Dynamic characteristics of motor responses evoked by stimulation of the motor cortex in unanesthetized cats

Kostyukov, A. I.; Marlinskii, V. V.

doi:10.1007/bf01066072

Cited by 1 publication

(3 citation statements)

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“…Together with the traces E(L, F), recorded in the form of three-dimensional curves ( Figures 5 , 6 ), we also obtained the opportunity to fix their projections onto the coordinate planes. It is known that the main features of nonlinear effects in active muscles are closely related to the direction of the hysteresis loops recorded in the main modes of contraction (for review see: Kostyukov, 2007 ). For all combinations of force and length direction changes, our study showed the coincidence of the directions of loops F(L), E(L), and E(F) in three quarters of all cases, including complete coincidence for the first two types of dependencies ( Figures 5 , 6 ).…”

Section: Discussionmentioning

confidence: 99%

“…This allows us to consider the “ flexion ” and “ extension ” movement types in a simplified form by dividing them into “ concentric ” and “ eccentric ” ( Figures 8 – 11 ). Neuromuscular studies have shown that muscles have strong contractile property asymmetry, which depends on the length of the muscle and the level of efferent activity, as well as on the direction of their change (for a review, see: Kostyukov, 2007 ). An individual muscle needs a higher intensity of efferent activation during concentric contractions compared to eccentric contractions; therefore, in the first case, a higher level of EMG intensity can be expected.…”

Section: Discussionmentioning

confidence: 99%

“…Most often, the coactivation of antagonist muscles is considered one of the mechanisms that can increase joint stiffness, which may be important for multijoint movements ( Kearney and Hunter, 1990 ; Hill et al, 2008 ; Hirai et al, 2015 ). On the other hand, the simultaneous contraction of antagonists can also have a profound stabilizing effect on the motor control system, reducing the so-called uncertainty effects associated with muscle hysteresis ( Kostyukov, 1998 , 2007 ; Gorkovenko et al, 2012 ).…”

Section: Discussionmentioning

confidence: 99%

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Central Commands to the Elbow and Shoulder Muscles During Circular Planar Movements of Hand With Simultaneous Generation of Tangential Forces

et al. 2022

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This study examines some of the non-linear effects of signal transduction in the human motor system, with particular emphasis on muscle hysteresis. The movement tests were analyzed in a group of eight subjects, which were asked to develop tangential force using visual biofeedback while performing slow, externally imposed, circular movements of right hand holding a moving handle operated by a computerized mechatronic system. The positional changes in the averaged EMGs of the elbow and shoulder muscles were compared for all combinations of direction of movement and generated force. Additionally, for one of the subjects, there was carried out MRI identification and 3D printing of the bones of the forelimb, shoulder, scapula and collarbone, which made it possible to reconstruct for him the length and force traces of all the muscles under study. The averaged EMG traces in muscles of both joints show their close correspondence to the related force traces, however, the co-activation patterns of activity in agonists and antagonists were also often encountered. The EMG waves related to the respective force waves were strongly dependent on the predominant direction of the muscle length changes within the correspondent force wave locations: the EMG intensities were higher for the shortening muscle movements (concentric contractions) and lower during muscle lengthening (eccentric contractions). The data obtained allows to suggest that for two-joint movements of the forelimbs, it is sufficient to consider the force and activation synergies (patterns of simultaneous activity in different muscles), ignoring at the first stage the effects associated with kinematic synergy. On the other hand, the data obtained indicate that the movement kinematics has a strong modulating effect on the activation synergy, dividing it into concentric and eccentric subtypes, in accordance with the known non-linear features of the muscle dynamics. It has been shown that the concentric and eccentric differences in the responses of the shoulder muscles are more clearly distinguishable than those in the elbow muscles. The shoulder muscles also have a more pronounced symmetry of the averaged EMG responses with respect to the ascending and descending phases of force waves, while demonstrating a lower degree of antagonist cocontraction. The data obtained suggest that the central commands in two-joint movements are determined mainly by the interdependence of force and activation synergies including both intra- and inter-joint components, while kinematic synergy can be interpreted as a potent modulator of activation synergy.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%