Within-Session and Between-Session Reproducibility of Cerebral Sensorimotor Activation: A Test–Retest Effect Evidenced with Functional Magnetic Resonance Imaging

Abstract

The aim of the current study was to assess the reproducibility of functional magnetic resonance imaging (fMRI) brain activation signals in a sensorimotor task in healthy subjects. Because random or systematic changes are likely to happen when movements are repeated over time, the authors searched for time-dependent changes in the fMRI signal intensity and the extent of activation within and between sessions. Reproducibility was studied on a sensorimotor task called "the active task" that includes a motor output and a sensory feedback, and also on a sensory stimulation called "the passive task" that assessed the sensory input alone. The active task consisted of flexion and extension of the right hand. The subjects had performed it several times before fMRI scanning so that it was well learned. The passive task consisted of a calibrated passive flexion and extension of the right wrist. Tasks were 1 Hz-paced. The control state was rest. Subjects naïve to the MRI environment and non--MRI-naïve subjects were studied. Twelve MRI-naïve subjects underwent 3 fMRI sessions separated by 5 hours and 49 days, respectively. During MRI scanning, they performed the active task. Six MRI-naïve subjects underwent 2 fMRI sessions with the passive task 1 month apart. Three non--MRI-naïve subjects performed twice an active 2-Hz self-paced task. The data were analyzed with SPM96 software. For within-session comparison, for active or passive tasks, good reproducibility of fMRI signal activation was found within a session (intra-and interrun reproducibility) whether it was the first, second, or third session. Therefore, no within-session habituation was found with a passive or a well-learned active task. For between-session comparison, for MRI-naïve or non--MRI-naïve subjects, and with the active or the passive task, activation was increased in the contralateral premotor cortex and in ispsilateral anterior cerebellar cortex but was decreased in the primary sensorimotor cortex, parietal cortex, and posterior supplementary motor area at the second session. The lower cortical signal was characterized by reduced activated areas with no change in maximum peak intensity in most cases. Changes were partially reversed at the third session. Part of the test-retest effect may come from habituation of the MRI experiment context. Less attention and stress at the second and third sessions may be components of the inhibition of cortical activity. Because the changes became reversed, the authors suggest that, beyond the habituation process, a learning process occurred that had nothing to do with procedural learning, because the tasks were well learned or passive. A long-term memory representation of the sensorimotor task, not only with its characteristics (for example, amplitude, frequency) but also with its context (fMRI), can become integrated into the motor system along the sessions. Furthermore, the pattern observed in the fMRI signal changes might evoke a consolidation process.

Mapping the After-effects of Theta Burst Stimulation on the Human Auditory Cortex with Functional Imaging

“…In fact it could be a good idea to run some pilot studies, repeating the scans after removing and reintroducing the subject (without TMS) to test the degree to which one may expect differences due to this factor alone. The between-session comparison could be affected by non-specific TMS factors such as habituation to the MRI experiment context, including the MRI environment, as well as the task to be performed 21 . To overcome this problem one could counterbalance the order of pre-and post-TMS fMRI sessions across participants.…”

Frontal recruitment during response inhibition in older adults replicated with fMRI

“…The reasons for this difference are not known, although it could be due to greater task difficulty at Time 1, although inhibition performance at the two time points was not significantly different. There are also possible effects of novelty and habituation (Fischer et al, 2003;Kiehl and Liddle, 2003;Loubinoux et al, 2001) and procedural learning (Eliassen et al, 2001) that could account for these minor differences between Time 1 and Time 2. Another possibility is that the use of four separate trial blocks at Time 1 (i.e., a longer task with more events) and a larger participant pool resulted in a higher signal to noise ratio than with two blocks at Time 2, which would have enabled better differentiation of significantly active clusters and greater inhibition-related activation compared to baseline.…”

Test–retest study of fMRI signal change evoked by electroacupuncture stimulation

“…Researchers have begun to investigate test-retest reliability of fMRI BOLD signal changes evoked by paradigms ranging from simple sensory motor tasks such as finger tapping and visual simulation to more complex cognitive paradigms such as auditory oddball stimulation, working memory and learning tasks (Casey et al, 1998;Machielsen et al, 2000;McGonigle et al, 2000;Waldvogel et al, 2000;Loubinoux et al, 2001;Rutten et al, 2002;Kurland et al, 2004;Marshall et al, 2004;Wei et al, 2004;Havel et al, 2005;Wagner et al, 2005;Yoo et al, 2005;Aron et al, 2006). For instance, several studies have used the finger-tapping task (Yetkin et al, 1996;McGonigle et al, 2000;Waldvogel et al, 2000;Liu et al, 2004a;Smith et al, 2005;Yoo et al, 2005), one of the most widely used tasks in fMRI studies, to investigate the reliability of fMRI signal changes.…”