Dopamine Important for Creating Persistent Memories

Hippocampal dopamine and the ventral tegmental area mediate long-term memory storage

MONDAY, Aug. 24 (HealthDay News) -- The brain's dopamine system in the hippocampus is responsible for creating persistent long-term memory (LTM) in rats, according to a study in the Aug. 21 issue of Science.

Janine I. Rossato and colleagues from Pontificia Universidade Catolica do Rio Grande do Sul in Porto Alegre, Brazil, investigated the role of hippocampal dopamine and the ventral tegmental area (VTA), an area critical for assessing the significance of punishments and rewards, on LTM persistence in rats trained to develop a long-lasting fear LTM.

The researchers found that a D1 dopamine receptor antagonist could block the development of the long-lasting LTM if injected into the dorsal hippocampus at 12 hours, but not earlier, after the fearful experience. In contrast, a D1 receptor agonist injected into the hippocampus during the same time frame converted the LTM into a persistent one. Further experiments showed that LTM formation was regulated by the VTA via brain-derived neurotrophic factor.

"Thus, the persistence of LTM depends on activation of VTA/hippocampus dopaminergic connections and can be specifically modulated by manipulating this system at definite post-learning time points," Rossato and colleagues conclude.

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