Shah, P.; Dev, A.; Lew, B.; Biuckians, C.; Oepen, A. S.; Ghirelli, A.; Boto, T.; Cervantes-Sandoval, I.

Traumatic brain injury (TBI) is a leading cause of neurological dysfunction, yet the mechanisms linking repeated concussions to cognitive impairment remain poorly defined. Here, we used a controlled Drosophila model of repetitive head trauma using a piezoelectric actuator to deliver reproducible mild, moderate, or severe concussions. Repeated trauma significantly reduced lifespan and induced transient locomotor deficits, persistent motivational impairments, and, surprisingly, sleep behavior was only altered with injury protocols expanding across more than one day. At the cellular level, concussions triggered a delayed but robust proliferation of astrocyte-like glia, consistent with neuroinflammatory responses observed in mammalian models. To investigate circuit-level consequences, we examined novelty detection within the mushroom body, focusing on MBON-3, a neuron that shows plasticity consistent with odor habituation similar to previously reported for MBON-'3. Functional calcium imaging revealed that concussed flies exhibited disrupted odor-induced plasticity and diminished baseline responsiveness in MBON-3 at one- and five- days post-injury, despite intact Kenyon cell input. Notably, these deficits were force-dependent and largely reversible by ten days, highlighting both vulnerability and resilience within this defined circuit. Together, our findings demonstrate that repeated concussions in Drosophila produce dose-dependent behavioral, cellular, and circuit dysfunctions that parallel mammalian TBI. This work establishes a genetically tractable platform for dissecting the mechanisms of concussion-induced cognitive decline and for identifying potential targets for intervention.