title: The strength of the corticospinal coherence depends on the predictability of modulated isometric forces.
abstract: Isometric compensation of predictably frequency-modulated low forces is associated with corticomuscular coherence (CMC) in beta and low gamma range. It remains unclear how the CMC is influenced by unpredictably modulated forces, which create a mismatch between expected and actual sensory feedback. We recorded electroencephalography from the contralateral hand motor area, electromyography (EMG), and the motor performance of 16 subjects during a visuomotor task in which they had to isometrically compensate target forces at 8% of the maximum voluntary contraction with their right index finger. The modulated forces were presented with predictable or unpredictable frequencies. We calculated the CMC, the cortical motor alpha-, beta-, and gamma-range spectral powers (SP), and the task-related desynchronization (TRD), as well as the EMG SP and the performance. We found that in the unpredictable condition the CMC was significantly lower and associated with lower cortical motor SP, stronger TRD, higher EMG SP, and worse performance. The findings suggest that due to the mismatch between predicted and actual sensory feedback leading to higher computational load and less stationary motor state, the unpredictable modulation of the force leads to a decrease in corticospinal synchrony, an increase in cortical and muscle activation, and a worse performance.
authors.affiliation: Neurological Clinic, University Freiburg, Freiburg, Germany.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Mendez-Balbuena
authors.forename: Jose Raul
authors.initials: JR
authors.lastname: Naranjo
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.forename: Agnieska
authors.initials: A
authors.lastname: Andrykiewicz
authors.forename: Frank
authors.initials: F
authors.lastname: Huethe
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schulte-Mönting
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Hepp-Reymond
authors.forename: Rumyana
authors.initials: R
authors.lastname: Kristeva
mesh_terms: D000293:Adolescent; D000328:Adult; D058256:Brain Waves; D056228:Feedback, Sensory; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D011597:Psychomotor Performance; D011712:Pyramidal Tracts / Q000502:physiology*