Spatial memory deficits in Alzheimer's disease and their connection to cognitive maps' formation by place cells and grid cells

Whenever we navigate through different contexts, we build a cognitive map: an internal representation of the territory. Spatial navigation is a complex skill that involves multiple types of information processing and integration. Place cells and grid cells, collectively with other hippocampal and medial entorhinal cortex neurons (MEC), form a neural network whose activity is critical for the representation of self-position and orientation along with spatial memory retrieval. Furthermore, this activity generates new representations adapting to changes in the environment. Though there is a normal decline in spatial memory related to aging, this is dramatically increased in pathological conditions such as Alzheimer's disease (AD). AD is a multi-factorial neurodegenerative disorder affecting mainly the hippocampus-entorhinal cortex (HP-EC) circuit. Consequently, the initial stages of the disease have disorientation and wandering behavior as two of its hallmarks. Recent electrophysiological studies have linked spatial memory deficits to difficulties in spatial information encoding. Here we will discuss map impairment and remapping disruption in the HP-EC network, as a possible circuit mechanism involved in the spatial memory and navigation deficits observed in AD, pointing out the benefits of virtual reality as a tool for early diagnosis and rehabilitation.

Automated summary

When navigating different contexts, our brain builds a cognitive map to internally represent the territory. Spatial navigation involves complex information processing and integration, with place cells, grid cells, and other neurons forming a neural network critical for self-position and spatial memory. Alzheimer's disease (AD), a neurodegenerative disorder affecting the hippocampus-entorhinal cortex (HP-EC) circuit, results in spatial memory deficits and disorientation. Recent studies suggest impairment in spatial information encoding as a possible mechanism, and virtual reality shows promise for early diagnosis and rehabilitation.