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Ramachandra, K. L.

Publications and source records attributed to Ramachandra, K. L..

2 recordsLinked to original sources

Detection and localization of conspecifics in ghost knifefish are influenced by the relationship between the spatial organization of receptors and signals.

The detection and localization of signals rely on arrays of receptors, and their spatial organization plays a key role in determining the accuracy of the system. Weakly electric ghost knifefish rely on a distributed array of electroreceptors to detect spatially diffuse electric signals from conspecifics. While we know that spatial resolution for small objects, such as prey, is enhanced near the head due to a high receptor density, it is not clear how receptor organization influences the processing of global and diffuse signals from conspecifics. Using spatially realistic modeling, we quantified how receptor density influences detection and localization accuracy for conspecific signals across varying distances. Our main result demonstrates that receptor density markedly enhances detection accuracy in frontal regions at intermediate distances (35-50 cm) yet surprisingly contributes minimally to improving localization accuracy. This highlights a fundamental principle: receptor convergence primarily benefits signal detection when dealing with spatially diffuse stimuli, even though higher receptor density can enhance localization accuracy for spatially delineated signals. Our findings extend beyond the electrosensory modality, drawing parallels with other sensory systems, and offer broader insights into spatial processing principles.

neuroscience↗

Stimulus-Specific Modulation is Enabled by Differential Serotonin Receptor Expression

Neural networks must be able to flexibly process information under different conditions. To this end, networks frequently rely on uniform expression of modulatory receptors by distinct classes of neurons to fine tune the computations supported by each neuronal class. In this study, we explore the consequences of heterogeneous, rather than uniform, serotonin (5-HT) receptor expression within a cell class for olfactory processing in Drosophila melanogaster. Here, we demonstrate that two distinct populations of olfactory output neurons (projection neurons, PNs) display heterogeneous receptor co-expression of all 5-HT receptors. Moreover, the PN populations that express distinct 5-HT receptors innervate different combinations of glomeruli, implying that the effects of 5-HT on these PNs may vary with their odor tuning. Furthermore, connectomic analyses reveal that PN subsets with different receptor profiles have little convergence upon downstream synaptic partners. Finally, 5-HT differentially modulates the odor-evoked responses of PNs with distinct receptor expression profiles and odor tuning. Overall, this implies that heterogeneous modulatory receptor expression enables differential tuning of activity within a neuronal class depending on the odor scene to which individual neurons respond.

neuroscience↗