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Douglas E. H. Hartley - One of the best experts on this subject based on the ideXlab platform.

  • Pre-operative Brain Imaging Using Functional Near-Infrared Spectroscopy Helps Predict Cochlear Implant Outcome in Deaf Adults
    Journal of the Association for Research in Otolaryngology, 2019
    Co-Authors: Carly A. Anderson, Ian M. Wiggins, Pádraig T. Kitterick, Douglas E. H. Hartley
    Abstract:

    Currently, it is not possible to accurately predict how well a deaf individual will be able to understand speech when hearing is (re)introduced via a cochlear implant. Differences in brain organisation following deafness are thought to contribute to variability in speech understanding with a cochlear implant and may offer unique insights that could help to more reliably predict outcomes. An emerging optical Neuroimaging Technique, functional near-infrared spectroscopy (fNIRS), was used to determine whether a pre-operative measure of brain activation could explain variability in cochlear implant (CI) outcomes and offer additional prognostic value above that provided by known clinical characteristics. Cross-modal activation to visual speech was measured in bilateral superior temporal cortex of pre- and post-lingually deaf adults before cochlear implantation. Behavioural measures of auditory speech understanding were obtained in the same individuals following 6 months of cochlear implant use. The results showed that stronger pre-operative cross-modal activation of auditory brain regions by visual speech was predictive of poorer auditory speech understanding after implantation. Further investigation suggested that this relationship may have been driven primarily by the inclusion of, and group differences between, pre- and post-lingually deaf individuals. Nonetheless, pre-operative cortical imaging provided additional prognostic value above that of influential clinical characteristics, including the age-at-onset and duration of auditory deprivation, suggesting that objectively assessing the physiological status of the brain using fNIRS imaging pre-operatively may support more accurate prediction of individual CI outcomes. Whilst activation of auditory brain regions by visual speech prior to implantation was related to the CI user’s clinical history of deafness, activation to visual speech did not relate to the future ability of these brain regions to respond to auditory speech stimulation with a CI. Greater pre-operative activation of left superior temporal cortex by visual speech was associated with enhanced speechreading abilities, suggesting that visual speech processing may help to maintain left temporal lobe specialisation for language processing during periods of profound deafness.

  • cortical cross modal plasticity following deafness measured using functional near infrared spectroscopy
    Hearing Research, 2015
    Co-Authors: Douglas E. H. Hartley, Rebecca S Dewey
    Abstract:

    Evidence from functional Neuroimaging studies suggests that the auditory cortex can become more responsive to visual and somatosensory stimulation following deafness, and that this occurs predominately in the right hemisphere. Extensive cross-modal plasticity in prospective cochlear implant recipients is correlated with poor speech outcomes following implantation, highlighting the potential impact of central auditory plasticity on subsequent aural rehabilitation. Conversely, the effects of hearing restoration with a cochlear implant on cortical plasticity are less well understood, since the use of most Neuroimaging Techniques in CI recipients is either unsafe or problematic due to the electromagnetic artefacts generated by CI stimulation. Additionally, Techniques such as functional magnetic resonance imaging (fMRI) are confounded by acoustic noise produced by the scanner that will be perceived more by hearing than by deaf individuals. Subsequently it is conceivable that auditory responses to acoustic noise produced by the MR scanner may mask auditory cortical responses to non-auditory stimulation, and render inter-group comparisons less significant. Uniquely, functional near-infrared spectroscopy (fNIRS) is a silent Neuroimaging Technique that is non-invasive and completely unaffected by the presence of a CI. Here, we used fNIRS to study temporal-lobe responses to auditory, visual and somatosensory stimuli in thirty profoundly-deaf participants and thirty normally-hearing controls. Compared with silence, acoustic noise stimuli elicited a significant group fNIRS response in the temporal region of normally-hearing individuals, which was not seen in profoundly-deaf participants. Visual motion elicited a larger group response within the right temporal lobe of profoundly-deaf participants, compared with normally-hearing controls. However, bilateral temporal lobe fNIRS activation to somatosensory stimulation was comparable in both groups. Using fNIRS these results confirm that auditory deprivation is associated with cross-modal plasticity of visual inputs to auditory cortex. Although we found no evidence for plasticity of somatosensory inputs, it is possible that our recordings may have included activation of somatosensory cortex that masked any group differences in auditory cortical responses due to the limited spatial resolution associated with fNIRS.

