This work was funded by a Stanford Dean's Fellowship (SEJdV), a National Institutes of Health Director's Pioneer Award (TRC DP0035350), a McKnight Foundation Scholar's Award (TRC) and R01 EY022638 (TRC).

1. Generate Channelrhodopsin Flies
<ol>
 <li>Cross UAS-ChR2 flies with the Gal4 driver of your choosing, we use G105-Gal4, which is expressed in Foma-1 neurons in the optic lobe.</li>
 <li>To eliminate the possibility of a visual response to the blue light stimulation, both fly lines are in a w+norpA background.</li>
 <li>End result: w+norpA;G105-Gal4/UAS-ChR2 +</li>
 <li>After adult flies eclose, put selected females on fresh food, supplemented with 10 &mu;M all-trans-retinal (a co-factor require...

<ol>
	<li>Venken, K., Simpson, J., Bellen, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+manipulations+of+genes+and+cells+in+the+nervous+system+of+the+fruit+fly.">Genetic manipulations of genes and cells in the nervous system of the fruit fly.</a> Neuron. 72, 202-230 (2011).</li><li>Gordon, M., Scott, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Motor+control+in+a+Drosophila+taste+circuit.">Motor control in a Drosophila taste circuit.</a> Neuron. 61, 373-384 (2009).</li><li>Suh, G. S. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light+activation+of+an+innate+olfactory+avoidance+response+in+Drosophila.">Light activation of an innate olfactory avoidance response in Drosophila.</a> Current Biology. 17, 905-908 (2007).</li><li>Zhang, W., Ge, W., Wang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+toolbox+for+light+control+of+Drosophila+behaviors+through+Channelrhodopsin+2-mediated+photoactivation+of+targeted+neurons.">A toolbox for light control of Drosophila behaviors through Channelrhodopsin 2-mediated photoactivation of targeted neurons.</a> European Journal of Neuroscience. 26, 2405-2416 (2007).</li><li>Nagel, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Channelrhodopsin-2,+a+directly+light-gated+cation-selective+membrane+channel.">Channelrhodopsin-2, a directly light-gated cation-selective membrane channel.</a> Proceedings of the National Academy of Science. 100, 13940-13945 (2003).</li><li>de Vries, S., Clandinin, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loom-sensitive+neurons+link+computation+to+action+in+the+Drosophila+visual+system.">Loom-sensitive neurons link computation to action in the Drosophila visual system.</a> Current Biology. 22, 353-362 (2012).</li><li>Card, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Escape+behaviors+in+insects.">Escape behaviors in insects.</a> Current Opinion in Neurobiology. 22, 1-7 (2012).</li><li>Card, G., Dickinson, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visually+mediated+motor+planning+in+the+escape+response+of+Drosophila.">Visually mediated motor planning in the escape response of Drosophila.</a> Current Biology. 18, 1300-1307 (2008).</li><li>Fotowat, H., Fayyazuddin, A., Bellen, H. J., Gabbiani, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+neuronal+pathway+for+visually+guided+escape+in+Drosophila+melanogaster.">A novel neuronal pathway for visually guided escape in Drosophila melanogaster.</a> Journal of Neurophysiology. 102, 875-885 (2009).</li><li>Card, G., Dickinson, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+trade-offs+in+the+flight+initiation+of+Drosophila+melanogaster.">Performance trade-offs in the flight initiation of Drosophila melanogaster.</a> The Journal of Experimental Biology. 211, 341-353 (2008).</li><li>Hammond, S., O'Shea, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Escape+flight+initiation+in+the+fly.">Escape flight initiation in the fly.</a> Journal of Comparative Phsyiology A. 193, 471-476 (2007).</li><li>Benzer, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+mutants+of+Drosophila+isolated+by+countercurrent+distribution.">Behavioral mutants of Drosophila isolated by countercurrent distribution.</a> PNAS. 58, 1112-1119 (1967).</li><li>Bloomquist, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+a+putative+phospholipase+C+gene+of+Drosophila,+norpA,+and+its+role+in+phototransduction.">Isolation of a putative phospholipase C gene of Drosophila, norpA, and its role in phototransduction.</a> Cell. 54, 723-733 (1988).</li><li>Gohl, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+versatile+in+vivo+system+for+directed+dissection+of+gene+expression+patterns.">A versatile in vivo system for directed dissection of gene expression patterns.</a> Nature Methods. 8, 231-237 (2011).</li><li>Zhang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Red-shifted+optogenetic+excitation:+a+tool+for+fast+neural+control+derived+from+Volvox+cateri.">Red-shifted optogenetic excitation: a tool for fast neural control derived from Volvox cateri.</a> Nature Neuroscience. 11, 631-633 (2008).</li></ol>

