Abstract
Small transient all-or-none depolarization (also termed in the literature fast prepotentials, spikelets, pseudospikes, d-spikes, or short latency depolarizations) and their association with lucifer yellow (LY) dye-coupling were analyzed in CA1–CA3 hippocampal pyramidal cells in urethane anesthetized rats. It was found that (a) 15 of the 24 LY-injected pyramidal neurons (63%) showed dye-coupling; (b) spontaneous, anti-and orthodromically evoked spikelets (3–7 ms in duration; 3- to 12-mV peak) were recorded in 40 of 95 cells (42%); (c) there was a significantly higher probability of dye-coupled neurons with spikelets and of uncoupled ones without spikelets; (d) spikelet waveform and amplitude were unaffected by spontaneous or imposed polarizations; (e) large hyperpolarizations could reduce the rate and even prevent spikelets; and (f) spikelets could precede or follow spikes, the latter were more frequent with large depolarizations. Electrophysiological findings, and the association of dye-coupling and spikelets, suggest strongly that at least some spikelets are coupling potentials. This implies that pyramidal cells may be electrotonically coupled under physiological conditions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have