Controlling the behaviour of Drosophila melanogaster via smartphone optogenetics

Abstract

Invertebrates such as Drosophila melanogaster have proven to be a valuable model organism for studies of the nervous system. In order to control neuronal activity, optogenetics has evolved as a powerful technique enabling non-invasive stimulation using light. This requires light sources that can deliver patterns of light with high temporal and spatial precision. Currently employed light sources for stimulation of small invertebrates, however, are either limited in spatial resolution or require sophisticated and bulky equipment. In this work, we used smartphone displays for optogenetic control of Drosophila melanogaster. We developed an open-source smartphone app that allows time-dependent display of light patterns and used this to activate and inhibit different neuronal populations in both larvae and adult flies. Characteristic behavioural responses were observed depending on the displayed colour and brightness and in agreement with the activation spectra and light sensitivity of the used channelrhodopsins. By displaying patterns of light, we constrained larval movement and were able to guide larvae on the display. Our method serves as a low-cost high-resolution testbench for optogenetic experiments using small invertebrate species and is particularly appealing to application in neuroscience teaching labs.

An economical and highly adaptable optogenetics system for individual and population-level manipulation of Caenorhabditis elegans

“…At present, required intensity for optogenetic stimulation of D. melanogaster is nowadays a few orders of magnitudes smaller. Commonly used intensities range from 50 u W/mm 2 to 0.3 mW/mm 2 , although much higher intensities (< 6.5 mW/mm 2 ) are also used [ 126 – 128 ]. To gain such small intensities with the OptoArm, one can use the systems intensity control, omit the use of lenses, and/or increase the working distance.…”

Optogenetic manipulation of individual or whole populationCaenorhabditis elegansworms with an under hundred-dollar tool: the OptoArm

“…At present, required intensity for optogenetic stimulation of D. melanogaster is nowadays a few orders of magnitudes smaller. Commonly used intensities range from 50 u W/mm 2 to 0.3 mW/mm 2 , although much higher intensities (<6.5 mW/mm2) are also used (Pulver et al, 2009; Dawydow et al, 2014; Meloni et al, 2020). To gain such small intensities with the OptoArm, one can use the systems intensity control, omit the use of lenses and/or increase the working-distance.…”

Red Light Optogenetics in Neuroscience

“…For example, optimization of the illumination to suit the specific optogenetic tool can be as effective; optimization of illumination has been done to match the kinetics of the red light-sensing anion opsin eNpHR3.0 (Zhang et al, 2019). A smartphone can work as well, as shown by Meloni et al (2020). Drosophila melanogaster larvae expressing Chrimson in their nociceptive neurons were placed on top of the smartphone screen on an agarose sheet.…”