We have demonstrated optogenetic stimulation of escape behaviors by bathing freely walking flies in bright blue light. This approach can be easily adapted to examine other behaviors in freely walking flies, and can be scaled to larger platforms by simply tiling the LED arrays we used over a larger area. Using either the inexpensive camera we describe, or other available camera systems, the user can tailor the frame rate and spatial resolution of the images acquired to suit the behavior of interest. Additionally, o...

A growing arsenal of genetically encoded tools have been developed to manipulate neural activity in specific cells in Drosophila melanogaster1. These tools enable the noninvasive activation or silencing of specific neurons in the intact and freely moving animal. Among these, Channelrhodopsin2 (ChR2), a light-activated cation channel, offers key advantages, since it can be temporally controlled and quickly induced. When neurons that express ChR2 are exposed to bright blue (470 nm) light they rapidly depolarize and exhibit elevated firing rates3-5. Such targeted activation of specific neurons in freely moving animals has revealed the sufficiency of particular neurons for behaviors such as CO2 avoidance3, proboscis extension2,4, and giant-fiber mediated startle responses4. However, as the intense light sources necessary to stimulate ChR2 also stimulate photoreceptors, applying optogenetic techniques to the visual system has been limited. By combining an optogenetic approach with a mutation that impairs phototransduction, we have demonstrated that activation of a specific cluster of neurons in the fly's optic lobe can drive the escape behavior used to avoid collision6.
	Most, if not all, visual animals exhibit an escape behavior to avoid collisions with oncoming objects. Walking or stationary flies, when presented with a looming collision, take-off into flight, away from the oncoming collision7-9. These take-offs are characterized by raised wings prior to take-off and an unstable flight trajectory10,11. This response is distinct from the giant-fiber mediated startle response, jumps that are not preceded by raised wings, and usually result in a free-falling tumble4,9 . Having identified a specific cluster of loom sensitive neurons in the optic lobe, Foma-1 neurons, that are uniquely tuned to encode approaching objects, we sought to probe their involvement in the fly's loom escape behavior. Here we demonstrate the use of optogenetics to selectively activate these neurons and elicit the fly's escape behavior.
	We use the Gal4-UAS transcriptional activator system to drive the expression of ChR2 in the Foma-1 neurons. ChR2 requires the cofactor all-trans-retinal and as this is found in low levels in the Drosophila central nervous system it must be supplemented in the flies' diet.3,4 As bright light is used to activate ChR2 and flies exhibit strong phototactic behaviors12, we sought to eliminate the possibility of a visual response to the stimulus. To do this, we used animals that were homozygous mutant for a null allele of the norpA gene, which encodes a critical component of the phototransduction cascade, phospholipase C-&beta;. Photoreceptors in such mutant flies are unable to respond to light13. To test the optogenetic stimulation of the escape response, we need to isolate a single fly and bathe it in bright blue light. To do this, we place individual flies in pipet tips. One pipet tip is placed in a custom holder, such that the fly will geotactically walk up the tip and out onto a rectangular platform. The fly is able to freely walk around on the top of this platform. The platform is surrounded by four blue LED arrays, each containing 3 LEDs, focused on the top of the platform. After the fly is on the platform, the LEDs are illuminated, and the fly's response is recorded using a high-speed camera6.

