Beyond Colour Vision: Ancestral Photoreceptor Diversity as the Basis of Visual Behaviour
Lead Research Organisation:
University of Sussex
Department Name: Sch of Life Sciences
Abstract
Colour vision is based on comparing signals from different photoreceptors, but we have long reverted this correspondence: The purpose of having multiple types of photoreceptors is to enable colour vision. I challenge this long held notion. I posit that the original purpose of having multiple types of photoreceptors is to serve as parallel feature channels that differentially underpin visual motor programs such as motion vision behaviours, prey capture, or predator evasion. In this view, colour vision is a derived trait that emerged as a secondary benefit of the ancestral circuits that originally supported the first aquatic vertebrates' newfound abilities to visually segment and navigate their underwater world. Specifically, I hypothesise that vertebrate vision was originally built around three main circuits that begin with distinct sets of ancestral photoreceptors:
i. Red-cones and rods for general purpose greyscale vision
ii. UV-cones for specialised foreground vision
iii. Green/Blue-cones for regulating red- and UV-circuits.
My project aims to explore this hypothesis through three complementary aims:
1. Understanding what different cones "see,"
2. Determining how cone-signals are combined and contrasted in the retina.
3. Establishing the necessity and sufficiency of different cone types for different behaviours.
We will combine state-of-the-art approaches in high-throughput neurophysiology and visual stimulation with genetic manipulationof visual circuits, behaviour, computational modelling and field work. All experiments will be centrally rooted in zebrafish, an experimentally accessible species that retains the complete ancestral photoreceptor complement to the present day, and that has a similar visual ecology compared to our earliest vertebrate ancestors where vision first evolved. To test generality, we will adapt key approaches from zebrafish for working with other vertebrate species, including amphibians, mammals and birds.
i. Red-cones and rods for general purpose greyscale vision
ii. UV-cones for specialised foreground vision
iii. Green/Blue-cones for regulating red- and UV-circuits.
My project aims to explore this hypothesis through three complementary aims:
1. Understanding what different cones "see,"
2. Determining how cone-signals are combined and contrasted in the retina.
3. Establishing the necessity and sufficiency of different cone types for different behaviours.
We will combine state-of-the-art approaches in high-throughput neurophysiology and visual stimulation with genetic manipulationof visual circuits, behaviour, computational modelling and field work. All experiments will be centrally rooted in zebrafish, an experimentally accessible species that retains the complete ancestral photoreceptor complement to the present day, and that has a similar visual ecology compared to our earliest vertebrate ancestors where vision first evolved. To test generality, we will adapt key approaches from zebrafish for working with other vertebrate species, including amphibians, mammals and birds.
