<Dl> <Dt> Persistence </Dt> <Dd> LTP is persistent, lasting from several minutes to many months, and it is this persistence that separates LTP from other forms of synaptic plasticity . </Dd> </Dl> <Dd> LTP is persistent, lasting from several minutes to many months, and it is this persistence that separates LTP from other forms of synaptic plasticity . </Dd> <P> While induction entails the transient activation of CaMKII and PKC, maintenance of E-LTP (early - form LTP) is characterized by their persistent activation . During this stage, PKMz (Protein kinase Mζ) which does not have dependence on calcium, become autonomously active . Consequently, they are able to carry out the phosphorylation events that underlie E-LTP expression . </P> <P> Phosphorylation is a chemical reaction in which a small phosphate group is added to another molecule to change that molecule's activity . Autonomously active CaMKII and PKC use phosphorylation to carry out the two major mechanisms underlying the expression of E-LTP . First, and most importantly, they phosphorylate existing AMPA receptors to increase their activity . Second, they mediate or modulate the insertion of additional AMPA receptors into the postsynaptic membrane . Importantly, the delivery of AMPA receptors to the synapse during E-LTP is independent of protein synthesis . This is achieved by having a nonsynaptic pool of AMPA receptors adjacent to the postsynaptic membrane . When the appropriate LTP - inducing stimulus arrives, nonsynaptic AMPA receptors are rapidly trafficked into the postsynaptic membrane under the influence of protein kinases . As mentioned previously, AMPA receptors are the brain's most abundant glutamate receptors and mediate the majority of its excitatory activity . By increasing the efficiency and number of AMPA receptors at the synapse, future excitatory stimuli generate larger postsynaptic responses . </P>

Who was the first researcher to demonstrate that neurons are separate from one another