We would like to thank Astha Maltare for generating the larval crawling data. We would like to thank Dr. Nicholas Lanson Jr. for giving his comments on the manuscript. This work was supported by the Robert Packard Center for ALS at Johns Hopkins (to UBP) and the Amyotrophic Lateral Sclerosis Association (UBP); and R01MH083689 from the National Institutes of Mental Health (CDN).

1. Larval Crawling Assay
1. Larvae Collection
<ol>
	<li>Set up an 8 ounce bottle of flies (10-15 males + 10-15 females).</li>
	<li>Let flies lay eggs for 24 hours, then clear bottle of flies. (Transfer the adults into a new bottle and repeat as necessary).</li>
	<li>Incubate bottle for 3-4 days, or until third instar larvae are visible.</li>
	<li>Add 50 - 100 ml of 20% sucrose to the bottle with larvae and let sit for 20 minutes. Larvae will float to the top.</li>
	<li>Collect larvae using a 25 ml serological pipette with the tip cut off, and place into a mesh basket.</li>
	<li>Wash larvae in the mesh basket two times with deionized H2O. Larvae are now ready for the experiments.</li>
</ol>
2. To treat larvae with drug
<ol>
	<li>Use a brush to transport the desired number of larvae to a 5 ml beaker containing a solution 5% sucrose + drug.</li>
	<li>Let larvae feed for at least 15 minutes.</li>
	<li>Pour drug-treated larvae into a mesh basket and rinse. They are now ready to use.</li>
</ol>
3. Locomotor Assay (measuring total distance travelled or body wall contractions)
<ol>
	<li>Use a brush to transport individual larva to a:
	<ol>
		<li>15 cm Petri dish containing 2% agarose (previously poured and allowed to harden) over graph paper with a 0.2 cm2 grid.
		<ol>
			<li>Count number of grid lines crossed in 1 minute.</li>
		</ol>
		</li>
		<li>Well of a glass dissection dish containing a dilute yeast paste solution.
		<ol>
			<li>Count peristalsis contractions (full anterior to posterior movement = 1 contraction) in one minute while observing under a dissection microscope.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Repeat until the desired numbers of larvae have been counted.</li>
</ol>
2. Rapid Iterative Negative Geotaxis (RING) Protocol
This assay was originally described by Gargano et al5.
<ol>
	<li>Collect newly emerged adult male flies under light CO2 anesthetization and place into a standard vial containing food (or food + drug).</li>
	<li>Maintain flies at room temperature (on the bench top. ~22 &deg;C) for 2-3 days to allow for recovery from CO2 (and accumulation of steady-state drug levels if appropriate).</li>
	<li>Transfer about 25 flies without anesthetizing to prepared polystyrene vials.</li>
	<li>Assemble vials with flies into the RING apparatus (Figure 1).</li>
	<li>Allow flies to acclimate to the environment, undisturbed, for 15-20 minutes.</li>
	<li>During this time place digital camera ~1 m in front of the apparatus (on a platform if necessary to align the center of the lens at mid-height of the vials), focus and zoom the camera onto the apparatus, and set a timer to 3.0 seconds.</li>
	<li>Carefully take hold of the RING apparatus with your left hand so as not to disturb the flies, and hold the timer with your right hand.</li>
	<li>Sharply tap the apparatus down on the surface of the bench three times, ensuring that the tap is hard enough to knock down all the flies to the bottom of the vials.</li>
	<li>Simultaneously with completion of the third tap, start the 3 second countdown timer.</li>
	<li>At three seconds take a picture.</li>
	<li>Reset the timer for 1 minute and start. During this time reset the camera and focus on the apparatus, and set another channel of the timer for three seconds.</li>
	<li>After 1 minute, repeat steps 1.7-1.10</li>
	<li>After a total of 5-6 trials, upload images onto a computer and use your favorite image viewer to open, and score the average height climbed for each vial.</li>
