Effect of Variation of Spatial and Temporal Frequencies of the Moving Field Visual Stimulus on Optokinetic Response of Adult Zebrafish.

The optokinetic response (OKR) is a reflexive behavior in which the eye intends to fixate the surrounding image in motion on its retina. The two important components of the OKR visual stimulus are the spatial frequency (SF) and the temporal frequency (TF). Zebrafish (Danio rerio) is considered an important model animal for visual physiology research. As a result, several works have been performed recently on zebrafish OKR in terms of their visual acuity or eye velocity. In the present study, a novel data pattern has been reported in terms of the relationship between ocular movement frequency (OMF) and TF of the visual stimulus in the presence of two types of SF of the optokinetic visual stimulus. The results indicated that at the basal SF (0.05 cycles per degree [cpd]), the OMF significantly increased (p < 0.05) with the corresponding elevation in the TF (till 240 deg.s-1). On the contrary, at a higher SF (0.29 cpd), there was a significant decrease (p < 0.05) in the OMF with the increase in TF.