Yuchung N Cheng - One of the best experts on this subject based on the ideXlab platform.

  • susceptibility weighted imaging technical aspects and clinical applications part 1
    American Journal of Neuroradiology, 2008
    Co-Authors: E M Haacke, Sandeep Mittal, Zhen Wu, Jaladhar Neelavalli, Yuchung N Cheng
    Abstract:

    SUMMARY: Susceptibility-weighted imaging (SWI) is a new Neuroimaging Technique, which uses tissue magnetic susceptibility differences to generate a unique contrast, different from that of spin density, T1, T2, and T2*. In this review (the first of 2 parts), we present the technical background for SWI. We discuss the concept of gradient-echo images and how we can measure local changes in susceptibility. Armed with this material, we introduce the steps required to transform the original magnitude and phase images into SWI data. The use of SWI filtered phase as a means to visualize and potentially quantify iron in the brain is presented. Advice for the correct interpretation of SWI data is discussed, and a set of recommended sequence parameters for different field strengths is given.

Binh V Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • susceptibility weighted imaging for differential diagnosis of cerebral vascular pathology a pictorial review
    Journal of the Neurological Sciences, 2009
    Co-Authors: Yukun Tsui, Fong Y Tsai, A N Hasso, Fred Greensite, Binh V Nguyen
    Abstract:

    Susceptibility-weighted imaging (SWI) is a high-spatial resolution, three-dimensional, gradient-echo (GRE) magnetic resonance (MR) Technique. This fully velocity-compensated pulse sequence utilizes the magnetic susceptibility differences of various tissues or substances, such as blood products, iron, and calcification. By postprocessing the magnitude images using a phase mask, it emphasizes the magnetic properties of different susceptibility effects. Generated minimal intensity projection (minIP) images can further demonstrate tortuous vasculature and the continuity of vessels or abnormalities across slices. SWI has been used to improve the diagnosis of neurological trauma, brain neoplasm, neurodegenerative disorders, and cerebrovascular disease because of its ability to demonstrate microbleeds and conspicuity of the veins and other sources with susceptibility effects. We have used SWI to identify cerebrovascular lesions which may be obscured on other MR sequences to aid in the differential diagnosis. We present a review with selected cases to demonstrate the usefulness of this new Neuroimaging Technique in improving the diagnosis of cerebral vascular pathology.

Adam De La Zerda - One of the best experts on this subject based on the ideXlab platform.

  • speckle modulation enables high resolution wide field human brain tumor margin detection and in vivo murine Neuroimaging
    Scientific Reports, 2019
    Co-Authors: Derek Yecies, Orly Liba, Elliott D Sorelle, Rebecca Dutta, Edwin Yuan, Hannes Vogel, Gerald A Grant, Adam De La Zerda
    Abstract:

    Current in vivo Neuroimaging Techniques provide limited field of view or spatial resolution and often require exogenous contrast. These limitations prohibit detailed structural imaging across wide fields of view and hinder intraoperative tumor margin detection. Here we present a novel Neuroimaging Technique, speckle-modulating optical coherence tomography (SM-OCT), which allows us to image the brains of live mice and ex vivo human samples with unprecedented resolution and wide field of view using only endogenous contrast. The increased visibility provided by speckle elimination reveals white matter fascicles and cortical layer architecture in brains of live mice. To our knowledge, the data reported herein represents the highest resolution imaging of murine white matter structure achieved in vivo across a wide field of view of several millimeters. When applied to an orthotopic murine glioblastoma xenograft model, SM-OCT readily identifies brain tumor margins with resolution of approximately 10 μm. SM-OCT of ex vivo human temporal lobe tissue reveals fine structures including cortical layers and myelinated axons. Finally, when applied to an ex vivo sample of a low-grade glioma resection margin, SM-OCT is able to resolve the brain tumor margin. Based on these findings, SM-OCT represents a novel approach for intraoperative tumor margin detection and in vivo Neuroimaging.

