Use of a physiological reflex to standardize vagal nerve stimulation intensity improves data reproducibility in a memory extinction assay

BackgroundModulating brainstem activity, via electrical vagus nerve stimulation (VNS), influences cognitive functions, including memory. However, controlling for changes in stimulus efficacy during chronic studies, and response variability between subjects, is problematic.Objective/Hypothesis: We hypothesized that recruitment of an autonomic reflex, the Hering-Breuer would provide robust confirmation VNS efficacy. compared this to measurement electrode resistance over time. also examined whether modulates contextual memory extinction.MethodsElectrodes diaphragm electromyography recording were implanted into anesthetized Sprague Dawley rats. When conscious, we measured as well minimum current required evoke before, after, inhibitory avoidance assay - a two chamber, dark/light model, where dark compartment was paired with aversive foot shock. The extinction assessed sham treated rats, administered 30 s at 1.5 times reflex threshold formation.ResultsAssessment VNS-evoked successfully identified defective electrodes. accelerated decreased multiple physiological metrics fear expression. observed inverse relationship respiratory rate behavioural assay. Additionally, no formation established.ConclusionThese data demonstrate reliable, experimental studies can be produced by verifying initiation consequence stimulation. Further, could standardised indexing stimulator reflexes.