Lateral Entorhinal Cortex Dysfunction in Alzheimer's Disease Mice.

Area of Science:

• Neuroscience
• Alzheimer's Disease Research
• Cognitive Neuroscience

Background:

• Alzheimer's disease (AD) involves amyloid beta and neurofibrillary tangles, causing neuronal loss in the entorhinal cortex (EC).
• The lateral EC (LEC) is vital for non-spatial memory, including object recognition, via object and trace cells.
• Dysfunction in LEC can lead to memory impairments like forgetfulness and disorientation.

Purpose of the Study:

• To investigate the impact of AD pathology on LEC neuronal function and object coding.
• To assess memory deficits in a transgenic mouse model (EC-App/Tau) mimicking AD-related EC pathology.
• To correlate neuronal firing patterns with memory performance in the context of AD.

Main Methods:

• Utilized a transgenic EC-App/Tau mouse model expressing amyloid precursor protein (APP) and tau in the EC.
• Performed in vivo single-unit electrophysiology recordings in the LEC of both transgenic and control mice.
• Assessed performance in LEC-specific memory tasks to evaluate functional deficits.

Main Results:

• EC-App/Tau mice exhibited deficits in LEC-specific memory tasks.
• LEC neurons in transgenic mice showed hyperactivity, low information content, and high sparsity, indicating poor firing fidelity.
• Object and trace cells in EC-App/Tau mice displayed reduced firing precision, suggesting impaired object encoding.

Conclusions:

• AD pathology in the EC leads to aberrant LEC neuronal firing and impaired object coding.
• These cellular and network-level defects contribute to the non-spatial memory impairments observed in Alzheimer's disease.
• The EC-App/Tau mouse model provides insights into the mechanisms underlying AD-related memory loss.