Figure 1.

Known age-related electrophysiological and morphological changes in neurons. Neuron is depicted as a generic myelinated neuron for simplicity, in order to summarize information from different animal models and neuronal cell type. (A) Age-related increase of altered neurotransmitter receptors (gray) and decreased expression of normal ones (green). (B) Representative AP traces of young and aged neuron. (C) Absence/disruption of paranodal ultrastructure (in red) leading K⁺ channels to be relocated adjacent to “Na_v” clusters. (D) Depletion of myelin layers (in red) leading to an increase of the occurrence of redundant myelin sheaths exposing the enclosed axon. (E) Alterations in Na⁺ and K⁺ channel properties or subtype expression patterns. (Illustration was created using Autodesk 3Ds Max and Adobe Photoshop).