Biology subjects

Bohra, A. A.

Publications and source records attributed to Bohra, A. A..

4 recordsLinked to original sources

bioRxiv2026

Associative learning reconfigures colour-guided behaviour in Drosophila larvae

Colour-guided behaviour can be innate or learned, yet how a numerically simple nervous system assigns value to spectral cues remains unresolved. We developed an automated differential-conditioning assay in which third-instar Drosophila larvae were trained with blue and green light, one of which was paired with electric shock. Wild-type larvae subsequently avoided the shock-paired colour, whereas naive controls showed no strong blue-green preference. This learned avoidance persisted when the relative intensity cue was transferred to the alternative colour, indicating that behavioural choice followed spectral identity rather than simply tracking the dimmer stimulus. Disruption of either the blue-sensitive Rh5 or green-sensitive Rh6 photoreceptor pathway significantly weakened the training-induced behavioural shift relative to wild type, with Rh5 mutants showing only a small residual shift. Complementary extracellular recordings confirmed light-evoked activity in the larval visual system, with robust responses to ultraviolet and broadband white illumination but smaller and more variable responses to blue and green light. Together, these results show that larvae can discriminate blue from green, demonstrating elementary colour vision; that associative experience reconfigures their colour-guided behaviour; and that both photoreceptor pathways contribute to this learned response. This paradigm separates learned spectral preference from baseline light preference and provides a tractable framework for linking defined sensory inputs to the circuit mechanisms of visual memory.

neuroscience↗

bioRxiv2025

Synaptic high-frequency jumping synchronises vision to high-speed behaviour

During high-speed behaviour, animals must synchronise perception and action despite rapid environmental and self-generated motion. How neural systems achieve such precision remains unclear. Here we show how the housefly (Musca domestica) maintains visual accuracy during fast motion. Using intracellular and photomechanical recordings during saccade-like stimulation, we traced information flow from photoreceptors to large monopolar cells (LMCs). Visual neurons achieved record-high information sampling ([~]2,500 bits{middle dot}s-1) and synaptic transmission ([~]4,100 bits{middle dot}s-1), far exceeding previous estimates. We identify a previously unknown mechanism - synaptic high-frequency jumping - in which photoreceptor-LMC synapses dynamically shift transmission toward higher frequencies during saccades, extending visual bandwidth to [~]1,000 Hz, effectively eliminating synaptic delays, and quadrupling classical flicker-fusion limits ([~]230 Hz). Behavioural experiments show flies respond synchronously within [~]13-20 ms, even before photoreceptor responses peak. A biophysically realistic model reveals how photomechanical-stochastic-refractory quantal sampling co-adapts with saccadic behaviour: through self-motion, flies efficiently translate image motion into temporally-precise, predictive high-speed vision.

neuroscience↗

bioRxiv2025

Drosophila larval Odd neurons process innate and learned information to regulate chemotaxis behavior

Adaptive decision-making emerges from the integration of innate preferences and learned experiences to guide behavior. Using Drosophila larvae as a model, we investigated the neural circuitry underlying olfactory processing, focusing on Odd neurons--a distinct neuronal population that receives innate valence signals from Kenyon cells (KCs) rather than lateral horn inputs. Through larval connectomics, trans-tango labeling, and detailed anatomical analyses, we found that Odd neurons integrate innate valence through dendro-dendritic connections with KCs and learned valence via inhibitory inputs from mushroom body output neurons (MBON-g1 and MBON-g2). Optogenetic silencing of Odd neurons disrupted larval chemotaxis and associative memory by selectively impairing memory retrieval, while sparing memory formation, and by altering the turn rate during navigation. These results suggest that Odd neurons serve as an integrative hub, converging innate olfactory cues with learned reinforcement signals to fine-tune navigational choices. This study illuminates how distinct neural pathways converge in the larval brain to shape behavior, offering novel insights into decision-making circuitry that may extend to more complex nervous systems.

neuroscience↗

bioRxiv2017

Identification of single pair of interneurons for bitter taste processing in the Drosophila brain

Drosophila has become an excellent model system for investigating the organization and function of the gustatory system due to the relatively simple neuroanatomical organization of its brain and the availability of powerful genetic and transgenic technology. Thus, at the molecular and cellular level, a great deal of insight into the peripheral detection and coding of gustatory information has already been attained. In contrast, much less is known about the central neural circuits that process this information and induce behaviorally appropriate motor output. Here we combine functional behavioral tests with targeted transgene expression through specific driver lines to identify a single bilaterally homologous pair of bitter sensitive interneurons that are located in the subesophageal zone of the brain. Anatomical and functional data indicate that these interneurons receive specific synaptic input from bitter sensitive gustatory receptor neurons. Targeted transgenic activation and inactivation experiments show that these bitter sensitive interneurons can largely suppress the proboscis extension reflex to appetitive stimuli such as sugar and water. These functional experiments together with calcium-imaging studies indicate that these first order local interneurons play an important role in the inhibition of the proboscis extension reflex that occurs in response to bitter tastants. Taken together, our studies present a cellular identification and functional characterization of a key gustatory interneuron in the bitter sensitive gustatory circuitry of the adult fly.

neuroscience↗