Disruption of the linear relationship between recognition memory and local functional connectivity of left perirhinal...

With the widespread utilization of S band (2 GHz ∼ 4 GHz) microwave (MW) in communication, its potential health risks have drawn significant attention. The purpose of this study was to investigate the impacts of acute 2.856 GHz MW exposure on recognition memory, its corresponding functional brain network, and the relationships between them in rats.

Novel object recognition (NOR) tests were conducted to examine the influence of 50 mW/cm² acute 2.856 GHz MW on rat's recognition memory. Subsequently, resting state functional magnetic resonance imaging (rs-fMRI) was implemented to investigate the changes in the topological characteristics, long-range functional connectivity (FC), local FC assessed by regional homogeneity (ReHo), and fractional amplitude of low frequency fluctuation (fALFF) of rats' brain network related to recognition memory. Furthermore, the relationships between recognition memory and the potentially changed functional characteristics were investigated.

Our findings revealed that the acute MW exposure induced recognition memory decline in rats. Though no significant alterations were detected in topological properties, long-range FCs, and fALFF within the brain network related to recognition memory, the local FCs of bilateral perirhinal cortex and right hippocampus in rats exhibited marginally significant increases following the MW exposure. Moreover, in the Sham group, the local FC of the left perirhinal cortex demonstrated a significantly positive linear correlation with recognition memory ability (p = 0.0193, r = 0.7182). However, this linear relationship was disrupted after the MW exposure.

In conclusion, acute 2.856 GHz MW exposure can induce recognition memory impairments in rats. There is a positive linear relationship between recognition memory and the local FC of the left perirhinal cortex in normal rats. However, this relationship is disrupted after MW exposure, potentially due to maladaptive reorganization or failure of compensation within the brain region.