Behavioral Effects
Single or repeated mild blasts impair novel object recognition memory at 1-hour and 24-hour retention intervals, as mice fail to distinguish familiar from novel objects post-exposure. Anxiety rises in elevated O-maze tests, with animals spending more time in closed arms, indicating avoidance generalization. Chronic exposures exacerbate these, mimicking PTSD symptoms like hypervigilance.[pmc.ncbi.nlm.nih +2]
Noradrenergic Role
Blast triggers NE surges, altering anterior cingulate cortex (ACC) firing patterns via general-to-specific neural cliques, causing post-event reverberations that consolidate fear memories. This hyperactivity sensitizes amygdala circuits, boosting anxiety while impairing hippocampal consolidation, as NE overloads α1/β-adrenergic receptors. Models show transient monoamine changes, including elevated NE in prefrontal regions.[frontiersin +4]
Neural Mechanisms
In vivo recordings reveal diverse ACC neuron responses: some excite during blasts, others inhibit, leading to synaptic imbalances and contextual fear overgeneralization. Repeated low-level blasts (e.g., 26-70 kPa) upregulate NLRP3 inflammasomes, amplifying microglial NE-driven inflammation and tau pathology in hippocampus/amygdala. No gross damage occurs, but mitochondrial stress and blood-brain barrier leaks contribute.[nature +3]