The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Jean Pelletier - One of the best experts on this subject based on the ideXlab platform.
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magnetic resonance study of the influence of tissue damage and cortical reorganization on pasat performance at the earliest stage of multiple sclerosis
Human Brain Mapping, 2005Co-Authors: Bertrand Audoin, Danielle Ibarrola, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, Sylviane Confortgouny, P. Viout, Jean-philippe Ranjeva, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the earliest stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann Area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these Areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the earliest stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.
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Magnetic resonance study of the influence of tissue damage and cortical reorganization on PASAT performance at the earliest stage of multiple sclerosis.
Human Brain Mapping, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Irina Malikova, My Van Au Duong, Elisabeth Soulier, Sylviane Confort-gouny, André Ali-chérif, P. Viout, Jean-philippe Ranjeva, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the earliest stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann Area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these Areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the earliest stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT. Hum. Brain Mapping 24:216–228, 2005. © 2004 Wiley-Liss, Inc.
Bertrand Audoin - One of the best experts on this subject based on the ideXlab platform.
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magnetic resonance study of the influence of tissue damage and cortical reorganization on pasat performance at the earliest stage of multiple sclerosis
Human Brain Mapping, 2005Co-Authors: Bertrand Audoin, Danielle Ibarrola, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, Sylviane Confortgouny, P. Viout, Jean-philippe Ranjeva, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the earliest stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann Area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these Areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the earliest stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.
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Magnetic resonance study of the influence of tissue damage and cortical reorganization on PASAT performance at the earliest stage of multiple sclerosis.
Human Brain Mapping, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Irina Malikova, My Van Au Duong, Elisabeth Soulier, Sylviane Confort-gouny, André Ali-chérif, P. Viout, Jean-philippe Ranjeva, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the earliest stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann Area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these Areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the earliest stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT. Hum. Brain Mapping 24:216–228, 2005. © 2004 Wiley-Liss, Inc.
Robert G. Shulman - One of the best experts on this subject based on the ideXlab platform.
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"Willed Action": A Functional MRI Study of the Human Prefrontal Cortex during a Sensorimotor Task
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Fahmeed Hyder, Elizabeth A. Phelps, Christopher J. Wiggins, Kevin S. Labar, Andrew M. Blamire, Robert G. ShulmanAbstract:Functional MRI (fMRI) was used to examine human brain activity within the dorsolateral prefrontal cortex during a sensorimotor task that had been proposed to require selection between several responses, a cognitive concept termed “willed action” in a positron emission tomography (PET) study by Frith et al. [Frith, C. D., Friston, K., Liddle, P. F. & Frackowiak, R. S. J. (1991) Proc. R. Soc. London Ser. B 244, 241–246]. We repeated their sensorimotor task, in which the subject chooses to move either of two fingers after a stimulus, by fMRI experiments in a 2.1-T imaging spectrometer. Echo-planar images were acquired from four coronal slices in the prefrontal cortex from nine healthy subjects. Slices were 5 mm thick, centers separated by 7 mm, with nominal in-plane spatial resolution of 9.6 × 5.0 mm2 for mean data. Our mean results are in agreement with the PET results in that we saw similar bilateral activations. The present results are compared with our previously published fMRI study of a verbal fluency task, which had also been proposed by Frith et al. to elicit a “willed action” response. We find a clear separation of activation foci in the left dorsolateral prefrontal cortex for the sensorimotor (Brodmann Area 46) and verbal fluency (Brodmann Area 45) tasks. Hence, assigning a particular activated region to “willed action” is not supported by the fMRI data when examined closely because identical regions are not activated with different modalities. Similar modality linked activations can be observed in the original PET study but the greater resolution of the fMRI data makes the modality linkages more definite.
