Synaptic dynamism measured over minutes to months: age-dependent decline in an autonomic ganglion

Gan, Wen‐Biao; Kwon, Elaine; Feng, Guoping; Sanes, Joshua R.; Lichtman, Jeff W.

doi:10.1038/nn1115

Cited by 73 publications

(46 citation statements)

References 34 publications

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“…This adolescent-typical remodeling of brain could provide a relatively delayed window of opportunity to sculpt the brain to match the environmental circumstances encountered by the organism as it approaches maturity (see Andersen, 2003). Indeed, the greater capacity for synaptic remodeling seen developmentally through adolescence diminishes markedly following adolescence (Gan et al, 2003).…”

Section: The Neuroscience Of Adolescencementioning

confidence: 99%

Assessment of adolescent neurotoxicity: Rationale and methodological considerations

Spear

2007

Neurotoxicology and Teratology

103

106

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This introduction to the special issue of Neurotoxicology and Teratology on "Risk of neurobehavioral toxicity in adolescence" begins by broadly considering the ontogeny and phylogeny of adolescence, and the potential value of animal models of adolescence. Major findings from the emerging neuroscience of adolescence are then highlighted to establish the importance of studies of adolescent neurotoxicity. A variety of methodological issues that are of particular relevance to adolescent exposures are then discussed. These include consideration of pharmacokinetic factors, inclusion of other-aged comparison group(s), and issues involving timing, route of administration, and exposureinduced alterations in growth rate. Despite such methodological challenges, research to determine whether adolescence is a time of increased vulnerability (or greater resiliency) to specific drugs and environmental toxicants is progressing rapidly, as exemplified by the work presented in the articles of this special issue. Keywordsadolescence; neurotoxicity; behavior; animal models; brain sculpting; pharmacokinetics; drug metabolism; body weight; methodology Most of what we know about neural and behavioral consequences of developmental exposure to drugs and other chemicals is based on exposures during the prenatal and early postnatal period, with little emphasis on exposure periods that subsume adolescence. With the increasing recognition that adolescence is a time of considerable neural restructuring and sculpting of the brain (for review, see Spear, 2000), there likewise has been a growing interest in assessing whether this developmental transition is a vulnerable period for neurotoxicity. This special issue is designed to highlight research examining "the question of whether adolescence is a…. (time) of enhanced neurobehavioral toxic risk associated with exposure to drugs of abuse, therapeutic drugs, hormones and environmental toxicants." By presenting examples of the emerging research in this area, the goal of the special issue is to encourage additional high quality work in this area, and to draw attention to Neurotoxicology and Teratology as an outlet for this research.

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Section: The Neuroscience Of Adolescencementioning

confidence: 99%

Assessment of adolescent neurotoxicity: Rationale and methodological considerations

Spear

2007

Neurotoxicology and Teratology

103

106

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“…Using time-lapse two-photon laser scanning microscopy imaging, Lendvai et al (41) observed greatest experience-dependent plasticity of dendritic spines during a critical period of the rats in vivo. Recently Gan et al (42), using transgenic mice that express yellow fluorescent protein in axons, found that axonal branches frequently retracted or extended on a time scale of minutes in young adult mice, but seldom in mature animals. Our observation of the practice effect in the activation patterns of human parietal cortex of adolescents, but not adults, might be parallel to these findings.…”

Section: Event-related Fmri Findings Exploratory Analysismentioning

confidence: 99%

The change of the brain activation patterns as children learn algebra equation solving

Qin

Carter

Silk

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

119

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In a brain imaging study of children learning algebra, it is shown that the same regions are active in children solving equations as are active in experienced adults solving equations. As with adults, practice in symbol manipulation produces a reduced activation in prefrontal cortex area. However, unlike adults, practice seems also to produce a decrease in a parietal area that is holding an image of the equation. This finding suggests that adolescents' brain responses are more plastic and change more with practice. These results are integrated in a cognitive model that predicts both the behavioral and brain imaging results.T he study reported here integrates behavioral methods, functional brain imaging (functional MRI), and cognitive modeling to study how children learn to solve equations. In particular, the children were solving equations like the following: 7x ϩ 1 ϭ 29. Past research with adult college students (1) modeled algebra equation solving by the interaction of three cognitive modules in the adaptive control of thought-rational (ACT-R) cognitive architecture (2, 3). There was an imaginal module that held a representation of the equation and performed imagined transformations on the equations. There was a retrieval module that retrieved algebraic rules and arithmetic facts in the solution of this equation. Finally, there was a manual module that programmed the output of the answer by the hand. A region in the left parietal cortex, which has been associated with imagery (4-6) and spatial processing (7) in other studies, was found to correspond to the imaginal module. A region in the left prefrontal cortex, which has been associated with retrieval in other studies (8)(9)(10)(11)(12)(13)(14), was found to correspond to the retrieval module. Finally, a region in the left motor and sensory cortices, which controls the right hand, was found to correspond to the manual module.After having identified these regions in algebra equation solving, we performed a series of experiments to determine whether they were specifically involved in algebra or were also involved in nonmathematical information-processing tasks (1,15,16). Similar involvement of these regions was found in a nonmathematical isomorph of algebra (artificial algebra) (1). Subsequent research (15), in which college students practiced the isomorph, found a speed-up that could be accounted for entirely in terms of reduced retrieval time. This finding was reflected in reduced activation in the prefrontal region of interest. There was not a comparable reduction in either the motor or parietal region.The present research addresses the question of whether the brain activation patterns observed from adults will be shown in children learning algebra. Specifically, do children who are just learning equation solving show activation of the same regions as in adults' algebra (1) and will their improvement be explained in terms of reduction just in the prefrontal retrieval region shown in adults' artificial algebra learning (15)? There is reason to suspect that we...

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“…Sanes calls Lichtman ''the world's greatest expert in live imaging of synapses as they form.'' Together, they fused Sanes' knowledge of molecular genetics with Lichtman's skills in imaging to determine how synapses form and how genotypes affect phenotypes in real time (18)(19)(20).…”

Section: A Different Washingtonmentioning

confidence: 99%

Biography of Joshua R. Sanes

Davis¹

2004

Proc. Natl. Acad. Sci. U.S.A.

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Synaptic dynamism measured over minutes to months: age-dependent decline in an autonomic ganglion

Cited by 73 publications

References 34 publications

Assessment of adolescent neurotoxicity: Rationale and methodological considerations

Assessment of adolescent neurotoxicity: Rationale and methodological considerations

The change of the brain activation patterns as children learn algebra equation solving

Biography of Joshua R. Sanes

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