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Neural Plasticity 2012
Topics: Brain; Humans; Neuronal Plasticity; Sensory Deprivation
PubMed: 23094163
DOI: 10.1155/2012/810370 -
Vision Research May 1995
Topics: Accommodation, Ocular; Animals; Chickens; Disease Models, Animal; Eye; Humans; Infant; Myopia; Sensory Deprivation; Vasoactive Intestinal Peptide
PubMed: 7610574
DOI: 10.1016/0042-6989(95)90012-8 -
Trends in Cognitive Sciences Jul 2018A growing body of evidence demonstrates that the brain can reorganize dramatically following sensory loss. Although the existence of such neuroplastic crossmodal changes... (Review)
Review
A growing body of evidence demonstrates that the brain can reorganize dramatically following sensory loss. Although the existence of such neuroplastic crossmodal changes is not in doubt, the functional significance of these changes remains unclear. The dominant belief is that reorganization is compensatory. However, results thus far do not unequivocally indicate that sensory deprivation results in markedly enhanced abilities in other senses. Here, we consider alternative reasons besides sensory compensation that might drive the brain to reorganize after sensory loss. One such possibility is that the cortex reorganizes not to confer functional benefits, but to avoid undesirable physiological consequences of sensory deafferentation. Empirical assessment of the validity of this and other possibilities defines a rich program for future research.
Topics: Animals; Cerebral Cortex; Humans; Models, Neurological; Neuronal Plasticity; Sensory Deprivation
PubMed: 29907530
DOI: 10.1016/j.tics.2018.04.004 -
The Journal of Neuroscience : the... Mar 2021Can alterations in experience trigger different plastic modifications in neuronal structure and function, and if so, how do they integrate at the cellular level? To...
Can alterations in experience trigger different plastic modifications in neuronal structure and function, and if so, how do they integrate at the cellular level? To address this question, we interrogated circuitry in the mouse olfactory bulb responsible for the earliest steps in odor processing. We induced experience-dependent plasticity in mice of either sex by blocking one nostril for one day, a minimally invasive manipulation that leaves the sensory organ undamaged and is akin to the natural transient blockage suffered during common mild rhinal infections. We found that such brief sensory deprivation produced structural and functional plasticity in one highly specialized bulbar cell type: axon-bearing dopaminergic neurons in the glomerular layer. After 24 h naris occlusion, the axon initial segment (AIS) in bulbar dopaminergic neurons became significantly shorter, a structural modification that was also associated with a decrease in intrinsic excitability. These effects were specific to the AIS-positive dopaminergic subpopulation because no experience-dependent alterations in intrinsic excitability were observed in AIS-negative dopaminergic cells. Moreover, 24 h naris occlusion produced no structural changes at the AIS of bulbar excitatory neurons, mitral/tufted and external tufted cells, nor did it alter their intrinsic excitability. By targeting excitability in one specialized dopaminergic subpopulation, experience-dependent plasticity in early olfactory networks might act to fine-tune sensory processing in the face of continually fluctuating inputs. Sensory networks need to be plastic so they can adapt to changes in incoming stimuli. To see how cells in mouse olfactory circuits can change in response to sensory challenges, we blocked a nostril for just one day, a naturally relevant manipulation akin to the deprivation that occurs with a mild cold. We found that this brief deprivation induces forms of axonal and intrinsic functional plasticity in one specific olfactory bulb cell subtype: axon-bearing dopaminergic interneurons. In contrast, intrinsic properties of axon-lacking bulbar dopaminergic neurons and neighboring excitatory neurons remained unchanged. Within the same sensory circuits, specific cell types can therefore make distinct plastic changes in response to an ever-changing external landscape.
Topics: Animals; Axon Initial Segment; Dopaminergic Neurons; Female; Male; Mice; Mice, Inbred C57BL; Neuronal Plasticity; Olfactory Bulb; Sensory Deprivation
PubMed: 33483429
DOI: 10.1523/JNEUROSCI.1606-20.2020 -
Investigative Ophthalmology & Visual... Dec 2022The sclera is believed to biomechanically influence eye size, facilitating the excessive axial elongation that occurs during myopigenesis. Here, we test the hypothesis...
