State-dependent mechanisms of LTP expression revealed by optical quantal analysis.
The expression mechanism of long-term potentiation (LTP) remains controversial. Here we combine electrophysiology and Ca(2+) imaging to examine the role of silent synapses in LTP expression. Induction of LTP fails to change p(r) at these synapses but instead mediates an unmasking process that is sensitive to the inhibition of postsynaptic membrane fusion. Once unmasked, however, further potentiation of formerly silent synapses leads to an increase in p(r). The state of the synapse thus determines how LTP is expressed.
Ward
Bonnie
B
Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom.
McGuinness
Lindsay
L
Akerman
Colin J
CJ
Fine
Alan
A
Bliss
Tim V P
TV
Emptage
Nigel J
NJ
D000818:Animals; D000831:Animals, Newborn; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005456:Fluorescent Dyes; D018698:Glutamic Acid / Q000378:metabolism / Q000494:pharmacology; D006624:Hippocampus / Q000502:physiology* / Q000648:ultrastructure; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D008561:Membrane Fusion / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology* / Q000648:ultrastructure; D055095:Optics and Photonics; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D013570:Synaptic Membranes / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure
D005456:Fluorescent Dyes; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D008274:Magnesium