Masking, De Lange curves and integration time as revealed by the electroretinogram of a tree shrew (Tupaia chinensis).

Dynamical characteristics of the electroretinogram (ERG) of a tree shrew were measured. Since this animal has a cone dominated receptor population (95%) comparison to human photopic vision is obvious. The light source was chosen to stimulate the red cones of this deuteranopic animal predominantly. Masking experiments displayed a reasonable correspondence to human foveal psychophysics. De Lange curves and CFF values revealed a maximum sensitivity at 15-20 HZ, which is higher than is found for human vision. A secondary maximum was observed in the De Lange curves at high adaptation levels, which is possibly due to interactions of the ERG components. The dependency of integration time on adaptation level appeared to be similar to known data of human psychophysics and electrophysiological data from Limulus receptor cells.