PURPOSE
The sclera is believed to biomechanically influence eye size, facilitating the excessive axial elongation that occurs during myopigenesis. Here, we test the hypothesis that the sclera will be remodeled and exhibit altered biomechanics in the mouse model of form-deprivation (FD) myopia, accompanied by altered retinoid concentrations, a potential signaling molecule involved in the process.
METHODS
Male C57 Bl/6J mice were subjected to unilateral FD (n = 44 eyes), leaving the contralateral eye untreated (contra; n = 44). Refractive error and ocular biometry were measured in vivo prior to and after 1 or 3 weeks of FD. Ex vivo measurements were made of scleral biomechanical properties (unconfined compression: n = 24), scleral sulfated glycosaminoglycan (sGAG) content (dimethylmethylene blue: n = 18, and immunohistochemistry: n = 22), and ocular all-trans retinoic acid (atRA) concentrations (retina and RPE + choroid + sclera, n = 24). Age-matched naïve controls were included for some outcomes (n = 32 eyes).
RESULTS
Significant myopia developed after 1 (-2.4 ± 1.1 diopters [D], P < 0.001) and 3 weeks of FD (-4.1 ± 0.7 D, P = 0.025; mean ± standard deviation). Scleral tensile stiffness and permeability were significantly altered during myopigenesis (stiffness = -31.4 ± 12.7%, P < 0.001, and permeability = 224.4 ± 205.5%, P < 0.001). Total scleral sGAG content was not measurably altered; however, immunohistochemistry indicated a sustained decrease in chondroitin-4-sulfate and a slower decline in dermatan sulfate. The atRA increased in the retinas of eyes form-deprived for 1 week.
CONCLUSIONS
We report that biomechanics and GAG content of the mouse sclera are altered during myopigenesis. All scleral outcomes generally follow the trends found in other species and support a retina-to-sclera signaling cascade underlying mouse myopigenesis.
Topics: Male; Mice; Animals; Sclera; Sensory Deprivation; Myopia; Choroid; Retina; Disease Models, Animal
PubMed: 36512347
DOI: 10.1167/iovs.63.13.13 -
BMJ Clinical Evidence Sep 2009Amblyopia is commonly associated with squint (strabismus) or refractive errors resulting in different visual inputs to each eye during the sensitive period of visual... (Review)
Review
INTRODUCTION
Amblyopia is commonly associated with squint (strabismus) or refractive errors resulting in different visual inputs to each eye during the sensitive period of visual development (<7-8 years of age). The cumulative incidence is estimated at 2% to 4% in children aged up to 15 years.
METHODS AND OUTCOMES
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to detect amblyopia early? What are the effects of medical treatments for amblyopia? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2008 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations, such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
RESULTS
We found 16 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
CONCLUSIONS
In this systematic review, we present information relating to the effectiveness and safety of the following interventions: active vision therapy; glasses alone or with occlusion; or penalisation to treat amblyopia; and screening to detect amblyopia early.
Topics: Amblyopia; Eyeglasses; Humans; Mydriatics; Sensory Deprivation; Strabismus; Visual Acuity
PubMed: 21726480
DOI: No ID Found -
The Journal of Neuroscience : the... Feb 2022The axon initial segment (AIS), nodes of Ranvier, and the oligodendrocyte-derived myelin sheath have significant influence on the firing patterns of neurons and the...
