Fig. 2.

Morphological and electrophysiological properties of L10 and Ipc neurons. (a) Intracellular biocytin fills of three tectal L10 neurons. The U-shaped axon (arrow head) characterizes the center neuron as a shepherd’s crook neuron, which projects to the nucleus isthmi. A U-shaped axon is also visible for the left neuron. Scale bar = 20 μm. (b) Response of a representative L10 neuron to a 0.1 nA current step. (c) Average firing rate (black diamonds) and instantaneous firing rate (the inverse of the first interspike intervals, red triangles) vs. current for the population of recorded L10 neurons. The black line represents a linear fit (F(I)= 217.86 × I − 4.61; r² = 0.9821) of the firing rate, F, as a function of the injected current, I, to the measured average firing rate data points. (d) Intracellular biocytin fill in an Ipc neuron (scale bar = 50 μm). (e) Response of a representative Ipc neuron to a 0.5 nA current step. (f) Average firing rate (black diamonds) and instantaneous firing rate (the inverse of the first interspike intervals, red triangles) vs. current for the population of recorded Ipc neurons. The black line represents a linear fit (F(I) = 63.427× I − 5.73; r² = 0.9988) of the firing rate as a function of the injected current to the measured average firing rate data points.