New York: Activities like playing video games or tennis may help enhance your memory, a study has found. Attention-grabbing experiences release memory-enhancing chemicals in brain, helping to store memories that occur just before or soon after the experience, the study mentioned. "Activation of the locus coeruleus (part of the brainstem) increases our memory of events that happen at the time of activation and may also increase the recall of those memories at a later time," said Robert Greene, Professor at the Peter O'Donnell Jr. Brain Institute at UT Southwestern Medical Center's Texas Institute for Brain Injury and Repair, at Dallas in Texas. The study, published in the journal Nature explains at the molecular level why people tend to remember certain events in their lives with particular clarity as well as unrelated details surrounding those events. The latest study established that dopamine in the brain can be naturally activated through behavioural actions and that these actions enhance memory retention. The study tested 120 mice to establish a link between locus coeruleus (LC) neurons and neuronal circuits of the hippocampus -- the region of the brain responsible for recording memories -- that receive dopamine from the LC. One part of the research involved putting the mice in an arena to search for food hidden in sand that changed location each day. The study found that the mice that were given a chance to explore an unfamiliar floor surface 30 minutes after being trained to remember the food location did better in remembering where to find the food the next day. Researchers correlated this memory enhancement to a molecular process in the brain by injecting the mice with a genetically encoded light-sensitive activator called channelrhodopsin. This sensor allowed them to selectively activate dopamine-carrying neurons of the locus coeruleus that go to the hippocampus and to see first-hand which neurons were responsible for the memory enhancement. They found that selectively activating the channelrhodopsin-labeled neurons with blue light (a technique called optogenetics) could substitute for the novelty experience as a memory enhancer in mice. They also found that this activation could cause a direct, long-lasting synaptic strengthening -- an enhancement of memory-relevant communication occurring at the junctions between neurons in the hippocampus. This process can mediate improvement of learning and memory. "Some next steps include investigating how big an impact this finding can have on human learning, whether it can eventually lead to an understanding of how patients can develop failing memories, and how to better target effective therapies for these patients," Greene added.