Selective Optical Control of Synaptic Transmission in the Subcortical Visual Pathway by Activation of Viral Vector-Expressed Halorhodopsin

Abstract

The superficial layer of the superior colliculus (sSC) receives visual inputs via two different pathways: from the retina and the primary visual cortex. However, the functional significance of each input for the operation of the sSC circuit remains to be identified. As a first step toward understanding the functional role of each of these inputs, we developed an optogenetic method to specifically suppress the synaptic transmission in the retino-tectal pathway. We introduced enhanced halorhodopsin (eNpHR), a yellow light-sensitive, membrane-targeting chloride pump, into mouse retinal ganglion cells (RGCs) by intravitreously injecting an adeno-associated virus serotype-2 vector carrying the CMV-eNpHR-EYFP construct. Several weeks after the injection, whole-cell recordings made from sSC neurons in slice preparations revealed that yellow laser illumination of the eNpHR-expressing retino-tectal axons, putatively synapsing onto the recorded cells, effectively inhibited EPSCs evoked by electrical stimulation of the optic nerve layer. We also showed that sSC spike activities elicited by visual stimulation were significantly reduced by laser illumination of the sSC in anesthetized mice. These results indicate that photo-activation of eNpHR expressed in RGC axons enables selective blockade of retino-tectal synaptic transmission. The method established here can most likely be applied to a variety of brain regions for studying the function of individual inputs to these regions.

GABAergic mechanisms for shaping transient visual responses in the mouse superior colliculus

“…Visual stimuli were generated by MATLAB (Mathworks, Natick, MA, USA) programs using the Psychophysics Toolbox extensions (Brainard, 1997;Pelli, 1997;Kaneda et al, 2011Kaneda et al, , 2012. The stimuli were displayed on a 17-inch liquid crystal display monitor placed 25 cm from the mouse's left eye contralateral to the recorded (right) hemisphere.…”

“…Upon entering the sSC, the electrodes were slowly advanced, and single unit activities were recorded. Electrical signals were bandpass-filtered (0.3-6 kHz) and amplified with a Multiclamp 700B amplifier (1,000×, Molecular Devices) before being captured on a computer using an analog-to-digital card (National Instruments).Visual stimuli were generated by MATLAB (Mathworks, Natick, MA, USA) programs using the Psychophysics Toolbox extensions (Brainard, 1997;Pelli, 1997;Kaneda et al, 2011Kaneda et al, , 2012. The stimuli were displayed on a 17-inch liquid crystal display monitor placed 25 cm from the mouse's left eye contralateral to the recorded (right) hemisphere.…”

Action potential block in neurons by infrared light

“…12 Optogenetic means of AP block, such as by halorhodopsins, light-activated chloride ion channels, require genetic manipulation of the target cells. 13,14 To date, a noninvasive, nongenetic, highly specific, and reversible method for AP block has remained elusive. Such a method could be transformative for overcoming present limitations in electrically based neural interfaces of prosthetics and in medical devices to control unwanted APs.…”

A glass-coated tungsten microelectrode enclosing optical fibers for optogenetic exploration in primate deep brain structures

“…With optogenetic methodology, the causal relationship between the activity and function of a specific neuronal circuit is elucidated with high temporal and cell-type specificity (Baier and Scott, 2009;Goard and Dan, 2009;Miesenbock, 2009;Johansen et al, 2010;Kaneda et al, 2011;Tsubota et al, 2011;Tsunematsu et al, 2011;Yizhar et al, 2011a). Pioneering works have successfully applied the technique to primates in the dorsal areas of neocortex (Han et al, 2009;Diester et al, 2011).…”