Brain activity during a motor learning task: An fMRI and skin conductance study

Abstract

Measuring electrodermal activity (EDA) during fMRI is an effective means of studying the influence of task-related arousal, inferred from autonomic nervous system activity, on brain activation patterns. The goals of this study were: (1) to measure reliable EDA from healthy individuals during fMRI involving an effortful unilateral motor task, (2) to explore how EDA recordings can be used to augment fMRI data analysis. In addition to conventional hemodynamic modeling, skin conductance time series data were used as model waveforms to generate activation images from fMRI data. Activations from the EDA model produced significantly different brain regions from those obtained with a standard hemodynamic model, primarily in the insula and cingulate cortices. Onsets of the EDA changes were synchronous with the hemodynamic model, but EDA data showed additional transient features, such as a decrease in amplitude with time, and helped to provide behavioral evidence suggesting task difficulty decreased with movement repetition. Univariate statistics also confirmed that several brain regions showed early versus late session effects. Partial least squares (PLS) multivariate analysis of EDA and fMRI data provided complimentary, additional insight on how the motor network varied over the course of a single fMRI session. Brain regions identified in this manner included the insula, cingulate gyrus, pre- and postcentral gyri, putamen and parietal cortices. These results suggest that recording EDA during motor fMRI experiments provides complementary information that can be used to improve the fMRI analysis, particularly when behavioral or task effects are difficult to model a priori.

Challenging the brain: Exploring the link between effort and cortical activation

“…The finding that the brain activation pattern was more profoundly distinguished when comparing groups based on EDR, suggests that the physiologic index may have the ability to characterize the link between effort and the underlying task challenge more directly. This is consistent with studies reporting improvements in modeling cortical responses during the performance of sensorimotor tasks when the EDR was used in both univariate and multivariate statistical models (MacIntosh et al, 2007).…”

Electrodermal Recording and fMRI to Inform Sensorimotor Recovery in Stroke Patients

“…7,18 Similarly, activation foci due to grip and hand tasks were comparable to a recent study involving young healthy participants performing a complex fractionated finger movement task. 13 Due to the small sample size, it was not possible to assess the variability in autonomic tone or its effect on the fMRI signal when patients moved the affected versus unaffected limbs. However, given that the fMRI-compatible EDA system is relatively easy to use, is costeffective, and requires immobilization of 2 digits only (ie, digits 4 and 5 of the unaffected hand), EDA measurements can be incorporated into future studies.…”

“…A fruitful application of EDA is to incorporate the autonomic signal as a physiological covariate in fMRI studies to investigate brain and behavior relationships. 13,14 The present pilot study incorporates an fMRI-compatible EDA system in a small group of subacute and chronic stroke patients to provide a physiological marker of the sense of effort during tasks with the affected limb. It is hypothesized that EDA can be incorporated into fMRI analysis to provide interpretation of activation patterns that is complementary to typical task-related analyses.…”

Use of Optoelectronics to Measure Biosignals Concurrently During Functional Magnetic Resonance Imaging of the Brain

“…The circuit design is based on the Wheatstone bridge preamplifier with a gain of 1000 and is based on early work described by others (Shastri, Lomarev et al 2001). Additional details associated with this system can be found elsewhere (MacIntosh, Mraz et al 2007). …”

“…For example, the amplitude of the EDA signals at later trials is decreased compared to early trials. These data are based on published work (MacIntosh, Mraz et al 2007). …”