Disorder of a derived mechanism of nervous system functions, capable to have evolved, provides a testable explanation for age-related neurodegeneration

By viewing memories as first-person internal sensations, it was possible to derive a potential mechanism of nervous system functions. Accordingly, a spectrum inter-postsynaptic functional LINKs (IPLs) are the key structural changes responsible for encoding learning-changes in physiological time-scales of milliseconds that can be retained for variable lengths of time. The inter-spine interaction that lead to the formation of IPLs was examined for its feasibility to have evolved through the simple steps of variation and selection. A stage of significant spine and neuronal loss during the early stages of development indicates that a corresponding stage of IPL fusion that led to neuronal loss during evolution. In the surviving cells is expected that a mechanism for stabilizing IPLs for the rest of life was triggered. This sequence of events can be achieved if the initial stage of transient inter-neuronal inter-spine fusion can trigger the lifelong expression of specific proteins that can stabilize the intermediate stage of inter-spine hemifusion. This is supported by the presence of proteins within the spines that arrest fusion between the spines. Since IPL mechanisms are expected to be utilized during every event of learning, any defect in the continued expression of proteins that stabilizes IPLs at the stage of hemifusion can lead to age-related neurodegeneration.