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Flexible adaptive paradigms for fMRI using a novel software package 'Brain Analysis in Real-Time' (BART).

Hellrung L, Hollmann M, Zscheyge O, Schlumm T, Kalberlah C, Roggenhofer E, Okon-Singer H, Villringer A, Horstmann A - PLoS ONE (2015)

Bottom Line: This can have a significant impact on the results.Our fMRI findings clearly show the benefits of an adapted paradigm in terms of statistical power and higher effect sizes in emotion-related brain regions.This can be of special interest for all experiments with low statistical power due to a limited number of subjects, a limited amount of time, costs or available data to analyze, as is the case with real-time fMRI.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig,Germany; Leipzig University Medical Center, Leipzig, Germany.

ABSTRACT
In this work we present a new open source software package offering a unified framework for the real-time adaptation of fMRI stimulation procedures. The software provides a straightforward setup and highly flexible approach to adapt fMRI paradigms while the experiment is running. The general framework comprises the inclusion of parameters from subject's compliance, such as directing gaze to visually presented stimuli and physiological fluctuations, like blood pressure or pulse. Additionally, this approach yields possibilities to investigate complex scientific questions, for example the influence of EEG rhythms or fMRI signals results themselves. To prove the concept of this approach, we used our software in a usability example for an fMRI experiment where the presentation of emotional pictures was dependent on the subject's gaze position. This can have a significant impact on the results. So far, if this is taken into account during fMRI data analysis, it is commonly done by the post-hoc removal of erroneous trials. Here, we propose an a priori adaptation of the paradigm during the experiment's runtime. Our fMRI findings clearly show the benefits of an adapted paradigm in terms of statistical power and higher effect sizes in emotion-related brain regions. This can be of special interest for all experiments with low statistical power due to a limited number of subjects, a limited amount of time, costs or available data to analyze, as is the case with real-time fMRI.

No MeSH data available.


Related in: MedlinePlus

Behavioral results.The post-hoc analysis of eye tracking data shows the correct functionality of the software by 100% fixations for all subjects in the adapted condition. In addition, it shows difference in fixation compliance and gaze distance from the center of the screen for the non-adapted picture presentation. Due to the bimodal distribution of this parameter, subjects were divided into subgroups.
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pone.0118890.g004: Behavioral results.The post-hoc analysis of eye tracking data shows the correct functionality of the software by 100% fixations for all subjects in the adapted condition. In addition, it shows difference in fixation compliance and gaze distance from the center of the screen for the non-adapted picture presentation. Due to the bimodal distribution of this parameter, subjects were divided into subgroups.

Mentions: Offline, we examined the gaze position at the beginning of each picture presentation. For the non-adapted trials, these show that the overall fixation compliance was 67% (± 22%) for all subjects. The results have shown a bimodal distribution of this parameter. According to this, subjects were divided into two groups (‘High-Compliant’ and ‘Low-Compliant’) by a median split on fixation compliance. The High-Compliant group fixated in 83% of the non-adapted trials (± 6.2%), whereas the Low-Compliant group had a fixation rate of only 49% (± 20%). Additionally, we examined the gaze position at the beginning of stimulus presentation. In a descriptive manner, the results illustrate that in the non-adapted condition eye position of the Low-Compliant group does not coincide with the center of the screen in contrast to the High-Compliant group. There is no difference for the adapted picture presentation. Fig. 4 illustrates the behavioral results for fixation success and describes a difference for the distances between gaze position and screen center between the two groups. Due to the functionality of our software all trials for all subjects are valid in the adapted presentation condition, i.e. eye position deviates from screen center by less than 1° visual angle.


Flexible adaptive paradigms for fMRI using a novel software package 'Brain Analysis in Real-Time' (BART).

Hellrung L, Hollmann M, Zscheyge O, Schlumm T, Kalberlah C, Roggenhofer E, Okon-Singer H, Villringer A, Horstmann A - PLoS ONE (2015)

Behavioral results.The post-hoc analysis of eye tracking data shows the correct functionality of the software by 100% fixations for all subjects in the adapted condition. In addition, it shows difference in fixation compliance and gaze distance from the center of the screen for the non-adapted picture presentation. Due to the bimodal distribution of this parameter, subjects were divided into subgroups.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383593&req=5

pone.0118890.g004: Behavioral results.The post-hoc analysis of eye tracking data shows the correct functionality of the software by 100% fixations for all subjects in the adapted condition. In addition, it shows difference in fixation compliance and gaze distance from the center of the screen for the non-adapted picture presentation. Due to the bimodal distribution of this parameter, subjects were divided into subgroups.
Mentions: Offline, we examined the gaze position at the beginning of each picture presentation. For the non-adapted trials, these show that the overall fixation compliance was 67% (± 22%) for all subjects. The results have shown a bimodal distribution of this parameter. According to this, subjects were divided into two groups (‘High-Compliant’ and ‘Low-Compliant’) by a median split on fixation compliance. The High-Compliant group fixated in 83% of the non-adapted trials (± 6.2%), whereas the Low-Compliant group had a fixation rate of only 49% (± 20%). Additionally, we examined the gaze position at the beginning of stimulus presentation. In a descriptive manner, the results illustrate that in the non-adapted condition eye position of the Low-Compliant group does not coincide with the center of the screen in contrast to the High-Compliant group. There is no difference for the adapted picture presentation. Fig. 4 illustrates the behavioral results for fixation success and describes a difference for the distances between gaze position and screen center between the two groups. Due to the functionality of our software all trials for all subjects are valid in the adapted presentation condition, i.e. eye position deviates from screen center by less than 1° visual angle.

Bottom Line: This can have a significant impact on the results.Our fMRI findings clearly show the benefits of an adapted paradigm in terms of statistical power and higher effect sizes in emotion-related brain regions.This can be of special interest for all experiments with low statistical power due to a limited number of subjects, a limited amount of time, costs or available data to analyze, as is the case with real-time fMRI.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig,Germany; Leipzig University Medical Center, Leipzig, Germany.

ABSTRACT
In this work we present a new open source software package offering a unified framework for the real-time adaptation of fMRI stimulation procedures. The software provides a straightforward setup and highly flexible approach to adapt fMRI paradigms while the experiment is running. The general framework comprises the inclusion of parameters from subject's compliance, such as directing gaze to visually presented stimuli and physiological fluctuations, like blood pressure or pulse. Additionally, this approach yields possibilities to investigate complex scientific questions, for example the influence of EEG rhythms or fMRI signals results themselves. To prove the concept of this approach, we used our software in a usability example for an fMRI experiment where the presentation of emotional pictures was dependent on the subject's gaze position. This can have a significant impact on the results. So far, if this is taken into account during fMRI data analysis, it is commonly done by the post-hoc removal of erroneous trials. Here, we propose an a priori adaptation of the paradigm during the experiment's runtime. Our fMRI findings clearly show the benefits of an adapted paradigm in terms of statistical power and higher effect sizes in emotion-related brain regions. This can be of special interest for all experiments with low statistical power due to a limited number of subjects, a limited amount of time, costs or available data to analyze, as is the case with real-time fMRI.

No MeSH data available.


Related in: MedlinePlus