Effects of hunger on the brain's response to food cues read more at here www.spinonews.com/index.php/item/858-effects-of-hunger-on-the-brain-s-response-to-food-cues

Our brain pays more attention to food when we are hungrier than when we are sated.

A team of scientists at Beth Israel Deaconess Medical Center (BIDMC) has shed light on how the needs of the body affect the way the brain processes visual food cues.

Researchers examined the brain circuits responsible for the differences in the way the brain responds to visual food cues during hunger versus satiety.

Researchers in Andermann's lab recorded images of brain activity in mice across different states of hunger and satiety.

In food-restricted mice, just being shown the visual cue associated with the liquid treat provoked a strong response in sets of neurons in three different brain areas. When these same mice were tested after a meal, the same food cue produced a decreased response in the neurons in a subset of these same brain areas.

Scientists used this information to map the circuitry controlling motivation-dependent processing of sensory responses.

The andermann said, this turns out to be very similar to the situation in humans. We hope this new model that we've developed can be used to study the circuitry underpinning the brain's responses to food cues in health and in obesity.

The team's findings suggest that neurons in two regions of the brain, the postrhinal association cortex and the lateral amygdala help integrate information about external food cues and hunger state.

Researchers compared the behavior of well-fed mice to that of mice that had been on a restricted diet for 24 hours. Food-restricted mice avoided shocks, much less frequently than fed mice. That is, the motivation to eat overpowered the tendency to avoid threats. Conversely, fed mice prioritized avoiding shocks over seeking more food.

Researchers then used a technique called optogenetics, to stimulate specific neurons the agouti-related peptide neurons (AgRP), known to induce food consumption in sated mice. When AgRP neurons were stimulated in sated mice well before being placed into the experimental arena, the animals behaved like naturally hungry mice.

However, when mice were placed in the threatening arena prior to activation of AgRP neurons, mice behaved more similarly to sated animals, prioritizing shock avoidance over seeking food. The observations suggest AgRP neurons help regulate competing drives, and that, in the face of competing motivations.

This work may be helpful in understanding the motivation to restrict food intake in eating disorders, as well as the tug-of-war between the neural circuits driving food-seeking and those driving self-defensive behaviors.