Sound Affects the Discrimination of Weak Intensities of Light in the Visual Cortex of the Rabbit Depending on Time Intervals between Sound and Light

In this paper, we researched an influence of sound (2000 Hz, 70 dB, 40 ms) to the discrimination of low-light intensities (0.3 and 1 cd/m(2)) in the visual cortex of the rabbit. We used a recording of evoked potentials from the visual cortex of awaked rabbits in chronic experiments. The sound was switched on with different time slots before and after the replacement of the light intensities at each other (range from -750 to +150 ms). Sound itself caused no response. In 42 experiments on 3 rabbits we revealed that the sound has a significant modulating effect on the discrimination of low-light intensities in the range of time shifts from -300 to +50 ms. Maximum sound effect was manifested in the transition of light from a high-intensity (1 cd/m(2)) to lower (0.3 cd/m(2)). Analyses of the phases of visual evoked potentials revealed that significant influence of sound to the light occurs in the intervals 300, 100, 60, 40, 20, 0, +20 and +50 ms. We found that phase P2(120-150 ms from the moment of replacement of the light stimuli) is most affected by sound in response to the replacement of low-light intensities both in the