Response: Commentary: “Prdm13 regulates subtype specification of retinal amacrine interneurons and modulates visual sensitivity”

Citation: Sugita Y, Watanabe S and Furukawa T (2016) Response: Commentary: " Prdm13 regulates subtype specification of retinal amacrine interneurons and modulates visual sensitivity ". First, on behalf of all of the authors of our paper, we thank Drs. Bowrey and James for their interest in our paper and for giving us their comments on the OKRs (Optokinetic Responses) of Prdm13-deficient (Prdm13 −/−) mice (Watanabe et al., 2015). Drs. Bowrey and James hypothesized that Prdm13 −/− mice showed enhanced sensitivities to moving visual stimuli through " aliasing " caused by the decreased sampling function of the reduced numbers of amacrine cells in the retina (Bowrey and James, 2015). Aliasing is a phenomenon in which the presentation of continuously moving visual stimulus of high spatial frequency causes reduced neural sampling function, leading to misrecognition of a high frequency stimulus as a low According to the previous studies on mouse visual function analysis, the optimal spatial frequency range, that which elicits smooth eye movement, is 0.01–0.5 cycle/degree, and the maximum spatial frequency for maintaining smooth eye movement without causing aliasing is 1.0 cycle/degree (Prusky et al., 2000; Geng et al., 2011). However, in fact, many experiments set the highest spatial frequencies lower than 1.0 cycle/degree In our study, we set the highest spatial frequency at 0.5 cycle/degree, at which aliasing is very unlikely to occur. Even if we suppose that aliasing can occur at 0.5 cycle/degree, the OKRs of Prdm13 −/− mice at 0.5 cycle/degree were unchanged in both initial and late phases compared with those in WT mice. This strongly suggests that an aliasing effect, which shows stronger responses at higher frequencies, was not observed at 0.5 cycle/degree. Visual responses in classical OKR were measured basically by whether or not the mouse head or eye moves. On the other hand, the visual responses used in our OKR system are based on the speed of the smooth eye movements elicited by moving visual stimuli. In other words, the classical OKR digitally detected the existence of responses to visual stimuli, whereas our OKR continuously measured the extent of moving stimuli speeds. Hence, if aliasing occurred in our OKR system, eye movement speed would become slower, and reduced OKRs would be observed. Most studies of retinal sampling function have focused on photoreceptors and ganglion cells The relationship between amacrine cell subtypes and retinal sampling function has barely been explored. On the other hand, it …