SYNAPTIC REMODELLING
Neurons communicate with each other by chemical messengers called neurotransmitters, which diffuse from one cell to another at specialized junctions called synapses. Cells can modulate their communication by strengthening or weakening synaptic strengths, which in turn alters information flow through the brain. This information flow is the basis of human cognition. The strength of these connections can be modulated rapidly through mechanisms such as long-term potentiation and depression. The connections between neurons can also undergo direct structural modifications by altering the total number of synapses. Such structural changes underlie long-term plasticity and are more permanent and occur more slowly. It is important to realize that changes in neuronal connectivity which arise from synaptic plasticity are the basis for human learning and memory.
Change in the information flow in a large neuronal network can be thought of as the sum of individual synaptic changes that occur in groups of functionally related neurons. However while the output of a network is determined by the integrated activity of the individual neurons, the activity dependent changes at a single synapse is driven by the network dynamics itself. This produces a challenging situation, in which the network is modifying its own behavior dynamically. Even if challenging, the ability to understand information flow through in vitro neuronal networks is of tremendous value, in that it is akin to what determines the cognitive function (or dysfunction) in an individual.