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optogenetic stimulation of escape behavior in drosophila melanogaster

A growing number of genetically encoded tools are becoming available that allow non-invasive manipulation of the neural activity of specific neurons in Drosophila melanogaster1. Chief among these are optogenetic tools, which enable the activation or silencing of specific neurons in the intact and freely moving animal using bright light. Channelrhodopsin (ChR2) is a light-activated cation channel that, when activated by blue light, causes depolarization of neurons that express it. ChR2 has been effective for identifying neurons critical for specific behaviors, such as CO2 avoidance, proboscis extension and giant-fiber mediated startle response2-4. However, as the intense light sources used to stimulate ChR2 also stimulate photoreceptors, these optogenetic techniques have not previously been used in the visual system. Here, we combine an optogenetic approach with a mutation that impairs phototransduction to demonstrate that activation of a cluster of loom-sensitive neurons in the fly's optic lobe, Foma-1 neurons, can drive an escape behavior used to avoid collision. We used a null allele of a critical component of the phototransduction cascade, phospholipase C-&beta;, encoded by the norpA gene, to render the flies blind and also use the Gal4-UAS transcriptional activator system to drive expression of ChR2 in the Foma-1 neurons. Individual flies are placed on a small platform surrounded by blue LEDs. When the LEDs are illuminated, the flies quickly take-off into flight, in a manner similar to visually driven loom-escape behavior. We believe that this technique can be easily adapted to examine other behaviors in freely moving flies.

Blind flies expressing either ChR2 or the G105 driver alone show a low rate of take-off following their illumination with bright blue light. Blind flies exhibited the same rate of take-off regardless of illumination (Figure 2), suggesting that these take-offs were spontaneous rather than due to the illumination with blue light. When the ChR2 is expressed in the Foma1 neurons, however, illumination with blue light elicits the escape response. Over 50% of the flies tested took off within 1 sec of illuminat...

Watch this Scientific Journal Video about Optogenetic Stimulation of Escape Behavior in Drosophila melanogaster at JoVE.com

Optogenetic Stimulation of Escape Behavior in Drosophila melanogaster

Genetically encoded optogenetic tools enable noninvasive manipulation of specific neurons in the Drosophila brain. Such tools can identify neurons whose activation is sufficient to elicit or suppress particular behaviors. Here we present a method for activating Channelrhodopsin2 that is expressed in targeted neurons in freely walking flies.

Optogenetic Stimulation of Escape Behavior in Drosophila melanogaster

A  growing number of genetically encoded tools are becoming available that allow non-invasive  manipulation of the neural activity of specific neurons in ...

optogenetic-stimulation-of-escape-behavior-in-drosophila-melanogaster

Research

JoVE Journal

Neuroscience

17.2K ビュー.  Stanford University. 遺伝的にコードされoptogeneticツール内の特定の神経細胞の非侵襲的な操作を可能にショウジョウバエ脳。このようなツールは、そのアクティベーション、特定の行動を誘発または抑制するのに十分である神経細胞を識別することができます。ここでは、自由に歩いてハエの標的ニューロンに発現しているChannelrhodopsin2を活性化するための方法を?...

ビデオ: Optogenetic Stimulation of Escape Behavior in Drosophila melanogaster

Genetically encoded optogenetic tools enable noninvasive manipulation of specific neurons in the Drosophila brain. Such tools can identify neurons whose activation is sufficient to elicit or suppress particular behaviors. Here we present a method for activating Channelrhodopsin2 that is expressed in targeted neurons in freely walking...

an improved method for accurate and rapid measurement of flight performance in drosophila

An Improved Method for Accurate and Rapid Measurement of Flight Performance in Drosophila

Here we describe a method for rapid and accurate measurement of flight performance in Drosophila, enabling high-throughput...

An Improved Method for Accurate and Rapid Measurement of Flight Performance in Drosophila

drosophila optogenetics: a method to manipulate neuronal circuits

Optogenetics enables the use of light to manipulate neurons that are genetically engineered to express specific opsins&#8211;light-sensitive proteins whose light activation triggers a change in the state of the neuron. Here we describe an optogenetic approach in Drosophila using the opsin Channelrhodopsin2. The example protocol features an optogenetics assay set to study the neuronal circuitry behind the fly&#39;s escape...

