Life‐span dendritic and spine changes in areas 10 and 18 of human cortex: A quantitative golgi study

Abstract

Dendritic neuropil is a sensitive indicator of the aging process and may exhibit regional cortical variations. The present study examined regional differences and age-related changes in the basilar dendrites/spines of supragranular pyramidal cells in human prefrontal (area 10) and secondary occipital (area 18) cortices. Tissue was obtained from the left hemisphere of 26 neurologically normal individuals ranging in age from 14 to 106 years (M(age) = 57 +/- 22 years; 13 males, 13 females). In tissue prepared by a modified rapid Golgi technique, ten neurons were sampled from each cortical region (N = 520) and were evaluated according to the following parameters: total dendritic length, mean segment length, dendritic segment count, dendritic spine number, and dendritic spine density. The effects of age and Brodmann areas were analyzed with a nested multiple analysis of variance design. Despite considerable interindividual variation, several clear findings emerged: 1) Dendritic systems were significantly larger in area 10 than in area 18 across the sampled life span, presumably because of the more integrative function of area 10 neurons. 2) There was a significant age effect, with a substantial decline in dendritic neuropil from the younger (< or =50 years) group to the older (>50 years) group, especially in spine measures, which decreased almost 50%. 3) Dendritic values were relatively stable after 40 years of age, suggesting that dendritic/spine degeneration in older, relatively healthy individuals may not be an inevitable consequence of the aging process. These findings underscore the importance of life-long commitment to a cognitively invigorating environment.

Decreased pyramidal neuron size in Brodmann areas 44 and 45 in patients with autism

“…If the somatic size of pyramidal neurons is reduced, it is very likely that their functional integrity is compromised. A smaller cell body may also reflect a reduction in dendritic complexity and axonal length [25,35,41,54], which would cause a detrimental effect on connectivity. In this context, Casanova and colleagues investigated minicolumnar size in patients with autism and controls in nine areas of the neocortex, and found the most significant reduction in minicolumnar width in area 44 in patients with autism [10].…”

Pyramidal cells in prefrontal cortex of primates: marked differences in neuronal structure among species

“…Thus, it is tempting to conclude that highly complex pyramidal cells in the dorsolateral gPFC is a characteristic of the latter species, which may differ from that in other primates that diverged earlier, such as New World monkeys and the great apes. Alternatively, the apparent species differences may reflect regional variation in neuronal maturation rates (Jacobs and Scheibel, 1993; Jacobs et al, 1995, 1997; Page et al, 2002; Duan et al, 2003; Elston et al, 2009, 2010a,b) or arise through sampling different subsets of projection neurons in the different cortical areas, which have been shown to differ in both their morphology (Schofield et al, 1987; Hallman et al, 1988; Hübener and Bolz, 1988; de Lima et al, 1990; Hübener et al, 1990; Einstein, 1996; Matsubara et al, 1996; Duan et al, 2002; Soloway et al, 2002; Elston and Rosa, 2006) and density (Jones and Powell, 1970; Barbas, 1992; Young, 1992; Pandya and Yeterian, 2000; Petrides, 2000; Collins et al, 2005) in different cortical areas. In either case, the result is consistent with our main conclusion that pyramidal cells develop differently among cortical areas and mature into specialized circuits.…”

Neuronal morphology in the African elephant (Loxodonta africana) neocortex

“…To be consistent with previous studies (Jacobs et al 1997(Jacobs et al , 2001, processed tissue was serially sectioned at 120 lm with a vibratome. Tissue blocks adjacent to those removed for Golgi analysis were examined with a routine Nissl stain to establish laminar and cortical depth.…”