Analysis of light-triggered activity in current-clamped cells.

<p>(A) Sample traces of a cell entering depolarization block after the first stimulation pulse. Note the pronounced spike amplitude attenuation. The second pulse induced a smaller depolarization and a series of APs. (B – D) Spike train parameters. Cells were classified based on their response to the first stimulation pulse. Train firing: >30 APs, n = 6. Depolarization block, n = 7. Subthreshold depolarization, n = 4. Sparse firing: 1–30 APs, n = 5. (E) Spike trains in a pyramidal neuron stimulated with very low or high light intensity. Analysis of the instantaneous firing frequency reveals a similar rapid frequency drop under both conditions.