Optical quantal analysis reveals a presynaptic component of LTP at hippocampal Schaffer-associational synapses.
The mechanisms by which long-term potentiation (LTP) is expressed are controversial, with evidence for both presynaptic and postsynaptic involvement. We have used confocal microscopy and Ca(2+)-sensitive dyes to study LTP at individual visualized synapses. Synaptically evoked Ca(2+) transients were imaged in distal dendritic spines of pyramidal cells in cultured hippocampal slices, before and after the induction of LTP. At most synapses, from as early as 10 min to at least 60 min after induction, LTP was associated with an increase in the probability of a single stimulus evoking a postsynaptic Ca(2+) response. These observations provide compelling evidence of a presynaptic component to the expression of early LTP at Schaffer-associational synapses. In most cases, the store-dependent evoked Ca(2+) transient in the spine was also increased after induction, a novel postsynaptic aspect of LTP.
Emptage
Nigel J
NJ
Division of Neurophysiology, National Institute for Medical Research, Mill Hill, NW7 1AA, London, United Kingdom.
Reid
Christopher A
CA
Fine
Alan
A
Bliss
Timothy V P
TV
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism; D004558:Electric Stimulation; D001330:Electronic Data Processing; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005456:Fluorescent Dyes; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D008275:Magnesium Deficiency / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D018377:Neurotransmitter Agents / Q000378:metabolism; D009924:Organ Culture Techniques; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D018377:Neurotransmitter Agents; D016194:Receptors, N-Methyl-D-Aspartate; D002118:Calcium