Corticomuscular interactions during different movement periods in a multi-joint compound movement

Abstract

While much is known about motor control during simple movements, corticomuscular communication profiles during compound movement control remain largely unexplored. Here, we aimed at examining frequency band related interactions between brain and muscles during different movement periods of a bipedal squat (BpS) task utilizing regression corticomuscular coherence (rCMC), as well as partial directed coherence (PDC) analyses. Participants performed 40 squats, divided into three successive movement periods (Eccentric (ECC), Isometric (ISO) and Concentric (CON)) in a standardized manner. EEG was recorded from 32 channels specifically-tailored to cover bilateral sensorimotor areas while bilateral EMG was recorded from four main muscles of BpS. We found both significant CMC and PDC (in beta and gamma bands) during BpS execution, where CMC was significantly elevated during ECC and CON when compared to ISO. Further, the dominant direction of information flow (DIF) was most prominent in EEG-EMG direction for CON and EMG-EEG direction for ECC. Collectively, we provide novel evidence that motor control during BpS is potentially achieved through central motor commands driven by a combination of directed inputs spanning across multiple frequency bands. These results serve as an important step toward a better understanding of brain-muscle relationships during multi joint compound movements.Many muscles are involved in the execution and control of a bipedal squat (BpS) 1-3 , with Solomonow, et al. 4 estimating over 200 muscles to be recruited. In contrast to simple movements, BpS, as well as compound everyday life activities, i.e. walking stairs, picking up loads or carrying loads across distance, require extensive intra-and interlimb coordination 5 , which is why BpS is an ideal, naturalistic model for compound movement control. In contrast to simple movements, voluntary control of each muscle during BpS seems unlikely, especially when considering varying requirements on acting muscles due to changes in muscle function throughout different movement periods. Movement periods, i.e. dynamic (eccentric (ECC) and concentric (CON)) and static (isometric (ISO)) contraction periods require all muscles involved to dynamically change their function throughout the movement. This is evident for example from elevated proprioception, reflected by increased muscle spindle activities during eccentric contractions compared to both isometric and concentric contractions 6,7 . Thus, BpS demands continuous, extensive central-nervous information integration while placing high physical stress on the body 1-3 , signifying that motor commands have to be flexibly deployed and adapted throughout this movement in order to enable successful execution. Frequency band related neural synchrony between brain regions and muscles, detectable through corticomuscular coherence (CMC) measurements 8,9 , potentially provides an efficient solution to the challenge of enabling dynamic information processing on a whole body level during compound movement control. Indeed...

Specific modulation of corticomuscular coherence during submaximal voluntary isometric, shortening and lengthening contractions

“…Therefore, even though our results point toward a specific regulation of gamma-band CMC during anisometric contractions, we did not find any increase in gamma-band CMC during lengthening contractions that could explain, due to a ‘shift’ in the CMC frequency from beta- to gamma-band, the lower amount of beta-band CMC observed for the SOL during lengthening contractions compared to isometric ones. This discrepancy with the findings of certain studies 33 – 35 , 41 could be due on the one hand to the fact that CMC is task related 6 . Indeed, contrary to previous studies that involved weaker contractions 34 , 41 and/or multi-joint compound movements 33 , 35 , the current study was the first to analytically investigate the muscle contraction type effect during isokinetic contractions with stronger contractions.…”

“…This discrepancy with the findings of certain studies 33 – 35 , 41 could be due on the one hand to the fact that CMC is task related 6 . Indeed, contrary to previous studies that involved weaker contractions 34 , 41 and/or multi-joint compound movements 33 , 35 , the current study was the first to analytically investigate the muscle contraction type effect during isokinetic contractions with stronger contractions. On the other hand, while the method we used for CMC processing rendered a meaningful interpretation of synchronization processes with an excellent balance between the localization of time and frequency 42 , it may also induce differences with previous studies.…”

“…Beta-band CMC has been initially reported to be reduced during movements, due to differences in somatosensory afference integration 32 . However, more recent studies whose aim was to investigate CMC modulation between isometric and dynamic contractions reported that beta band CMC may be similar between isometric and anisometric contractions 33 – 35 . Accordingly, no difference in beta-band CMC between isometric and shortening contractions in the SOL was observed in the current study suggesting that differences in somatosensory afference integration between isometric and anisometric contractions do not seem to mainly explain the lower beta-band CMC found in the SOL during lengthening contractions either.…”

Intermuscular coherence between homologous muscles during dynamic and static movement periods of bipedal squatting

“…The following descriptions of our experimental setup, as well as all acquired behavioral data, are based on a previous study we conducted ( Kenville et al 2020 ). For details, please refer to the respective article.…”

New Directions in Exercise Prescription: Is There a Role for Brain-Derived Parameters Obtained by Functional Near-Infrared Spectroscopy?

“…Using fNIRS, brain activity is indirectly assessed by measuring cortical hemodynamic changes as a proxy of brain activity [ 50 , 55 ]. EEG has been applied in a variety of physical tasks and/or physical exercises (for review see [ 56 ]), such as balancing [ 57 , 58 , 59 , 60 , 61 , 62 , 63 ], walking [ 64 , 65 , 66 , 67 , 68 , 69 ], resistance exercises [ 70 , 71 , 72 ], or cycling [ 73 , 74 , 75 , 76 , 77 , 78 , 79 ]. Compared to fNIRS, EEG provides the advantage of a high temporal resolution (e.g., >1000 Hz) [ 80 , 81 , 82 , 83 , 84 , 85 ].…”