Repeated unpredictable threats without harm impair spatial working memory in the Barnes maze

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Stress Research

Background:

• Psychological stressors involve anticipating challenges, while physical stressors pose direct threats to homeostasis.
• Existing rodent stress models often combine both psychological and physical stressors, making it difficult to isolate the effects of psychological stress on cognitive functions like working memory.

Purpose of the Study:

• To determine if intermittent psychological stressors, specifically the anticipation of threat, are sufficient to impair spatial working memory in adolescent male rats.
• To develop and utilize a novel rodent stress model that isolates psychological stress without physical challenge.

Main Methods:

• Adolescent male Sprague-Dawley rats were housed in control (CT) or stress (ST) conditions for three weeks.
• The ST group experienced random presentations of ferret odor, abrupt lights, and sound in a tunnel, simulating threat anticipation.
• Spatial working memory was assessed using the Barnes maze after the stress exposure period.

Main Results:

• The ST group exhibited avoidance behaviors, indicated by fewer tunnel crossings, confirming the psychological stressor's effectiveness.
• Despite similar body weights and circadian activity patterns, the ST group showed significant spatial working memory deficits.
• These deficits included longer latencies to find the goal and more errors on the Barnes maze.

Conclusions:

• Intermittent psychological stressors, characterized by the anticipation of threat, are sufficient to impair spatial working memory in adolescent male rats.
• The findings suggest that psychological stress, independent of physical challenge, plays a critical role in adolescent cognitive development and memory function.