The latest study conducted by researchers from the Duke University Medical Center was performed on two groups of (old and young) adults. The first group had an average age of about 70 while the younger ones were about 24 years old. Neuroscientists found out that the mechanism behind the part of the brain responsable for remembering (especially emotional content) was different for the two groups.
They were shown a group of 30 photographs; during the period in which they were shown the pictures, their brains were connected to a functional MRI (fMRI). The pictures varied in content and emotional impact; some had just neutral landscapes or pictures from nature, while some were very violent or just repulsive (such as snakes attacking, corpses, mutilated bodies, etc). They were then asked to place the pictures in a “pleasantness” scale. Then, the neuroscientists analyzed the data by interpreting how many neutral and negative pictures the groups missed.
The direct result was that the older people have less connectivity between the area that generates emotions and feelings and the part of the brain responsable for learning new things. Younger people used the part of the brain responsable for creating emotions to help them remember, while older people have a tighter connection with the frontal cortex.
“The younger adults were able to recall more of the negative photos,” said Roberto Cabeza, Ph.D., senior author and Duke professor in the Center for Cognitive Neuroscience. If the older adults are using more thinking than feeling, “that may be one reason why older adults showed a reduction in memory for pictures with a more negative emotional content.”
“It wasn’t surprising that older people showed a reduction in memory for negative pictures, but it was surprising that the older subjects were using a different system to help them to better encode those pictures they could remember,” said lead author Peggy St. Jacques, a graduate student in the Cabeza laboratory.
“Perhaps at different stages of life, there are different brain strategies,” Cabeza speculated. “Younger adults might need to keep an accurate memory for both positive and negative information in the world. Older people dwell in a world with a lot of negatives, so perhaps they have learned to reduce the impact of negative information and remember in a different way.” According to Cabeza, the results of the study are consistent with a theory about emotional processes in older adults proposed by Dr. Laura Carstensen at Stanford University, an expert in cognitive processing in old age.