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Atypical Retinal Ganglion Cell Function in a Mouse Model of Fragile X Syndrome
Anna L Vlasits1,2, Maria Syeda3, Annelise Wickman3
1Department of Neurobiology, Northwestern University, Evanston, Illinois 60208 avlasits@uic.edu.
Summary
Altered retinal neuron function in fragile X syndrome (FXS) may explain visual sensitivities in autism. In FXS mice, "sustained On alpha" retinal cells show dampened light responses due to altered inhibitory input.
Area of Science:
- Neuroscience
- Genetics
- Ophthalmology
Background:
- Peripheral sensory neuron dysfunction is increasingly linked to autism spectrum disorder (ASD) symptoms.
- Visual sensitivities are common in ASD, but retinal contributions remain unclear, particularly in fragile X syndrome (FXS), a leading syndromic cause of ASD.
Purpose of the Study:
- To investigate retinal function in the Fmr1 knock-out mouse model of FXS.
- To examine the role of the "sustained On alpha" retinal ganglion cell, homologous to primate ganglion cells, in visual processing within the context of FXS.
Main Methods:
- Electrophysiological recordings and morphological analysis of "sustained On alpha" retinal ganglion cells in male Fmr1 knock-out mice.
- Assessment of light responses, dendritic structure, and inhibitory/excitatory (E-I) balance.
Main Results:
- Fmr1 knock-out mice exhibited altered dendritic structure in "sustained On alpha" retinal ganglion cells.
- These cells showed dampened responses to light, characterized by increased inhibitory input and reduced E-I balance.
- Changes in E-I balance affected circuit excitability and reshaped the tuning properties of these retinal neurons.
Conclusions:
- Loss of Fmr1 in the mouse retina impairs the sensory function of "sustained On alpha" retinal ganglion cells.
- FXS may broadly affect retinal cell tuning due to Fmr1 expression in various retinal cell types.
- The retina is a potential area of focus for understanding visual dysfunction in FXS and ASD.
