Abstract
Optogenetic channels and ion pumps have become indispensable tools in neuroscience to manipulate neuronal activity and thus to establish synaptic connectivity and behavioral causality. Inhibitory channels are particularly advantageous to explore signal processing in neural circuits since they permit the functional removal of selected neurons on a trial-by-trial basis. However, applying these tools to study the visual system poses a considerable challenge because the illumination required for their activation usually also stimulates photoreceptors substantially, precluding the simultaneous probing of visual responses. Here, we explore the utility of the recently discovered anion channelrhodopsins GtACR1 and GtACR2 for application in the visual system of Drosophila. We first characterized their properties using a larval crawling assay. We further obtained whole-cell recordings from cells expressing GtACR1, which mediated strong and light-sensitive photocurrents. Finally, using physiological recordings and a behavioral readout, we demonstrate that GtACR1 enables the fast and reversible silencing of genetically targeted neurons within circuits engaged in visual processing.
Highlights
Expressed optogenetic ion channels and pumps confer light sensitivity to neurons of interest, allowing to control their activity on demand[1,2]
Our results demonstrate that optogenetics via GtACR1 permits selective, fast and reversible neuronal silencing in visually active circuits
We expressed GtACR1 and GtACR2 using vGlut-Gal[4] driving expression in glutamatergic neurons including motorneurons and reasoned that silencing those should manifest in quantifiable reduction in crawling activity
Summary
Expressed optogenetic ion channels and pumps confer light sensitivity to neurons of interest, allowing to control their activity on demand[1,2]. Remote control of neuronal activity by light has many advantages: it is fast, reversible, easy to parameterize and applicable in intact behaving animals It poses challenges for studies in visual systems, since here endogenous light-sensing cells, the photoreceptors, are activated by light required for optogenetic control. Anion channelrhodopsins (ACRs) have been discovered in the cryptophyte algae species Guillardia theta[13] (GtACR1 and GtACR2) These channels are promising versatile inhibitory tools since they impart strong light-gated chloride conductance, which is much more light-sensitive than, for instance, the Halorhodopsin class of chloride pumps[14,15]. All data are presented as mean ± standard error of the mean
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
