Anterior Cingulate Cortex Ablation Disrupts Affective Vigor and Vigilance

Area of Science:

• Neuroscience
• Primate Behavior
• Affective Science

Background:

• The anterior cingulate cortex (ACC) is implicated in cognition and affect, but its causal role is poorly understood.
• Primate ACC shares structural and functional homology with humans, making it a relevant model.
• Understanding ACC's function is vital for neurological and psychological health.

Purpose of the Study:

• To investigate the causal role of the ACC in affective responding to threat in rhesus monkeys.
• To determine if ACC lesions affect initial or sustained threat processing.
• To explore implications for mood disorders characterized by disrupted threat and novelty responses.

Main Methods:

• Bilateral ibotenate axon-sparing lesions to the ACC (areas 24, 32, 25) in adult male rhesus monkeys.
• Testing lesioned and control monkeys in human intruder and object responsiveness tasks.
• Assessing reactivity to threatening and novel stimuli across multiple test days.

Main Results:

• Monkeys with ACC lesions showed no difference in initial reactivity compared to controls.
• ACC-lesioned monkeys exhibited reduced reactivity over time, even to novel stimuli.
• This pattern suggests ACC is necessary for sustained affective responses to threat and novelty.

Conclusions:

• The primate ACC is essential for maintaining appropriate affective responses to potentially harmful or novel stimuli.
• ACC lesions lead to attenuated threat responses, a pattern observed in mood disorders.
• These findings highlight the ACC's critical role in affective regulation and mental health.