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Soros P.,Sunnybrook Health science Center | Macintosh B.J.,Sunnybrook Health science Center | Macintosh B.J.,University of Oxford | Tam F.,Sunnybrook Health science Center | And 5 more authors.
Frontiers in Human Neuroscience | Year: 2010

A functional magnetic resonance imaging (fMRI)-compatible fi ber-optic bend sensor was investigated to assess whether the device could be used effectively to monitor opening and closing of the jaw during an fMRI experiment at 3 T. In contrast to surface electromyography, a bend sensor fi xed to the chin of the participant is fast and easy to use and is not affected by strong electromagnetic fields. Bend sensor recordings are characterized by high validity (compared with concurrent video recordings of mouth opening) and high reliability (comparing two independent measurements). The results of this study indicate that a bend sensor is able to record the opening and closing of the jaw associated with different overt speech conditions (producing the utterances /a/, /pa/, /pataka/) and the opening of the mouth without speech production. Data post-processing such as fi ltering was not necessary. There are several potential applications for bend sensor recordings of speech-related jaw movements. First, bend sensor recordings are a valuable tool to assess behavioral performance, such as response latencies, accuracies, and completion times, which is particularly important in children, seniors, or patients with various neurological or psychiatric conditions. Second, the timing information provided by bend sensor data may improve the predicted hemodynamic response that is used for fMRI analysis based on the general linear model (GLM). Third, bend sensor recordings may be included in GLM analyses not for statistical contrast purposes, but as a covariate of no interest, accounting for part of the data variance to model fMRI artifacts due to motion outside the field of view. © 2010 Sörös, MacIntosh, Tam and Graham. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited. © 2010 Söro7die;s, MacIntosh, Tam and Graham.

Soros P.,Imaging Research | Bose A.,University of Windsor | Sokoloff L.G.,Communication Disorders Technology, Inc | Sokoloff L.G.,University of Toronto | And 6 more authors.
Neurobiology of Aging | Year: 2011

Alterations of existing neural networks during healthy aging, resulting in behavioral deficits and changes in brain activity, have been described for cognitive, motor, and sensory functions. To investigate age-related changes in the neural circuitry underlying overt non-lexical speech production, functional MRI was performed in 14 healthy younger (21-32 years) and 14 healthy older individuals (62-84 years). The experimental task involved the acoustically cued overt production of the vowel /a/ and the polysyllabic utterance /pataka/. In younger and older individuals, overt speech production was associated with the activation of a widespread articulo-phonological network, including the primary motor cortex, the supplementary motor area, the cingulate motor areas, and the posterior superior temporal cortex, similar in the /a/ and /pataka/ condition. An analysis of variance with the factors age and condition revealed a significant main effect of age. Irrespective of the experimental condition, significantly greater activation was found in the bilateral posterior superior temporal cortex, the posterior temporal plane, and the transverse temporal gyri in younger compared to older individuals. Significantly greater activation was found in the bilateral middle temporal gyri, medial frontal gyri, middle frontal gyri, and inferior frontal gyri in older vs. younger individuals. The analysis of variance did not reveal a significant main effect of condition and no significant interaction of age and condition. These results suggest a complex reorganization of neural networks dedicated to the production of speech during healthy aging. © 2009 Elsevier Inc.

Miller D.I.,University of Ottawa | Taler V.,University of Ottawa | Taler V.,Elisabeth Bruyere Research Institute | Davidson P.S.R.,University of Ottawa | And 3 more authors.
Neurobiology of Aging | Year: 2012

Physical exercise and fitness have been proposed as potential factors that promote healthy cognitive aging. Support for this hypothesis has come from cross sectional, longitudinal, and intervention studies. In the present review, we discuss several methodological problems that limit the conclusions of many studies. The lack of consensus on how to retrospectively measure exercise intensity is a major difficulty for all studies that attempt to estimate lifelong impact of exercise on cognitive performance in older adults. Intervention studies have a much better capacity to establish causality, but still suffer from difficulties arising from inadequate control groups and the choice and modality of administration of cognitive measures. We argue that, while the association between exercise and preserved cognition during aging is clearly demonstrated, the specific hypothesis that physical exercise is a cause of healthy cognitive aging has yet to be validated. A number of factors could mediate the exercise-cognition association, including depression, and social or cognitive stimulation. The complex interactions among these 3 factors and the potential impact of exercise on cognition remain to be systematically studied. At this time, the best prescription for lifestyle interventions for healthy cognitive aging would be sustained physical, social, and mental activities. What remains unknown is which type of activity might be most useful, and whether everyone benefits similarly from the same interventions. © 2012 Elsevier Inc.

Schweizer T.A.,St. Michaels Hospital | Schweizer T.A.,University of Toronto | Schweizer T.A.,Heart and Stroke Foundation of Ontario Center for Stroke Recovery | MacDonald R.L.,St. Michaels Hospital | MacDonald R.L.,University of Toronto
Journal of the Neurological Sciences | Year: 2012

Objective: Recent studies suggest that the Montreal Cognitive Assessment (MoCA) is more sensitive to stroke-associated cognitive dysfunction than the Mini-Mental State Examination (MMSE), but little is known about how these screening measures relate to neurocognitive test performance or real-world functioning in patients with good recovery after aneurysmal subarachnoid hemorrhage (aSAH). The aim of the present study was to determine how MoCA and MMSE scores relate to neurocognitive impairment and return to work after aSAH. Methods: Thirty-two patients with aSAH who had made a good recovery completed the MoCA, the MMSE, and a battery of neurocognitive tests. Results: 42% and 0% of aSAH patients were impaired on the MoCA and MMSE, respectively. The MoCA had acceptable sensitivity (40-100%) and specificity (54-68%) (Table 3). The MMSE failed to detect impairment in any cognitive domain. The MoCA, but not the MMSE, predicted performance on tests of verbal learning, executive function, working memory, visuospatial function, and motor function. Superior performance on the Animal naming and Abstraction subtests of the MoCA score were associated with return to work following aSAH. Conclusion: Compared to the MMSE, the MoCA is more sensitive to aSAH-associated cognitive impairment. Certain MoCA subtests are also sensitive to functional difficulties after aSAH such as return to work. These findings support the utility of the MoCA as a brief bedside assessment of cognitive and real-world outcome in aSAH survivors. © 2012 Elsevier B.V. All rights reserved.

Rotenberg D.,Rotman Research Institute | Rotenberg D.,University of Toronto | Chiew M.,Rotman Research Institute | Chiew M.,University of Toronto | And 9 more authors.
Magnetic Resonance in Medicine | Year: 2013

Head motion artifacts are a major problem in functional MRI that limit its use in neuroscience research and clinical settings. Real-time scan-plane correction by optical tracking has been shown to correct slice misalignment and nonlinear spin-history artifacts; however, residual artifacts due to dynamic magnetic field nonuniformity may remain in the data. A recently developed correction technique, Phase Labeling for Additional Coordinate Encoding, can correct for absolute geometric distortion using only the complex image data from two echo planar images with slightly shifted k-space trajectories. An approach is presented that integrates Phase Labeling for Additional Coordinate Encoding into a real-time scan-plane update system by optical tracking, applied to a tissue-equivalent phantom undergoing complex motion and an functional MRI finger tapping experiment with overt head motion to induce dynamic field nonuniformity. Experiments suggest that such integrated volume-by-volume corrections are very effective at artifact suppression, with potential to expand functional MRI applications. Copyright © 2012 Wiley Periodicals, Inc.

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