Drosophila Optogenetics: A Method to Manipulate Neuronal Circuits

tracking drosophila larval behavior in response to optogenetic stimulation of olfactory neurons

Tracking Drosophila Larval Behavior in Response to Optogenetic Stimulation of Olfactory Neurons

This protocol analyzes navigational behavior of Drosophila larva in response to simultaneous optogenetic stimulation of its olfactory neurons. Light of 630 nm wavelength is used to activate individual olfactory neurons expressing a red-shifted channel rhodopsin. Larval movement is simultaneously tracked, digitally recorded, and analyzed using custom-written...

Tracking Drosophila Larval Behavior in Response to Optogenetic Stimulation of Olfactory Neurons

navigational behavior of drosophila larvae in response to optogenetic stimulation of olfactory sensory neurons

Allow the agarose to solidify and cool for 1 to 2 hours in the Petri dishes, before using them in the behavior assay. After the agarose has solidified, transfer no more than 20 of the prepped third-instar larvae to the center of the Petri dish and cover the Petri dish with its...

Navigational Behavior of Drosophila Larvae in Response to Optogenetic Stimulation of Olfactory Sensory Neurons

This video demonstrates a study of the navigational behavior of Drosophila larvae in response to optogenetic stimulation of olfactory sensory neurons (ORNs). Transgenic Drosophila larvae expressing light-sensitive ion channels in the ORNs are placed on agarose within a behavior arena. Optogenetic stimulation with light opens the channels, causing a cation influx that triggers the transmission of the signal to the brain, and the navigation behavior is...

developing drosophila melanogaster models for imaging and optogenetic control of cardiac function

Developing Drosophila melanogaster Models for Imaging and Optogenetic Control of Cardiac Function

The present protocol describes the generation of Drosophila melanogaster expressing eNpHR2.0 or ReaChR opsins in the heart for OCT imaging and optogenetic heart pacing. Detailed instructions for Drosophila OCT imaging and heart beating modulation, including the simulation of restorable heart arrest, bradycardia, and tachycardia in live animals at different developmental stages, are...

Developing Drosophila melanogaster Models for Imaging and Optogenetic Control of Cardiac Function

optogenetic inhibition of rho1-mediated actomyosin contractility coupled with measurement of epithelial tension in drosophila embryos

Author Spotlight: Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility Coupled with Measurement of Epithelial Tension in Drosophila Embryos  

Actomyosin contractility plays an important role in cell and tissue morphogenesis. However, it is challenging to manipulate actomyosin contractility in vivo acutely. This protocol describes an optogenetic system that rapidly inhibits Rho1-mediated actomyosin contractility in Drosophila embryos, revealing the immediate loss of epithelial tension after the inactivation of actomyosin in...

Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility in &lt;em&gt;Drosophila&lt;/em&gt;

optogenetic stimulation, laser ablation, and imaging of drosophila embryos

Optogenetic Stimulation, Laser Ablation, and Imaging of Drosophila Embryos  

Optogenetic Stimulation, Laser Ablation, and Imaging of Drosophila Embryos

high-resolution quantification of odor-guided behavior in drosophila melanogaster using the flywalk paradigm

High-resolution Quantification of Odor-guided Behavior in Drosophila melanogaster Using the Flywalk Paradigm

The automated tracking system Flywalk is used for high-resolution quantification of odor-guided behavior in Drosophila...

High-resolution Quantification of Odor-guided Behavior in Drosophila melanogaster Using the Flywalk Paradigm

in vivo wireless optogenetic control of skilled motor behavior

In Vivo Wireless Optogenetic Control of Skilled Motor Behavior

The present protocol describes how to use wireless optogenetics combined with high-speed videography in a single pellet reach-to-grasp task to characterize the neural circuits involved in the performance of skilled motor behavior in freely moving mice.

