An integrative sensor of body states: how the mushroom body modulates behavior depending on physiological context.

The brain constantly compares past and present experiences to predict the future, thereby enabling instantaneous and future behavioral adjustments. Integration of external information with the animal's current internal needs and behavioral state represents a key challenge of the nervous system. Recent advancements in dissecting the function of the mushroom body (MB) at the single-cell level have uncovered its three-layered logic and parallel systems conveying positive and negative values during associative learning.

The caloric value of food intake structurally adjusts a neuronal mushroom body circuit mediating olfactory learning in .

Associative learning enables the adaptive adjustment of behavioral decisions based on acquired, predicted outcomes. The valence of what is learned is influenced not only by the learned stimuli and their temporal relations, but also by prior experiences and internal states. In this study, we used the fruit fly to demonstrate that neuronal circuits involved in associative olfactory learning undergo restructuring during extended periods of low-caloric food intake.

The preoptic area and dorsal habenula jointly support homeostatic navigation in larval zebrafish.

Animals must maintain physiological processes within an optimal temperature range despite changes in their environment. Through behavioral assays, whole-brain functional imaging, and neural ablations, we show that larval zebrafish, an ectothermic vertebrate, achieves thermoregulation through homeostatic navigation-non-directional and directional movements toward the temperature closest to its physiological setpoint. A brain-wide circuit encompassing several brain regions enables this behavior.

Large Language Models in Medical Education: Comparing ChatGPT- to Human-Generated Exam Questions.

Problem: Creating medical exam questions is time consuming, but well-written questions can be used for test-enhanced learning, which has been shown to have a positive effect on student learning. The automated generation of high-quality questions using large language models (LLMs), such as ChatGPT, would therefore be desirable. However, there are no current studies that compare students' performance on LLM-generated questions to questions developed by humans.

Optimized design and in vivo application of optogenetically functionalized Drosophila dopamine receptors.

Neuromodulatory signaling via G protein-coupled receptors (GPCRs) plays a pivotal role in regulating neural network function and animal behavior. The recent development of optogenetic tools to induce G protein-mediated signaling provides the promise of acute and cell type-specific manipulation of neuromodulatory signals. However, designing and deploying optogenetically functionalized GPCRs (optoXRs) with accurate specificity and activity to mimic endogenous signaling in vivo remains challenging.

The ecology of nutrient sensation and perception in insects.

Insects are equipped with neurological, physiological, and behavioral tools to locate potential food sources and assess their nutritional quality based on volatile and chemotactile cues. We summarize current knowledge on insect taste perception and the different modalities of reception and perception. We suggest that the neurophysiological mechanisms of reception and perception are closely linked to the species-specific ecology of different insects.

Global change in brain state during spontaneous and forced walk in is composed of combined activity patterns of different neuron classes.

Movement-correlated brain activity has been found across species and brain regions. Here, we used fast whole brain lightfield imaging in adult to investigate the relationship between walk and brain-wide neuronal activity. We observed a global change in activity that tightly correlated with spontaneous bouts of walk.

Decision making: Dopaminergic neurons for better or worse.

All animals constantly need to weigh their options based on new experiences: something initially considered bad can become better in the light of something worse. A new study now shows how flies re-evaluate between better and worse.

A dopamine-gated learning circuit underpins reproductive state-dependent odor preference in females.

Motherhood induces a drastic, sometimes long-lasting, change in internal state and behavior in many female animals. How a change in reproductive state or the discrete event of mating modulates specific female behaviors is still incompletely understood. Using calcium imaging of the whole brain of females, we find that mating does not induce a global change in brain activity.

A role for glia in cellular and systemic metabolism: insights from the fly.

Excitability and synaptic transmission make neurons high-energy consumers. However, neurons do not store carbohydrates or lipids. Instead, they need support cells to fuel their metabolic demands.

Action selection: Neuropeptidergic gates of behavior.

Nervous systems continuously receive environmental signals with distinct behavioral meanings. To process ambiguous sensory inputs, neural circuits rely on hubs with compartmentalized synaptic structures. A new study has revealed how, in Drosophila larvae, this architecture with the local release of neuropeptides enables the control of flexible and context-dependent behavioral outcomes.

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

We present a method developed specifically to image the whole Drosophila brain during ongoing behavior such as walking. Head fixation and dissection are optimized to minimize their impact on behavior. This is first achieved by using a holder that minimizes movement hindrances.

