title: Cortical activity differs between position- and force-control knee extension tasks.
abstract: Neural control differs between position- and force-control tasks as evident from divergent effects of fatigue and pain. Unlike force-control tasks, position-control tasks focus on a postural goal to maintain a joint angle. Cortical involvement is suggested to be less during postural control, but whether this differs between position- and force-control paradigms remains unclear. Coherence estimates the functional communication between spatially distinct active regions within the cortex (cortico-cortical coherence; CCC) and between the cortex and muscles (corticomuscular coherence; CMC). We investigated whether cortical involvement differed between force-control and more posturally focused, position-control tasks. Seventeen adults performed position- and force-control knee extensor efforts at a submaximal load (10 % maximum voluntary contraction). Surface electromyography was recorded from the right knee extensor and flexor muscles and brain activity using electroencephalography (EEG). CCC and CMC in the beta (13-30 Hz) and gamma (30-45 Hz) frequency bands were calculated between combinations of intra- and inter-hemispheric pairs of electrodes, and between four EEG electrodes that approximated the left motor cortical area, and right knee extensor EMG, respectively. Differences in EEG power and muscle activity were also calculated. CCC was greater across distributed regions in the force-control task. Beta EEG power in the left hemisphere was higher for the position-control task. Although averaged CMC data differed between tasks, there was no task difference for individual CMC data. Muscle activity and force did not differ between tasks. The results demonstrate differential cortical contributions to control force- versus position-control tasks. This might contribute to differences in performance outcomes of these tasks that have been shown previously.
authors: Centre for Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia.|Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia.|Asia-Pacific Centre for Neuromodulation, Centre for Clinical Research, The University of Queensland, Brisbane, Australia.
authors: Peter C
authors: PC
authors: Poortvliet
authors: Centre for Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia.|School of Biomedical Sciences, The University of Queensland, Brisbane, Australia.
authors: Kylie J
authors: KJ
authors: Tucker
authors: Centre for Clinical Research, Royal Brisbane and Women's Hospital, The University of Queensland, Brisbane, Australia.|Gallipoli Medical Research Foundation, Greenslopes Private Hospital, Brisbane, Australia.
authors: Simon
authors: S
authors: Finnigan
authors: Centre for Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia.
authors: Dion
authors: D
authors: Scott
authors: Department of Cognitive Science, Macquarie University, Sydney, Australia.
authors: Paul
authors: P
authors: Sowman
authors: Centre for Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia. p.hodges@uq.edu.au.
authors: Paul W
authors: http://orcid.org/0000-0002-1206-9107
authors: PW
authors: Hodges
mesh_terms: D000328:Adult; D001611:Beta Rhythm / Q000502:physiology; D004569:Electroencephalography / Q000379:methods*; D004576:Electromyography / Q000379:methods*; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007717:Knee / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology*
keywords: Cortico-cortical coherence; Corticomuscular coherence; Electroencephalography; Electromyography; Knee extensor muscles; Postural control