High-speed mapping of synaptic connectivity using photostimulation in Channelrhodopsin-2 transgenic mice

Abstract

To permit rapid optical control of brain activity, we have engineered multiple lines of transgenic mice that express the lightactivated cation channel Channelrhodopsin-2 (ChR2) in subsets of neurons. Illumination of ChR2-positive neurons in brain slices produced photocurrents that generated action potentials within milliseconds and with precisely timed latencies. The number of light-evoked action potentials could be controlled by varying either the amplitude or duration of illumination. Furthermore, the frequency of light-evoked action potentials could be precisely controlled up to 30 Hz. Photostimulation also could evoke synaptic transmission between neurons, and, by scanning with a small laser light spot, we were able to map the spatial distribution of synaptic circuits connecting neurons within living cerebral cortex. We conclude that ChR2 is a genetically based photostimulation technology that permits analysis of neural circuits with high spatial and temporal resolution in transgenic mammals.brain networks ͉ cortical circuitry ͉ synaptic transmission

Holographic optogenetic stimulation of patterned neuronal activity for vision restoration

“…5d) was B20 mm (corresponding to B0.7°and B0.07°of visual angle in mice and humans, respectively), contrasts with a previous report, which argued that ChR2 cellular excitation requires very large (4100 mm) excitation spots 12,14 . A recent report suggested that a retinal prosthetic system with cellular activity emulating natural RGCs encoding strategies, could underlie the restoration of vision to normal performance levels 9 .…”

“…A pattern photo-stimulation system for artificially controlling neural activity in a vision prosthesis or for general neurostimulation applications is not expected to have this limitation (due to minimal light scattering in the inner retinal layers) and will ideally allow cellular-resolution, rapid, massively parallel, light-efficient stimulation across macroscopic (millimeter-scale) coverage areas. To date, however, optical excitation of optogenetically targeted populations is often delivered nonspecifically to the whole population using wide-field flashes with intense lamps 1,3,10 , LEDs (light-emitting diodes) and optical fibre coupled illumination 11,12 or in simple patterns using rapid random-access laser deflection 13,14 , digital micromirror arrays 8,9,[15][16][17][18] and micro-LED arrays 6,19 .…”

Single-neuron labeling with inducible Cre-mediated knockout in transgenic mice

“…Many genetically encoded tools to both monitor and manipulate various physiological properties of neurons have been developed in recent years [2][3][4][5][6][7][8][29][30][31][32] . These include fluorescent reporters of synaptic transmission and ion concentrations, as well as reagents to modulate neuronal excitability and neurotransmitter release.…”

Immune responses to adeno-associated virus type 2 encoding channelrhodopsin-2 in a genetically blind rat model for gene therapy

“…6 We have already demonstrated that the responses induced by various stimulus frequencies (Hz) in ChR2-transduced rats are in no way inferior to those in normal rats, 7 as supported by the finding that ChR2-induced photocurrents are extremely fast. 8,9 Visual function was also well analysed by using transgenic rats with ChR2 transduction into RGCs: the spatial frequencies based on behavioural responses of photoreceptordegenerated ChR2 transgenic rats were the same as those of normal rats. 10 These studies indicate that transfer of the ChR2 gene into the remaining retinal neurons is a useful method for restoring vision in progressed RP.…”