Scientists have found that alcohol impairs the brain's ability to adapt by altering the activity of cholinergic interneurons (CINs). These neurons, which release acetylcholine, an important neurotransmitter, play a key role in the brain's striatum, affecting reward-based learning and motivation. The findings are published in the journal Science Advances (SciAdv). According to Jun Wang, head of the research lab at Texas A&M College of Medicine, dopamine neurons regulate the brain's reward system, and CINs act as filters, controlling the stimuli that activate these neurons. Studies have shown that chronic alcohol exposure leads to altered patterns of CIN activity, which negatively affects learning processes. Using the latest technologies, including optogenetics, which allows controlling cellular activity with light, and fiber photometry to monitor acetylcholine release in real time, the scientists investigated how different phases of CIN activity affect behavior. It turned out that in normals, CIN neurons operate on a burst-pause principle: a rapid burst of activity is followed by a pause that is necessary for adaptation and learning new behavior. In animals chronically exposed to alcohol, however, this pattern is disrupted: the pauses become shorter and less pronounced, complicating important thought processes such as reversible learning-the ability to replace old behaviors with new ones. These findings highlight how alcohol can disrupt key neurobiological mechanisms that are essential for adaptation and learning.