Fig. 5: Collision of synaptic inputs and bAP-induced dSpikes triggers plateau potentials.

a Kymographs (∆F/F) along the apical trunk (red line) showed the effects of (top) optogenetic stimuli targeted to the soma (30 ms duration to trigger 3-4 bAPs), (middle) EFS-triggered synaptic inputs (0.1 ms duration), and (bottom) combined optical and electrical stimuli. b Area under the curve (AUC) for combined stimulus normalized to the sum of AUC for optical and EFS stimuli alone (n = 28 cells from 12 animals). c Top: Fluorescence in a distal dendrite ( > 200 µm from the soma) in response to combinations of optogenetic (30 ms, 3 bAPs) and EFS stimulation at various time offsets (∆Time). Bottom: Corresponding data using 10 ms optogenetic stimulation (1 bAP). d AUC for combined stimulus as a function of ∆Time. Data for each cell scaled to the range [0, 1] (n = 8 cells from 7 animals for 30 ms stimulus; n = 5 cells from 4 animals for 10 ms stimulus). Open symbols represent individual data and filled symbols represent mean at each ∆Time. Red lines: exponential fit from −245 to 0 ms; sigmoidal fit from 0 to +245 ms. e EFS and ramped soma-targeted optogenetic stimulation. Under weak optogenetic stimulus, EFS #1 evoked a plateau potential in the dendrites (purple) with an accompanying complex spike in the soma (orange). Under strong optogenetic stimulus, EFS #2 did not evoke a complex spike or plateau potential. f AUC for the EFS-evoked event was significantly lower when paired with strong optogenetic stimuli vs. weak stimuli (p = 0.01, n = 8 neurons from 5 animals, paired two-sided t-test). g Repeated EFS under tonic weak optogenetic stimulus. Both EFS stimuli evoked plateau potentials. h AUC for the first and second EFS-evoked events was similar when paired with tonic weak optogenetic stimuli (p = 0.19, n = 8 neurons from 5 animals, paired two-sided t-test). Box plots in 5b, f, h show median, 25th and 75th percentiles, and extrema. Source data for Fig. 5b, f, h are provided as a Source Data file.