Motor Cortex Activation During Writing in Focal Upper-Limb Dystonia: An fNIRS Study

Abstract

Background Functional imaging studies have associated dystonia with abnormal activation in motor and sensory brain regions. Commonly used techniques such as functional magnetic resonance imaging impose physical constraints, limiting the experimental paradigms. Functional near-infrared spectroscopy (fNIRS) offers a new noninvasive possibility for investigating cortical areas and the neural correlates of complex motor behaviors in unconstrained settings. Methods We compared the cortical brain activation of patients with focal upper-limb dystonia and controls during the writing task under naturalistic conditions using fNIRS. The primary motor cortex (M1), the primary somatosensory cortex (S1), and the supplementary motor area were chosen as regions of interest (ROIs) to assess differences in changes in both oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb) between groups. Results Group average activation maps revealed an expected pattern of contralateral recruitment of motor and somatosensory cortices in the control group and a more bilateral pattern of activation in the dystonia group. Between-group comparisons focused on specific ROIs revealed an increased activation of the contralateral M1 and S1 cortices and also of the ipsilateral M1 cortex in patients. Conclusions Overactivity of contralateral M1 and S1 in dystonia suggest a reduced specificity of the task-related cortical areas, whereas ipsilateral activation possibly indicates a primary disorder of the motor cortex or an endophenotypic pattern. To our knowledge, this is the first study using fNIRS to assess cortical activity in dystonia during the writing task under natural settings, outlining the potential of this technique for monitoring sensory and motor retraining in dystonia rehabilitation.

fNIRS-Based Upper Limb Motion Intention Recognition Using an Artificial Neural Network for Transhumeral Amputees

“…For the evaluation of the performance of acquired fNIRS signals, a widely used [ 38 ] classifier in pattern recognition was implemented, namely, artificial neural network (ANN). It uses various neuron layers to plan information starting with one circulation then onto the next one for better and enhanced results, i.e., returning less error [ 46 , 48 ]. A system called backpropagation assists ANN to form a bridge between input and output layers in which the corresponding labels/indicators are present [ 49 ].…”

A Comparison of Immersive vs. Non-Immersive Virtual Reality Exercises for the Upper Limb: A Functional Near-Infrared Spectroscopy Pilot Study with Healthy Participants

“…Functional near-infrared spectroscopy (fNIRS) is suitable for the investigation of the effects of movement on cerebral oxygenation and hemodynamics—it is able to quantify changes in the concentration of oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) non-invasively [ 12 ]. A number of previous studies used fNIRS to assess various upper limb movements and conditions, such as simple hand movements [ 13 ], hand-grip strength [ 14 ], skill development [ 15 ], focal upper limb dystonia [ 16 ], stroke rehabilitation [ 3 , 17 ], cortical reorganization [ 18 ] and so on. However, to the best of our knowledge, up to now there are no studies which have combined VR and fNIRS to track upper limb movements.…”