Figure 3. Preferential existence of bidirectional chemical connections in electrically coupled pairs.

(a) A representative sample pair with bidirectional chemical connection and reciprocal electrical connection between two layer 1 interneurons. APs and hyperpolarization sequentially triggered in the presynaptic neurons (blue traces) and responses (red traces) of GABAergic connections (inward currents) and electrical connections (outward currents) recorded in the postsynaptic neurons. The bold traces represent the average and the grey traces represent the individual traces. A schematic diagram showing electrical and GABAergic connections between the two neurons (inset). Wavy red arrowheads indicate electrical connections, and green arrowheads indicate GABAergic connections. (b) Bidirectional chemical connections between layer 1 interneurons preferentially existed in electrically coupled pairs. (c) Layer 1 interneuron pairs connected by bidirectional chemical synapses preferentially formed electrical synapses. ***P<0.001, χ²-test.