	<li>Perform statistical analysis on your different groups comparing the mean height climbed.</li>
</ol>
3. Courtship and Mating Assay
<ol>
	<li>First thing in the morning, clear well-producing bottles of flies to be used.</li>
	<li>Over the course of the day (every 3-4 hours), collect newly emerged sexually naive males and females:
	<ol>
		<li>Place males individually in vials or tubes with medium.</li>
		<li>Place 5-6 females together per vial/tube.</li>
		<li>Isolate collected flies at 25 &deg;C under 12 hr light/dark for 5 days.</li>
		<li>Transfer one female into the chamber of a mating wheel.</li>
		<li>Transfer one male into the chamber of a mating wheel.</li>
		<li>Observe pair under a dissection microscope for the following behaviors:
		<ol>
			<li>Orientation (the male orients towards the female)</li>
			<li>Tapping (the male taps the female)</li>
			<li>Wing song (the male extends and vibrates one wing)</li>
			<li>Licking (the male licks the female genitalia)</li>
			<li>Curling (the male curls its abdomen under itself)</li>
			<li>Copulation attempt (Curling activity while attempting to mount the female)</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Observe for 10 minutes or until successful copulation, noting the time at which each behavior occurs (latency), the total time engaged in courtship behavior until copulation (to calculate the courtship index), as well as the number of pairs that successfully perform a given behavior (frequency). 100% of wild type pairs will generally mate within 5 minutes.</li>
	<li>Calculate a courtship index (CI) by dividing the time spent in courtship divided by the total time until copulation. For wild type pairs this usually ranges between 0.6-0.8.</li>
</ol>
4. Representative Results
Crawling assay
Normal wild type larva will wander ~3 cm/minute, and exhibit ~40-50 body wall contractions in one minute. We have recently developed a Drosophila model of FUS/TLS-related amyotrophic lateral sclerosis that shows larval crawling defect, reduced life span and adult climbing impairment6. We targeted expression of wild type and mutant forms of FUS/TLS to the motor neurons (OK-371-gal4 driver) and performed a larval crawling assay. As shown below, wild type larvae crawl up to 12 cm, whereas expression of wild type FUS decreased the larval crawling ability to approximately 6 cm. Animals expressing the ALS-causing mutation R521C in FUS/TLS demonstrate a very severe impairment in their crawling movement (Figure 1), crawling only about 1 cm/minute.
Negative geotaxis RING assay
Young wild-type adult flies should have an average climbing height of ~4-5 cm in a 3-second time period (the time can be adjusted from 3 seconds to accommodate different strains or activity levels to define a given average height for a given strain/treatment). Flies that remain at the bottom are assigned a value of 0. It is not advised to use more than 25 flies per vial because it then becomes difficult to determine the location of each individual fly to measure height. No desensitization has been observed at up to the 6 consecutive trials spaced 1 minute apart that we have employed. It is critical NOT to reuse the polystyrene testing vials in this assay after the initial sets of data are gathered because new flies placed into used vials will not climb to the same extent as in fresh vials.
<img alt="Figure 1" src="/files/ftp_upload/3795/3795fig1.jpg" /> 
Figure 1. Setup for the RING Assay. The digital camera is placed ~1 m in front of the apparatus containing flies in the polystyrene vials; focus and zoom the camera onto the apparatus; and set a timer to 3.0 seconds.
<img alt="Figure 2" src="/files/ftp_upload/3795/3795fig2.jpg" />
Figure 2. Representative data from the larval crawling assay using flies ectopically expressing UAS-FUS WT, and UAS-FUS R521C under the control of a motor neuron driver (OK371-gal4).