The axon initial segment (AIS), nodes of Ranvier, and the oligodendrocyte-derived myelin sheath have significant influence on the firing patterns of neurons and the faithful, coordinated transmission of action potentials (APs) to downstream brain regions. In the olfactory bulb (OB), olfactory discrimination tasks lead to adaptive changes in cell firing patterns, and the output signals must reliably travel large distances to other brain regions along highly myelinated tracts. Whether myelinated axons adapt to facilitate olfactory sensory processing is unknown. Here, we investigate the morphology and physiology of mitral cell (MC) axons in the olfactory system of adult male and female mice and show that unilateral sensory deprivation causes system-wide adaptations in axonal morphology and myelin thickness. MC spiking patterns and APs also adapted to sensory deprivation. Strikingly, myelination and MC physiology were altered on both the deprived and nondeprived sides, indicating system level adaptations to reduced sensory input. Our work demonstrates a previously unstudied mechanism of plasticity in the olfactory system. Successful transmission of information from the olfactory bulb (OB) to piriform cortex through the lateral olfactory tract (LOT) relies on synchronized arrival of action potentials (APs). The coincident arrival of APs is dependent on reliable generation of APs in the axon initial segment (AIS) and fast conduction mediated by axon myelination. Here, we studied changes in mitral cell (MC) firing and AIS structure as well as changes in myelination of the LOT on unilateral olfactory deprivation in the adult mouse. Strikingly, myelination and MC physiology were altered on both the deprived and nondeprived sides, indicating system level adaptations to reduced sensory input. Our work demonstrates a previously unstudied mechanism of plasticity in the olfactory system.
Topics: Animals; Axons; Female; Male; Mice; Myelin Sheath; Olfactory Bulb; Sensory Deprivation; Smell
PubMed: 35022219
DOI: 10.1523/JNEUROSCI.0305-21.2021 -
Current Opinion in Neurobiology Dec 2015Sensory loss leads to widespread adaptation of brain circuits to allow an organism to navigate its environment with its remaining senses, which is broadly referred to as... (Review)
Review
Sensory loss leads to widespread adaptation of brain circuits to allow an organism to navigate its environment with its remaining senses, which is broadly referred to as cross-modal plasticity. Such adaptation can be observed even in the primary sensory cortices, and falls into two distinct categories: recruitment of the deprived sensory cortex for processing the remaining senses, which we term 'cross-modal recruitment', and experience-dependent refinement of the spared sensory cortices referred to as 'compensatory plasticity.' Here we will review recent studies demonstrating that cortical adaptation to sensory loss involves LTP/LTD and homeostatic synaptic plasticity. Cross-modal synaptic plasticity is observed in adults, hence cross-modal sensory deprivation may be an effective way to promote plasticity in adult primary sensory cortices.
Topics: Adult; Animals; Humans; Neuronal Plasticity; Sensorimotor Cortex; Sensory Deprivation
PubMed: 26310109
DOI: 10.1016/j.conb.2015.08.002 -
Eye (London, England) Sep 2020
Topics: Amblyopia; Child; Child, Preschool; Cohort Studies; Humans; Retrospective Studies; Sensory Deprivation; Treatment Outcome
PubMed: 32094471
DOI: 10.1038/s41433-020-0823-2 -
Neural Plasticity 2012During postnatal development, sensory experience modulates cortical development, inducing numerous changes in all of the components of the cortex. Most of the cortical... (Review)
Review
During postnatal development, sensory experience modulates cortical development, inducing numerous changes in all of the components of the cortex. Most of the cortical changes thus induced occur during the critical period, when the functional and structural properties of cortical neurons are particularly susceptible to alterations. Although the time course for experience-mediated sensory development is specific for each system, postnatal development acts as a whole, and if one cortical area is deprived of its normal sensory inputs during early stages, it will be reorganized by the nondeprived senses in a process of cross-modal plasticity that not only increases performance in the remaining senses when one is deprived, but also rewires the brain allowing the deprived cortex to process inputs from other senses and cortices, maintaining the modular configuration. This paper summarizes our current understanding of sensory systems development, focused specially in the visual system. It delineates sensory enhancement and sensory deprivation effects at both physiological and anatomical levels and describes the use of enriched environment as a tool to rewire loss of brain areas to enhance other active senses. Finally, strategies to apply restorative features in human-deprived senses are studied, discussing the beneficial and detrimental effects of cross-modal plasticity in prostheses and sensory substitution devices implantation.
Topics: Animals; Brain; Cerebral Cortex; Environment; Humans; Neural Pathways; Neuronal Plasticity; Rats; Sensation; Sensory Deprivation; Visual Pathways
PubMed: 22848849
DOI: 10.1155/2012/305693