Tedre, E. | Search bioRxiv

bioRxiv2025

Sleep Facilitates Pattern Separation through SK Channel-Mediated Sparse Coding

The roles of sleep in priming the brain for associative learning remain unclear. Here, we report that acute sleep deprivation in Drosophila selectively impairs pattern separation--the ability to distinguish between similar stimuli--without affecting classical conditioning. This deficit correlates with disrupted sparse coding in the mushroom body, reflected by an increased number of active Kenyon cells and greater overlap in their odor representations. Electrophysiological analyses reveal that sleep loss enhances small conductance calcium-activated potassium (SK) channel-mediated afterhyperpolarization in GABAergic anterior paired lateral (APL) neurons, leading to reduced levels of feedback inhibition onto Kenyon cells and compromised sparse coding. Targeted knockdown of SK channels in APL neurons reduce their augmented afterhyperpolarization and rescues the pattern separation deficits caused by sleep deprivation. These findings identify a critical role for SK channels in inhibitory interneurons to enable sleep to preserve sparse and decorrelated neural representations, supporting cognitive processes such as pattern separation.

neuroscience↗

bioRxiv2024

A High-Throughput Platform for Assessing Single Fly Learning and Memory: Individual Drosophila Olfactory Conditioner (iDOC)

Olfactory conditioning in Drosophila melanogaster is a widely used behavioral paradigm for uncovering the neural basis of learning and memory. The traditional T-maze assay, however, relies on group-level assessments and cannot examine individual flies learning and memory abilities. To address this limitation, we developed the Individual Drosophila Olfactory Conditioner (iDOC), an apparatus for single-fly conditioning and memory assessment. Using iDOC, we demonstrated aversive olfactory learning, short-term memory (STM), anesthesia-resistant memory (ARM), and protein synthesis-dependent long-term memory (LTM) in individual flies, consistent with previous experiments conducted using the T-maze. As an individual memory assessment method, iDOC can be integrated with other behavioral assays at the single animal level, such as sleep monitoring. Notably, we found that spaced training, which induces LTM, also promotes post-learning sleep, while massed training, which induces ARM, did not. iDOC thus provides a powerful platform for investigating learning and memory and its interplay with other behavioral processes at the individual animal level. HighlightsO_LIDeveloped iDOC for high-throughput, single-fly aversive olfactory training and memory assessment C_LIO_LIDemonstrated aversive learning, STM, ARM, and LTM in individual flies using iDOC C_LIO_LISpaced conditioning, and not massed conditioning, promotes sleep C_LI

animal behavior and cognition↗