Reproducibility of activation in Broca's area during covert generation of single words at high field: A single trial FMRI study at 4 T

doi:10.1016/j.neuroimage.2006.03.021

NeuroImage

Volume 32, Issue 1, 1 August 2006, Pages 129-137

https://doi.org/10.1016/j.neuroimage.2006.03.021 Get rights and content

Abstract

Although functional magnetic resonance imaging (FMRI) has arguably become the most ubiquitously used imaging modality, questions remain about the reproducibility of the observed patterns of activation and the acquisition time required to achieve statistically significant and reproducible maps. In the current study, we investigated the reliability of activation in Broca's area, on both a voxel-wise and region of interest level, in response to the covert generation of a single word at 4 T. We also assessed the effects of different parametric (P < 0.01; P < 0.005; P < 0.001) and spatial thresholds (25%, 50% and 75%) on the reproducibility of activation within our region of interest and other randomly selected areas of the brain. We report that the inter-trial consistency of activation within Broca's area for a single trial design using multi-echo EPI is roughly equivalent to previous studies that averaged across a much larger number of trials. However, reliability estimates varied dramatically (approximately 55%) depending on the different parametric and spatial criteria thresholds that were applied to the data. These results show that increased sensitivity at high field strength can be used to reduce the time needed to localize functional activation patterns, which is beneficial for clinical studies such as pre-surgical mapping. Additional benefits of single trial designs, such as the ability to immediately assess for extraneous cognitive processes, are also discussed.

Section snippets

Subjects

Eight (3 males; 5 females) right-handed adult (age range 22–49 years) volunteers participated in the study. Handedness was determined by self-report on a questionnaire. Subjects with a history of neurological disease, major psychiatric disturbance, substance abuse or psychoactive prescriptive medication use were excluded. This study was approved by the Human Research Review Committee at the University of New Mexico, and all volunteers gave informed consent prior to participation.

Procedures

Subjects rested

Behavioral data

On one trial, a subject was unable to covertly generate a word. On four of the trials, a response time was not recorded from the input device due to either subject failure to press the response button or equipment failure in recording the response. The mean response time for the remaining 59 trials across all eight subjects was 3075.27 ms (SD ± 2362.94). Response times were positively correlated with subjective ratings of difficulty in generating the target word (Q1; r = 0.344; P < 0.01) and

Discussion

To our knowledge, this is the first FMRI study to assess the reliability of activation during a single, brief cognitive task. Reliable activation of Broca's area was observed on approximately 50% of the trials, dependent on the parametric threshold and the spatial criteria used to define activity. Specifically, there was a 55% difference in the ITC values when the most liberal parametric and spatial thresholds were applied to the data compared to the most conservative thresholds. The voxel-wise

Acknowledgments

Thanks to Dr. Nancy Andreasen for supporting this work and for stimulating discussions on the significance and clinical applications of real-time FMRI. We gratefully acknowledge Dr. Oliver Speck for providing the multi-echo EPI sequence. We thank Diana South, Ranee Barrow and Rosabelle DeNoi for excellent help with data acquisition and recruitment of subjects. Supported by NIH NIBIB 1 R01 EB002618-01 and The MIND Institute-Mental Illness and Neuroscience Discovery DOE Grant No.

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Reproducibility of activation in Broca's area during covert generation of single words at high field: A single trial FMRI study at 4 T

Abstract

Section snippets

Subjects

Procedures

Behavioral data

Discussion

Acknowledgments

NeuroImage

NeuroImage

NeuroImage

Comput. Biomed. Res.

NeuroImage

NeuroImage

NeuroImage

NeuroImage

NeuroImage

NeuroImage

Clin. Neurol. Neurosurg.

NeuroImage

NeuroImage

NeuroImage

Magn. Reson. Imaging

Brain Lang.

NeuroImage

Brain Res. Cogn. Brain Res.

Functional MRI assessment of the hemispheric predominance for language in epileptic patients using a simple rhyme detection task

Epileptic Disord.

Reliability of functional MR imaging with word-generation tasks for mapping Broca's area. AJNR

Am. J. Neuroradiol.