Mapping individual brains to guide restorative therapy after stroke: Rationale and pilot studies

Abstract

Some treatments under development to improve motor outcome after stroke require information about organization of individual subject's brain. The current study aimed to characterize normal inter-subject differences in localization of motor functions, and to consider these findings in relation to a potential treatment of motor deficits after stroke. Functional MRI (fMRI) scanning in 14 subjects examined right index finger tapping, shoulder rotation, or facial movement. The largest activation cluster in left sensorimotor cortex was identified for each task, and its center expressed in Talairach stereotaxic coordinates. Across subjects, each task showed considerable variability in activation site coordinates. For example, during finger tapping, the range for center of activation was 7 mm in the x-axis, 19 mm in the y-axis, and 11 mm in the z-axis. The mean value for center of activation was significantly different for all three coordinates for all pairwise task comparisons. However, the distribution of activation site centers for the finger task overlapped with the other two tasks in the x- and y-axes, and with the shoulder task in the z-axis. On average, the center of activation for the three motor tasks were spatially separated and somatotopically distributed. However, across the population, there was considerable overlap in the center of activation site, especially for finger and shoulder movements. Restorative therapies that aim to target specific body segments, such as the hand, in the post-stroke motor system may need to map the individual brain rather than rely on population averages. Initial details are presented of a study using this approach to evaluate such a therapy.

Use of Functional MRI to Guide Decisions in a Clinical Stroke Trial

“…5 The range was similar to the range in healthy controls 6 and approximated electrode size. These data emphasize the anatomical variability in human motor system functional organization.…”

Dodecapus: An MR-compatible system for somatosensory stimulation

“…Accurate and detailed somatotopic mapping of the human body surface will improve basic understanding of the somatosensory system, guide neurosurgical planning, and assess plasticity and recovery after brain damage or body injuries (Borsook et al, 1998;Corbetta et al, 2002;Cramer et al, , 2003Cramer and Bastings, 2000;Cramer and Crafton, 2006;Lee et al, 1998Lee et al, , 1999Moore et al, 2000b;Ramachandran, 2005;Ramachandran and Rogers-Ramachandran, 2000;Rijntjes et al, 1997). Studies using fMRI have revealed somatotopic representations of the hand, fingers, wrist, elbow, shoulder, foot, toes, lips, and tongue in human brains (Alkadhi et al, 2002;Beisteiner et al, 2001;Blankenburg et al, 2003;Dechent and Frahm, 2003;Francis et al, 2000;Gelnar et al, 1998;Golaszewski et al, 2006;Hanakawa et al, 2005;Hlustik et al, 2001;Kurth et al, 2000;Lotze et al, 2000;McGlone et al, 2002;Miyamoto et al, 2006;Moore et al, 2000a;Overduin and Servos, 2004;Ruben et al, 2001;Servos et al, 1998;Stippich et al, 1999Stippich et al, , 2004van Westen et al, 2004; also see reviews in Burton, 2002).…”

Longitudinal Functional MRI of Motor and Cognitive Recovery Following Stroke: A Review

“…This suggests that cross-sectional studies of motor recovery, even those with the most homogeneous of patient populations, may be subject to high variability in measurements of cortical activity across the population. In fact, one pilot study demonstrated, using a finger movement task, that centers of activation show considerable spatial variation across subjects and concluded that studies aimed at investigating hand representations in the post-stroke motor system may need to investigate individuals, rather than relying on population averages [18].…”