Dendritic Growth in the Aged Human Brain and Failure of Growth in Senile Dementia

Abstract

Golgi-stained dendrites of single randomly chosen layer-II pyramidal neurons in the human parahippocampal gyrus were quantified with a computer-microscope system. In nondemented aged cases (average age, 79.6 years), dendritic trees were more extensive than in adult cases (average age, 51.2), with most of the difference resulting from increases in the number and average length of terminal segments of the dendritic tree. These results provide morphological evidence for plasticity in the mature and aged human brain. In senile dementia (average age, 76.0), dendritic trees were less extensive than in adult brains, largely because their terminal segments were fewer and shorter. Cells with shrunken dendritic trees were found in all brains. These data suggest a model of aging in the central nervous system in which one population of neurons dies and regresses and the other survives and grows. The latter appears to be the dominant population in aging without dementia.

Outgrowth-regulating actions of glutamate in isolated hippocampal pyramidal neurons

“…The progression of dendritic outgrowth and stabilization during development has been well documented. In addition, there is considerable evidence that dendritic architecture undergoes significant changes throughout adult life (Beull and Coleman, 1979;Purves et al, 1986). Furthermore, structural correlates of brain function have also been found; plastic structural changes in synapses on hippocampal neuron dendrites occur during the long-term potentiation of synaptic transmission believed to underlie learning and memory (Desmond and Levy, 1983;Lynch, 1986).…”

Age-related spatial learning impairment is unrelated to spinophilin immunoreactive spine number and protein levels in rat hippocampus

“…Across a series of investigations in humans, Coleman and colleagues reported that, whereas the dendritic extent of hippocampal CA3 pyramidal cells remains relatively stable (Flood et al, 1987a,b), neurons in other medial temporal lobe regions, including the dentate gyrus (Flood et al, 1987a,b) and parahippocampal gyrus (Buell and Coleman, 1979), exhibit a significant increase in dendritic length during normal aging, followed by regression in the "oldest old" (over 90 years), and in patients with Alzheimer's disease. This research involved the analysis of histological material stained by the Golgi-Cox method, and a potential concern is that aging influences the sensitivity or other characteristics of dendritic labeling visualized by this approach.…”

Neurobiology and cellular pathogenesis of glycolipid storage diseases

“…During this time there is evidence that an initial overgrowth of some dendritic processes is followed by sculpting and loss of redundant processes before stabilization of the characteristic arbor. In normal, mature mammalian brain, distal branches of established dendrites on pyramidal neurons may slowly elongate (Buell & Coleman 1979), and dendritic spines themselves may exhibit remarkable plasticity (Matus 2000), but further initiation of new primary dendrites on normal mature neurons has not been observed. Based on these findings, dendritogenesis is often viewed as occurring in three somewhat overlapping stages consisting of initiation of sprouting, elongation and branching of processes forming secondary and tertiary dendrites, and finally sculpting/pruning and stabilization leading to the formation and maintenance of characteristic dendritic arbors of mature neurons.…”