In Vivo Wireless Optogenetic Control of Skilled Motor Behavior

collection of drosophila embryos and preparing them for optogenetic stimulation

Collection of Drosophila Embryos and Preparing Them for Optogenetic Stimulation  

Collection of Drosophila Embryos and Preparing Them for Optogenetic Stimulation

simultaneous recording of calcium signals from identified neurons and feeding behavior of drosophila melanogaster

Simultaneous Recording of Calcium Signals from Identified Neurons and Feeding Behavior of Drosophila melanogaster

The fruit fly, Drosophila melanogaster, extends its proboscis for feeding, responding to a sugar stimulus from its proboscis or tarsus.  I have combined observations of the proboscis extension response (PER) with a calcium imaging technique, allowing us to monitor the activity of neurons in the brain, simultaneously with behavioral...

Simultaneous Recording of Calcium Signals from Identified Neurons and Feeding Behavior of Drosophila melanogaster

a method to test the effect of environmental cues on mating behavior in drosophila melanogaster

A Method to Test the Effect of Environmental Cues on Mating Behavior in Drosophila melanogaster

We demonstrate an assay to analyze the environmental and genetic cues that influence mating behavior in the fruit fly Drosophila...

A Method to Test the Effect of Environmental Cues on Mating Behavior in Drosophila melanogaster

in vivo optogenetic stimulation of the rodent central nervous system

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

Optogenetics has become a powerful tool for use in behavioral neuroscience experiments. This protocol offers a step-by-step guide to the design and set-up of laser systems, and provides a full protocol for carrying out multiple and simultaneous in vivo optogenetic stimulations compatible with most rodent behavioral testing...

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

optogenetic stimulation of the auditory nerve

Optogenetic Stimulation of the Auditory Nerve

Cochlear implants (CIs) enable hearing by direct electrical stimulation of the auditory nerve. However, poor frequency and intensity resolution limits the quality of hearing with CIs. Here we describe optogenetic stimulation of the auditory nerve in mice as an alternative strategy for auditory research and developing future CIs.

a simple way to measure alterations in reward-seeking behavior using drosophila melanogaster

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

We describe a protocol for inducing rewarding and nonrewarding experiences in fruit flies (Drosophila melanogaster) using voluntary ethanol consumption as a measure for changes in reward...

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

optogenetic manipulation of neuronal activity to modulate behavior in freely moving mice

Optogenetic Manipulation of Neuronal Activity to Modulate Behavior in Freely Moving Mice

With optogenetic manipulation of specific neuronal populations or brain regions, behavior can be modified with high temporal and spatial resolution in freely moving animals. By using different optogenetic tools in combination with chronically implanted optical fibers, a variety of neuronal modulations and behavioral testing can be...

preparing adult drosophila melanogaster for whole brain imaging during behavior and stimuli responses

Preparing Adult Drosophila melanogaster for Whole Brain Imaging during Behavior and Stimuli Responses

We present a method specifically tailored to image the whole brain of adult Drosophila during behavior and in response to stimuli. The head is positioned to allow optical access to the whole brain, while the fly can move its legs and the antennae, the tip of the proboscis, and the eyes can receive sensory...

Preparing Adult Drosophila melanogaster for Whole Brain Imaging during Behavior and Stimuli Responses

Single Sensillum Recordings in the Insects Drosophila melanogaster and Anopheles gambiae

The sense of smell is essential for insects to find foods, mates, predators, and oviposition sites3. Insect olfactory sensory neurons (OSNs) are enclosed in sensory hairs called sensilla, which cover the surface of olfactory organs. The surface of each sensillum is covered with tiny pores, through which odorants pass and dissolve in a fluid called sensillum lymph, which bathes the sensory dendrites of the OSNs housed in a given sensillum. The OSN dendrites express odorant receptor (OR) proteins, which in insects function as odor-gated ion channels4, 5. The interaction of odorants with ORs either increases or decreases the basal firing rate of the OSN. This neuronal activity in the form of action potentials embodies the first representation of the quality, intensity, and temporal characteristics of the odorant6, 7.
Given the easy access to these sensory hairs, it is possible to perform extracellular recordings from single OSNs by introducing a recording electrode into the sensillum lymph, while the reference electrode is placed in the lymph of the eye or body of the insect. In Drosophila, sensilla house between one and four OSNs, but each OSN typically displays a characteristic spike amplitude. Spike sorting techniques make it possible to assign spiking responses to individual OSNs. This single sensillum recording (SSR) technique monitors the difference in potential between the sensillum lymph and the reference electrode as electrical spikes that are generated by the receptor activity on OSNs1, 2, 8. Changes in the number of spikes in response to the odorant represent the cellular basis of odor coding in insects. Here, we describe the preparation method currently used in our lab to perform SSR on Drosophila melanogaster and Anopheles gambiae, and show representative traces induced by the odorants in a sensillum-specific manner.

