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O Kazennikov

Publications and source records attributed to O Kazennikov.

8 recordsLinked to original sources
PubMed2002

Kinematics of a coordinated goal-directed bimanual task.

The experiments address the problem of bimanual coordination in a familiar task of everyday life. A goal-directed drawer-pulling task, with asymmetrical assignments among hands, was analyzed with the objective to detect discrete kinematic events ('anchors') that potentially could serve in proper goal synchronization. The left hand reached out for the drawer and opened it while the right hand performed a prehension movement to pick up a peg from the drawer. The task was smoothly performed, independently of vision. Typically, trajectories and velocity profiles of the leading pull-hand were more stereotypical than the more variable ones of the pick-hand. The pull-hand had a large velocity peak during reaching, followed by a small peak during pulling. Velocity profiles of the pick-hand were not bell-shaped and exhibited one or two broad waves, often with an irregular and probing evolution. Velocity profiles of both hands were aligned with the first or the second velocity peak of the leading pull-hand. In the majority of cases, temporal associations of events in the kinematics of the two limbs could thus be identified, which could serve to synchronize the hands at the goal. The nearly straight biphasic reach-and-pull trajectory of the leading hand contrasted with the more curved trajectory of the right pick-hand whereas, in the same unimanual action, the latter trajectories were quasi-rectilinear. Changing constraints (no vision, cutaneous anesthesia of pulling fingers) could change the coordination pattern. We argue that bimanual coordination relies on two interacting mechanisms: (1) feedforward control on the basis of sensorimotor memory; (2) temporal adjustments during the evolving bimanual synergy. Multiple strategies, imposed by the leading pull-hand, appeared to be responsible for feedback-induced corrections in the pick-hand and were found to contribute to the goal-invariance and to the principle of motor equivalence.

Adult↗
PubMed1999

Time structure of a goal-directed bimanual skill and its dependence on task constraints.

The aim of the study was to elucidate the underlying principles of bimanual coordination and to establish quantitative coordination criteria. Healthy human subjects were instructed to open a loaded drawer with the left hand and to grasp, lift and reinsert with the right hand a small peg in the drawer recess. This bimanual goal-oriented task was executed promptly and consistently after a few trials. The temporal structure of the individual limb actions was assessed for computing interlimb synchronization and temporal correlation. In all subjects, both hands were well synchronized at the goal with high intermanual correlation in reaching the goal (event times of drawer opening and grasping the peg). This temporal goal-invariance was independent of movement speed and of the highly variable timing of the individual hands and persisted when subjects were blindfolded. Unilateral loading of the pulling hand and cutaneous anesthesia of the left index finger and thumb used for grasping the drawer handle significantly increased the pull-phase. This slowing of the left hand was matched by an adaptive delay of the right non-disturbed hand, thus preserving goal invariance. As a working hypothesis, we propose that multimodal sensory signals generated in the leading arm be transmitted centrally to re-parameterize the non-disturbed arm.

Adult↗
PubMed1999

Neural activity of supplementary and primary motor areas in monkeys and its relation to bimanual and unimanual movement sequences.

A chronic single-unit study of motor cortical activity was undertaken in two monkeys trained to perform a bimanually coordinated task. The hypothesis was tested that the supplementary motor area plays a specific role in coordinating the two hands for common goal-oriented actions. With this objective, a special search was made for neurons that might exhibit properties exclusively related to bimanual task performance. Monkeys learned to reach for and to pull open a spring-loaded drawer with one hand, while the other hand reached out to grasp food from the drawer recess. The two hands were precisely coordinated for achievement of this goal. Monkeys also performed, in separate blocks of trials, only the pulling or grasping movements, using the same hands as in the bimanual task. Task-related activity of 348 neurons from the supplementary motor area and 341 neurons from the primary motor area, each examined in the bimanual and in both unimanual tasks, was recorded in the two hemispheres. Most neurons from the supplementary motor area were recorded within its caudal microexcitable portion. Contrary to expectation, the proportion of neurons with activity patterns related exclusively to the bimanual task was small, but somewhat higher in the supplementary motor area (5%) than in the primary motor cortex (2%). Another group of neurons that were equally modulated during the bimanual as well as to both unimanual task components might also contribute in controlling bimanual actions. Such "task-dependent" rather than "effector-dependent" activity patterns were more common in neurons of the supplementary motor area (19%) than of the primary motor cortex (5%). Bilateral receptive fields were also more numerous among the supplementary motor area neurons. However, a large majority of neurons from primary and supplementary motor areas had activity profiles clearly related only to contralateral hand movements (65% in the primary motor and 51% in the supplementary motor area). A similar group of neurons showed an additional slight modulation with ipsilateral movements; they were equally common in the two areas (14% and 16%, respectively) and their significance for bimanual coordination is questionable. Summed activity profiles of all neurons recorded in the primary and supplementary motor areas of the same hemisphere were compared. The modulations of the three histograms, corresponding to the two unimanual and the bimanual tasks, were similar for the two motor areas, i.e. prominent with bimanual and contralateral movements and weak with ipsilateral movements. It is concluded that the supplementary motor area is likely to contribute to bimanual coordination, perhaps more than the primary motor cortex, but that it is not a defining function for the former cortical area. Instead, it is suggested that the supplementary motor area is part of a callosally interconnected and distributed network of frontal and parietal cortical areas that together orchestrate bimanual coordination.

