Lowering extracellular calcium reverses paired pulse habituation into facilitation in dentate granule cells and removes a late IPSP.
Simultaneous measurements of cellular responses and extracellular field potentials as well as extracellular Ca2+ concentration [( Ca2+]0) were performed in the dentate gyrus granule cell layer during paired pulse stimulation of the lateral perforant path at resting [Ca2+]o and during washout of calcium. At resting [Ca2+]o the second response to a paired stimulus was smaller than the first response. This frequency habituation reversed into frequency potentiation (second response larger than the first one) during lowering of [Ca2+]o at about the same time when a late presumed inhibitory postsynaptic potential (IPSP) was abolished. This suggests that a slow inhibition can account for part of frequency habituation in the dentate gyrus.
Rausche
G
G
Institut für normale und pathologische Physiologie, Cologne Universität zu Köln, F.R.G.
Sarvey
J M
JM
Heinemann
U
U
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000494:pharmacology* / Q000502:physiology; D004558:Electric Stimulation; D006185:Habituation, Psychophysiologic / Q000187:drug effects* / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects*; D051381:Rats
D002118:Calcium