Single Sensillum Recordings in the Insects Drosophila melanogaster and Anopheles gambiae

Electrophysiological responses of olfactory sensory neurons to odorants can be measured in insects using single sensillum recordings. In this video article we will demonstrate how to perform single sensillum recordings in the antennae of the vinegar fly (Drosophila melanogaster) and the maxillary palps of the malaria mosquito (Anopheles gambiae).

The sense of smell is essential for insects to find foods, mates, predators, and oviposition sites3. Insect olfactory sensory neurons (OSNs) are enclosed ...

To study neuronal networks in terms of their function in behavior, we must analyze how neurons operate when each behavioral pattern is generated. Thus, simultaneous recordings of neuronal activity and behavior are essential to correlate brain activity to behavior. For such behavioral analyses, the fruit fly, Drosophila melanogaster, allows us to incorporate genetically encoded calcium indicators such as GCaMP1, to monitor neuronal activity, and to use sophisticated genetic manipulations for optogenetic or thermogenetic techniques to specifically activate identified neurons2-5. Use of a thermogenetic technique has led us to find critical neurons for feeding behavior (Flood et al., under revision). As a main part of feeding behavior, a Drosophila adult extends its proboscis for feeding6 (proboscis extension response; PER), responding to a sweet stimulus from sensory cells on its proboscis or tarsi. Combining the protocol for PER7 with a calcium imaging technique8 using GCaMP3.01, 9, I have established an experimental system, where we can monitor activity of neurons in the feeding center &#x2013; the suboesophageal ganglion (SOG), simultaneously with behavioral observation of the proboscis. I have designed an apparatus ("Fly brain Live Imaging and Electrophysiology Stage": "FLIES") to accommodate a Drosophila adult, allowing its proboscis to freely move while its brain is exposed to the bath for Ca2+ imaging through a water immersion lens. The FLIES is also appropriate for many types of live experiments on fly brains such as electrophysiological recording or time lapse imaging of synaptic morphology. Because the results from live imaging can be directly correlated with the simultaneous PER behavior, this methodology can provide an excellent experimental system to study information processing of neuronal networks, and how this cellular activity is coupled to plastic processes and memory.

The fruit fly, Drosophila melanogaster, extends its proboscis for feeding, responding to a sugar stimulus from its proboscis or tarsus. I have combined observations of the proboscis extension response (PER) with a calcium imaging technique, allowing us to monitor the activity of neurons in the brain, simultaneously with behavioral observation.

To study neuronal networks in terms of their function in behavior, we must analyze how neurons operate when each behavioral pattern is generated.  Thus, ...

Determination of the Spontaneous Locomotor Activity in Drosophila melanogaster

Drosophila melanogaster has been used as an excellent model organism to study environmental and genetic manipulations that affect behavior. One such behavior is spontaneous locomotor activity. Here we describe our protocol that utilizes Drosophila population monitors and a tracking system that allows continuous monitoring of the spontaneous locomotor activity of flies for several days at a time. This method is simple, reliable, and objective and can be used to examine the effects of aging, sex, changes in caloric content of food, addition of drugs, or genetic manipulations that mimic human diseases.

Determination of the Spontaneous Locomotor Activity in Drosophila melanogaster

Drosophila melanogaster are useful in studying genetic or environmental manipulations that affect behaviors such as spontaneous locomotor activity.&#160; Here we describe a protocol that utilizes monitors with infrared beams and data analysis software to quantify spontaneous locomotor activity.&#160;

Drosophila melanogaster has been used as an excellent model organism to study environmental and genetic manipulations that affect behavior. One such ...