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We have nothing to disclose.

Drosophila behavior is tightly regulated by genetic and environmental factors. We, and others, have previously used the assays described here to gather data to examine genes related to fly behaviors and to human neurodegenerative diseases modeled in Drosophila5-19. For the crawling assay, careful selection of 3rd instar larvae is a critical step. If treating with a drug, it will take 10-15 minutes (or more depending on the type and nature of the drug) to achieve maximal effect if i...

<table border="1">
 <tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 </tr>
 <tr>
 <td>Sucrose</td>
 <td>Fisher Scientific</td>
 <td>S5-500</td>
 </tr>
 <tr>
 <td>Agarose</td>
 <td>Invitrogen</td>
 <td>16500-500</td>
 </tr>
 <tr>
 <td>6 oz Drosophila bottle</td>
 <td>Genesee Scientific</td>
 <td>32-130</td>
 </tr>
 <tr>
 <td>Paint Brush (#1)</td>
 <td>Ted Pella,Inc.</td>
 <td>11859 </td>
 </tr>
 <tr>
 <td>Fly food components</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Cornmeal</td>
 <td>Fisher Scientific</td>
 <td>NC9109741</td>
 </tr>
 <tr>
 <td>Agar</td>
 <td>Genesee Scientific</td>
 <td>66-104</td>
 </tr>
 <tr>
 <td>Molasses</td>
 <td>Fisher Scientific</td>
 <td>NC9349176</td>
 </tr>
 <tr>
 <td>Propionic acid</td>
 <td>Acros</td>
 <td>14930-0010</td>
 </tr>
 <tr>
 <td>Tegosept</td>
 <td>Apex</td>
 <td>20-258</td>
 </tr>
 <tr>
 <td>Ethanol</td>
 <td>Fisher Scientific</td>
 <td>BP2818-4</td>
 </tr>
 <tr>
 <td>Yeast</td>
 <td>Genesee Scientific</td>
 <td>62-107</td>
 </tr>
 </tbody>
</table>

methods to assay drosophila behavior

Drosophila melanogaster, the fruit fly, has been used to study molecular mechanisms of a wide range of human diseases such as cancer, cardiovascular disease and various neurological diseases1. We have optimized simple and robust behavioral assays for determining larval locomotion, adult climbing ability (RING assay), and courtship behaviors of Drosophila. These behavioral assays are widely applicable for studying the role of genetic and environmental factors on fly behavior. Larval crawling ability can be reliably used for determining early stage changes in the crawling abilities of Drosophila larvae and also for examining effect of drugs or human disease genes (in transgenic flies) on their locomotion. The larval crawling assay becomes more applicable if expression or abolition of a gene causes lethality in pupal or adult stages, as these flies do not survive to adulthood where they otherwise could be assessed. This basic assay can also be used in conjunction with bright light or stress to examine additional behavioral responses in Drosophila larvae. Courtship behavior has been widely used to investigate genetic basis of sexual behavior, and can also be used to examine activity and coordination, as well as learning and memory. Drosophila courtship behavior involves the exchange of various sensory stimuli including visual, auditory, and chemosensory signals between males and females that lead to a complex series of well characterized motor behaviors culminating in successful copulation. Traditional adult climbing assays (negative geotaxis) are tedious, labor intensive, and time consuming, with significant variation between different trials2-4. The rapid iterative negative geotaxis (RING) assay5 has many advantages over more widely employed protocols, providing a reproducible, sensitive, and high throughput approach to quantify adult locomotor and negative geotaxis behaviors. In the RING assay, several genotypes or drug treatments can be tested simultaneously using large number of animals, with the high-throughput approach making it more amenable for screening experiments.

Watch this Scientific Journal Video about Methods to Assay Drosophila Behavior at JoVE.com

Methods to Assay Drosophila Behavior

Drosophila melanogaster is a genetically and behaviorally tractable model system that has been used to understand the molecular and cellular basis of many important biological processes for over a century 1. Drosophila has been well exploited to gain insights into the genetic basis of fly behavior.

Methods to Assay Drosophila Behavior

Drosophila melanogaster, the fruit fly, has been used to study molecular mechanisms of a wide range of human diseases such as cancer, cardiovascular ...

Research

JoVE Journal

Neuroscience

42.7K vistas.  Louisiana State University Health Sciences Center. Drosophila melanogaster es un sistema de genética y de comportamiento modelo manejable que se ha utilizado para entender las bases moleculares y celulares de muchos procesos biológicos importantes para más de un siglo 1. Drosophila ha sido bien aprovechado para hacerse una idea de la base genética del comportamiento de las moscas.

Video: Methods to Assay Drosophila Behavior

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 ...

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.

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.

