High Resolution Brain Imaging Provides Clues to Age Related Memory Loss

Summary: The decline of signalling in the anterolateral entorhinal cortex has been linked to memory loss associated with aging, a new neuroimaging study reveals.

Source: Cell Press.

As we get older, it’s not uncommon to experience “senior moments,” in which we forget where we parked our car or call our children by the wrong names. But currently there are no good ways to determine which memory lapses are normal parts of aging and which may signal the early stages of a severe disorder like Alzheimer’s disease. In a study appearing March 7 in the journal Neuron, researchers report that data from high-resolution functional brain imaging can be used to show some of the underlying causes for differences in memory proficiency between older and younger adults.


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ABSTRACT

Functional Imbalance of Anterolateral Entorhinal Cortex and Hippocampal Dentate/CA3 Underlies Age-Related Object Pattern Separation Deficits

Highlights •The anterolateral entorhinal cortex (alEC) is hypoactive in older adults •The hippocampal dentate and CA3 (DG/CA3) regions are hyperactive in older adults •Imbalance of DG/CA3-alEC predicts deficits in object mnemonic discrimination •Imbalance of DG/CA3-alEC is a novel biomarker for age-related memory decline

Summary The entorhinal cortex (EC) is among the earliest brain areas to deteriorate in Alzheimer’s disease (AD). However, the extent to which functional properties of the EC are altered in the aging brain, even in the absence of clinical symptoms, is not understood. Recent human fMRI studies have identified a functional dissociation within the EC, similar to what is found in rodents. Here, we used high-resolution fMRI to identify a specific hypoactivity in the anterolateral EC (alEC) commensurate with major behavioral deficits on an object pattern separation task in asymptomatic older adults. Only subtle deficits were found in a comparable spatial condition, with no associated differences in posteromedial EC between young and older adults. We additionally linked this condition to dentate/CA3 hyperactivity, and the ratio of activity between the regions was associated with object mnemonic discrimination impairment. These results provide novel evidence of alEC-dentate/CA3 circuit dysfunction in cognitively normal aged humans.

Source: Joseph Caputo – Cell Press Publisher: Organized by NeuroscienceNews.com. Image Source: NeuroscienceNews.com image is credited to Zachariah Reagh. Original Research: Open access research in Neuron. doi:10.1016/j.neuron.2018.01.039