A professor from Washington University in St. Louis (WUSTL), Missouri, has looked at the brain activity of older adults through a slightly different set of tests than common ones for memory. Zachariah Reagh found that aging adults don’t necessarily have “quieter” memory – “It’s just different,” he said.

Reagh used a data set from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) that included functional MRI (fMRI) scans of people aged 18-88 watching a short movie. It was outwardly a relaxing affair. Meanwhile, the subjects’ brains were hard at work recognising, interpreting and categorising events in the movie. One particular way to categorise events is by marking boundaries – where one event ends and another begins – and what constitutes a boundary is actually consistent among people.

The fMRI results, which used changes in blood flow and blood oxygen to highlight brain activity, showed similarly increased activity in older adults as a control group at the boundaries of events. Overall activity did decline pretty reliably across subjects, and when grouped into “younger, middle aged, and older,” there was a statistically reliable drop in activity from one group to another.

Older adults likely lose some responsiveness in posterior parts of the brain. In addition to memory, posterior areas are heavily involved in representing context and situational awareness. “They may be shifting away from the more detailed contextual information,” Reagh said. But as activity levels ramp up in the anterior portions, “things might become more schematic or more ‘gist-like.'”

“Older adults might just be representing events in different ways, and transitions might be picked up differently than, say, a 20-year-old,” Reagh concluded.