Children born prematurely show differences in a subtle but important aspect of memory: the ability to form and retrieve memories about context, such as what, when, and where something happened, according to a recent study.

Researchers from the University of the Saarland and Saarland University Hospital found that the hippocampus region of the brain is smaller in children born prematurely. This is the part of the brain that's essential for forming and retrieving contextual memories.

This type of memory is important, but can be missed on the usual set of direct assessments. The new research suggests that it may be valuable to find targeted ways to help strengthen this aspect of memory in children born preterm.

"Our study provides evidence that prematurity can result in problems with a particular subprocess of recollection," Kerstin H. Kipp, principal investigator of study, said in a statement. "The specific modification in the memory network is so subtle that it could be overlooked because it doesn't manifest itself in clear memory impairment. But memory deficits can appear in situations in which retrieving contextual information is essential."

In everyday life, this could lead to problems like forgetting where you put your keys or trying to remember the color of a car in a traffic accident you witnessed.

For the study, researchers examined 33 German 8- to 10-year-olds, 18 of whom were born preterm (defined in the study as born at 26 to 33 weeks) and 15 of whom were born full term (defined in the study as born at 39 to 42 weeks.) Researchers used magnetic resonance imaging to measure the volume of the hippocampi. Later, the children performed a memory task on which they were asked to learn and recognize certain items: Previously studied pictures of line drawings were mixed with new pictures, and the children had to indicate whether the picture was old or new. Their brain activity was measured by an electroencephalogram (EEG) as they did so, allowing the researchers to gauge the processes involved in memory retrieval.

The ability to recognize whether the picture was old or new was not reduced in the children who were born prematurely. However, the EEG index of recollection-based memory retrieval, which is important for remembering contextual information, was reduced.

"Our results have important implications for improving the treatment of children born preterm. Instead of applying unspecific memory training, the affected children might benefit more from learning how to strengthen associations between different elements of memories," Kipp noted.

The findings are detailed in the journal Child Development.