ANSWER: Entorhinal cortex
Explanation:
Young adults with increased risk of Alzheimer’s from a genetic perspective have activation patterns in brain region critical for spatial navigation. The grid cell system in the entorhinal cortex was exampled by German researchers. In this cortex, grid cells fire in spatial grid pattern. Risk carriers have a less stable grid pattern in the entorhinal cortex decades before they develop this dementia. They also moved less frequently in centre of virtual landscape which suggests altered navigation strategy.