Fig. 4 | Nature Communications

Fig. 4

From: Precisely timed inhibition facilitates action potential firing for spatial coding in the auditory brainstem

Fig. 4

Inhibition modulates spike generation in vitro. a, b Voltage traces from an example conductance-clamp recording in response to six-event trains with an inter-stimulus interval (ISI) of 5 ms. Excitation alone generated at most an onset spike (gray traces) at all excitatory conductances (Ges) tested. The same protocol performed with an identical inhibitory train [peak conductance (Gi) = 50 nS] at a relative timing difference (rTD) of –2.5 ms suppressed spiking (a, red traces), but at an rTD of –3.5 ms promoted spiking and recruited spiking throughout the train (b, red traces). Scale bar: 20 mV, 2 ms. c Event-wise spike probability heat maps as a function of Ge vs. rTD for the experiment shown in a, b with corresponding IPSP trace overlaid (green, scale bar: 5 mV). Red border outlines Ge conditions that resulted in 100% spike probability on more than one rTD (ceiling). Dotted red line indicates the ceiling threshold for this recording. Spike probability from excitation alone (e) is shown at the right of each plot. Dotted white line and arrowhead indicates the calculated “Best rTD” for this recording. d Event-wise plot of spike probability for pooled data (at Best rTD) for Ge values relative to the value generating a ceiling effect (Ge rel. ceil.) and with Gi = 50 nS. e Population average spike probability as a function of rTDs relative to the Best rTD for events three to six. Trace intensity reflects the Ge rel. ceil. values in d. f Post-inhibitory facilitation (PIF) function half-widths for each Ge rel. ceil. value tested. g Event-wise, population averaged spike probability at ceiling threshold Ge and Gi = 50 nS. h Same as in e, but for ceiling threshold Ge and different Gi values. i Same as in f, except for all Gi values tested. All averaged data represent mean ± s.e.m