Synaptic recruitment during long-term potentiation at synapses of the medial perforant pathway in the dentate gyrus of the rat brain.
Long-term potentiation (LTP) in synapses of the medial perforant pathway of the rat dentate gyrus has been studied using the whole-cell voltage clamp technique and a standard hippocampal slice preparation. The rate of LTP induction by 2-4 brief trains of stimuli at 100 Hz, paired with postsynaptic depolarization to -20 mV, in individual granule neurons was only 42% but the average magnitude was large. In a representative series of nine experiments the average potentiation was 339% (s.d. 255%). The variable magnitude of LTP appeared to be related to the relative size of the NMDA receptor dependent current in individual neurons. LTP was further characterized by the selective enhancement of the AMPA (but not the NMDA) component in the excitatory synaptic responses. This selective enhancement of the AMPA component and a graphical variance analysis suggest that the large magnitude of LTP in dentate gyrus can be best explained by recruitment of previously silent synapses by a combination of pre- and post-synaptic mechanisms.
Wang
S
S
University of Toronto, Ontario, Canada.
Wojtowicz
J M
JM
Atwood
H L
HL
D000344:Afferent Pathways / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D018891:Dentate Gyrus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D011999:Recruitment, Neurophysiological / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D002118:Calcium