Figure 7.

Multiple axonal paths and targets within a neuronal pair. A. Map of neuronal pair MK181221–1 (7 months), with the interneuron making 15 synapses onto the postsynaptic pyramidal neuron. The numbered axonal paths here are defined as those that are separated by two or more branching points. Axonal paths with the same color originate from the same third- or fourth-order axonal branch. The same axonal paths (e.g., AP4 and 6) can make synapses onto more than one postsynaptic domain, and the same postsynaptic domain can receive input from more than one axonal path (e.g., the postsynaptic cell body and the one of the basal dendrites). B. Distribution of the number of targeted postsynaptic domains per neuron among the mapped pairs. C. Distribution of the number of postsynaptic domains with converging input per neuron. For B and C, n = 10 PV+ interneuron–pyramidal neuron pairs, and n = 3 PV+ interneuron–interneuron pairs. D. Correlation between conduction velocity and the number of postsynaptic domains with converging input from different axonal paths, P < 0.01 for all pairs and P < 0.01 for PV+ interneuron–pyramidal neuron pairs only. Interneuron–interneuron pairs are shown in darker gray.