Extraordinary neoteny of synaptic spines in the human prefrontal cortex

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 108; no. 32; pp. 13281 - 13286
• Main Authors: Petanjek, Zdravko, JudaÅ¡, MiloÅ, Å imić, Goran, RaÅ¡in, Mladen Roko, Uylings, Harry B.M, Rakic, Pasko, Kostović, Ivica
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 09.08.2011; National Acad Sciences
• Subjects: Adolescence; Adolescent; Adolescents; Adult; Adults; Age; Aged; Aged, 80 and over; Behavioral neuroscience; Biological Sciences; Brain; cerebral cortex; Child; Child, Preschool; childhood; Children; cognition; Cognitive ability; Cortex; Cortex (prefrontal); Dendrites; Dendritic spines; Dendritic Spines - metabolism; Emotions; Environmental effects; Environmental impact; Gene expression; human development; Humans; Infant; Infant, Newborn; Mental disorders; Middle Aged; Neonates; Neoteny; Neurological disorders; Neurons; Prefrontal cortex; Prefrontal Cortex - cytology; Prefrontal Cortex - growth & development; Prefrontal Cortex - metabolism; Primates; Proteins; Pruning; Puberty; Pyramidal cells; Pyramidal Cells - cytology; Pyramidal Cells - growth & development; Spine; Synapses; Synapses - metabolism; Synaptic density; Young Adult
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1105108108

The major mechanism for generating diversity of neuronal connections beyond their genetic determination is the activity-dependent stabilization and selective elimination of the initially overproduced synapses [Changeux JP, Danchin A (1976) Nature 264:705–712]. The largest number of supranumerary synapses has been recorded in the cerebral cortex of human and nonhuman primates. It is generally accepted that synaptic pruning in the cerebral cortex, including prefrontal areas, occurs at puberty and is completed during early adolescence [Huttenlocher PR, et al. (1979) Brain Res 163:195–205]. In the present study we analyzed synaptic spine density on the dendrites of layer IIIC cortico–cortical and layer V cortico–subcortical projecting pyramidal neurons in a large sample of human prefrontal cortices in subjects ranging in age from newborn to 91 y. We confirm that dendritic spine density in childhood exceeds adult values by two- to threefold and begins to decrease during puberty. However, we also obtained evidence that overproduction and developmental remodeling, including substantial elimination of synaptic spines, continues beyond adolescence and throughout the third decade of life before stabilizing at the adult level. Such an extraordinarily long phase of developmental reorganization of cortical neuronal circuitry has implications for understanding the effect of environmental impact on the development of human cognitive and emotional capacities as well as the late onset of human-specific neuropsychiatric disorders.