Fig. 4: Dendritic excitations implement a spike-rate accelerometer.
From: Dendritic excitations govern back-propagation via a spike-rate accelerometer
a Structural image (gray) overlayed with fluorescence of eYFP (blue) showing the optogenetic stimulus. Kymograph along the red line. Example traces taken from the regions indicated by colored arrows. b Top: number of bAPs (gray) and bAPs with dSpikes (red), as a function of time after stimulus onset, showing how acceleration of the somatic spike rate evokes a transient burst of dSpikes (n = 43 dendrite stimulus locations, 16 cells, and 13 animals). Bottom: percent of dSpikes among all bAPs. c Equivalent experiment to (a) using wide-field illumination which covered the soma and apical trunk (blue). d Amplitude maps of the first 12 bAPs showing two bAP failures, followed by alternating dSpikes and bAP failures. e Plots showing period-doubling bifurcations (n = 9 cells from 9 animals). Left: bAP frequency as a function of time after stimulation onset. Middle: Normalized bAP amplitude relative to average of the final 5 bAPs. Right: Relationship between amplitudes of successive bAPs, bAPn+1 vs. bAPn showing an alternating motif. f, g Simulations showing spiking at the soma (orange) and distal dendrites (purple) and the dynamics of A-type KV channels (blue) and NaV channels (red). Neuron morphology from modelDB:64167. f Soma-targeted stimulation opens a transient window for dSpike excitation. g Wide-field stimulation evokes transient period-doubling bifurcation. NaV channel reserve defined by the slow inactivation gate (fast inactivation and recovery not shown).
