In older adults, changes in brain structure and function are associated with declines in some aspects of cognitive performance. One phenomenon that may play an important role in cognitive aging is “neural dedifferentiation” – the finding that older adult brains tend to show less selective patterns of neural activity for certain types of information. This reduction in neural selectivity could be associated with cognitive decline.
A new study published in the Journal of Neuroscience builds on previous work at the Center for Vital Longevity, from the laboratory of Director of Research Dr. Denise Park, which showed that less selectivity in neural activity was associated with poorer cognitive performance in healthy older adults.
The new study, from the laboratory of Center Director Dr. Michael Rugg, measured how neural selectivity in a region of the brain called the “parahippocampal place area” or PPA, a region implicated in processing visual scenes, differed with age and measures of memory.
For the study, groups of 24 young and 24 older adults underwent functional magnetic resonance imaging (fMRI) while viewing images that included scenes and objects. As has been described many time before, viewing scenes resulted in selective activity of the PPA. This pattern of neural selectivity, however, was reduced in healthy older individuals, a finding that replicates previous results.
The novel result was that neural selectivity in the PPA predicted cognitive performance regardless of the participant’s age. In both young and older adults, higher levels of neural selectivity were associated with better memory for the objects and scenes they viewed while undergoing fMRI, as well as with better performance on some cognitive tests.
This “age-invariant” relationship between neural selectivity and cognitive performance likely reflects a general principle of brain function, said first author and now assistant professor Dr. Joshua Koen, who undertook this work as a postdoctoral researcher at CVL prior to joining the faculty at the University of Notre Dame earlier this year. Dr. Rugg, who leads the Functional Neuroimaging of Memory laboratory at CVL, is the senior author on the paper, while former research assistant Nedra Hauck is the middle author. The research was supported by a grant from the National Institute on Aging, and a fellowship from the Aging Mind Foundation.