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"Willed action": A functional MRI study of the human prefrontal cortex during a sensorimotor task (positron emission tomographyyhuman brain mappingydorsolateral prefrontal cortexyverbal f luencyyBrodmann Areas 6, 8, 9, 24, 32, 45, and 46)
1997Co-Authors: Fahmeed Hyder, Elizabeth A. Phelps, Kevin S. Labar, Hristopher J. Wiggins, M. Blamirei, Robert G. ShulmanAbstract:Functional MRI (fMRI) was used to examine human brain activity within the dorsolateral prefrontal cortex during a sensorimotor task that had been proposed to require selection between several responses, a cognitive concept termed ''willed action'' in a positron emission tomography (PET) study by Frith et al. (Frith, C. D., Friston, K., Liddle, P. F. & Frackowiak, R. S. J. (1991) Proc. R. Soc. London Ser. B 244, 241-246). We repeated their sensorimotor task, in which the subject chooses to move either of two fingers after a stimulus, by fMRI experiments in a 2.1-T imaging spec- trometer. Echo-planar images were acquired from four coro- nal slices in the prefrontal cortex from nine healthy subjects. Slices were 5 mm thick, centers separated by 7 mm, with nominal in-plane spatial resolution of 9.6 3 5.0 mm 2 for mean data. Our mean results are in agreement with the PET results in that we saw similar bilateral activations. The present results are compared with our previously published fMRI study of a verbal f luency task, which had also been proposed by Frith et al. to elicit a ''willed action'' response. We find a clear separation of activation foci in the left dorsolateral prefrontal cortex for the sensorimotor (Brodmann Area 46) and verbal f luency (Brodmann Area 45) tasks. Hence, assigning a par- ticular activated region to ''willed action'' is not supported by the fMRI data when examined closely because identical regions are not activated with different modalities. Similar modality linked activations can be observed in the original PET study but the greater resolution of the fMRI data makes the modality linkages more definite. correct response. The difference between these two conditions was defined as the ''willed action'' response. It was hypothe- sized by Frith and co-workers that any common Areas of cerebral activation found in the two cognitive tasks would be the result of a ''willed action'' component, because these two tasks had very few other common characteristics. In both cognitive tasks activation in a large Area of the dorsolateral prefrontal cortex was observed, which led Frith and co- workers to conclude that brain activity in this Area is due to ''willed action'' and is independent of the stimulus modality (i.e., verbal or sensorimotor). However, they reported some differences in the hemispheric locations of the dorsolateral prefrontal cortex activations for the two cognitive tasks. Most significantly, brain activity for the verbal fluency task was lateralized to the left hemisphere, whereas the activity for the sensorimotor task was bilateral. Although the coordinates of the reported center of mass (COM) of the large Area of activation in the left dorsolateral prefrontal cortex differed
Wen Shen - One of the best experts on this subject based on the ideXlab platform.
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Altered Brain Functional Activity in Infants with Congenital Bilateral Severe Sensorineural Hearing Loss: A Resting-State Functional MRI Study under Sedation.
Neural plasticity, 2017Co-Authors: Shuang Xia, Tianbin Song, Jing Che, Chao Chai, Meizhu Zheng, Wen ShenAbstract:Early hearing deprivation could affect the development of auditory, language, and vision ability. Insufficient or no stimulation of the auditory cortex during the sensitive periods of plasticity could affect the function of hearing, language, and vision development. Twenty-three infants with congenital severe sensorineural hearing loss (CSSHL) and 17 age and sex matched normal hearing subjects were recruited. The amplitude of low frequency fluctuations (ALFF) and regional homogeneity (ReHo) of the auditory, language, and vision related brain Areas were compared between deaf infants and normal subjects. Compared with normal hearing subjects, decreased ALFF and ReHo were observed in auditory and language-related cortex. Increased ALFF and ReHo were observed in vision related cortex, which suggest that hearing and language function were impaired and vision function was enhanced due to the loss of hearing. ALFF of left Brodmann Area 45 (BA45) was negatively correlated with deaf duration in infants with CSSHL. ALFF of right BA39 was positively correlated with deaf duration in infants with CSSHL. In conclusion, ALFF and ReHo can reflect the abnormal brain function in language, auditory, and visual information processing in infants with CSSHL. This demonstrates that the development of auditory, language, and vision processing function has been affected by congenital severe sensorineural hearing loss before 4 years of age.
Jean-philippe Ranjeva - One of the best experts on this subject based on the ideXlab platform.
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magnetic resonance study of the influence of tissue damage and cortical reorganization on pasat performance at the earliest stage of multiple sclerosis
Human Brain Mapping, 2005Co-Authors: Bertrand Audoin, Danielle Ibarrola, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, Sylviane Confortgouny, P. Viout, Jean-philippe Ranjeva, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the earliest stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann Area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these Areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the earliest stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.
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Magnetic resonance study of the influence of tissue damage and cortical reorganization on PASAT performance at the earliest stage of multiple sclerosis.
Human Brain Mapping, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Irina Malikova, My Van Au Duong, Elisabeth Soulier, Sylviane Confort-gouny, André Ali-chérif, P. Viout, Jean-philippe Ranjeva, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the earliest stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann Area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these Areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the earliest stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT. Hum. Brain Mapping 24:216–228, 2005. © 2004 Wiley-Liss, Inc.
