NRGN and Alzheimer disease: Consistent with our observations in the MTG, AD-related hDEGs in the downregulated EXC-M1 (Fig. 5K), include SNAP25, NRGN, THY1, and RTN3, which are implicated in various processes central to AD pathophysiology, including synaptic neurotransmission, synaptic plasticity, synaptic signaling, immune response, neuron development, and endoplasmic reticulum (ER) morphology and function (Fig. 5N).