Article Abstract:
A study was conducted to understand the underlying synaptic modification which occurs during long-term potentiation (LTP) in the hippocampus. The results show that a high proportion of synapses in the CA1 hippocampal area transmit with N-methyl-D-aspartate (NMDA) receptors, but not alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate (AMPA). This indicates that these synapses are inactive at normal resting potentials but acquire AMPA-type responses after LTP induction. A simple post-synaptic mechanism for induction and expression of LTP is proposed to challenge the view that LTP in CA1 involves a presynaptic modification process.
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Article Abstract:
The key functional characteristics of single presynaptic hippocampal boutons were investigated to improve the understanding of synaptic transmission between pre-synaptic terminals and post-synaptic dendrites. The results show that localized application of elevated K+/Ca2+ solution evoked excitatory post-synaptic currents (EPSC). Frequent repetitive stimulation caused a decline in EPSC incidence, which usually recovers after 40 seconds. The amplitude, average size of synaptic currents and varied responses to glutamate depending on cell type and synaptic innervation are also reported.
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Article Abstract:
The use of dyes with varying rates of membrane departitioning makes it possible to show the existence of fast endocytosis in hippocampal nerve terminals. The kinetics of the fast endocytosis can be derived from fluorescence measurements. It has been proved that rapid endocytosis of vesicles takes place at synapses between hippocampal neurons. It appears that the rate of rapid endocytosis rises with stimulus strength.
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