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

A Single-fly Assay for Foraging Behavior in Drosophila

For many animals, hunger promotes changes in the olfactory system in a manner that facilitates the search for appropriate food sources. In this video article, we describe an automated assay to measure the effect of hunger or satiety on olfactory dependent food search behavior in the adult fruit fly Drosophila melanogaster. In a light-tight box illuminated by red light that is invisible to fruit flies, a camera linked to custom data acquisition software monitors the position of six flies simultaneously. Each fly is confined to walk in individual arenas containing a food odor at the center. The testing arenas rest on a porous floor that functions to prevent odor accumulation. Latency to locate the odor source, a metric that reflects olfactory sensitivity under different physiological states, is determined by software analysis. Here, we discuss the critical mechanics of running this behavioral paradigm and cover specific issues regarding fly loading, odor contamination, assay temperature, data quality, and statistical analysis.

A Single-fly Assay for Foraging Behavior in Drosophila

In this video article, we describe an automated assay to measure the effect of hunger or satiety on olfactory dependent food search behavior in the adult fruit fly Drosophila melanogaster.

For many animals, hunger promotes changes in the olfactory system in a manner that facilitates the search for appropriate food sources. In this video ...

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex,&#160;including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed1. In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

The Drosophila larva is a powerful model system to study neural control of behavior. This publication describes the use of linear agarose channels to elicit sustained bouts of linear crawling and methods to quantify the dynamics of larval structures during repetitive crawling behavior.

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat ...

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

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.

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 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 ...

High-throughput Analysis of Locomotor Behavior in the Drosophila Island Assay

Advances in next-generation sequencing technologies contribute to the identification of (candidate) disease genes for movement disorders and other neurological diseases at an increasing speed. However, little is known about the molecular mechanisms that underlie these disorders. The genetic, molecular, and behavioral toolbox of Drosophila melanogaster makes this model organism particularly useful to characterize new disease genes and mechanisms in a high-throughput manner. Nevertheless, high-throughput screens require efficient and reliable assays that, ideally, are cost-effective and allow for the automatized quantification of traits relevant to these disorders. The island assay is a cost-effective and easily set-up method to evaluate Drosophila locomotor behavior. In this assay, flies are thrown onto a platform from a fixed height. This induces an innate motor response that enables the flies to escape from the platform within seconds. At present, quantitative analyses of filmed island assays are done manually, which is a laborious undertaking, particularly when performing large screens.
This manuscript describes the &#34;Drosophila Island Assay&#34; and &#34;Island Assay Analysis&#34; algorithms for&#160;high-throughput, automated data processing and quantification of island assay data. In the setup, a simple webcam connected to a laptop collects an image series of the platform while the assay is performed. The &#34;Drosophila Island Assay&#34; algorithm developed for the open-source software Fiji processes these image series and quantifies, for each experimental condition, the number of flies on the platform over time. The &#34;Island Assay Analysis&#34; script, compatible with the free software R, was developed to automatically process the obtained data and to calculate whether treatments/genotypes are statistically different. This greatly improves the efficiency of the island assay and makes it a powerful readout for basic locomotion and flight behavior. It can thus be applied to large screens investigating fly locomotor ability, Drosophila models of movement disorders, and drug efficacy.

High-throughput Analysis of Locomotor Behavior in the Drosophila Island Assay

The island assay is a relatively new, cost-effective assay that can be used to evaluate the basic locomotor behavior of Drosophila melanogaster. This manuscript describes algorithms for automatic data processing and objective quantification of island assay data, making this assay a sensitive, high-throughput readout for large genetic or pharmacological screens.

Advances in next-generation sequencing technologies contribute to the identification of (candidate) disease genes for movement disorders and other ...

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

The ability of insects to navigate toward odor sources is based on the activities of their first-order olfactory receptor neurons (ORNs). While a considerable amount of information has been generated regarding ORN responses to odorants, the role of specific ORNs in driving behavioral responses remains poorly understood. Complications in behavior analyses arise due to different volatilities of odorants that activate individual ORNs, multiple ORNs activated by single odorants, and the difficulty in replicating naturally observed temporal variations in olfactory stimuli using conventional odor-delivery methods in the laboratory. Here, we describe a protocol that analyzes Drosophila larval behavior in response to simultaneous optogenetic stimulation of its ORNs. The optogenetic technology used here allows for specificity of ORN activation and precise control of temporal patterns of ORN activation. Corresponding larval movement is tracked, digitally recorded, and analyzed using custom written software. By replacing odor stimuli with light stimuli, this method allows for a more precise control of individual ORN activation in order to study its impact on larval behavior. Our method could be further extended to study the impact of second-order projection neurons (PNs) as well as local neurons (LNs) on larval behavior. This method will thus enable a comprehensive dissection of olfactory circuit function and complement studies on how olfactory neuron activities translate in to behavior responses.