  • high resolution wide field human brain tumor margin detection and in vivo murine Neuroimaging
    bioRxiv, 2018
    Co-Authors: Derek Yecies, Orly Liba, Elliott D Sorelle, Rebecca Dutta, Edwin Yuan, Hannes Vogel, Gerald A Grant, Adam De La Zerda
    Abstract:

    Current in vivo Neuroimaging Techniques provide limited field of view or spatial resolution and often require exogenous contrast. These limitations prohibit detailed structural imaging across wide fields of view and hinder intraoperative tumor margin detection. Here we present a novel Neuroimaging Technique, speckle-modulating optical coherence tomography (SM-OCT), which allows us to image the brains of live mice and ex vivo human samples with unprecedented resolution and wide field of view using only endogenous contrast. The increased effective resolution provided by speckle elimination reveals white matter fascicles and cortical layer architecture in the brains of live mice. To our knowledge, the data reported herein represents the highest resolution imaging of murine white matter structure achieved in vivo across a wide field of view of several millimeters. When applied to an orthotopic murine glioblastoma xenograft model, SM-OCT readily identifies brain tumor margins with near single-cell resolution. SM-OCT of ex vivo human temporal lobe tissue reveals fine structures including cortical layers and myelinated axons. Finally, when applied to an ex vivo sample of a low-grade glioma resection margin, SM-OCT is able to resolve the brain tumor margin. Based on these findings, SM-OCT represents a novel approach for intraoperative tumor margin detection and in vivo Neuroimaging.

Bo Xu - One of the best experts on this subject based on the ideXlab platform.

  • decreased prefrontal brain activation during verbal fluency task in patients with somatoform pain disorder an exploratory multi channel near infrared spectroscopy study
    Progress in Neuro-psychopharmacology & Biological Psychiatry, 2017
    Co-Authors: Jinlong Lu, Xiaoqian Zhang, Chenyu Shen, Kun Feng, Bo Xu
    Abstract:

    Abstract Background Pain is a common phenomenon. Patients with somatoform pain disorder (SPD) suffer from lasting chronic pain which may cause cognitive impairment. The dysfunction of prefrontal cortex (PFC) may be involved in pain-induced cognition impairment, which is the most important part in regulating of cognitive function. Multi-channel near-infrared spectroscopy (NIRS) is a noninvasive and low-cost functional Neuroimaging Technique being used to detect the prefrontal cortex activation during cognitive tasks to demonstrate the relationship between PFC dysfunction and cognition impairment in SPD patients. Methods 24 patients with SPD and 24 age-, gender- and education level-matched healthy controls were examined by NIRS of the relative concentration of oxygenated hemoglobin (oxy-Hb) in PFC during verbal fluency task (VFT). All data analysis procedures were accomplished under MATLAB, SPM and SPM-fNIRS which is an SPM12-based software for fNIRS analysis. Results 1. The number of words generated during the VFT tasks in SPD patients were fewer than healthy controls. 2. The activated areas in SPD patients were smaller than healthy controls. 3. The average activation strength of [oxy-Hb] in SPD patients was much lower than healthy controls. 4. The difference of activation areas between left and right lobe were particularly obvious in SPD patients. Conclusion There are evidences suggested that the markedly dysfunction in PFC especially bilateral dorsolateral prefrontal cortex (DLPFC) areas may be involved in the cognitive deficiency in patients with SPD.

