Enhanced startle responsivity 24 hours after acute stress exposure

Area of Science:

• Neuroscience
• Psychology
• Psychophysiology

Background:

• Stress impacts memory encoding and consolidation.
• Environmental cues, like odors, can trigger memories of stressful events.
• The long-term effects of stress on startle responsivity and emotional memory reactivation require further investigation.

Purpose of the Study:

• To assess the lasting effects of acute stress on startle responsivity 24 hours post-stress.
• To determine if stress implicitly reactivates emotional memory traces associated with a specific odor.
• To investigate the influence of stress on odor valence perception.

Main Methods:

• Participants underwent either a stressful (Trier Social Stress Test) or control condition with an ambient odor.
• The following day, auditory startle paradigms measured eyeblink reflex (electromyography).
• Olfactory stimuli included a target odor from the previous day, alongside negative, positive, and neutral stimuli.

Main Results:

• The stress group exhibited significantly enhanced startle responses to all stimuli compared to the control group.
• A typical fear-potentiated startle response was observed.
• Stressed participants perceived the target odor as more aversive, suggesting implicit effects on odor valence, though odor recognition memory did not differ.

Conclusions:

• Acute stress exposure leads to heightened startle responsivity 24 hours later.
• This generalized increase in responsivity may be linked to altered amygdala function, promoting heightened sensitivity but reduced specificity.
• Stress appears to implicitly influence emotional memory and odor valence without affecting explicit odor recognition.