Brain control of functional reach in healthy adults and stroke survivors

Abstract

Purpose: Recovery of the most basic shoulder-flexion/elbow-extension components of functional reach is critical for effective arm function following stroke. In order to understand the mechanisms of motor recovery, it is important to characterize the pattern of brain activation during the reach task. Methods: We evaluated 11 controls and 23 moderately to severely impaired chronic stroke survivors (>6 months), with impaired shoulder flexion and elbow extension. Measures were acquired for Arm Motor Ability Test (AMAT) and functional Magnetic Resonance Imaging (fMRI) during the basic shoulder/elbow reach. Results: First, in controls, lateralization of fMRI signal during the reach task was less pronounced in comparison to other tasks, and even further diminished after stroke (p < 0.05). Second, for the stroke group, centroid locations, for specific ipsilesional (contralateral to working limb) motor-sensory regions and for contralesional (ipsilateral to working arm) somatosensory and SMA regions, were significantly more distant from the centroid location of average healthy controls (p < 0.05). Third, both greater activation volume and greater degree of signal intensity were correlated with better motor function in stroke survivors. Conclusions: These findings can be useful in guiding the development of more targeted brain training methods for recovery of impaired reach coordination.

"Investigating Reliable Recovery Biomarkers of Ischemic Stroke: An Evidence-Based Study"

“…In post-stroke fMRI investigations, it has been used to identify neuro plastic alterations in stroke survivors [37]. Further, it was found to be associated with greater activation in the hemisphere contralateral to the working limb (lesioned hemisphere) versus the hemisphere ipsilateral to the working limb (non-lesioned hemisphere) [24].…”

Home-based portable fNIRS-derived cortical laterality correlates with impairment and function in chronic stroke

“…One candidate biomarker of motor recovery in stroke is the ratio of activity between the primary motor cortices during movement of one's paretic limb (i.e., motor cortex laterality; M1-LAT). Using functional magnetic resonance imaging (fMRI) (Marshall et al, 2000;Tombari et al, 2004;Daly et al, 2014), functional near-infrared spectroscopy (fNIRS) (Takeda et al, 2007;Delorme et al, 2017), or electroencephalography (EEG) (Kaiser et al, 2012), it has been shown that deviation from a typical contralateralized pattern of M1-LAT corresponds to worse upper-extremity movement deficits. Moreover, fNIRS studies have also found that the inverse pattern (i.e., a departure from the typically symmetrical pattern of M1-LAT) corresponds to worse gait abilities (Miyai et al, 2006).…”