Alzheimer's disease is one of the most serious diseases in an aging society, yet the cause is often unclear and there is no appropriate treatment method. Many patients with Alzheimer's disease develop spatial memory impairment which causes symptoms such as wandering, putting a great stress on caregivers. However, the cause of spatial memory impairment has been long unclear.
A research group led by Kei Igarashi, an assistant professor at University of California, Irvine elucidated the brain circuit mechanism that cause of spatial memory impairment in Alzheimer's disease. The research group used Alzheimer's disease model mice developed at RIKEN in 2014 and analyzed the brain activity of mice performing memory behaviors using an electrophysiological technique(1). The results showed that brain function to distinguish different locations called as "remapping"(2), a function of the hippocampus(3) of healthy brain, become impaired. The results also showed that this hippocampal dysfunction was caused by decreased activity in the brain region called the entorhinal cortex(4).
These results indicate that the impairment of remapping causes spatial memory impairment in Alzheimer's disease. In the future, improving brain remapping function may reverse spatial memory impairment in patients with Alzheimer's disease, for example using deep brain stimulation methods.
The study was conducted jointly with Takaomi Saido, a team leader at the RIKEN and Professor Takashi Saito at Nagoya City University, as part of the JST Strategic Basic Research Programs.
Jun, H., et al. (2020) Disrupted Place Cell Remapping and Impaired Grid Cells in a Knockin Model of Alzheimer's Disease. Neuron. doi.org/10.1016/j.neuron.2020.06.023.