Quantifying Drosophila melanogaster Feeding Behavior Using flyPAD and optoPAD
Quantifying feeding behavior with high temporal and spatial precision is critical for understanding how internal state, sensory cues, and neural activity shape food intake and dietary choice. Here, we describe a detailed protocol for performing consumption and dietary choice assays in Drosophila melanogaster using the flyPAD/optoPAD system. This method enables simultaneous measurement of feeding events across multiple arenas while allowing precise control of sensory and optogenetic stimulation. We provide step-by-step instructions for assay food preparation, flyPAD arena setup, data acquisition, and downstream data organization with suggested analyses. This approach is suitable for studying nutrient preference, learning, and state-dependent modulation of feeding behavior, and can be readily adapted for optogenetic manipulations and comparative choice assays.
### Competing Interest Statement
The authors have declared no competing interest.
National Institute of General Medical Sciences, R35GM147504
π° "Neural circuits regulating social dominance implement a strategy predicted by evolutionary game theory"
https://www.biorxiv.org/content/10.64898/2026.02.20.706896v1?rss=1 #InternalState #DrosophilaNeural circuits regulating social dominance implement a strategy predicted by evolutionary game theory
Social conflict is a fundamental challenge for all animals and determines access to critical resources like mates and food. Evolutionary game theory predicts that natural selection should yield competitive strategies that balance the benefits and costs of social conflict. However, whether such strategies are embedded within the neural circuits that regulate aggression remains unclear. Here, we identify a neural circuit regulating the decision to flee during fighting in male Drosophila and show that the onset of defeat is governed by a probabilistic strategy predicted by evolutionary game theory. This mechanism arises from the inhibition of Tk-GAL4FruM neurons that promote aggressive arousal in males. Inhibition is mediated by a mushroom body circuit involving PPL1 dopaminergic neurons and V2 mushroom body output neurons, both classically associated with aversive learning. Silencing this circuit disrupts the onset of defeat, while activating it induces rapid defeat. Conversely, activation of reward-encoding PAM dopaminergic neurons promotes winning, revealing a dual role for dopamine in shaping contest dynamics. Finally, we find that internal state variables such as hunger and motivation shift the defeat onset probability distribution, consistent with game theory predictions of how payoff modulates fighting persistence. Together, our results provide direct evidence that evolutionary strategies based on payoff, long described by game theory, are implemented as circuit-level computations that regulate aggression.
### Competing Interest Statement
The authors have declared no competing interest.
National Institute of General Medical Sciences
Salk Institute for Biological Studies, Pioneer Fund Postdoctoral Scholar Award
Kavli Institute for Brain and Mind, KIBM Postdoctoral Award
Frontiers | Sleep regulation in Drosophila: a review of neural circuits and genetics
Sleep in Drosophila melanogaster is regulated by a complex and distributed network of neural circuits that are influenced by factors such as internal state, ...
A state-dependent neural circuit resolves approach-avoidance conflicts
To survive, animals must balance opportunity and risk, yet how internal motivational state biases this trade-off remains poorly understood. Here we show that hunger gates nociceptive avoidance in Drosophila to enable food approach under conflict. Using a behavioural assay in which flies must cross an electric shock barrier to reach food, we find that starvation promotes shock tolerance only when food-related olfactory cues are present. This state- and context-dependent behavioural shift is mediated by a defined neuromodulatory circuit. Leucokinin neurons encode hunger and convey this information to PV5K1 lateral horn output neurons, which integrate internal state signals with food odour cues and suppress shock-responsive FB2B neurons in the ventral fan-shaped body. Accordingly, electric shock-evoked activity in FB2B neurons is suppressed in starved flies exposed to food cues. These findings identify a circuit mechanism by which motivational state gates aversive processing to bias action selection towards goal-directed behaviour.
### Competing Interest Statement
The authors have declared no competing interest.
BBSRC to C.R, BB/W016249/1, BB/S009299/1
The Leverhulme Trut to C.R, RPG-2023-009
DFG under GermanyΒs Excellence Strategy to L.S, EXC-2049, 390688087
Emmy Noether Programme to L/S, 495407463
MIBTP BBSRC to M.B, BB/T00746X/1
Hunger Recruits a Parallel Circuit Encoding Alcohol Reward
Internal states like hunger, pain, thirst and arousal can bias behavior by affecting sensory and memory processing. Internal states are critical to understand in the context of alcohol addiction because they influence cravings, reinstatement, and relapse. Norepinephrine plays a key role in both hunger and alcohol-induced arousal and preference, but the circuit-level mechanisms through which it modulates the influence of hunger on alcohol preference are not well understood. We sought to address this using intersectional genetic tools for manipulating neurons expressing octopamine, the invertebrate analogue of vertebrate norepinephrine. We identified a single octopamine neuron required for ethanol seeking only when Drosophila are food-deprived. Hunger increased baseline activity in this neuron, making it more responsive to an odor cue previously paired with ethanol. A combination of genetic and connectome analyses revealed that synaptic partners of this octopaminergic neuron form a functional module that acts on Drosophila memory circuitry. Thus, we show that hunger recruits a parallel circuit that drives learned ethanol preference, providing a neuronal framework through which internal state influences the expression of memory for ethanol-associated cues.
### Competing Interest Statement
The authors have declared no competing interest.
National Institute on Alcohol Abuse and Alcoholism, R01AA024434
National Institute of Neurological Disorders and Stroke, F99NS118741
National Institute of General Medical Sciences, R01GM115510
National Institute on Deafness and Other Communication Disorders, R01DC017146, R01DC020703
Howard Hughes Medical Institute, https://ror.org/006w34k90, Gilliam award to K.M.N.
Hubert & Richard Hanlon Trust
Carney Institute for Brain Science at Brown University, Innovation Award to G.B.
π° "A positive feedback loop between sensory and octopaminergic neurons underlies nociceptive plasticity in Drosophila larvae"
https://www.biorxiv.org/content/10.1101/2025.07.17.665309v1?rss=1 #InternalState #Drosophila #Behaviour #Sensory #LarvaYour word, is one of the most powerful forces of nature.
Listen to yours to find out what you really think.
And speak them wisely to pave the path before you in gold.
#psychozoicera #mindset #lawoftheuniverse #lawofcorrespondence #internalstate #guidinglight #lifesjourney #manifestation #manifest #visualize #dreamlife
flypapers
Psychozoic Era