Fig. 7: A model of early- and late-phase motor inhibition mediated by Ifb-B and Canon neurons during backward locomotion.

When the wave front reaches the segment (n), Ifb-Bwd neurons in segment (n) and Canon neurons in segment (n−1) and segment (n−2) are activated. Ifb-Bwd and Canon neurons in turn activate inhibitory premotor neurons (inPMN) innervating L-MNs in segment (n−1) and in segments (n−2) to (n−4), respectively, via their ascending axons. Ifb-Bwd neuron activates excitatory premotor neurons (ePMN) that innervate T-MNs. Neurons outlined by dotted or solid lines indicate inactive or active neurons, respectively. Arrows with filled heads indicate excitatory synapses while those with bar heads indicate inhibitory outputs.