944 resultados para Retinal Axon Guidance
Resumo:
We investigated the ability of a population of rat neural stem and precursor cells derived from rat embryonic spinal cord to protect injured neurons in the rat central nervous system (CNS). The neonatal rat optic pathway was used as a model of CNS injury, whereby retinal ganglion cells (RGCs) were axotomized by lesion of the lateral geniculate nucleus one day after birth. Neural stem and precursor cells derived from expanded neurospheres (NS) were transplanted into the lesion site at the time of injury. Application of Fast Blue tracer dye to the lesion site demonstrated that significant numbers of RGCs survived at 4 and 8 weeks in animals that received a transplant, with an average of 28% survival, though in some individual cases survival was greater than 50%. No RGCs survived in animals that received a lesion alone. Furthermore, labeled RGCs were also observed when Fast Blue was applied to the superior colliculus (SC) at 4 weeks, suggesting that neurosphere cells also facilitated RGC to regenerate to their normal target. Transplanted cells did not migrate or express neural markers after transplantation, and secreted several neurotrophic factors in vitro. We conclude that NS cells can protect injured CNS neurons and promote their regeneration. These effects are not attributable to cell replacement, and may be mediated via secretion of neurotrophic factors. Thus, neuroprotection by stem cell populations may be a more viable approach for treatment of CNS disorders than cell replacement therapy.
Resumo:
The contribution of retinal flow (RF), extraretinal (ER), and egocentric visual direction (VD) information in locomotor control was explored. First, the recovery of heading from RF was examined when ER information was manipulated; results confirmed that ER signals affect heading judgments. Then the task was translated to steering curved paths, and the availability and veracity of VD were manipulated with either degraded or systematically biased RE Large steering errors resulted from selective manipulation of RF and VD, providing strong evidence for the combination of RF, ER, and VD. The relative weighting applied to RF and VD was estimated. A point-attractor model is proposed that combines redundant sources of information for robust locomotor control with flexible trajectory planning through active gaze.
Resumo:
Locomoting through the environment typically involves anticipating impending changes in heading trajectory in addition to maintaining the current direction of travel. We explored the neural systems involved in the “far road” and “near road” mechanisms proposed by Land and Horwood (1995) using simulated forward or backward travel where participants were required to gauge their current direction of travel (rather than directly control it). During forward egomotion, the distant road edges provided future path information, which participants used to improve their heading judgments. During backward egomotion, the road edges did not enhance performance because they no longer provided prospective information. This behavioral dissociation was reflected at the neural level, where only simulated forward travel increased activation in a region of the superior parietal lobe and the medial intraparietal sulcus. Providing only near road information during a forward heading judgment task resulted in activation in the motion complex. We propose a complementary role for the posterior parietal cortex and motion complex in detecting future path information and maintaining current lane positioning, respectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Resumo:
Good information and career guidance about what post-compulsory educational routes are available and where these routes lead is important in ensuring that young people make choices that are most appropriate to their needs and aspirations. Yet the Association of School and College Leaders (2011) express fears that future provision will be inadequate. This paper reports the findings from an on-line survey of 300 secondary school teachers, and follow up telephone interviews with 18 in the South East of England which explored teachers’ experiences of delivering post-compulsory educational and career guidance and their knowledge and confidence in doing so. Results suggest that teachers lack confidence in delivering information, advice and guidance outside their own area of specialism and experience. In particular, teachers knew little in relation to alternative local provision of post-16 education and lacked knowledge of more non-traditional, vocational routes. This paper will therefore raises important policy considerations with respect to supporting teachers’ knowledge, ability and confidence in delivering information in relation to future pathways and career guidance.
Resumo:
Social anxiety disorder is one of the most persistent and common of the anxiety disorders, with lifetime prevalence rates in Europe of 6.7% (range 3.9-13.7%).1 It often coexists with depression, substance use disorder, generalised anxiety disorder, panic disorder, and post-traumatic stress disorder.2 It can severely impair a person’s daily functioning by impeding the formation of relationships, reducing quality of life, and negatively affecting performance at work or school. Despite this, and the fact that effective treatments exist, only about half of people with this condition seek treatment, many after waiting 10-15 years.3 Although about 40% of those who develop the condition in childhood or adolescence recover before adulthood,4 for many the disorder persists into adulthood, with the chance of spontaneous recovery then limited compared with other mental health problems. This article summarises the most recent recommendations from the National Institute for Health and Care Excellence (NICE) on recognising, assessing, and treating social anxiety disorder in children, young people, and adults.5
Resumo:
background: Guidance encourages oncologists to engage patients and relatives in discussing the emotions that accompany cancer diagnosis and treatment. We investigated the perspectives of parents of children with leukaemia on the role of paediatric oncologists in such discussion. methods: Qualitative study comprising 33 audio-recorded parent–oncologist consultations and semi-structured interviews with 67 parents during the year following diagnosis. results: Consultations soon after the diagnosis were largely devoid of overt discussion of parental emotion. Interviewed parents did not describe a need for such discussion. They spoke of being comforted by oncologists’ clinical focus, by the biomedical information they provided and by their calmness and constancy. When we explicitly asked parents 1 year later about the oncologists’ role in emotional support, they overwhelmingly told us that they did not want to discuss their feelings with oncologists. They wanted to preserve the oncologists’ focus on their child’s clinical care, deprecated anything that diverted from this and spoke of the value of boundaries in the parent–oncologist relationship. conclusion: Parents were usually comforted by oncologists, but this was not achieved in the way suggested by communication guidance. Communication guidance would benefit from an enhanced understanding of how emotional support is experienced by those who rely on it.