Imipramine, clomipramine, FG 4963 and quipazine potentiated the flexor reflex of hind limb of the spinal rat, imipramine and clomipramine being relatively weak, and quipazine the most potent in this respect. The potentiation is prevented by serotonin receptor blocking agents, cyproheptadine and danitracen. Imipramine and clomipramine prevented the potentiation of flexor reflex by fenfluramine; this indicates a presynaptic mechanism of action of the latter compound. The stimulatory action of LSD is only partially inhibited by imipramine. The action of quipazine seems to be mainly postsynaptic, as it is not prevented by severe depletion of serotonin stores by reserpine and an inhibitor of serotonin synthesis, H 22/54.
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Rhythmic motor behaviors are generated by neural networks termed central pattern generators (CPGs). Although locomotor CPGs have been extensively characterized, it remains unknown how the neuronal populations composing them interact to generate adaptive rhythms. We explored the non-linear cooperation dynamics among the three main populations of ipsilaterally projecting spinal CPG neurons - V1, V2a, V2b neurons - in scratch reflex rhythmogenesis.
View Article and Find Full Text PDFJ Electromyogr Kinesiol
February 2025
Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road E, Guelph, ON N1G 2W1, Canada. Electronic address:
Rate of torque development (RTD) measures how rapidly one can generate torque and is crucial for balance and athletic performance. Fast RTD depends on the rapid recruitment of high threshold motor units (MUs). Cutaneous electrical stimulation has been shown to alter MU excitability, favoring high threshold MUs via reduced recruitment thresholds.
View Article and Find Full Text PDFMov Disord
January 2025
Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy.
Background: Quantitative evidence of levodopa-induced beneficial effects on parkinsonian rigidity in Parkinson's disease (PD) is lacking. Recent research has demonstrated the velocity-dependent nature of objective rigidity in PD and revealed its neural underpinning.
Objective: The present study aimed to examine the effect of levodopa on objective rigidity in PD.
Exp Physiol
January 2025
Strength and Conditioning Research Laboratory, College of Physical Education, University of Brasília, Brasília, Brazil.
This study examined the acute effects of dynamic stretching at different velocities on the neuromuscular system. Fourteen participants underwent four experimental sessions in random order: (1) control (lying at rest with the ankle in a neutral position); (2) slow velocity dynamic stretching (50 beats/min; SLOW); (3) moderate velocity dynamic stretching (70 beats/min; MOD); and (4) fast velocity dynamic stretching (90 beats/min; FAST). The stretching protocols consisted of four sets of 10 repetitions and targeted the plantar flexor muscles of the right ankle.
View Article and Find Full Text PDFPLoS Comput Biol
January 2025
Biorobotics Laboratory, EPFL, Lausanne, Switzerland.
Humans can perform movements in various physical environments and positions (corresponding to different experienced gravity), requiring the interaction of the musculoskeletal system, the neural system and the external environment. The neural system is itself comprised of several interactive components, from the brain mainly conducting motor planning, to the spinal cord (SC) implementing its own motor control centres through sensory reflexes. Nevertheless, it remains unclear whether similar movements in various environmental dynamics necessitate adapting modulation at the brain level, correcting modulation at the spinal level, or both.
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