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 software.

The ability of insects to navigate toward odor sources is based on the activities of their first-order olfactory receptor neurons (ORNs). While a ...

In Vivo Optical Calcium Imaging of Learning-Induced Synaptic Plasticity in Drosophila melanogaster

Decades of research in many model organisms have led to the current concept of synaptic plasticity underlying learning and memory formation. Learning-induced changes in synaptic transmission are often distributed across many neurons and levels of processing in the brain. Therefore, methods to visualize learning-dependent synaptic plasticity across neurons are needed. The fruit fly Drosophila melanogaster represents a particularly favorable model organism to study neuronal circuits underlying learning. The protocol presented here demonstrates a way in which the processes underlying the formation of associative olfactory memories, i.e., synaptic activity and their changes, can be monitored in vivo. Using the broad array of genetic tools available in Drosophila, it is possible to specifically express genetically encoded calcium indicators in determined cell populations and even single cells. By fixing a fly in place, and opening the head capsule, it is possible to visualize calcium dynamics in these cells whilst delivering olfactory stimuli. Additionally, we demonstrate a set-up in which the fly can be subjected, simultaneously, to electric shocks to the body. This provides a system in which flies can undergo classical olfactory conditioning - whereby a previously na&#239;ve odor is learned to be associated with electric shock punishment - at the same time as the representation of this odor (and other untrained odors) is observed in the brain via two-photon microscopy. Our lab has previously reported the generation of synaptically localized calcium sensors, which enables one to confine the fluorescent calcium signals to pre- or postsynaptic compartments. Two-photon microscopy provides a way to spatially resolve fine structures. We exemplify this by focusing on neurons integrating information from the mushroom body, a higher-order center of the insect brain. Overall, this protocol provides a method to examine the synaptic connections between neurons whose activity is modulated as a result of olfactory learning.

In Vivo Optical Calcium Imaging of Learning-Induced Synaptic Plasticity in Drosophila melanogaster

Here we present a protocol with which pre- and/or postsynaptic calcium can be visualized in the context of Drosophila learning and memory. In vivo calcium imaging using synaptically localized calcium sensors is combined with a classical olfactory conditioning paradigm such that the synaptic plasticity underlying this type of associative learning may be determined.

Decades of research in many model organisms have led to the current concept of synaptic plasticity underlying learning and memory formation. ...

Mechanical Conflict-Avoidance Assay to Measure Pain Behavior in Mice

Pain comprises of both sensory (nociceptive) and affective (unpleasant) dimensions. In preclinical models, pain has traditionally been assessed using reflexive tests that allow inferences regarding pain's nociceptive component but provide little information about the affective or motivational component of pain. Developing tests that capture these components of pain are therefore translationally important. Hence, researchers need to use non-reflexive behavioral assays to study pain perception at that level. Mechanical conflict-avoidance (MCA) is an established voluntary non-reflexive behavior assay, for studying motivational responses to a noxious mechanical stimulus in a 3 chamber paradigm. A change in a mouse's location preference, when faced with competing noxious stimuli, is used to infer the perceived unpleasantness of bright light versus tactile stimulation of the paws. This protocol outlines a modified version of the MCA assay which pain researchers can use to understand affective-motivational responses in a variety of mouse pain models. Though not specifically described here, our example MCA data use the intraplantar complete Freund's adjuvant (CFA), spared nerve injury (SNI), and a fracture/casting model as pain models to illustrate the MCA procedure.

The mechanical conflict-avoidance assay is used as a non-reflexive readout of pain sensitivity in mice which can be used to better understand affective-motivational responses in a variety of mouse pain models.

Pain comprises of both sensory (nociceptive) and affective (unpleasant) dimensions. In preclinical models, pain has traditionally been assessed using ...