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. 2015 Jan 21;35(3):1217–1227. doi: 10.1523/JNEUROSCI.4346-14.2015

Figure 5.

Figure 5.

Synaptic interactions between HVC(RA) neurons and interneurons. A, B, Reconstruction of an HVC(RA) neuron (axon = red; A) and an HVC interneuron (axon = blue; B) recorded in vitro. Inset are responses of these cells to hyperpolarizing (−400 pA) and depolarizing current steps (HVC(RA): 200 pA, interneuron: 400 pA). C, D, Reciprocal synaptic connectivity between the neurons shown in A and B (black trace = average response). E, F, Synaptic strength of all recorded HVC(RA)→interneuron (E) and interneuron→HVC(RA) (F) connections with respect to intersomatic distance (gray is nonconnected). G, Frequency dependence of the HVC(RA)→interneuron connections showing that a 300 Hz HVC(RA) burst activates a postsynaptic interneuron (RMP = −54.5 mV). H, An HVC(RA) burst often produces a reliable spike in postsynaptic interneurons (7 pairs, average in black). I, A typical HVC(RA)→interneuron pair in which facilitating EPSCs can be visualized using voltage-clamp. J, Triplet recording from one HVC(RA) neuron connected to two interneurons, as shown by the schematic on top. A single 300 Hz burst (3 spikes) in the HVC(RA) neuron (red trace) was able to reliably evoke synchronous spiking in two postsynaptic interneurons (blue = example traces, black = raster plots from 15 trials).