Showing papers on "Neural tract published in 2017"

Diffusion tensor imaging profiles reveal specific neural tract distortion in normal pressure hydrocephalus

Abstract: Nicole C Keong was supported by a Joint Royal College of Surgeons of England and Dunhill Medical Trust Fellowship and a Tunku Abdul Rahman Centenary Grant and other from National Medical Research Council Transition Award Grant, Singapore (supporting ongoing work). A Medical Research Council Programme Grant [Wolfson Brain Imaging Centre Cooperative] supported the study imaging work. Marek Czosnyka was supported by grants from Johnson and Johnson – Codman, Integra, Sophysa and Aesculap. Zofia Czosnyka was supported by grants from Johnson and Johnson – Codman, Integra, Sophysa and Aesculap. Elise DeVito was funded by the Pinsent-Darwin Studentship in Mental Pathology. Charlotte Housden took up employment with Cambridge Cognition Ltd following her PhD. Barbara J Sahakian was supported by a Medical Research Council Grant and reports personal fees from Cambridge Cognition, Lundbeck, Servier, grants from Janssen/J&J, other from Otsuka and personal fees from Peak (Brainbow). JDP was supported by an NIHR Senior Investigator Award, a Medical Research Council Programme grant and an NIHR Cambridge Biomedical Research Centre grant [brain injury theme] and also wishes to declare the following - Past advisor to Codman and Medtronic international advisory board, Director (unpaid) of Medicam, Scientific Collaboration with GSK (unpaid), Trustee of Brain Research Trust, Patron of Headway Cambridgeshire, Honorary Director of National Institute for Health Research Brain Injury Healthcare Technology Cooperative.

A Comparison of Different Slicing Planes in Preservation of Major Hippocampal Pathway Fibers in the Mouse

Abstract: The hippocampus plays a critical role in learning and memory and higher cognitive functions, and its dysfunction has been implicated in various neuropathological disorders. Electrophysiological recording undertaken in live brain slices is one of the most powerful tools for investigating hippocampal cellular and network activities. The plane for cutting the slices determines which afferent and/or efferent connections are best preserved, and there are three commonly used slices: hippocampal-entorhinal cortex (HEC), coronal and transverse. All three slices have been widely used for studying the major afferent hippocampal pathways including the perforant path (PP), the mossy fibers (MFs) and the Schaffer collaterals (SCs). Surprisingly, there has never been a systematic investigation of the anatomical and functional consequences of slicing at a particular angle. In the present study, we focused on how well fiber pathways are preserved from the entorhinal cortex (EC) to the hippocampus, and within the hippocampus, in slices generated by sectioning at different angles. The postmortem neural tract tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI) was used to label afferent fibers to hippocampal principal neurons in fixed slices or whole brains. Laser scanning confocal microscopy was adopted for imaging DiI-labeled axons and terminals. We demonstrated that PP fibers were well preserved in HEC slices, MFs in both HEC and transverse slices and SCs in all three types of slices. Correspondingly, field excitatory postsynaptic potentials (fEPSPs) could be consistently evoked in HEC slices when stimulating PP fibers and recorded in stratum lacunosum-moleculare (sl-m) of area CA1, and when stimulating the dentate granule cell layer (gcl) and recording in stratum lucidum (sl) of area CA3. The MF evoked fEPSPs could not be recorded in CA3 from coronal slices. In contrast to our DiI-tracing data demonstrating severely truncated PP fibers in coronal slices, fEPSPs could still be recorded in CA1 sl-m in this plane, suggesting that an additional afferent fiber pathway other than PP might be involved. The present study increases our understanding of which hippocampal pathways are best preserved in the three most common brain slice preparations, and will help investigators determine the appropriate slices to use for physiological studies depending on the subregion of interest.

Preparation and in vivo characterization of 51 MnCl 2 as PET tracer of Ca 2+ channel-mediated transport.

Abstract: Manganese has long been employed as a T1-shortening agent in magnetic resonance imaging (MRI) applications, but these techniques are limited by the biotoxicity of bulk-manganese Positron emission tomography (PET) offers superior contrast sensitivity compared with MRI, and recent preclinical PET studies employing 52gMn (t1/2: 56 d, β+: 29%) show promise for a variety of applications including cell tracking, neural tract tracing, immunoPET, and functional β-cell mass quantification The half-life and confounding gamma emissions of 52gMn are prohibitive to clinical translation, but the short-lived 51Mn (t1/2: 46 min, β+: 97%) represents a viable alternative This work develops methods to produce 51Mn on low-energy medical cyclotrons, characterizes the in vivo behavior of 51MnCl2 in mice, and performs preliminary human dosimetry predictions 51Mn was produced by proton irradiation of electrodeposited isotopically-enriched 54Fe targets Radiochemically isolated 51MnCl2 was intravenously administered to ICR mice which were scanned by dynamic and static PET, followed by ex vivo gamma counting Rapid blood clearance was observed with stable uptake in the pancreas, kidneys, liver, heart, and salivary gland Dosimetry calculations predict that 370 MBq of 51Mn in an adult human male would yield an effective dose equivalent of approximately 135 mSv, roughly equivalent to a clinical [18F]-FDG procedure

Connectivity and ultrastructure of dopaminergic innervation of the inner ear and auditory efferent system of a vocal fish

Abstract: Dopamine (DA) is a conserved modulator of vertebrate neural circuitry, yet our knowledge of its role in peripheral auditory processing is limited to mammals. The present study combines immunohistochemistry, neural tract tracing, and electron microscopy to investigate the origin and synaptic characteristics of DA fibers innervating the inner ear and the hindbrain auditory efferent nucleus in the plainfin midshipman, a vocal fish that relies upon the detection of mate calls for reproductive success. We identify a DA cell group in the diencephalon as a common source for innervation of both the hindbrain auditory efferent nucleus and saccule, the main hearing endorgan of the inner ear. We show that DA terminals in the saccule contain vesicles but transmitter release appears paracrine in nature, due to the apparent lack of synaptic contacts. In contrast, in the hindbrain, DA terminals form traditional synaptic contacts with auditory efferent neuronal cell bodies and dendrites, as well as unlabeled axon terminals, which, in turn, form inhibitory-like synapses on auditory efferent somata. Our results suggest a distinct functional role for brain-derived DA in the direct and indirect modulation of the peripheral auditory system of a vocal nonmammalian vertebrate.

Aberrant Pyramidal Tract in Comparison with Pyramidal Tract on Diffusion Tensor Tractography: A Mini-Review.

Abstract: The pyramidal tract (PT) is a major neural tract that controls voluntary movements in the human brain. The PT has several collateral pathways, including the aberrant pyramidal tract (APT), which passes through the medial lemniscus location at the midbrain and pons. Diffusion tensor tractography (DTT) allows visualization and estimation of the APT in three dimensions. In this mini-review, eight DTT studies on the APT were reviewed. Two studies for normal subjects reported the prevalence (17~18% of hemispheres) and the different characteristics (different cortical origin, less directionality and fewer neural fibers) of the APT compared with the PT. Six studies reported on the APT in patients with cerebral infarct, traumatic brain injury and cerebral palsy, and suggested that the APT could contribute to motor recovery following brain injury. The research on the APT in patients with brain injury has important implications for neuro-rehabilitation because understanding of the motor recovery mechanism can provide the basis for scientific rehabilitation strategies. Therefore, studies involving various brain pathologies with large numbers of patients on this topic should be encouraged. In addition, further studies are needed on the exact role of the APT in normal subjects.