NRGN and Alzheimer disease: The mossy fibre CA3 synapses contain NMDA types of glutamate receptors with different subunits expressed at post- and pre-synaptic (recurrent connections) locations.31 While the pre-synaptic receptors may have a modulatory role, excitotoxicity may be induced at post-synaptic or extra-synaptic receptors, where Aß-oligomers may induce spine loss and neurodegeneration, leading to Ng release in Alzheimer’s disease.12,32–34 Memantine is currently the only clinically approved NMDA-receptor antagonist used in Alzheimer’s disease.