Brain activation during human finger extension and flexion movements
ABSTRACT Corticospinal projections to the motor neuron pool of upper-limb extensor muscles have been reported to differ from those of the flexor muscles in humans and other primates. The influence of this difference on the central nervous system control for extension and flexion movements is unknown. Cortical activation during thumb extension and flexion movements of eight human volunteers was measured using functional magnetic resonance imaging (fMRI), which detects signal changes caused by an alteration in the local blood oxygenation level. Although the relative activity of the extensor and flexor muscles of the thumb was similar, the brain volume activated during extension was substantially larger than that during flexion. These fMRI results were confirmed by measurements of EEG-derived movement-related cortical potential. Higher brain activity during thumb extension movement may be a result of differential corticospinal, and possibly other pathway projections to the motoneuron pools of extensor and flexor muscles of upper the extremities.
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- "finger extension) generate stronger patterns in the ongoing EEG compared to other movements (e.g. natural finger flexion)   . At the same time, it has been reported that right and left movements (regardless of what the movement is) generate patterns in "
ABSTRACT: The low-frequency asynchronous switch design (LF-ASD) is a direct brain interface (BI) that detects the presence of a specific finger movement in the ongoing EEG. Asynchronous interfaces have the advantage of being operational at all times and not only at specific system-defined periods. In this paper, we present the design of a 3-state asynchronous BI for the detection of two different movements from the ongoing EEG. The proposed 3-state asynchronous BI detects right and left hand extensions. Using data collected from two able-bodied individuals, it is shown that the error characteristics of the new system in detecting the presence of movement are significantly better than the 2-state LF-ASD, with true positive rate increases of up to 22.4% for false positive rates in the 1-2% range. An average performance of 61.5% was achieved in differentiating between left and right hand movementsAcoustics, Speech and Signal Processing, 2006. ICASSP 2006 Proceedings. 2006 IEEE International Conference on; 06/2006
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- "Previous experiments using fMRI (Stephan et al., 1999; Jantzen et al., 2002, 2004; Mayville et al., 2002), magnetoencephalography (MEG) (Kelso et al., 1992; Fuchs et al., 2000) and transcranial magnetic stimulation (TMS) (Meyer-Lindenberg et al., 2002; Steyvers et al., 2003) have shown that coordination patterns of differing behavioral stability (Kelso et al., 1990; Kelso, 1995) are supported by different patterns of neural activity. If stability differences and underlying differences in neural activity (Yue et al., 2000; Mayville et al., 2002) are due only to neuromusculoskeletal factors, which are ultimately linked to cerebral processes through the production of motor output and the resulting feedback, these neural differences should be extinguished (or at least greatly diminished) during imagination conditions. However, if both perceptual and motor processes play a role in determining the stability of coordination (Kelso et al., 2001), some aspects of the coordinationdependent differences observed between the two neural activation patterns should persist, even in the absence of overt movement. "
ABSTRACT: Much debate in the behavioral literature focuses on the relative contribution of motor and perceptual processes in mediating coordinative stability. To a large degree, such debate has proceeded independently of what is going on in the brain. Here, using blood oxygen level-dependent measures of neural activation, we compare physically executed and imagined rhythmic coordination in order to better assess the relative contribution of hypothesized neuromusculoskeletal mechanisms in modulating behavioral stability. The executed tasks were to coordinate index finger to thumb opposition movements of the right hand with an auditory metronome in either a synchronized (on the beat) or syncopated (off the beat) pattern. Imagination involved the same tasks, except without physical movement. Thus, the sensory stimulus and coordination constraints were the same in both physical and imagination tasks, but the motoric requirements were not. Results showed that neural differences between executed synchronization and syncopation found in premotor cortex, supplementary motor area, basal ganglia and lateral cerebellum persist even when the coordinative patterns were only imagined. Neural indices reflecting behavioral stability were not abolished by the absence of overt movement suggesting that coordination phenomena are not exclusively rooted in purely motoric constraints. On the other hand, activity in the superior temporal gyrus was modulated by both the presence of movement and the nature of the coordination, attesting to the intimacy between perceptual and motoric processes in coordination dynamics.Cerebral Cortex 08/2005; 15(7):975-85. DOI:10.1093/cercor/bhh198 · 8.67 Impact Factor
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- "A number of studies have described cortical changes in the months following a stroke (Weiller et al., 1993; Nudo, 1998; Hallett, 2001; Ward et al., 2003). It is possible that this restructuring favours flexion, especially as extension may require greater cortical activity, even in unimpaired individuals (Yue et al., 2000). Conceivably, axonal sprouting from these cortical pathways could spread to both flexor and extensor motoneurons, especially in the absence of competing extensor pathways, thereby leading to increased coactivation. "
ABSTRACT: The objective of this study was to explore motor impairment of the index finger following stroke. More specifically, the kinetics and kinematics of the index finger were analysed throughout its workspace. Twenty-four stroke survivors with chronic hemiparesis of the hand participated in the trials, along with six age-matched controls. Hand impairment was classified according to the clinical Chedoke-McMaster Stage of Hand scale. Subjects were instructed to generate fingertip force in six orthogonal directions at five different positions within the workspace. Split-plot analysis of variance revealed that clinical impairment level had a significant effect on measured force (P < 0.001), with the weakness in stroke survivors being directionally dependent (P < 0.01). Electromyographic recordings revealed altered muscle activation patterns in the more impaired subjects. Unlike the control subjects, these subjects exhibited peak muscle excitation of flexor digitorum superficialis, extensor digitorum communis and first dorsal interosseous during the generation of fingertip flexion forces. Subjects also attempted to reach locations scattered throughout the theoretical workspace of the index finger. Quantification of the active kinematic workspace demonstrated a relationship between impairment level and the percentage of the theoretical workspace that could be attained (P < 0.001). The stroke survivors exhibited a high correlation between mean force production and active workspace (R = 0.90). Thus, our data suggest that altered muscle activation patterns contribute to directionally dependent weakness following stroke. Both the modulation of muscle excitation with force direction and the independence of muscle activation seem to be reduced. These alterations translate into a significantly reduced active range of motion for the fingers.Brain 05/2005; 128(Pt 5):1112-21. DOI:10.1093/brain/awh432 · 10.23 Impact Factor