New Insights into the Amygdala's Role in Linking Unrelated Events in Decision-Making

Recent research from the Hospital del Mar Medical Research Institute sheds light on how the brain connects seemingly unrelated stimuli to influence decision-making. Published in the Proceedings of the National Academy of Sciences, the study focuses on the neural mechanisms underlying indirect associations, particularly involving the amygdala—a brain region known for processing fear and emotional responses.

Using experiments with mice, led by Ph.D. student José Antonio González Parra and supervised by Dr. Arnau Busquets, researchers explored how the brain forms associations between different stimuli that are not directly linked. The mice were trained to associate certain smells with specific tastes—for example, a banana scent with a sweet taste, and an almond scent with a salty taste. When a negative stimulus was later attached to the banana scent, the mice began to reject the sweet taste even though it had no direct connection to the negative experience. This demonstrated the formation of an indirect association mediated by the brain.

The team employed genetic techniques via viral vectors to observe brain activity during the process of encoding and consolidating these associations. They identified the amygdala as a key player in linking olfactory cues with taste stimuli, especially in forming these indirect relationships. Additional brain regions interacting with the amygdala, including parts of the cerebral cortex, were also involved. When the activity of the amygdala was inhibited, the mice failed to establish these associations, highlighting its crucial role.

The implications of this research extend beyond animal models. Since the neural circuits involved in decision-making and association formation are believed to be similar in humans, understanding these pathways could provide insights into mental health disorders such as PTSD and psychosis, which are often characterized by abnormal associative processes. Dr. Busquets emphasizes that disruptions in these circuits might underlie many cognitive and emotional disorders. Therefore, targeting these brain areas through therapies like brain stimulation could offer novel treatment approaches in the future.

This groundbreaking study advances our understanding of the neural basis of how the brain links unrelated events and makes decisions, opening avenues for potential interventions in cognitive and emotional disorders.