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. Author manuscript; available in PMC: 2015 Aug 6.
Published in final edited form as: Neuron. 2014 Jul 24;83(3):708–721. doi: 10.1016/j.neuron.2014.06.021

Figure 6. High Frequency Firing of nMLF Neurons Precedes the Motor Response to Changes in Illumination.

Figure 6

(A) Example traces of whole-cell recordings on the MeM (left), MeLc (middle), and MeLr (right) neurons together with motor nerve activity in response to light onset (at open arrowheads) and offset (at filled arrowheads). The action potentials of the MeLc and MeLr neurons are truncated.

(B) Upper: raster plots demonstrate the firing pattern of the nMLF neurons in response to light onset (n = 15 trials from 3 neurons in each class, marked on the left of the raster plot). Firing is aligned to the start of the first swim bout (motor nerve activity) after the light stimulus (black ticks: nMLF action potential, circles: visual stimulus, gray bars: swim bout). Middle: Instantaneous firing frequency of nMLF action potentials shown in the raster plot. Lower: a histogram illustrates the distribution of nMLF action potentials (black line) and motor nerve swim bursts (gray bars). MeM, n = 16 trials from 4 neurons; MeLc, n = 31 trials from 5 neurons; MeLr, n = 34 trials from 5 neurons.

(C) Response to the light offset. Figures are arranged as in B. MeM, n = 40 trials from 5 neurons; MeLc, n = 32 trials from 5 neurons; MeLr, n = 33 trials from 5 neurons.

(D) Maximum spike frequency during light evoked swim bouts (M activity; MeM, 58 trials from 5 neurons; MeLc, 63 trials from 5 neurons; MeLr, 68 trials from 7 neurons). The MeLc spike frequencies that successfully activated motoneurons during current injection (Mn activity, illustrated in 4B, D) fall within the natural spike frequency range of MeLc neurons during swimming. The MeM neuron has more events at the 0–100 Hz frequency bin because in more trials the cell only fires a single action potential in response to light.