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Neuromuscular Physiology
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
Simplistically, voluntary movement is initiated by the primary motor cortex (MC) with input from the premotor cortex (PMC) and the supplementary motor area (SMA) (109). Information from cortical and subcortical nuclei is relayed by the PMC to the primary MC. For coordinated movement to occur sensory information transfer from subcortical areas to the MC is necessary. The PMC functions in the preparation for voluntary movements and also in postural control, visual guidance of movement, and rapid corrections during movement in response to sensory cues (109, 136). The function of the SMA include postural stabilization, bilateral coordination, control of movements that are internally generated rather than triggered by sensory events, and the control of movement sequencing (109, 117, 169, 199).
Anatomy of the head and neck
Published in Helen Whitwell, Christopher Milroy, Daniel du Plessis, Forensic Neuropathology, 2021
The central sulcus separates the motor and sensory areas of the cortex, with the precentral gyrus of the frontal lobe forming the anterior border of the sulcus. This region is the primary motor cortex. Specialist pyramidal cells within the primary motor cortex are responsible for voluntary movements by controlling somatic motor neurons in the brainstem and spinal cord.
Brain Motor Centers and Pathways
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
In humans, lesions of the primary motor cortex disturb the dexterous execution of movements and cause deficits ranging from muscle weakness and discoordination to paralysis when upper motoneurons are completely destroyed.
Transcranial Direct Current Stimulation of Motor Cortex Enhances Spike Performances of Professional Female Volleyball Players
Published in Journal of Motor Behavior, 2023
Seung-Bo Park, Doug Hyun Han, Junggi Hong, Jea-Woog Lee
In female volleyball competitions, high skill levels and general motor coordination are undoubtedly performance-related elements that can impact success (Pion et al., 2015). Stamm et al. (2005) have found that fundamental volleyball abilities such as spiking, blocking, and feinting are associated with success of volleyball players. In this regard, the primary motor cortex (M1) is an essential region for motor coordination and functions in terms of speed, endurance, strength, precision, and execution of motor tasks (Levasseur-Moreau et al., 2013). This cortical region is a complex network that interconnects localized groups of neurons with similar input and output processes to control arm and leg movements (Huang et al., 2019; Schieber, 2001). The M1 is responsible for the production of neural impulses that regulate movement execution (Huang et al., 2019; Moscatelli et al., 2016). It is thought that these networks can control the induction of plasticity. Their sensitivity to exercise-induced manipulation is of special interest (Singh & Staines, 2015). Various connections of the M1 that react and adapt to external stimuli appear to be highly plastic (Moscatelli et al., 2021). Several studies have reported that increased excitability of the M1 region can increase exercise performance (Wang et al., 2021).
Increased prefrontal cortical activation during challenging walking conditions in persons with lower limb amputation – an fNIRS observational study
Published in Physiotherapy Theory and Practice, 2022
Jette Schack, aAre Hugo Pripp, Peyman Mirtaheri, Harald Steen, Evin Güler, Terje Gjøvaag
Except for a recent study (Pruziner et al., 2019), dual-task studies in persons with LLA have mainly looked at cognitive and mobility performance and not on the underlying cortical activation during the performance. Pruziner et al. (2019) evaluated both gait mechanics (i.e. dual-task walking with a visual task) and cortical activity by electroencephalography (EEG) in a population with and without transtibial amputation and both groups showed overall similar cortical dynamics. Cortical structures play an important role in the control of mobility during daily activities (Hamacher et al., 2015). Neuroimaging studies have revealed that several different cortical and subcortical regions are involved during walking (Hamacher et al., 2015) and the literature describes two pathways (Bayot et al., 2018; Herold et al., 2017): 1) a direct locomotor pathway (primary motor cortex, cerebellum and spinal cord); and 2) indirect locomotor pathway (prefrontal cortex (PFC), premotor areas, and basal ganglia). During attentional demanding and challenging walking conditions, the activation of the indirect locomotor pathway increases and the PFC, in particular, plays a key role (Clark, 2015; Hamacher et al., 2015; Yogev-Seligmann, Hausdorff, and Giladi, 2008). According to the capacity sharing theory (Kahneman, 1973), the attentional capacity is limited; hence, there might be a risk of attentional overload during challenging mobility conditions.
Is it accurate to classify ALS as a neuromuscular disorder?
Published in Expert Review of Neurotherapeutics, 2020
Michael A. van Es, H. Stephan Goedee, Henk-Jan Westeneng, Tanja C.W. Nijboer, Leonard H. van den Berg
Many imaging modalities have been applied to study to brain morphologic changes in ALS, of which MRI has been used most frequently. As is to be expected, there is clear involvement of the primary motor cortex and corticospinal tract. Many studies have however also demonstrated involvement of other brain areas (Figure 3)[32]. Both gray and white matter involvement has been found. Widespread cerebral involvement is most prominent in patients with C9orf72 repeat expansions, but is not limited to this group[33]. Intriguingly, asymptomatic C9orf72 carriers also have been found to have a thinner cerebral cortex in non-motor regions in comparison to their non-carrier family members[34]. Although atrophy of posterior brain regions is not frequently reported, Figure 3 and a previous case report [35] demonstrate that these regions might be involved and are possibly related to cognitive deficits as well. Deep gray matter has been studied less frequently than cortical gray matter, but studies have demonstrated atrophy of the deep gray matter. This includes atrophy of the hippocampi at an early stage, which is also correlated with cognitive and behavioral deficits as well as shorter survival [36,37]. Similarly, white matter involvement is not limited to motor connections, but also includes connections between more remote brain locations [38,39]. In line with this observation, it has been proposed that, although the pathogenic process might start in the motor system, it propagates to functionally linked areas through white matter connections [40,41].