Alterations in neural oscillations reveal transient impairment of working memory in key brain regions after indoor toluene exposure.

Indoor toluene exposure impairs working memory (WM), particularly during the encoding phase; however, the underlying dynamic effects on WM-specific neural circuits remain incompletely understood. The ventral hippocampus (vHPC), medial prefrontal cortex (mPFC), and basolateral amygdala (BLA) are key regions involved in WM encoding circuits. Using multichannel microelectrode array technology, the local field potentials (LFPs) were recorded from these regions in a rodent model during a 4-hour exposure to low concentrations of toluene (0, 17.5, 35, and 70 ppb). Although no significant differences in behavioral WM performance were observed across exposure groups (p > 0.05), exposure to 70 ppb toluene selectively suppressed theta-band (4-8 Hz) power in the BLA (p = 0.0064) and vHPC (p = 0.047). This suppression persisted until Day 3 post-exposure (p < 0.05), with full recovery observed by Days 4-7 (p > 0.05). In contrast, mPFC oscillatory activity remained unaffected across all exposure levels (p > 0.05). These findings suggest that the BLA and vHPC, as core components of the WM encoding circuits, are selectively and transiently disrupted by short-term exposure to low-level indoor toluene. Notably, this neurophysiological impairment appears reversible over time.