Flies Avoid Current Atmospheric CO Concentrations.

CO differs from most other odors by being ubiquitously present in the air animals inhale. CO levels of the atmosphere, however, are subject to change. Depending on the landscape, temperature, and time of the year, CO levels can change even on shortest time scales.

Dopamine modulation of sensory processing and adaptive behavior in flies.

Behavioral flexibility for appropriate action selection is an advantage when animals are faced with decisions that will determine their survival or death. In order to arrive at the right decision, animals evaluate information from their external environment, internal state, and past experiences. How these different signals are integrated and modulated in the brain, and how context- and state-dependent behavioral decisions are controlled are poorly understood questions.

Immune Receptor Signaling and the Mushroom Body Mediate Post-ingestion Pathogen Avoidance.

In spite of the positive effects of bacteria on health, certain species are harmful, and therefore, animals must weigh nutritional benefits against negative post-ingestion consequences and adapt their behavior accordingly. Here, we use Drosophila to unravel how the immune system communicates with the brain, enabling avoidance of harmful foods. Using two different known fly pathogens, mildly pathogenic Erwinia carotovora (Ecc15) and highly virulent Pseudomonas entomophila (Pe), we analyzed preference behavior in naive flies and after ingestion of either of these pathogens.

Sensory Evolution: Making Sense of the Noni Scent.

A recent study identifies the neuronal and molecular underpinnings of a key ecological difference between two Drosophila species using a remarkable genetic toolbox for a non-model species.

Valence and State-Dependent Population Coding in Dopaminergic Neurons in the Fly Mushroom Body.

Neuromodulation permits flexibility of synapses, neural circuits, and ultimately behavior. One neuromodulator, dopamine, has been studied extensively in its role as a reward signal during learning and memory across animal species. Newer evidence suggests that dopaminergic neurons (DANs) can modulate sensory perception acutely, thereby allowing an animal to adapt its behavior and decision making to its internal and behavioral state.

Studying complex brain dynamics using .

The field has successfully used genetic tools to identify neurons and sub-circuits important for specific functions. However, for an organism with complex and changing internal states to succeed in a complex and changing natural environment, many neurons and circuits need to interact dynamically. 's many advantages, combined with new imaging tools, offer unique opportunities to study how the brain functions as a complex dynamical system.

A Neural Circuit Arbitrates between Persistence and Withdrawal in Hungry Drosophila.

In pursuit of food, hungry animals mobilize significant energy resources and overcome exhaustion and fear. How need and motivation control the decision to continue or change behavior is not understood. Using a single fly treadmill, we show that hungry flies persistently track a food odor and increase their effort over repeated trials in the absence of reward suggesting that need dominates negative experience.

Flies spring a surprise.

A combination of genetic, anatomical and physiological techniques has revealed that the lateral horn, a region of the brain involved in olfaction in flies, has many more types of neurons than expected.

Functional identity of hypothalamic melanocortin neurons depends on Tbx3.

Heterogeneous populations of hypothalamic neurons orchestrate energy balance via the release of specific signatures of neuropeptides. However, how specific intracellular machinery controls peptidergic identities and function of individual hypothalamic neurons remains largely unknown. The transcription factor T-box 3 (Tbx3) is expressed in hypothalamic neurons sensing and governing energy status, whereas human TBX3 haploinsufficiency has been linked with obesity.

State-dependent plasticity of innate behavior in fruit flies.

Behaviors are often categorized into innate or learned. Innate behaviors are thought to be genetically encoded and hardwired into the brain, while learned behavior is a product of the interaction between experience and the plasticity of synapses and neurons. Recent work in different models show that innate behavior, too, is plastic and depends on the current behavioral context and the internal state of an animal.

Eph Receptor Effector Ephexin Mediates Olfactory Dendrite Targeting in Drosophila.

Deciphering the mechanisms of sensory neural map formation is a central aim in neurosciences. Failure to form a correct map frequently leads to defects in sensory processing and perception. The olfactory map develops in subsequent steps initially forming a rough and later a precise map of glomeruli in the antennal lobe (AL), mainly consisting of olfactory receptor neuron (ORN) axons and projection neuron (PN) dendrites.

Revisiting the developmental and cellular role of the pigmentation gene yellow in Drosophila using a tagged allele.

Pigmentation is a diverse and ecologically relevant trait in insects. Pigment formation has been studied extensively at the genetic and biochemical levels. The temporality of pigment formation during animal development, however, is more elusive.