Models to Tailor Brain Stimulation Therapies in Stroke

Figure 1

Role of ipsilesional premotor areas: from our work in Cunningham et al. [38]. PMC: premotor cortex (synonymous with PMd here); MAL: motor activity log. The figure explains the potential of ipsilesional higher motor areas including ipsilesional PMd in recovery. Patients with wide-ranging baseline impairments undergo functional MRI during movement of the paretic hand. Activation of ipsilesional versus contralesional cortices is computed using a laterality index, where a higher positive value suggests cortices contralateral to the paretic limb are activated. (a) demonstrates that patients who show better laterality for PMd, that is, greater activation of ipsilesional versus contralesional PMd (-axis), perceive less disability in using their paretic hand (-axis). Perception of disability is signified using a popular scale, known as MAL. Values on MAL range anywhere from 0 to 5, where 5 signifies no disability in the use of the paretic hand. (b) presents an illustration of subjective examples. Two patients, labeled 1 and 2, underwent fMRI during movement of their paretic hand. Images show fMRI activation in transverse (top) and coronal (bottom) planes. For simplicity, the lesioned hemisphere is shown to the right of each image. Patient 1 demonstrates focused activation of ipsilesional PMd that coincides with greater laterality, while patient 2 shows weaker laterality because activation of most regions is bilateral. MAL scores for patients 1 and 2, respectively, are 2.3 and 0.66. Therefore, patient 1 who perceived lesser disability in using the paretic hand showed greater activation of ipsilesional PMd, though patient 2 with extreme perception of disability activated multiple other regions. Patients who recover, albeit incompletely, can rely on plasticity of their ipsilesional premotor areas.

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