Wrist Posture Does Not Influence Finger Interdependence

A task involving an instructed finger movement causes involuntary movements in the noninstructed fingers of the hand, also known as finger interdependence. It is associated with both mechanical and neural mechanisms. The current experiment investigated the effect of finger interdependence due to systematic changes of the wrist posture, close to neutral. Eight right-handed healthy human participants performed submaximal cyclic flexion and extension at the metacarpophalangeal joint at 0° neutral, 30° extension, and 30° flexion wrist postures, respectively. The experiment comprised of an instruction to move one of the 4 fingers—index, middle, ring, and little. Movements of the instructed and noninstructed fingers were recorded. Finger interdependence was quantified using enslavement matrix, individuation index, and stationarity index, and it was compared across wrist postures. The authors found that the finger interdependence does not change with changes in wrist posture. Further analysis showed that individuation and stationarity indices were mostly equivalent across wrist postures, and their effects were much smaller than the average differences present among the fingers. The authors conclude that at wrist postures close to neutral, the finger interdependence is not affected by wrist posture.

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Sex-related differences in response to masseteric injections of glutamate and nerve growth factor in healthy human participants

Scientific Reports ◽

10.1038/s41598-021-93171-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Abdelrahman M. Alhilou ◽

Akiko Shimada ◽

Camilla I. Svensson ◽

Peter Svensson ◽

Malin Ernberg ◽

...

Keyword(s):

Nmda Receptors ◽

Nerve Fiber ◽

Masseter Muscle ◽

Pain Sensitivity ◽

Nerve Fibers ◽

Receptor Expression ◽

Healthy Human ◽

Neurophysiological Mechanisms ◽

Human Participants ◽

Positive Correlations

AbstractThe neurophysiological mechanisms underlying NGF-induced masseter muscle sensitization and sex-related differences in its effect are not well understood in humans. Therefore, this longitudinal cohort study aimed to investigate the effect of NGF injection on the density and expression of substance P, NMDA-receptors and NGF by the nerve fibers in the human masseter muscle, to correlate expression with pain characteristics, and to determine any possible sex-related differences in these effects of NGF. The magnitude of NGF-induced mechanical sensitization and pain during oral function was significantly greater in women than in men (P < 0.050). Significant positive correlations were found between nerve fiber expression of NMDA-receptors and peak pain intensity (rs = 0.620, P = 0.048), and expression of NMDA-receptors by putative nociceptors and change in temporal summation pain after glutamate injection (rs = 0.561, P = 0.003). In women, there was a significant inverse relationship between the degree of NGF-induced mechanical sensitization and the change in nerve fiber expression of NMDA-receptors alone (rs = − 0.659, P = 0.013), and in combination with NGF (rs = − 0.764, P = 0.001). In conclusion, women displayed a greater magnitude of NGF-induced mechanical sensitization that also was associated with nerve fibers expression of NMDA-receptors, when compared to men. The present findings suggest that, in women, increased peripheral NMDA-receptor expression could be associated with masseter muscle pain sensitivity.

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Decoupling countermands nonselective response inhibition during selective stopping

Journal of Neurophysiology ◽

10.1152/jn.00495.2021 ◽

2021 ◽

Author(s):

Corey George Wadsley ◽

John Cirillo ◽

Arne Nieuwenhuys ◽

Winston D Byblow

Keyword(s):

Response Inhibition ◽

Interference Effect ◽

Complex Form ◽

Functional Coupling ◽

Response Preparation ◽

Response Delay ◽

Healthy Human ◽

Human Participants ◽

Goal Directed Behavior ◽

Effector Response

Response inhibition is essential for goal-directed behavior within dynamic environments. Selective stopping is a complex form of response inhibition where only part of a multi-effector response must be cancelled. A substantial response delay emerges on unstopped effectors when a cued effector is successfully stopped. This stopping-interference effect is indicative of nonselective response inhibition during selective stopping which may, in-part, be a consequence of functional coupling. The present study examined selective stopping of (de)coupled bimanual responses in healthy human participants of either sex. Participants performed synchronous and asynchronous versions of an anticipatory stop-signal paradigm across two sessions while mu (µ) and beta (β) rhythm were measured with electroencephalography. Results showed that responses were behaviorally decoupled during asynchronous go trials and the extent of response asynchrony was associated with lateralized sensorimotor µ and β desynchronization during response preparation. Selective stopping produced a stopping-interference effect and was marked by a nonselective increase and subsequent rebound in prefrontal and sensorimotor β. In support of the coupling account, stopping-interference was smaller during selective stopping of asynchronous responses, and negatively associated with the magnitude of decoupling. However, the increase in sensorimotor β during selective stopping was equivalent between the stopped and unstopped hand irrespective of response synchrony. Overall, the findings demonstrate that decoupling facilitates selective stopping after a global pause process and emphasizes the importance of considering the influence of both the go and stop context when investigating response inhibition.

