Foxd1 dependent induction of temporal retinal character is required for visual function

Appropriate patterning of the retina during embryonic development is assumed to underlie the establishment of spatially localised specialisations that mediate the perception of specific visual features. For instance, in zebrafish, an area involved in high acuity vision (HAA) is thought to be present in the ventro-temporal retina. Here we show that the interplay of the transcription factor Rx3 with Fibroblast Growth Factor and Hedgehog signals, initiates and restricts foxd1 expression to the prospective temporal retina, initiating naso-temporal regionalisation of the retina. Abrogation of FoxD1 results in the loss of temporal and expansion of nasal retinal character, and consequent absence of the HAA. These structural defects correlate with severe visual defects as assessed in optokinetic and optomotor response assays. In contrast, optokinetic responses are unaffected in the opposite condition in which nasal retinal character is lost at the expense of expanded temporal character. Our study indicates that the establishment of temporal retinal character during early retinal development is required for the specification of the HAA, and suggests a prominent role of the temporal retina in controlling specific visual functions. Summary statementThis study provides a mechanistic link between eye patterning and the establishment of functionally distinct retinal regions and reveals the temporal retina preferentially controls specific aspects of visual function.