Synaptogenesis in human visual cortex — evidence for synapse elimination during normal development

Huttenlocher, Peter R.; Courten, Christian de; Garey, L. J.; Loos, H. Van der

doi:10.1016/0304-3940(82)90379-2

Cited by 687 publications

(365 citation statements)

References 19 publications

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“…In early visual areas, this cyclic pattern of growth and pruning occurs at very early ages with a rapid burst of synapse formation in the first postnatal months and a peak of synaptic density, which exceeds 150% of the adult level, between four and twelve months. At the end of the first year, synaptic density starts to decrease and gradually reaches adult levels in middle childhood (Huttenlocher and de Courten, 1987;Huttenlocher et al, 1982). Therefore, we suggest that the higher P1/N1 peak amplitudes for children observed in the present study reflect, at least to some degree, higher synaptic densities in visual areas relative to younger and older adults.…”

Section: Erp and Evoked Gamma-band Responses In Children: Immaturity supporting

confidence: 55%

EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

Werkle‐Bergner

Shing

Müller

et al. 2009

Clinical Neurophysiology

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a b s t r a c tObjective: To investigate lifespan age differences in neuronal mechanisms of visual coding in the context of perceptual discrimination. Methods: We recorded EEG from 17 children (10-12 years), 16 younger adults (20-26 years), and 17 older adults (70-76 years) during a simple choice-reaction task requiring discrimination of squares and circles of different sizes. We examined age-group differences in the effect of stimulus size on early ERP components, evoked gamma-band power, and inter-trial phase-stability in the gamma band as assessed by the phase-locking index (PLI). Results: In the absence of age differences in discrimination accuracy, we observed reliable age differences in patterns of ERP, evoked gamma power, and PLI. P1 and N1 peak amplitudes were larger and the peak latencies longer in children than in adults. Children also showed lower levels of evoked power and PLI than adults. Older adults showed smaller increments in evoked power with increasing stimulus size than younger adults, but similar amounts of phase locking for small-and medium-sized stimuli as younger adults. Conclusions: The relative importance of different coding mechanisms in early visual areas changes from childhood to old age. Due to synaptic overproduction and immature myelination, the visual system of children is less entrained by incoming information, resulting in less synchronized neuronal responses. Adults primarily rely on sparse representations formed through experience-dependent temporally synchronized neuronal interactions. In old age, senescent decline in neuronal density and neurotransmitter availability further increase the reliance on temporally synchronized processing. Significance: Findings from this study defy the notion that sensory aging consists in a reversal of sensory development in childhood, and point to a high degree of age specificity in mechanisms of visual coding.

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Section: Erp and Evoked Gamma-band Responses In Children: Immaturity supporting

confidence: 55%

EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

Werkle‐Bergner

Shing

Müller

et al. 2009

Clinical Neurophysiology

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“…Such pruning processes are driven either by apoptosis (Cusack, Swahari, Hampton Henley, Michael Ramsey, & Deshmukh, 2013) or by experience (Eyding, Schweigart, & Eysel, 2002; Yu et al., 2013), but in all likelihood by a combination of both factors. It is well known from neurophysiological studies that the rapid phase of synaptogenesis in early childhood is followed by subsequent longer periods of pruning, during which synapses are eliminated by about 40% to reach near‐mature levels at 11 years of age (Huttenlocher, 1984, 1990; Huttenlocher & de Courten, 1987; Huttenlocher, de Courten, Garey, & Van der Loos, 1982). For example, it has been suggested that sensory deprivation during early childhood might cause a substantial reduction in pruning of the exuberant cortico‐cortical and/or cortico‐thalamo‐cortical connections that exist in early infancy.…”

Section: Discussionmentioning

confidence: 99%

Structural and functional hyperconnectivity within the sensorimotor system in xenomelia

et al. 2017

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IntroductionXenomelia is a rare condition characterized by the persistent and compulsive desire for the amputation of one or more physically healthy limbs. We highlight the neurological underpinnings of xenomelia by assessing structural and functional connectivity by means of whole‐brain connectome and network analyses of regions previously implicated in empirical research in this condition.MethodsWe compared structural and functional connectivity between 13 xenomelic men with matched controls using diffusion tensor imaging combined with fiber tractography and resting state functional magnetic resonance imaging. Altered connectivity in xenomelia within the sensorimotor system has been predicted.ResultsWe found subnetworks showing structural and functional hyperconnectivity in xenomelia compared with controls. These subnetworks were lateralized to the right hemisphere and mainly comprised by nodes belonging to the sensorimotor system. In the connectome analyses, the paracentral lobule, supplementary motor area, postcentral gyrus, basal ganglia, and the cerebellum were hyperconnected to each other, whereas in the xenomelia‐specific network analyses, hyperconnected nodes have been found in the superior parietal lobule, primary and secondary somatosensory cortex, premotor cortex, basal ganglia, thalamus, and insula.ConclusionsOur study provides empirical evidence of structural and functional hyperconnectivity within the sensorimotor system including those regions that are core for the reconstruction of a coherent body image. Aberrant connectivity is a common response to focal neurological damage. As exemplified here, it may affect different brain regions differentially. Due to the small sample size, our findings must be interpreted cautiously and future studies are needed to elucidate potential associations between hyperconnectivity and limb disownership reported in xenomelia.

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“…After the initial development in the mammalian brain, synapse elimination and refinement occur though interaction with the environment via sensory inputs (Huttenlocher et al, 1982;Elston et al, 2009). However, the detailed mechanisms of this elimination and refinement remain unclear.…”

Section: Relationship Between Synaptic Densities and Network Electricmentioning

confidence: 99%

Measurement of saturation processes in glutamatergic and GABAergic synapse densities during long-term development of cultured rat cortical networks

2013

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The aim of this study was to clarify the saturation processes of excitatory and inhibitory synapse densities during the long-term development of cultured neuronal networks. For this purpose, we performed a long-term culture of rat cortical cells for 35 days in vitro (DIV). During this culture period, we labeled glutamatergic and GABAergic synapses separately using antibodies against vesicular glutamate transporter 1 (VGluT1) and vesicular transporter of -aminobutyric acid (VGAT). The densities and distributions of both types of synaptic terminals were measured simultaneously. Observations and subsequent measurements of immunofluorescence demonstrated that the densities of both types of antibody-labeled terminals increased gradually from 7 to 21-28 DIV. The densities did not show a further increase at 35 DIV and tended to become saturated.Triple staining with VGluT1, VGAT, and microtubule-associated protein 2 (MAP2) enabled analysis of the distribution of both types of synapses, and revealed that the densities of the two types of synaptic terminals on somata were not significantly different, but that glutamatergic synapses predominated on the dendrites during long-term culture.However, some neurons did not fall within this distribution, suggesting differences in synapse distribution on target neurons. The electrical activity also showed an initial increase and subsequent saturation of the firing rate and synchronized burst rate during long-term culture, and the number of days of culture to saturation from the initial increase followed the same pattern under this culture condition.

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Synaptogenesis in human visual cortex — evidence for synapse elimination during normal development

Cited by 687 publications

References 19 publications

EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

Structural and functional hyperconnectivity within the sensorimotor system in xenomelia

Measurement of saturation processes in glutamatergic and GABAergic synapse densities during long-term development of cultured rat cortical networks

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