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Absence of systematic relationships between REMS duration episodes and spectral power Delta and Ultra-Slow bands in contiguous NREMS episodes in healthy humans

Journal of Neurophysiology ◽

10.1152/jn.00020.2013 ◽

2013 ◽

Vol 110 (1) ◽

pp. 162-169 ◽

Cited By ~ 5

Author(s):

O. Le Bon ◽

P. Linkowski

Keyword(s):

Spectral Power ◽

Sleep Cycle ◽

Consecutive Series ◽

Sleep Regulation ◽

Healthy Human ◽

Sleep Quantity ◽

Healthy Humans ◽

Crucial Component ◽

Sleep Physiology ◽

Human Participants

Previous studies in animals and humans have reported correlations between the durations of rapid eye movement sleep (REMS) episodes and immediately preceding or subsequent non-REMS (NREMS) episodes. The relationship between these two types of sleep is a crucial component in understanding the regulation and neurophysiology of ultradian alternations that occur during sleep. Although the present study replicated previous studies, we also measured NREMS in terms of spectral power Delta and Ultra-Slow bands in addition to duration in examining correlations. The spectral power Delta band, also known as slow-wave activity, measures sleep quantity and is believed to reflect sleep physiology better than mere episode durations. The Ultra-Slow spectral power band was analyzed in parallel. Healthy human participants of both sexes ( n = 26, age range 15–45 yr, n = 12 female) were carefully selected to participate in two consecutive series of home polysomnograms performed after 2 nights of habituation to the equipment. In the analyses, REMS episode durations (minutes) were compared with immediately preceding and immediately subsequent NREMS episodes (Delta and Ultra-Slow power) in each sleep cycle. REMS episode duration was more strongly correlated with preceding NREMS episodes than with subsequent NREMS episodes. However, in most cases, no correlations were observed in either direction. One ultradian sleep regulation hypothesis, which is based on stronger correlations between REMS and subsequent NREMS episode durations, holds that the main purpose of REMS is to reactivate NREMS during each sleep cycle. The present results do not support that hypothesis.

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Effect of standardized aqueous extract of Withania somniferaon tests of cognitive and psychomotor performance in healthy human participants

Pharmacognosy Research ◽

10.4103/0974-8490.122912 ◽

2014 ◽

Vol 6 (1) ◽

pp. 12 ◽

Cited By ~ 31

Author(s):

Usharani Pingali ◽

Raveendranadh Pilli ◽

Nishat Fatima

Keyword(s):

Aqueous Extract ◽

Psychomotor Performance ◽

Healthy Human ◽

Human Participants

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Antioxidant Activity with Increased Endogenous Levels of Vitamin C, E and A Following Dietary Supplementation with a Combination of Glutathione and Resveratrol Precursors

Nutrients ◽

10.3390/nu12113224 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3224 ◽

Cited By ~ 1

Author(s):

Priscilla Biswas ◽

Cinzia Dellanoce ◽

Alessandra Vezzoli ◽

Simona Mrakic-Sposta ◽

Mauro Malnati ◽

...

Keyword(s):

Dietary Supplements ◽

Immune Status ◽

Inflammatory Marker ◽

Dietary Supplementation ◽

Positive Outcome ◽

Redox Status ◽

Healthy Human ◽

Treatment Groups ◽

Human Participants ◽

Endogenous Synthesis

The effects of two different dietary supplements on the redox status of healthy human participants were evaluated. The first supplement (GluS, Glutathione Synthesis) contains the precursors for the endogenous synthesis of glutathione and the second (GluReS, Glutathione and Resveratrol Synthesis) contains in addition polydatin, a precursor of resveratrol. To assess the influence of GluS and GluReS on the redox status, ten thiol species and three vitamins were measured before (t0) and after 8 weeks (t1) of dietary supplementation. An inflammatory marker, neopterin, was also assessed at the same time points. Both supplements were highly effective in improving the redox status by significantly increasing the reduced-glutathione (GSH) content and other reduced thiol species while significantly decreasing the oxidized species. The positive outcome of the redox status was most significant in the GluRes treatment group which also experienced a significant reduction in neopterin levels. Of note, the endogenous levels of vitamins C, E and A were significantly increased in both treatment groups, with best results in the GluReS group. While both dietary supplements significantly contributed to recognized antioxidant and anti-inflammatory outcomes, the effects of GluReS, the combination of glutathione and resveratrol precursors, were more pronounced. Thus, dietary supplementation with GluReS may represent a valuable strategy for maintaining a competent immune status and a healthy lifespan.