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing.

Optogenetics has become a powerful tool for use in behavioral neuroscience experiments. This protocol offers a step-by-step guide to the design and set-up of laser systems, and provides a full protocol for carrying out multiple and simultaneous in vivo optogenetic stimulations compatible with most rodent behavioral testing paradigms.

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution ...

Straightforward Assay for Quantification of Social Avoidance in Drosophila melanogaster

Drosophila melanogaster is an emerging model to study different aspects of social interactions. For example, flies avoid areas previously occupied by stressed conspecifics due to an odorant released during stress known as the Drosophila stress odorant (dSO). Through the use of the T-maze apparatus, one can quantify the avoidance of the dSO by responder flies in a very affordable and robust assay. Conditions necessary to obtain a strong performance are presented here. A stressful experience is necessary for the flies to emit dSO, as well as enough emitter flies to cause a robust avoidance response to the presence of dSO. Genetic background, but not their group size, strongly altered the avoidance of the dSO by the responder flies. Canton-S and Elwood display a higher performance in avoiding the dSO than Oregon and Samarkand strains. This behavioral assay will allow identification of mechanisms underlying this social behavior, and the assessment of the influence of genes and environmental conditions on both emission and avoidance of the dSO. Such an assay can be included in batteries of simple diagnostic tests used to identify social deficiencies of mutants or environmental conditions of interest.

Straightforward Assay for Quantification of Social Avoidance in Drosophila melanogaster

Here, we present a protocol to quantify the avoidance of stressed individuals. This paradigm is powerful yet user-friendly and can be used to assess the influence of genes and environment on one kind of social interaction in Drosophila melanogaster.

Drosophila melanogaster is an emerging model to study different aspects of social interactions. For example, flies avoid areas previously occupied by ...

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted deaf subjects1-6. Nonetheless, sound coding with current CIs has poor frequency and intensity resolution due to broad current spread from each electrode contact activating a large number of SGNs along the tonotopic axis of the cochlea7-9. Optical stimulation is proposed as an alternative to electrical stimulation that promises spatially more confined activation of SGNs and, hence, higher frequency resolution of coding. In recent years, direct infrared illumination of&#160;the cochlea has been used to evoke responses in the auditory nerve10. Nevertheless it requires higher energies than electrical stimulation10,11 and uncertainty remains as to the underlying mechanism12. Here we describe a method based on optogenetics to stimulate SGNs with low intensity blue light, using transgenic mice with neuronal expression of channelrhodopsin 2 (ChR2)13 or virus-mediated expression of the ChR2-variant CatCh14. We used micro-light emitting diodes (&#181;LEDs) and fiber-coupled lasers to stimulate ChR2-expressing SGNs through a small artificial opening (cochleostomy) or the round window. We assayed the responses by scalp recordings of light-evoked potentials (optogenetic auditory brainstem response: oABR) or by microelectrode recordings from the auditory pathway and compared them with acoustic and electrical stimulation.

Cochlear implants (CIs) enable hearing by direct electrical stimulation of the auditory nerve. However, poor frequency and intensity resolution limits the quality of hearing with CIs. Here we describe optogenetic stimulation of the auditory nerve in mice as an alternative strategy for auditory research and developing future CIs.

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted ...

Conditions Affecting Social Space in Drosophila melanogaster

The social space assay described here can be used to quantify social interactions of Drosophila melanogaster &#8212; or other small insects &#8212; in a straightforward manner. As we previously demonstrated 1, in a two-dimensional chamber, we first force the flies to form a tight group, subsequently allowing them to take their preferred distance from each other. After the flies have settled, we measure the distance to the closest neighbor (or social space), processing a static picture with free online software (ImageJ). The analysis of the distance to the closest neighbor allows researchers to determine the effects of genetic and environmental factors on social interaction, while controlling for potential confounding factors. Diverse factors such as climbing ability, time of day, sex, and number of flies, can modify social spacing of flies. We thus propose a series of experimental controls to mitigate these confounding effects. This assay can be used for at least two purposes. First, researchers can determine how their favorite environmental shift (such as isolation, temperature, stress or toxins) will impact social spacing 1,2. Second, researchers can dissect the genetic and neural underpinnings of this basic form of social behavior 1,3. Specifically, we used it as a diagnostic tool to study the role of orthologous genes thought to be involved in social behavior in other organisms, such as candidate genes for autism in humans 4.

