Memory Capacity; In this study team of neuroscience researchers at the University of Southern California have identified a surprising new role for the “hunger hormone” ghrelin. Ghrelin has previously been recognized for its unique role in sending hunger signals from the gut to the brain, but, as presented this week at the annual meeting of the Society for the Study of Ingestive Behavior, these new findings suggest that it may also be important for memory control.
Ghrelin is produced in the stomach and secreted in anticipation of eating, and is known for its role to increase hunger. “For example, ghrelin levels be high if you were at a restaurant; so looking forward to a delicious dinner that was going to serve shortly,” said Dr. Elizabeth Davis, lead author on the study.
The memory capacity
Once it is secreted, ghrelin binds to specialize receptors on the vagus nerve a nerve that communicates a variety of signals from the gut to the brain. “They recently discover that in addition to influencing the amount of food consume during a meal; so the vagus nerve also influences memory function,” said Dr. Scott Kanoski, senior author of the study. The team hypothesize that ghrelin is a key molecule that helps the vagus nerve promote memory.
Using an approach called RNA interference to reduce; so the amount of ghrelin receptor; so the researchers block ghrelin signaling in the vagus nerve of laboratory rats. When given a series of memory tasks; also animals with reduce vagal ghrelin signaling were impaire in a test of episodic memory; so a type of memory that involves remembering what, when; also where something occurred, such as recalling your first day of school. For the rats, this require remembering a specific object in a specific location.
Episodic memory problems
The team also investigate whether vagal ghrelin signaling influences feeding behavior. They find that when the vagus nerve could not receive the ghrelin signal, the animals ate more frequently; hence yet consume smaller amounts at each meal. Dr. Davis thinks these results may relate to the episodic memory problems.
“Deciding to eat or not to eat is influence by the memory of the previous meal,” says Davis. “Ghrelin signaling to the vagus nerve may be a share molecular link between remembering a past meal; and also the hunger signals that are generate in anticipation of the next meal.”
These novel findings add to our understanding of how episodic memories are generate; so as well as the relationship between memory and eating behavior. In the future, researchers may be able to develop strategies; so for improving memory capacity in humans by manipulating ghrelin signaling from the gut to the brain.