The research indicates that when foods rich in sugar are eaten, neurons in the dorsal hippocampus are activated and an “episodic memory” is stored. This type of memory allows someone to recall an event and tie it to a time and place.
This finding came about through a study, summarized by Lab Manager magazine. Rats, in a test group, were given a meal containing a sweetened solution of sucrose or saccharin. These rats were compared to a control group given normal food. The rats were then offered food at different times during the day.
Rats that eat the sweet food were less likely to eat as soon as the rats not given the sweet food. The researchers think this is because the brain remembers the previous meal and the feeling of being sated. However, when the dorsal hippocampal neurons in the brain of rats is disrupted, the rats who eat the sweet food eat more.
After the study the rats were dissected and their brains examined. It was found that meals with a high “sweet” content led to a higher expression of a synaptic plasticity marker called activity-regulated cytoskeleton-associated protein (Arc) in dorsal hippocampal neurons. Synaptic plasticity is involved in the formation of memories.
The inference is that forming memories about meals is necessary for a healthy diet. Where this doesn’t happen effectively, this can cause animals to overeat. The researchers think the same process could happen with humans.
Episodic memories of food eating can be disrupted, for example, when people watch television while eating rather than sitting at a table away from distractions. Further development of such findings could help with tackling obesity.
The research was a collaborative effort between researchers from Georgia State University, Georgia Regents University and Charlie Norwood VA Medical Center. The findings are published in the journal Hippocampus, with the study headed “Sweet orosensation induces Arc expression in dorsal hippocampal CA1 neurons in an Experience-dependent manner.”