Conditions Affecting Social Space in Drosophila melanogaster

The effect of genes and environment on social space of Drosophila melanogaster can be quantified through a powerful but straightforward analytical paradigm. We show here different factors that can affect this social space, and thus need to be taken into consideration when designing experiments in this paradigm.

The social space assay described here can be used to quantify social interactions of Drosophila melanogaster &#8212; or other small insects &#8212; in a ...

In their natural environment, insects such as the vinegar fly Drosophila melanogaster are bombarded with a huge amount of chemically distinct odorants. To complicate matters even further, the odors detected by the insect nervous system usually are not single compounds but mixtures whose composition and concentration ratios vary. This leads to an almost infinite amount of different olfactory stimuli which have to be evaluated by the nervous system.
To understand which aspects of an odor stimulus determine its evaluation by the fly, it is therefore desirable to efficiently examine odor-guided behavior towards many odorants and odor mixtures. To directly correlate behavior to neuronal activity, behavior should be quantified in a comparable time frame and under identical stimulus conditions as in neurophysiological experiments. However, many currently used olfactory bioassays in Drosophila neuroethology are rather specialized either towards efficiency or towards resolution.
Flywalk, an automated odor delivery and tracking system, bridges the gap between efficiency and resolution. It allows the determination of exactly when an odor packet stimulated a freely walking fly, and to determine the animal&#180;s dynamic behavioral reaction.

The automated tracking system Flywalk is used for high-resolution quantification of odor-guided behavior in Drosophila melanogaster.

In their natural environment, insects such as the vinegar fly Drosophila melanogaster are bombarded with a huge amount of chemically distinct odorants. To ...

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We demonstrate a simple way to tap into the fly reward system, modify experiences related to natural reward, and use voluntary ethanol consumption as a measure for changes in reward states. The approach serves as a relevant tool to study the neurons and genes that play a role in experience-mediated changes of internal state. The protocol is composed of two discrete parts: exposing the flies to rewarding and nonrewarding experiences, and assaying voluntary ethanol consumption as a measure of the motivation to obtain a drug reward. The two parts can be used independently to induce the modulation of experience as an initial step for further downstream assays or as an independent two-choice feeding assay, respectively. The protocol does not require a complicated setup and can therefore be applied in any laboratory with basic fly culture tools.

We describe a protocol for inducing rewarding and nonrewarding experiences in fruit flies (Drosophila melanogaster) using voluntary ethanol consumption as a measure for changes in reward states.

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We ...

Quantification of Drosophila Grooming Behavior

Drosophila grooming behavior is a complex multi-step locomotor program that requires coordinated movement of both forelegs and hindlegs. Here we present a grooming assay protocol and novel chamber design that is cost-efficient and scalable for either small or large-scale studies of Drosophila grooming. Flies are dusted all over their body with Brilliant Yellow dye and given time to remove the dye from their bodies within the chamber. Flies are then deposited in a set volume of ethanol to solubilize the dye. The relative spectral absorbance of dye-ethanol samples for groomed versus ungroomed animals are measured and recorded. The protocol yields quantitative data of dye accumulation for individual flies, which can be easily averaged and compared across samples. This allows experimental designs to easily evaluate grooming ability for mutant animal studies or circuit manipulations. This efficient procedure is both versatile and scalable. We show work-flow of the protocol and comparative data between WT animals and mutant animals for the Drosophila type I Dopamine Receptor (DopR).

This protocol describes a scalable individual grooming assay technique in Drosophila that yields robust, quantitative data to measure grooming behavior. The method is based on comparing the difference in dye accumulation on the bodies of un-groomed versus groomed animals over a set period of time.

Drosophila grooming behavior is a complex multi-step locomotor program that requires coordinated movement of both forelegs and hindlegs. Here we present a ...