Age-related changes in the cerebellum: parallel fibers

Between the ages of 3 and 23 months, the cerebella of NM Fischer 344 rats l ose 30% of the thickness of the molecular layer, 60% of the length of paral lel fibers, and 80% of the synaptic varicosities along parallel fibers. Nea rly 60% of these synaptic varicosities disappear between 3 and 9 months. Th us, the loss of cerebellar synapses is unusual, may have begun early in lif e, and continue into old age, causing profound synaptic losses in older rat s. In addition to serious implications to functional losses, we speculate t hat these synaptic losses may trigger other age-related cellular losses in the cerebellum. (C) 1999 Published by Elsevier Science B.V. All rights rese rved.