The morphological basis of age-induced memory changes.

The results are presented of a layer-by-layer electron microscopic study of the cortex (40th area) in persons aged 78, 79, and 83 years whose anamneses did not include any neuropsychic disorders and who had died during surgical intervention These findings are examined in the light of current hypotheses about the morphological substrate of the mechanisms of memory. Cortical changes are uncovered which, according to these hypotheses, lie at the basis of the memory mechanisms. These include changes of the cytoplasm, neurocytes, dendrites, spines, axons, and their terminals. The same types of changes are found in the auditory cortex of old cats used for the control of the degree of preservation of elements of the human cortex.