Understanding the neurobiological mechanisms of learning and memory:: Memory systems of the brain, long term potentiation, and synaptic plasticity.: Part III A

Recent theories postulate that memory can be divided into multiple brain memory systems. Although memory systems depend on the function of variables based on the level of analysis and are subserved by different neural substrates, current definitions of memory systems have categorized them as psychological and biological entities. Under such context, the studies of different memory systems have shown that complex interactions take place during performance of any memory task. Such interactions among multiple memory systems arc based on dynamic interactive independent neural networks which make possible the better understanding of how memory systems work in the brain of mammals. Both behavioral and electrophysiological studies over the last decades demonstrate that learning and memory are encoded through activity dependent changes of the strength of synaptic connections between neurons, as experimentally demonstrated by Long-Term Potentiation (LTP) in mammalian synapses, LTP is a form of synaptic plasticity, and is considered as an accepted cellular model for stabilization of synapses involved in the expression of several neurobiological phenomena. Most of the understanding of the neurochemical, pharmacological, and molecular mechanisms involved in LTP induction, expression, and maintenance, have been demonstrated through the involvement of glutamate neurotransmission system, as well as through the different glutamate receptor subtypes, known to be expressed widely in different neural networks of the brain of mammals.