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AbstractFunctional magnetic resonance imaging (fMRI) has previously been used in humans to show functional separation between activation of dorsal and ventral visual areas using three dimensional structure from motion (SFM) stimuli (Naumer et al., Human Brain Mapping Abstr. 2000). We used identical stimuli to measure BOLD signals in ketamine anesthetized macaque monkeys (N=5). This imaging technique has recently been applied to monkeys anesthetized with isoflurane in a high magnetic field (4.7 T) scanner (Logothetis et al., 1999) and to awake monkeys in a standard 1.5T scanner (Vanduffel et al., Soc. Neurosci. Abst. 1998). Our fMRI study was performed at 1.5T using standard EPI sequences (Siemens Magnetom Vision, 8-16 slices, voxel size: 1.6 - 3.2 mm3, TR = 2-3 s). The head of the anesthetized monkeys was restrained in sphinx position with bolt implant and custom head holder or in supine position with cushions. Eye refraction was corrected with contact lenses. FMRI signals was analyzed using BrainVoyager 2000 incl...Nov 8, 2000
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AbstractBased on recent reports of impairments in visual motion processing and pursuit eye movements in autism, we conducted a functional MRI study of visual motion perception to examine neurophysiology of visual system function in autism. Participants were 17 ...Nov 6, 2007
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AbstractIndependence after stroke depends largely on the recovery of motor function. Accurate prediction of motor recovery may help clinicians and patients manage expectations, set realistic rehabilitation goals, and use their resources efficiently. However, ac...Nov 15, 2016
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AbstractKeeping and appropriate distance from the surrounding world is a defensive mechanism that helps to prevent injuries (Graziano & Cooke, 2006) and ensures the preservation of personal space boundaries (Hayduk, 1983). Research has shown that atypical perso...Nov 14, 2017
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AbstractBackground. Cognitive problems following traumatic brain injury (TBI) are common. The heterogeneous nature of TBI means that the basis of these cognitive deficits is likely to be multi-factorial. Previous studies show dopaminergic dysfunction following ...Nov 12, 2017
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AbstractThe HFE protein is critical in the regulation of cellular iron uptake. Mutations within this protein cause increased iron accumulation within parenchymal cells. One HFE mutation, H63D, has been shown to be increased in neurodegenerative diseases, such a...Nov 12, 2017
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AbstractMicroelectrode recording and stimulation techniques as well as microinjections of pharmacologic agents to record or manipulate the activity of neuronal cell groups play an outstanding role in neurophysiology. Commonly, such experiments depend on accurate determination of the anatomic structure investigated. This has traditionally been done histologically by placing small dye marks or electrolytic lesions which are visualised on brain sections after sacrificing the experimental animal. MRI is now widely used as an aid in the planning of neurophysiological experiments to improve stereotaxic localisation of target structures. To further the benefit from MRI we developed a technique similar to traditional histological procedures, to directly visualise recording sites in deep brain structures of the monkey, consisting in local injections of small volumes of gadolinium (GDA), a clinically used MRI contrast agent. These GDA-microinjections were visualized by MRI sequences [TIR (TR=3500 ms, TE=66 ms, TI=350 ms) an...Nov 14, 2005
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AbstractAim Noninvasive observation and visualization of cellular and molecular events are important for understanding of brain function. Manganese-enhanced MRI (MEMRI) has recently been applied for various kinds of modalities such as for tract tracing, neuroarchitecture, neurotransmitter-induced neural activation (PhAIM), and functional MRI (AIM). These MEMRIs rely on many kinds of molecular and physiologic functions such as Ca channel opening, chemical-induced activation, and transport in the brain. The aim of this study was to reveal morphological and functional architecture of the hippocampus and develop new visualization methods that combine the use of the different modalities of MEMRI. Methods Three types of MEMRI were performed using SD rats. 1) Neuroarchitectural MEMRI (n=5): 75 mg/kg MnCl2 was IV administrated. 2) AIM MRI with (n=5) or without (n=5) whisker stimulation: The BBB was disrupted by mannitol injection. Whiskers were stimulated with 2Hz during the MnCl2 infusion. 3) PhAIM MRI for glutamate (n=5...Nov 16, 2005
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Select adhesion proteins control the development of synapses and modulate their structural and functional properties. Despite these important roles, the extent to which different synapse-organizing mechanisms act across brain regions to establish connectivity and regulate network properties is incompletely understood. Further, their functional roles in different neuronal populations remain to be defined. Here, we applied diffusion tensor imaging (DTI), a modality of magnetic resonance imaging (MRI), to map connectivity changes in knock-out (KO) mice lacking the synaptogenic cell adhesion protein SynCAM 1. This identified reduced fractional anisotropy in the hippocampal CA3 area in absence of SynCAM 1. In agreement, mossy fiber refinement in CA3 was impaired in SynCAM 1 KO mice. Mossy fibers make excitatory inputs onto postsynaptic specializations of CA3 pyramidal neurons termed thorny excrescences and these structures were smaller in the absence of SynCAM 1. However, the most prevalent targets of mossy fib...Jul 13, 2016
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AbstractIntroduction: Rapid progress in the development of real time MRI imaging of specific nerve projections in the CNS has been made in the last few years. Of particular interest has been the demonstration of MnCl2 as an MRI contrast agent enabling visualisation of specific axonal pathways in the nervous system. We report here for the first time in vivo transynaptic transport of MnCL2 in the visual system of rats demonstrated with MRI. Materials and Methods: Adult inbred Fisher rats (n=4) were subjected to unilateral intravitreal injection of 2 ul of 100 mM MnCl2 with all procedures in accordance to national local authority regulations. MRI was performed at 2.35 T using a Bruker Biospec Avance DBX-100 (Bruker AG, Germany), with a 72 mm volume coil for transmission and an actively decoupled quadrature rat head surface coil for receive-only. Water-cooled BGA-12 (200 mT/m) gradients were used. The MRI protocol was according to Brekken et al. 2003. Results: MRI performed 36 hours post-injection demonstrated specifi...Oct 26, 2004