MAPT and Alzheimer disease: Although these general tau expression experiments demonstrated the toxicity of tau accumulation, certain issues remain unaddressed: (1) whether various hippocampal subregions and neuron types exhibit distinct susceptibilities to tau pathology; (2) whether and how differential impairments in episodic memory domains result from cell type-specific tau accumulation; and (3) how to target tau accumulation to rescue episodic memory disorders in AD patients.