Neural structures mediating expression and extinction of platform-mediated avoidance.

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Systems Neuroscience

Background:

• Defensive behaviors are crucial for survival.
• While passive responses like freezing are well-studied, active avoidance mechanisms remain less understood.
• Understanding active avoidance is key to addressing disorders involving threat perception.

Purpose of the Study:

• To investigate the neural circuits underlying active avoidance behavior.
• To differentiate the roles of specific brain regions in active avoidance versus freezing.
• To develop a task minimizing freezing to better study active avoidance.

Main Methods:

• Developed an active avoidance task where rats learned to step on a platform to avoid footshock.
• Used muscimol to inactivate the prelimbic cortex (PL), infralimbic cortex (IL), ventral striatum (VS), and basolateral amygdala (BLA).
• Assessed the effects of inactivation on avoidance learning, expression, extinction, and freezing behavior.

Main Results:

• Inactivation of PL, VS, and BLA impaired active avoidance.
• BLA inactivation reduced freezing, suggesting a loss of the tone-shock association.
• VS inactivation increased freezing, indicating a loss of avoidance memory. IL inactivation impaired extinction but not initial avoidance.
• PL inactivation had no effect on freezing.

Conclusions:

• Active avoidance is mediated by prefrontal-striatal circuits.
• These circuits may be overactive in trauma-related disorders.
• Findings highlight distinct roles for brain regions in active versus passive threat responses.