  • reduced prefrontal activation during verbal fluency task in chronic insomnia disorder a multichannel near infrared spectroscopy study
    Neuropsychiatric Disease and Treatment, 2017
    Co-Authors: Chenyu Shen, Xiaoqian Zhang, Kun Feng, Bo Xu
    Abstract:

    PURPOSE: Daytime complaints such as memory and attention deficits and failure to accomplish daily tasks are common in insomnia patients. However, objective psychological tests to detect cognitive impairment are equivocal. Neural function associated with cognitive performance may explain the discrepancy. The aim of this study was to investigate the hemodynamic response patterns of patients with chronic insomnia disorder (CID) using the noninvasive and low-cost functional Neuroimaging Technique of multichannel near-infrared spectroscopy (NIRS) in order to identify changes of neural function associated with cognitive performance. PATIENTS AND METHODS: Twenty-four CID patients and twenty-five healthy controls matched for age, right-hand dominance, educational level, and gender were examined during verbal fluency tasks (VFT) using NIRS. A covariance analysis was conducted to analyze differences of oxygenated hemoglobin (oxy-Hb) changes in prefrontal cortex (PFC) between the two groups and reduce the influence of the severity of depression. Pearson correlation coeffcients were calculated to examine the relationship between the oxy-Hb changes, with the severity of insomnia and depressive symptoms assessed by the Pittsburgh Sleep Quality Index (PSQI) and the Hamilton Rating Scale for Depression (HAMD). RESULTS: The number of words generated during the VFT in CID groups showed no statistical differences with healthy controls. CID patients showed hypoactivation in the PFC during the cognitive task. In addition, we found that the function of left orbitofrontal cortex (OFC) during the VFT was significantly negatively correlated with the PSQI scores and the function of right dorsolateral PFC (DLPFC) was significantly negatively correlated with the HAMD scores. CONCLUSION: The present study detected dysfunctions in PFC in spite of intact performance which indicates the role of PFC in the neurophysiological underpinnings. Left OFC function is associated with insomnia symptoms and right DLPFC function is associated with depressive symptoms.

  • relationship between the prefrontal function and the severity of the emotional symptoms during a verbal fluency task in patients with major depressive disorder a multi channel nirs study
    Progress in Neuro-psychopharmacology & Biological Psychiatry, 2014
    Co-Authors: Xiaoqian Zhang, Bo Xu, Chenyu Shen, Kun Feng
    Abstract:

    Abstract Multi-channel near-infrared spectroscopy (NIRS) is a noninvasive and low-cost functional Neuroimaging Technique in psychiatric research, and it has been wildly used for detecting the spatiotemporal characteristics of brain activity. In order to evaluate the clinical value of NIRS data in the assistant diagnosis of major depressive disorder (MDD), prefrontal cortex (PFC) hemoglobin concentration exchange of 30 MDD patients combined with anxious and obsessive–compulsive symptom was detected by NIRS under voice fluency task (VFT), then the relationship between the severity of depressive, anxious and obsessive–compulsive symptom assessed by Hamilton Rating Scale for Depression (HAMD), Hamilton Anxiety Rating Scale (HAMA) and Yale-Brown Obsessive Compulsive Scale (Y-BOCS) with NIRS data in PFC was analyzed. Hypoactivation in lateral and lower PFC of MDD patients was confirmed in this study. Furthermore, Spearman correlation found that oxy-hemoglobin concentration ([oxy-Hb]) exchange in right-lateral PFC was associated with the severity of anxiety, while bilateral PFC and antero-medial PFC were associated with severity of depression. Meanwhile, no statistical correlation was observed on the severity of obsessive–compulsive symptom. The results prompted that MDD patients with anxiety and obsession–compulsion symptom showed a PFC hypoactivation state in NIRS. Furthermore, the function of right-lateral PFC was associated with anxiety symptom, while bilateral PFC and antero-medial PFC were associated with depression symptom. Different from depression and anxiety, obsession–compulsion may have a different biological character in PFC function.