Photo credit: www.sciencedaily.com
The brain orchestrates our eating and drinking behaviors through a sophisticated interplay of cells, signals, and pathways, ensuring we meet our caloric and hydration needs. However, many elements of how the brain interprets physiological signals and translates them into actions remain elusive. A recent study from the Max Planck Institute for Biological Intelligence, in collaboration with the University of Regensburg and Stanford University, has pinpointed certain neuron populations within the amygdala—an area critical for emotional and motivational functions—that significantly influence these processes.
The research identifies distinct groups of “thirst” and “hunger” neurons that operate via specialized circuits, thereby affecting our urges to consume food and beverages. Conducted on mice, this study offers fresh perspectives on the amygdala’s function in managing our nutritional requirements and has potential implications for understanding eating disorders and addiction.
The amygdala’s involvement in emotional responses is well-documented, but its role in regulating our appetites for food and drink is equally significant. Previous work spearheaded by Rüdiger Klein’s team has shown that neurons in the central nucleus of the amygdala link food with emotional responses—such as associating delicious foods with pleasure, creating aversions to unhealthy options, and moderating appetite during episodes of nausea. Furthermore, manipulating the activity of these neurons can lead to changes in behavior, encouraging mice to eat even beyond their satiety or during moments of discomfort.
Expanding on these foundational findings, the recent research meticulously describes unique neuron groups within the central amygdala that respond specifically to thirst, while others are dedicated to hunger, regulated by a complex interplay of molecular signals. “One identified group of neurons focuses exclusively on the drive to drink, marking the discovery of the first ‘thirst neuron’ in the amygdala,” points out Federica Fermani, the lead researcher. “Activating these neurons prompted increased drinking, whereas their suppression led to reduced consumption. We also found another set of neurons in this area that targets thirst while also influencing hunger. These results underscore the specialization of some neurons for specific drives, while others play broader roles in directing food and drink preferences.”
To investigate the regulation of eating and drinking by these neurons, the researchers employed cutting-edge genetic techniques to observe brain activity in mice under different states of hunger and thirst. Utilizing a technique known as optogenetics, researchers could activate specific neurons with light-sensitive proteins, allowing precise control over their activity. They also employed methods to deactivate neurons, studying how these changes impacted the mice’s eating or drinking behaviors. This combined approach enabled the identification of how neurons interacted with one another across various brain regions.
Raising new questions
The findings on neuronal communication pathways reveal connections with brain areas responsible for processing sensory information related to food and water, such as the parabrachial complex. The study further examines the balance of various factors, including taste preferences, in influencing behavior. For instance, by pairing a less-favored drink flavor with targeted neuron stimulation in the central amygdala, the researchers successfully altered the mice’s preferences, turning an initially aversive flavor into a new favorite. Given the similarities in amygdala structure between mice and humans, the researchers believe these insights may enhance our understanding of how emotional and motivational states influence human food and beverage choices.
Rüdiger Klein, Director at the Max Planck Institute for Biological Intelligence, comments, “Core drives such as thirst and hunger ensure we adequately hydrate and nourish ourselves, which is vital for survival. However, these same neural networks can lead to imbalances in consumption, resulting in overeating or undereating based on the brain’s messaging. By uncovering these mechanisms, we improve our comprehension of how the brain evaluates food and drink emotionally, learns to connect them with pleasure or distaste, and how these processes are molded through neural development.”
This research paves the way for further inquiries into the brain’s management of appetite, thirst, and emotions; the mechanisms that tell us when we’ve consumed too little or too much; how competing needs are coordinated; and the effects of these neural circuits in conditions such as obesity, anorexia, or alcohol dependence.
Source
www.sciencedaily.com