Fig 7

(A) Parallel sensory pathways transmit acoustic information to M-cells (“Mc_L” and “Mc_R”) and prepontine escape neurons (“Pp_L” and “Pp_R”). Decision-making is based on reaction time: VIIIth nerve activation of M-cells is direct, whereas prepontine neurons receive auditory information only via an indirect pathway, allowing active M-cells to prevent the initiation of delayed escapes. Additionally, Mauthner cells inhibit prepontine escape neurons, likely through an indirect pathway. Dashed lines indicate indirect connections. (B) Anatomy corresponding to the model in (A). Auditory signals from the statoacoustic ganglion (VIII, brown) excite M-cells (“Mc,” blue) directly (top) or prepontine escape neurons (“Pp,” green) indirectly (bottom). M-cells receive predominantly ipsilateral inputs and project commissurally to drive fast escapes, whereas prepontine escape neurons project both ipsi- and contralaterally and may drive escape in either direction, although predominantly ipsilaterally. LLC, long-latency C-start; M-cell, Mauthner cell; SLC, short-latency C-start.