Project Summary/Abstract
The superior colliculus (SC) is a sensorimotor mammalian midbrain structure that integrates multimodal
sensory input and guides our everyday responses to environmental cues and determines what events are
most relevant and deserve our attention. Accumulating evidence has implicated the SC in
neurodevelopmental disorders, such as autism spectrum disorder (ASD), and in neurodegenerative
disorders, such as Lewy body dementia, Parkinson disease, progressive supranuclear palsy etc.
Establishing a functional neurocircuitry that leads to proper behavioral responses requires correct neuronal
differentiation and specification during development. One mechanism thought to regulate neuronal
differentiation is the reduction-oxidation (redox) state of the cell. Regulation of the redox state of a cell can
be crucial in inducing protein modifications, therefore regulating their function in cells and tissues. In a
recent paper, our labs showed that treatment of the developing zebrafish embryos/larvae with the drug
valproic acid (VPA) led to 1) delay in the specification of neurons in the homologous, non-mammalian
structure of the SC, named the optic tectum (OT) and 2) lack of formation of at least one subtype of neurons
in the OT. Since VPA has been shown to perturb the redox state in other neurons (and has been associated
with a higher incidence of ASD in children with fetal exposure to VPA), this study suggests that redox state
might in fact be important during neuronal development in the OT. Our proposal is designed to follow up on
these initial studies and fill the gap in understanding how OT neurocircuitry and associated behaviors are
regulated by changes in redox state during OT development. In the first aim, we plan to follow in vivo how
the redox state of different cell-compartments in OT neurons changes during normal development and after
the redox state is perturbed by VPA-treatment. In the second aim, we would like to determine when are the
different neuronal cell-subtypes generated in the OT, and if their formation is affected upon redox state
changes by VPA-treatment. Finally, in the third aim, we would like to explore how the changes of redox
state, specifically in the OT, affect behavior. Very few studies have investigated the effects of redox state in
OT circuitry, therefore, our study would fill an important gap in the current understanding. Additionally, since
the SC is associated with ASD, and VPA exposure is also correlated with higher ASD incidence, this study
might shed light into the molecular and cellular underpinnings of ASD.