Brain : a journal of neurology
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Children born prematurely have a high incidence of visual disorders which cannot always be explained by focal retinal or brain lesions. The aim of this study was to test the hypothesis that visual function in preterm infants is related to the microstructural development of white matter in the optic radiations. We used diffusion tensor imaging (DTI) with probabilistic diffusion tractography to delineate the optic radiations at term equivalent age and compared the fractional anisotropy (FA) to a contemporaneous evaluation of visual function. ⋯ The occurrence of mild retinopathy of prematurity did not affect the FA measures or visual scores. We then performed a secondary analysis using tract-based spatial statistics to determine whether global brain white matter development was related to visual function and found that only FA in the optic radiations was correlated with visual assessment score. Our results suggest that in preterm infants at term equivalent age visual function is directly related to the development of white matter in the optic radiations.
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In addition to motor symptoms, patients with Parkinson's disease (PD) show deficits in sensory processing. These deficits are thought to result from deficient gating of sensory information due to basal ganglia dysfunction in PD. Deep brain stimulation of the subthalamic nucleus (STN-DBS) has been shown to improve sensory deficits in PD, e.g. ⋯ Thus, STN-DBS led to a significant enhancement of afferent urinary bladder information processing. The data suggest that STN-DBS facilitates the discrimination of different bodily states by supporting sensory perception and the underlying neural mechanisms. Furthermore, this is the first imaging study, which shows an effect of STN-DBS on sensory gating in PD patients and its neural basis.
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Neural correlates of cognitive inflexibility during task-switching in obsessive-compulsive disorder.
A deficit in cognitive flexibility is acknowledged as a cognitive trait for obsessive-compulsive disorder (OCD). However, no investigations to date have used a cognitive activation paradigm to specify the neural correlates of this deficit in OCD. The objective of this study was to clarify how abnormal brain activities relate to cognitive inflexibility in OCD, using a task-switching paradigm. ⋯ Correlation analysis indicated that the activations of orbitofrontal cortex were related with the performance in both groups and also with the activation of anterior cingulate cortex in the OCD group. These findings replicate previous studies of cognitive inflexibility in OCD and provide neural correlates related to a task-switching deficit in OCD. The results suggest that impaired task-switching ability in OCD patients might be associated with an imbalance in brain activation between dorsal and ventral frontal-striatal circuits.
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The need to use animal models to develop imaging markers that could be linked to electrophysiological abnormalities in epilepsy and able to predict epileptogenicity in human studies is widely acknowledged. This study aimed to investigate the value of early magnetic resonance imaging (MRI) in predicting the long-term increased seizure susceptibility in the clinically relevant model of post-traumatic epilepsy (PTE). Moderate traumatic brain injury (TBI) was induced by lateral fluid-percussion in two groups of adult rats (34 injured, 16 controls). ⋯ In both experiments, EEG parameters such as total number of spikes or EDs proved to be reliable indicators of increased seizure susceptibility in injured animals when compared to controls (P < 0.05). In the hippocampus ipsilateral to TBI, D(av) correlated with these EEG parameters at both early (3 h), and chronic (23 days, 2, 3, 6, 7 and 11 months) time points after TBI, as well as with the density of mossy fibre sprouting. These results for the first time demonstrate that quantitative diffusion MRI can serve as a tool to facilitate prediction of increased seizure susceptibility in a clinically relevant model of human PTE.
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Review Meta Analysis
Hypothermia in animal models of acute ischaemic stroke: a systematic review and meta-analysis.
Induced hypothermia is proposed as a treatment for acute ischaemic stroke, but there have been too few clinical trials involving too few patients to draw any conclusions about the therapeutic benefit of cooling. Animal studies of induced hypothermia in focal cerebral ischaemia have tested cooling throughout a wide range of target temperatures, durations and intervals between stroke onset and the initiation of hypothermia. These studies, therefore, provide an opportunity to evaluate the effectiveness of different treatment strategies in animal models to inform the design of future clinical trials. ⋯ The effects of hypothermia on functional outcome were broadly similar. We conclude that in animal models of focal cerebral ischaemia, hypothermia improves outcome by about one-third under conditions that may be achievable for large numbers of patients with ischaemic stroke. Large randomized clinical trials testing the effect of hypothermia in patients with acute ischaemic stroke are warranted.