COVID-19 can produce persistent cognitive and neuropsychiatric symptoms, including difficulties with memory, attention, concentration, sleep, and mood. The Human Neurobiology Laboratory investigates the biological mechanisms that may connect a respiratory infection to these changes in brain function. This work examines how systemic inflammation, disruption of the blood-brain barrier, activation of microglia, altered cytokine signaling, vascular injury, and impaired neurogenesis may affect brain regions involved in cognition and emotional regulation. By combining experimental models of SARS-CoV-2 infection with analyses of human postmortem brain tissue, Prof Dupont and collaborators found evidence of increased blood-brain barrier permeability and inflammatory activity in the brain even without extensive viral invasion of the central nervous system. COVID-19 was associated with microglial activation, increased expression of inflammatory cytokines, and fewer neuroblasts and immature neurons in the hippocampal dentate gyrus. These changes may help explain the learning, memory, and executive-function difficulties reported during and after infection. By identifying the vascular, immune, and cellular pathways affected by COVID-19, the lab aims to clarify the biological basis of its neurological consequences and uncover mechanisms that could guide future treatments for post-infectious cognitive and psychiatric symptoms.