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PROTOCOLS FOR INDUCING HOMEOSTATIC PLASTICITY REFLECTED IN THE CORTICOSPINAL EXCITABILITY IN HEALTHY HUMAN PARTICIPANTS: A SYSTEMATIC REVIEW AND META‐ANALYSIS

European Journal of Neuroscience ◽

10.1111/ejn.15389 ◽

2021 ◽

Author(s):

Priscilla G. Wittkopf ◽

Dennis B. Larsen ◽

Thomas Graven‐Nielsen

Keyword(s):

Systematic Review ◽

Meta Analysis ◽

Corticospinal Excitability ◽

Homeostatic Plasticity ◽

Healthy Human ◽

Human Participants

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Human Finger Independence: Limitations due to Passive Mechanical Coupling Versus Active Neuromuscular Control

Journal of Neurophysiology ◽

10.1152/jn.00480.2004 ◽

2004 ◽

Vol 92 (5) ◽

pp. 2802-2810 ◽

Cited By ~ 114

Author(s):

Catherine E. Lang ◽

Marc H. Schieber

Keyword(s):

Neuromuscular Control ◽

The Other ◽

Passive Condition ◽

Mechanical Coupling ◽

Complete Independence ◽

Active Condition ◽

Middle Ring ◽

Human Finger ◽

Passive Movements ◽

Flexion And Extension

We studied the extent to which mechanical coupling and neuromuscular control limit finger independence by studying passive and active individuated finger movements in healthy adults. For passive movements, subjects relaxed while each finger was rotated into flexion and extension by a custom-built device. For active movements, subjects moved each finger into flexion and extension while attempting to keep the other, noninstructed fingers still. Active movements were performed through approximately the same joint excursions and at approximately the same speeds as the passive movements. We quantified how mechanical coupling limited finger independence from the passive movements, and quantified how neuromuscular control limited finger independence using an analysis that subtracted the indices obtained in the passive condition from those obtained in the active condition. Finger independence was generally similar during passive and active movements, but showed a trend toward less independence in the middle, ring, and little fingers during active, large-arc movements. Mechanical coupling limited the independence of the index, middle, and ring fingers to the greatest degree, followed by the little finger, and placed only negligible limitations on the independence of the thumb. In contrast, neuromuscular control primarily limited the independence of the ring, and little fingers during large-arc movements, and had minimal effects on the other fingers, especially during small-arc movements. For the movement conditions tested here, mechanical coupling between the fingers appears to be a major factor limiting the complete independence of finger movement.

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First PET Imaging Studies With 63Zn-Zinc Citrate in Healthy Human Participants and Patients With Alzheimer Disease

Molecular Imaging ◽

10.1177/1536012116673793 ◽

2016 ◽

Vol 15 ◽

pp. 153601211667379 ◽

Cited By ~ 10

Author(s):

Timothy R. DeGrado ◽

Bradley J. Kemp ◽

Mukesh K. Pandey ◽

Huailei Jiang ◽

Tina M. Gunderson ◽

...

Keyword(s):

Alzheimer Disease ◽

Pet Imaging ◽

Imaging Studies ◽

Healthy Human ◽

Human Participants

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Vigor in the Face of Fluctuating Rates of Reward: An Experimental Examination

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00090 ◽

2011 ◽

Vol 23 (12) ◽

pp. 3933-3938 ◽

Cited By ~ 41

Author(s):

Marc Guitart-Masip ◽

Ulrik R. Beierholm ◽

Raymond Dolan ◽

Emrah Duzel ◽

Peter Dayan

Keyword(s):

Reinforcement Learning ◽

Computational Models ◽

Average Rate ◽

Empirical Studies ◽

Empirical Work ◽

Healthy Human ◽

Average Return ◽

The Face ◽

Cost Of Time ◽

Human Participants

Two fundamental questions underlie the expression of behavior, namely what to do and how vigorously to do it. The former is the topic of an overwhelming wealth of theoretical and empirical work particularly in the fields of reinforcement learning and decision-making, with various forms of affective prediction error playing key roles. Although vigor concerns motivation, and so is the subject of many empirical studies in diverse fields, it has suffered a dearth of computational models. Recently, Niv et al. [Niv, Y., Daw, N. D., Joel, D., & Dayan, P. Tonic dopamine: Opportunity costs and the control of response vigor. Psychopharmacology (Berlin), 191, 507–520, 2007] suggested that vigor should be controlled by the opportunity cost of time, which is itself determined by the average rate of reward. This coupling of reward rate and vigor can be shown to be optimal under the theory of average return reinforcement learning for a particular class of tasks but may also be a more general, perhaps hard-wired, characteristic of the architecture of control. We, therefore, tested the hypothesis that healthy human participants would adjust their RTs on the basis of the average rate of reward. We measured RTs in an odd-ball discrimination task for rewards whose magnitudes varied slowly but systematically. Linear regression on the subjects' individual RTs using the time varying average rate of reward as the regressor of interest, and including nuisance regressors such as the immediate reward in a round and in the preceding round, showed that a significant fraction of the variance in subjects' RTs could indeed be explained by the rate of experienced reward. This validates one of the key proposals associated with the model, illuminating an apparently mandatory form of coupling that may involve tonic levels of dopamine.

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