Abstract
We present a high-throughput optogenetic illumination system capable of simultaneous closed-loop light delivery to specified targets in populations of moving Caenorhabditis elegans. The instrument addresses three technical challenges: It delivers targeted illumination to specified regions of the animal’s body such as its head or tail; it automatically delivers stimuli triggered upon the animal’s behavior; and it achieves high throughput by targeting many animals simultaneously. The instrument was used to optogenetically probe the animal’s behavioral response to competing mechanosensory stimuli in the the anterior and posterior gentle touch receptor neurons. Responses to more than 43,418 stimulus events from a range of anterior–posterior intensity combinations were measured. The animal’s probability of sprinting forward in response to a mechanosensory stimulus depended on both the anterior and posterior stimulation intensity, while the probability of reversing depended primarily on the anterior stimulation intensity. We also probed the animal’s response to mechanosensory stimulation during the onset of turning, a relatively rare behavioral event, by delivering stimuli automatically when the animal began to turn. Using this closed-loop approach, over 9,700 stimulus events were delivered during turning onset at a rate of 9.2 events per worm hour, a greater than 25-fold increase in throughput compared to previous investigations. These measurements validate with greater statistical power previous findings that turning acts to gate mechanosensory evoked reversals. Compared to previous approaches, the current system offers targeted optogenetic stimulation to specific body regions or behaviors with many fold increases in throughput to better constrain quantitative models of sensorimotor processing.
Highlights
How sensory signals are transformed into motor outputs is a fundamental question in systems neuroscience [1]
Strains from this work are being distributed by the C. elegans Genetics Center (CGC), which is funded by the NIH Office of Research Infrastructure Programs (P40 OD010440)
Optogenetic investigations of neural circuits underlying behavior confront 3 technical challenges: the first is to deliver stimulation targeted only to the desired neuron or neurons; the second is to deliver the stimulus at the correct time in order to probe the circuit in a relevant state or behavioral context; and the third is to efficiently acquire enough observations of stimupublish, or preparation of the manuscript
Summary
How sensory signals are transformed into motor outputs is a fundamental question in systems neuroscience [1]. In optically transparent animals, such as Caenorhabditis elegans and Drosophila, such. Perturbing neural activity and observing behavior has been widely used to study specific neural circuits, such as those involved in chemotaxis [8,9,10,11] (reviewed for Drosophila in [12]), olfaction [13], learning and memory [14,15], and locomotion and escape [16,17,18,19], to name just a few examples. In Drosophila, highthroughput optogenetic delivery to behaving animals has been used to screen libraries of neunumber DP2-NS116768 to AML. Optogenetic investigations of neural circuits underlying behavior confront 3 technical challenges: the first is to deliver stimulation targeted only to the desired neuron or neurons; the second is to deliver the stimulus at the correct time in order to probe the circuit in a relevant state or behavioral context; and the third is to efficiently acquire enough observations of stimupublish, or preparation of the manuscript
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