known as the retrograde signal or reverse signal. Usually, the signals move from pre-synaptic neuron to the post-synaptic neuron. But this retrograde signal is sent to pre-synaptic neuron from post-synaptic neuron. And this is a feedback mechanism in which the post-synaptic neuron shares pre-synaptic neuron with its own experiences and the changes come through the retrograde signal. Dear students, the synaptic plasticity occurs by two types of mechanisms. The first mechanism is called pre-synaptic mechanisms and the second is post-synaptic mechanisms. Pre-synaptic mechanisms involve those changes which occur in the functioning of pre-synaptic terminals. For example, a pre-synaptic terminal neuro-transmitter produces the effect of the post-synaptic neuron. Post-synaptic mechanisms involve changes in post-synaptic neurons. For example, a post-synaptic neuron generates action potentials on a particular frequency. That is another manifestation of neural plasticity.