Ask your competent? doctor EXACTLY HOW THIS WILL GET YOU RECOVERED! Because I see nothing useful.
Use of functional magnetic resonance imaging to identify cortical loci for lower limb movements and their efficacy for individuals after stroke
Journal of NeuroEngineering and Rehabilitation volume 21, Article number: 58 (2024)
Abstract
Background
Identification of cortical loci for lower limb movements for stroke rehabilitation is crucial for better rehabilitation outcomes via noninvasive brain stimulation by targeting the fine-grained cortical loci of the movements. However, identification of the cortical loci for lower limb movements using functional MRI (fMRI) is challenging due to head motion and difficulty in isolating different types of movement. Therefore, we developed a custom-made MR-compatible footplate and leg cushion to identify the cortical loci for lower limb movements and conducted multivariate analysis on the fMRI data. We evaluated the validity of the identified loci using both fMRI and behavioral data, obtained from healthy participants as well as individuals after stroke.
Methods
We recruited 33 healthy participants who performed four different lower limb movements (ankle dorsiflexion, ankle rotation, knee extension, and toe flexion) using our custom-built equipment while fMRI data were acquired. A subgroup of these participants (Dataset 1; n = 21) was used to identify the cortical loci associated with each lower limb movement in the paracentral lobule (PCL) using multivoxel pattern analysis and representational similarity analysis. The identified cortical loci were then evaluated using the remaining healthy participants (Dataset 2; n = 11), for whom the laterality index (LI) was calculated for each lower limb movement using the cortical loci identified for the left and right lower limbs. In addition, we acquired a dataset from 15 individuals with chronic stroke for regression analysis using the LI and the Fugl–Meyer Assessment (FMA) scale.
Results
The cortical loci associated with the lower limb movements were hierarchically organized in the medial wall of the PCL following the cortical homunculus. The LI was clearer using the identified cortical loci than using the PCL. The healthy participants (mean ± standard deviation: 0.12 ± 0.30; range: – 0.63 to 0.91) exhibited a higher contralateral LI than the individuals after stroke (0.07 ± 0.47; – 0.83 to 0.97). The corresponding LI scores for individuals after stroke showed a significant positive correlation with the FMA scale for paretic side movement in ankle dorsiflexion (R2 = 0.33, p = 0.025) and toe flexion (R2 = 0.37, p = 0.016).
Conclusions
The cortical loci associated with lower limb movements in the PCL identified in healthy participants were validated using independent groups of healthy participants and individuals after stroke. Our findings suggest that these cortical loci may be beneficial(NOT GOOD ENOUGH! Come back when you have exact protocols for recovery!) for the neurorehabilitation of lower limb movement in individuals after stroke, such as in developing effective rehabilitation interventions guided by the LI scores obtained for neuronal activations calculated from the identified cortical loci across the paretic and non-paretic sides of the brain.
Background
Functional magnetic resonance imaging (fMRI) has been widely used to investigate the motor functions of the human brain, particularly upper limb movements such as finger tapping and hand grasping/clenching. Distinct cortical loci have been identified for different types of upper limb movement [1,2,3], and these cortical loci have been successfully employed for the neurorehabilitation/neuroplasticity of individuals in the chronic stage after stroke [4,5,6]. The importance of identifying the cortical loci for lower limb movement in stroke rehabilitation has been discussed in previous studies [7, 8]. For example, noninvasive brain stimulations such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) have been demonstrated to be effective in improving the gait and balance performance of individuals with subacute and chronic stroke by targeting the cortical loci, including the primary motor cortex (M1) [7]. We believe rehabilitation outcomes would be further enhanced by targeting the stimulation of fine-grained cortical loci for lower limb movement.
In this context, previous studies have investigated neuronal patterns observed from fMRI during lower limb movements [9,10,11,12]. For example, Luft and colleagues (2002) compared brain activations between upper and lower limb movements by incorporating finger, elbow, and knee movements in their lateralization index (LI) across various regions-of-interest (ROIs), including the M1, primary somatosensory cortex (S1), primary motor area (SMA), and cerebellum [10]. Kapreli et al. extended these findings by including the ankle and toes to differentiate the LI of brain activations for finger movement from that for the movement of lower limb joints [11, 12] and by combining movements across the ankle, knee, and hip [9]. These previous studies have generally reported different activation loci for lower limb movements compared with upper limb movements and overlapping spatial layouts for neuronal activations across lower limb movements. Another line of research has compared the neuronal activations of imagined lower limb movements with executed and/or observed movements for the right ankle [13], foot-kicking [14], and stepping [15].
However, few studies have investigated the distinct cortical loci considering hierarchical representations in the cortical homunculus for the movement of the ankle, toe, or knee, which are feasible movements of the lower limb extremities for fMRI acquisition because head motion is potentially more controllable compared with hip joint movement [11]. The identification of cortical loci specific to these lower limb movements in the median wall of the sensorimotor area mainly in the paracentral lobule (PCL) region is more challenging than for upper limb movements because the motor cortex associated with the lower limbs is smaller in volume than that for the upper limbs based on the cortical homunculus [16]. In addition, isolation of individual lower limb movements is more demanding due to the potentially greater head motion [10, 17,18,19].
Previous studies have investigated the neuronal activation patterns of lower limb movements based on the guidance of MR-compatible equipment. These studies include the identification of neuronal activation patterns for active and passive stepping movements [15, 20, 21] and pedaling [18] and the real-time monitoring of ankle, knee, and hip torques with their associated neuronal activations [22]. In the present study, we developed a custom-made MR-compatible footplate and leg cushion to isolate individual lower limb movements and minimize potential head motion during fMRI data acquisition. We then identified the cortical loci for lower limb movements using fMRI data acquired from healthy participants and subsequent multivariate analysis. Conventionally, it is not easy to delineate these loci due to the constrained cortical regions, particularly in the PCL, which is the medial continuation of the precentral and postcentral gyri [23], and overlapping functional territories across the lower limbs. We also investigated the efficacy of the cortical loci identified from healthy participants for individuals with chronic stroke. We hypothesized that our custom-built equipment and multivariate analytical methods would be useful for identifying hierarchically organized cortical loci for lower limb movements (i.e., an inferior location for the toe to a superior location for the knee). We also hypothesized that the identified cortical loci would be useful in evaluating the neural features of individuals with chronic stroke.
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