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  • 1
    In: Human Brain Mapping, Wiley, ( 2011), p. n/a-n/a
    Materialart: Online-Ressource
    ISSN: 1065-9471
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2011
    ZDB Id: 1492703-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Wiley ; 2011
    In:  Human Brain Mapping Vol. 32, No. 9 ( 2011-09), p. 1400-1418
    In: Human Brain Mapping, Wiley, Vol. 32, No. 9 ( 2011-09), p. 1400-1418
    Kurzfassung: This work presents a novel method of mapping the brain's response to single stimuli in space and time without prior knowledge of the paradigm timing: paradigm free mapping (PFM). This method is based on deconvolution of the hemodynamic response from the voxel time series assuming a linear response and using a ridge‐regression algorithm. Statistical inference is performed by defining a spatio‐temporal t ‐statistic and by controlling for multiple comparisons using the false discovery rate procedure. The methodology was validated on five subjects who performed self‐paced and visually cued finger tapping at 7 Tesla, with moderate (TR = 2 s) and high (TR = 0.4 s) temporal resolution. The results demonstrate that detection of single‐trial BOLD events is feasible without a priori information on the stimulus paradigm. The proposed method opens up the possibility of designing temporally unconstrained paradigms to study the cortical response to unpredictable mental events. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.
    Materialart: Online-Ressource
    ISSN: 1065-9471 , 1097-0193
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2011
    ZDB Id: 1492703-2
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    In: Human Brain Mapping, Wiley, Vol. 34, No. 6 ( 2013-06), p. 1319-1329
    Kurzfassung: fMRI studies of brain activity at rest study slow ( 〈 0.1 Hz) intrinsic fluctuations in the blood‐oxygenation‐level‐dependent (BOLD) signal that are observed in a temporal scale of several minutes. The origin of these fluctuations is not clear but has previously been associated with slow changes in rhythmic neuronal activity resulting from changes in cortical excitability or neuronal synchronization. In this work, we show that individual spontaneous BOLD events occur during rest, in addition to slow fluctuations. Individual spontaneous BOLD events were identified by deconvolving the hemodynamic impulse response function for each time point in the fMRI time series, thus requiring no information on timing or a‐priori spatial information of events. The patterns of activation detected were related to the motor, visual, default‐mode, and dorsal attention networks. The correspondence between spontaneous events and slow fluctuations in these networks was assessed using a sliding window, seed‐correlation analysis, where seed regions were selected based on the individual spontaneous event BOLD activity maps. We showed that the correlation varied considerably over time, peaking at the time of spontaneous events in these networks. By regressing spontaneous events out of the fMRI signal, we showed that both the correlation strength and the power in spectral frequencies 〈 0.1 Hz decreased, indicating that spontaneous activation events contribute to low‐frequency fluctuations observed in resting state networks with fMRI. This work provides new insights into the origin of signals detected in fMRI studies of functional connectivity. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
    Materialart: Online-Ressource
    ISSN: 1065-9471 , 1097-0193
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2013
    ZDB Id: 1492703-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    In: Human Brain Mapping, Wiley, Vol. 41, No. 12 ( 2020-08-15), p. 3439-3467
    Kurzfassung: Neurofeedback training using real‐time functional magnetic resonance imaging (rtfMRI‐NF) allows subjects voluntary control of localised and distributed brain activity. It has sparked increased interest as a promising non‐invasive treatment option in neuropsychiatric and neurocognitive disorders, although its efficacy and clinical significance are yet to be determined. In this work, we present the first extensive review of acquisition, processing and quality control methods available to improve the quality of the neurofeedback signal. Furthermore, we investigate the state of denoising and quality control practices in 128 recently published rtfMRI‐NF studies. We found: (a) that less than a third of the studies reported implementing standard real‐time fMRI denoising steps, (b) significant room for improvement with regards to methods reporting and (c) the need for methodological studies quantifying and comparing the contribution of denoising steps to the neurofeedback signal quality. Advances in rtfMRI‐NF research depend on reproducibility of methods and results. Notably, a systematic effort is needed to build up evidence that disentangles the various mechanisms influencing neurofeedback effects. To this end, we recommend that future rtfMRI‐NF studies: (a) report implementation of a set of standard real‐time fMRI denoising steps according to a proposed COBIDAS‐style checklist ( https://osf.io/kjwhf/ ), (b) ensure the quality of the neurofeedback signal by calculating and reporting community‐informed quality metrics and applying offline control checks and (c) strive to adopt transparent principles in the form of methods and data sharing and support of open‐source rtfMRI‐NF software. Code and data for reproducibility, as well as an interactive environment to explore the study data, can be accessed at https://github.com/jsheunis/quality‐and‐denoising‐in‐rtfmri‐nf.
    Materialart: Online-Ressource
    ISSN: 1065-9471 , 1097-0193
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2020
    ZDB Id: 1492703-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    In: Human Brain Mapping, Wiley, Vol. 38, No. 11 ( 2017-11), p. 5778-5794
    Kurzfassung: Most functional MRI (fMRI) studies map task‐driven brain activity using a block or event‐related paradigm. Sparse paradigm free mapping (SPFM) can detect the onset and spatial distribution of BOLD events in the brain without prior timing information, but relating the detected events to brain function remains a challenge. In this study, we developed a decoding method for SPFM using a coordinate‐based meta‐analysis method of activation likelihood estimation (ALE). We defined meta‐maps of statistically significant ALE values that correspond to types of events and calculated a summation overlap between the normalized meta‐maps and SPFM maps. As a proof of concept, this framework was applied to relate SPFM‐detected events in the sensorimotor network (SMN) to six motor functions (left/right fingers, left/right toes, swallowing, and eye blinks). We validated the framework using simultaneous electromyography (EMG)–fMRI experiments and motor tasks with short and long duration, and random interstimulus interval. The decoding scores were considerably lower for eye movements relative to other movement types tested. The average successful rate for short and long motor events were 77 ± 13% and 74 ± 16%, respectively, excluding eye movements. We found good agreement between the decoding results and EMG for most events and subjects, with a range in sensitivity between 55% and 100%, excluding eye movements. The proposed method was then used to classify the movement types of spontaneous single‐trial events in the SMN during resting state, which produced an average successful rate of 22 ± 12%. Finally, this article discusses methodological implications and improvements to increase the decoding performance. Hum Brain Mapp 38:5778–5794, 2017 . © 2017 Wiley Periodicals, Inc.
    Materialart: Online-Ressource
    ISSN: 1065-9471 , 1097-0193
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2017
    ZDB Id: 1492703-2
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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