Spike after-depolarization and burst generation in adult rat hippocampal CA1 pyramidal cells.

摘要: 1. Intracellular recordings in adult rat hippocampal slices were used to investigate the properties and origins of intrinsically generated bursts somata CA1 pyramidal cells (PCs). The PCs classified as either non-bursters or bursters according firing patterns evoked by intrasomatically applied long ( > = 100 ms) depolarizing current pulses. Non-bursters stimulus-graded trains independent action potentials, whereas clusters three more closely spaced spikes riding on a distinct envelope. 2. In all fast spike repolarization was incomplete ended at potential approximately 10 mV positive than resting potential. Solitary followed after-depolarizing (ADP) lasting 20-40 ms. ADP most declined monotonically baseline ('passive' ADP), it remained steady even re-depolarized before declining ('active' ADP). 3. Active, but not passive, ADPs associated with an apparent increase input conductance. They maximal amplitude when from reduced mild depolarization hyperpolarization (+/- 2 mV). 4. Evoked spontaneous burst sensitive small changes membrane cases curtailed depolarizations hyperpolarizations 5 5. Bursts comprising spikelets ('d-spikes') observed 12% bursters. Some d-spikes attained threshold for triggering full somatic spikes. Gradually hyperpolarizing these neurones blocked blocking d-spikes, suggesting that latter are remote sites. 6. data suggest active intrinsic slow, voltage-gated inward current. arise which this is sufficiently large generate suprathreshold ADPs, thereby initiate regenerative process recruitment slow depolarization.