Figure 4.

Response characteristics and morphology of conditionally polarization-sensitive CPU2 neurons. A, Spike train (lower trace) and mean spiking frequency (upper trace; gliding average, bin size 1 s) of a polarization-sensitive CPU2 neuron during 360° rotation of the polarizer (clockwise). B, Circular diagram of mean activity during four rotations of the polarizer (same neuron as A, bin size 10°; error bars, SD; p = 2.7 × 10⁻¹¹). C, Activity of a polarization-insensitive CPU2 neuron during rotation of the polarizer (spike train in lower trace, mean spiking frequency in upper trace). D, Circular diagram of mean activity during four rotations of the polarizer (same neuron as C; error bars, SD; bin size 10°). The mean activity of the neuron does not change significantly during rotation of the polarizer (p = 0.68). E, F, Neuronal activity during stimulation with large-field frontal light flashes. E, No response occurred in the polarization-sensitive neuron (same as in A). F, Excitatory responses were present in the polarization-insensitive neuron (same as in C). G, Frontal reconstruction of the CPU2 neuron recorded in A. Arborizations are present in the PB, in all layers of the CBU, and in both ventral shells of the LAL. Scale bar, 80 μm.