A study on the difference between functional connectivity in elbow flexion and extension according to object weight.

In this study, the results of functional connectivity between various areas were extracted when flexion and extension of the elbow were repeatedly performed with 500 g and 1000 g balls in hand. All subjects performed elbow bending and stretching at an angle of 90 degrees with the right back of their hand facing down. A total of 30 bending and stretching exercises were performed for 1 minute. At this time, the experiment was carried out under 2 conditions: (500 g motion) when performing the exercise with a 500-g object in the right hand and a 1000 g object (1000 g motion). To process functional magnetic resonance imaging data, we used the Functional Connectivity (CONN) toolbox, which was implemented in Statistical Parametric Mapping software version 12. Visual.lateral (right, R)-Visual.medial, Visual.medical-Visual.occipital, SensoriMotor.superior-SensoriMotor.lateral (left, L), FrontoParital.lateral prefrontal cortex (R)-FrontoParital.posterior cingulate cortex (R), and DorsalAttention.intraparietal sulcus (R)-SensoriMotor.superior connection reduced the effect size when flexion and extension of the elbow joint with 1000 g objects more than 500 g objects were carried out. On the other hand, when the task was performed with 1000 g objects rather than 500 g, the effect size of Visual.lateral (L)-Visual.medial, Salience.supramarginal gyrus (L)-DorsalAttention.intraparietal sulcus (R), Language.posterior superior temporal gyrus (L)-Language.inferior frontal gyrus (L), and Salience.AInsula (L)-Salience.AInsula (R) connection increased. The connection that showed the highest correlation coefficient when performing elbow exercise with a 500 g object was DorsalAttention.frontal eye fields (L)-SensoriMotor.superior, Language.inferior frontal gyrus (L)-Language.inferior frontal gyrus (R), and DorsalAttention.intraparietal sulcus (R)-SensoriMotor.lateral. On the other hand, when performing elbow exercises with 1000 g of objects, the highest correlation coefficients were Language.posterior superior temporal gyrus (L)-Language.posterior superior temporal gyrus (R), and Salience.supramarginal gyrus (R)-DorsalAttention.intraparietal sulcus (R). In conclusion, these findings suggest that the brain adapts its functional connectivity patterns in response to changes in physical load during motor tasks, potentially implicating different cognitive and sensorimotor processes depending on the exertion level required by the task. This has implications for understanding the neural mechanisms underlying motor control and could inform rehabilitation strategies for motor impairments.