Subthreshold membrane-potential oscillations in immature rat CA3 hippocampal neurones.
Subthreshold membrane potential oscillations (MPOs) were recorded intracellularly in 31 of 43 (>70%) immature CA3 hippocampal neurones (from 3-17 days postnatally). MPOs (3-5 mV, 3-15 Hz) occurred at resting membrane potential (RMP) in 20 of 31 neurones, or following depolarization (11 of 31 neurones); with sufficient depolarization spontaneous action potentials (APs) were generated from the positive-going phase of MPOs. In all cells, MPOs were blocked by steady membrane hyperpolarization. Tetrodotoxin abolished MPOs (n = 4); Co(2+) markedly reduced them (n = 3), and tetraethylammonium, added in the presence of TTX, revealed lower frequency oscillatory activity (n = 2). We conclude that subthreshold MPOs in immature hippocampus, possibly linked to theta rhythm generation and memory acquisition, depend on voltage-dependent Na+ electrogenesis and they might be additionally controlled by Ca(2+) and K+ conductances.
Psarropoulou
C
C
Montreal Neurological Institute, Department of Neurology & Neurosurgery and Department of Physiology, McGill University, Montreal, QC, Canada.
Avoli
M
M
D000818:Animals; D000831:Animals, Newborn; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013779:Tetrodotoxin / Q000494:pharmacology; D013826:Theta Rhythm
D013779:Tetrodotoxin