Updated March 5, 2024
Research Spotlight
The action of nicotine on the brain is in constant conflict between reward centers of the brain and those that mediate aversion to nicotine. One such region that regulates nicotine aversion is the medial habenula (MHb), which is commonly associated with the limitation of nicotine intake as well as the negative effects felt during nicotine withdrawal. Olszewski and colleagues demonstrate that MHb activity is enhanced or diminished depending on the amount of nicotine taken, the dosage of nicotine (± menthol), as well as the sex of the subject that intakes the dosage of nicotine. Further, the authors have shown that in key reward centers of the brain (the ventral tegmental area), enhanced or diminished activation is not encoded by the amount of nicotine administered by the subject as seen in the MHb, rather, its activation is determined by reinforcement-related behaviors.
Sensory cues potentiate VTA dopamine mediated reinforcement
Animals rely on environmental cues to successfully acquire rewards, a process that involves dopamine neurons in the brain. Despite a long history of research in this area, it has remained unclear to what extent dopamine neurons signal reward value themselves, versus directing learning about reward-paired cues. Wolff and Saunders show that both are true - artificial activation of dopamine neurons is rewarding, but this process interacts with cues to modulate the vigor of reward seeking. These results emphasize the delicate interplay of the environment and brain states in the regulation of motivated behavior.
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