Orosensory stimulation produced by consuming a sweetened solution and possibly the hedonic value of that sweet stimulation induces synaptic plasticity in dHC CA1 neurons in an experience-dependent manner. Collectively, these findings are consistent with our hypothesis that dHC neurons form a memory of a meal.
Neurons in the dorsal hippocampus, the part of the brain that is critical for episodic memory, are activated by consuming sweets. Episodic memory is the memory of autobiographical events experienced at a particular time and place.
In the study, a meal consisting of a sweetened solution, either sucrose or saccharin, significantly increased the expression of the synaptic plasticity marker called activity-regulated cytoskeleton-associated protein (Arc) in dorsal hippocampal neurons in rats. Synaptic plasticity is a process that is necessary for making memories.
“We think that episodic memory can be used to control eating behavior,” said Prof Marise Parent. “We make decisions like ‘I probably won’t eat now. I had a big breakfast.’ We make decisions based on our memory of what and when we ate.” That possibility is supported by the researchers’ previous work, which showed that temporarily inactivating dorsal hippocampal neurons following a sucrose meal- the period during which the memory of a meal forms -accelerates the onset of the next meal and causes rats to eat more.
Forming memories of meals is important to a healthy diet. A London-based study shows that disrupting the encoding of the memory of a meal in humans, such as by watching television, increases the amount of food they consume during the next meal. Researchers have found that people with amnesia will eat again if presented with food, even if they’ve already eaten, because they have no memory of the meal.
To understand energy regulation and the causes of obesity, scientists must consider how the brain controls meal onset and frequency. Studies have found that increased snacking is correlated positively with obesity, and obese individuals snack more frequently than people who aren’t obese. Research also shows that over the past 3 decades, children and adults are eating more snacks per day and deriving more of their daily calories from snacks, mostly in the form of desserts and sweetened beverages.
In the future, the research team would like to determine if nutritionally balanced liquid or solid diets that typically contain protein, fat and carbohydrates have a similar effect on Arc expression in dorsal hippocampal neurons and whether increases in Arc expression are necessary for the memory of sweet foods.
http://news.gsu.edu/2015/11/12/consuming-sweets-forms-memories-that-may-control-eating-habits-neuroscience-study-finds/
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