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RISS 인기검색어
- 검색키워드
- 저자 : Jolesz, Ferenc A. (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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The Functional Anatomy of Sleep-dependent Visual Skill Learning
Walker, Matthew P.,Stickgold, Robert,Jolesz, Ferenc A.,Yoo, Seung-Schik Oxford University Press 2005 Cerebral cortex Vol.15 No.11
<P>Learning of procedural skills develops gradually, with performance improving significantly with practice. But improvement on some tasks, including a visual texture discrimination task, continues in the absence of further practice, expressly during periods of sleep and not across equivalent waking episodes. Here we report that the brain activation revealed significantly different patterns of performance-related functional activity following a night of sleep relative to 1 h post-training without intervening sleep. When task activation patterns after a night of sleep were compared with activation patterns without intervening sleep (1 h post-training), significant regions of increased signal intensity were observed in the primary visual cortex, the occipital temporal junction, the medial temporal lobe and the inferior parietal lobe. In contrast, a region of decreased signal intensity was found in the right temporal pole. Corroborating these condition differences, correlations between behavioural performance and brain activation revealed significantly different patterns of performance-related functional activity following a night of sleep relative to those without intervening sleep. Together, these data provide evidence of overnight bi-directional changes in functional anatomy, differences that may form the neural basis of sleep-dependent learning expressed on this task.</P>
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Lee, Jong-Hwan,Oh, Sungsuk,Jolesz, Ferenc A,Park, Hyunwook,Yoo, Seung-Schik Gordon and Breach 2009 International journal of neuroscience Vol.119 No.8
<P>The simultaneous acquisition of electroencephalogram (EEG) and functional MRI (fMRI) signals is potentially advantageous because of the superior resolution that is achieved in both the temporal and spatial domains, respectively. However, ballistocardiographic artifacts along with ocular artifacts are a major obstacle for the detection of the EEG signatures of interest. Since the sources corresponding to these artifacts are independent from those producing the EEG signatures, we applied the Infomax-based independent component analysis (ICA) technique to separate the EEG signatures from the artifacts. The isolated EEG signatures were further utilized to model the canonical hemodynamic response functions (HRFs). Subsequently, the brain areas from which these EEG signatures originated were identified as locales of activation patterns from the analysis of fMRI data. Upon the identification and subsequent evaluation of brain areas generating interictal epileptic discharge (IED) spikes from an epileptic subject, the presented method was successfully applied to detect the theta and alpha rhythms that are sleep onset-related EEG signatures along with the subsequent neural circuitries from a sleep-deprived volunteer. These results suggest that the ICA technique may be useful for the preprocessing of simultaneous EEG-fMRI acquisitions, especially when a reference paradigm is unavailable.</P>
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Functional magnetic resonance imaging-mediated learning of increased activity in auditory areas
Yoo, Seung-Schik,Lee, Jong-Hwan,O’Leary, Heather,Lee, Vivian,Choo, Seh-Eun,Jolesz, Ferenc A. Lippincott Williams & Wilkins 2007 NeuroReport Vol.18 No.18
Our earlier study indicated that functional magnetic resonance imaging (fMRI)-based detection and feedback of regional cortical activity from the auditory area enabled a group of individuals to increase the level of activation mediated by auditory attention during sound stimulation. The long-term ability to maintain an increased level of cortical activation, extending to a time period of a few weeks, however, has not been investigated. We used real-time fMRI to confirm the utility of fMRI in forming a basis for the regulation of brain function to increase the activation in the auditory areas, and demonstrated that the learned ability could be retained after a 2-week period, with additional involvement of an attention-related neural network.
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REPRODUCIBILITY OF TRIAL-BASED FUNCTIONAL MRI ON MOTOR IMAGERY
Yoo, Seung-Schik,O'Leary, Heather M.,Lee, Jong-Hwan,Chen, Nan-Kuei,Panych, Lawrence P.,Jolesz, Ferenc A. Informa Healthcare 2007 International journal of neuroscience Vol.117 No.2
<P> The investigation of the reproducibility in functional MRI (fMRI) is an important step in the quantification and analysis of paradigm-related brain activation. This article reports on reproducibility of cortical activation characterized by repeated fMRI runs (10 times) during the performance of a motor imagery and a passive auditory stimulation as a control task. Two parameters, the size of activation and BOLD signal contrast, were measured from regions-of-interest for 10 subjects across different threshold conditions. The variability of these parameters was normalized with respect to the mean obtained from 10 runs, and represented as the intrasession variability. It was found that the variability was significantly lower in the measurement of BOLD signal contrast as compared to the measurement of the size of activation. The variability of the activation volume measurement was greater in the motor imagery task than in the auditory tasks across all thresholds. This task-dependent difference was not apparent from the measurement of the BOLD signal contrast. The presence of threshold dependence in the variability measurement was also examined, but no such dependency was found. The results suggest that a measurement of BOLD signal itself is a more reliable indicator of paradigm-related brain activation during repeated fMRI scans.</P>
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