Fig. 2. Spontaneous and light-evoked activity recorded from the separated proximal
optic stalk of a dark-adapted eye before and after injection of 10 pmol
serotonin at daytime. Responsiveness increased with increments in light
intensity. Injection of serotonin into the optic lobe reduced the spontaneous
activity as well as the light-induced responses. Duration of light pulses to
the contralateral eye was 1000 ms, as shown at the bottom of the waveform. The
highest intensity tested was 0.4mW cm-2 designated as
logI=0.
