Extensive but not Limited Repeated Trials in Passive Avoidance Task Induce Stress-like Symptoms and Affect Memory...

Area of Science:

• Neuroscience
• Behavioral Science

Background:

• Stressful experiences enhance emotional learning.
• Repeated exposure to stress can improve memory, but intensity and duration are critical.
• Repeated training for memory enhancement may induce unintended stress effects.

Purpose of the Study:

• To investigate the impact of limited versus extensive repetitive learning trials on emotional memory in rats.
• To explore the underlying neurochemical and physiological mechanisms of these effects.

Main Methods:

• Rats were subjected to a passive avoidance task (PAT) with either limited (4 trials) or extensive (16 trials) repetitive learning in a single day.
• Corticosterone levels, 5-hydroxytryptamine (5-HT) levels, and oxidative stress markers were measured.

Main Results:

• Extensive exposure led to a negative impact on emotional memory compared to limited exposure.
• Increased corticosterone and decreased 5-HT levels were observed after extensive exposure.
• Abnormal oxidative stress levels correlated with compromised memory function in the extensive exposure group.

Conclusions:

• Limited repetitive learning trials are beneficial for enhancing emotional memory.
• Extensive repetitive learning can induce a chronic stress-like state, leading to compromised memory performance.
• Hormonal and oxidative stress alterations mediate the detrimental effects of excessive training on memory consolidation.