Animals↗
PubMed1998

Effects of lesions in the mesial frontal cortex on bimanual co-ordination in monkeys.

The hypothesis was tested that the mesial frontal cortex, including the supplementary motor area, is engaged in bimanual co-ordination. Three monkeys, trained in a well-co-ordinated bimanual pull-and-grasp task, were subjected to unilateral or bilateral lesions of the mesial frontal cortex. With unilateral lesions, the deficit consisted in a delay in movement initiation of the contralateral arm. With a bilateral lesion, the deficit was more pronounced with marked bilateral delays in movement onset and slowing in reaching. However, in the three monkeys bimanual co-ordination at the moment of goal achievement remained intact with an excellent temporal co-variation of the two limbs. In the two unilateral cases, an adaptive strategy developed after a few sessions, either by catching up during reaching with the limb contralateral to the lesion (monkey M1) or by delaying movement initiation of the limb ipsilateral to the lesion (monkey M2). This outcome is discussed in terms of Lashley's principle of motor equivalence, i.e. invariant goal achievement with variable means. Bilateral lesions led to a transient and near-total impairment in movement self-initiation when all external cues were absent. It is concluded that in monkeys the mesial frontal cortex does not play a crucial role in bimanual co-ordination but rather in movement initiation, especially when sensory cues are absent.

Animals↗
PubMed1994

Temporal structure of a bimanual goal-directed movement sequence in monkeys.

The aim of the present investigation was to assess a bimanual goal-oriented movement sequence with particular emphasis on its temporal structure. The three monkeys (Macaca fascicularis) used in this study chose the left arm as the leading and more postural arm to reach out and pull back a spring-loaded drawer containing a food morsel. The right arm followed the left and picked up the food with a precision grip. Video recordings, trajectory recordings of the two index fingers, drawer displacement and the measurements of discrete events of the left and right hand revealed a considerable trial-by-trial variability in the temporal and spatial domain. The variability of latencies progressively increased from the initiation of the bimanual sequence to the left-hand and right-hand events defining goal achievement. The main result was that, in spite of this variability in each of the two limbs, there was an invariant left-right goal-related synchronization. The timing of the goal-related event pairs covaried and showed high correlation coefficients. Covariation of the two hands resulting in an invariant synchronization was particularly striking when monkeys performed the task without vision, and timing of right and left movement components was delayed with further increase in variability. The results indicate that, in the present bimanual skill, kinaesthetic signals may be sufficient to coordinate the two limbs in a goal-oriented unitary action in accord with a memorized plan.

Acoustic Stimulation↗
PubMed1994

Transcallosal connections of the distal forelimb representations of the primary and supplementary motor cortical areas in macaque monkeys.

The goal of the present neuroanatomical study in macaque monkeys was twofold: (1) to clarify whether the hand representation of the primary motor cortex (M1) has a transcallosal projection to M1 of the opposite hemisphere; (2) to compare the topography and density of transcallosal connections for the hand representations of M1 and the supplementary motor area (SMA). The hand areas of M1 and the SMA were identified by intracortical microstimulation and then injected either with retrograde tracer substances in order to label the neurons of origin in the contralateral motor cortical areas (four monkeys) or, with an anterograde tracer, to establish the regional distribution and density of terminal fields in the opposite motor cortical areas (two monkeys). The main results were: (1) The hand representation of M1 exhibited a modest homotopic callosal projection, as judged by the small number of labeled neurons within the region corresponding to the contralateral injection. A modest heterotopic callosal projection originated from the opposite supplementary, premotor, and cingulate motor areas. (2) In contrast, the SMA hand representation showed a dense callosal projection to the opposite SMA. The SMA was found to receive also dense heterotopic callosal projections from the contralateral rostral and caudal cingulate motor areas, moderate projections from the lateral premotor cortex, and sparse projections from M1. (3) After injection of an anterograde tracer (biotinylated dextran amine) in the hand representation of M1, only a few small patches of axonal label were found in the corresponding region of M1, as well as in the lateral premotor cortex; virtually no label was found in the SMA or in cingulate motor areas. Injections of the same anterograde tracer in the hand representation of the SMA, however, resulted in dense and widely distributed axonal terminal fields in the opposite SMA, premotor cortex, and cingulate motor areas, while labeled terminals were clearly less dense in M1. It is concluded that the hand representations of the SMA and M1 strongly differ with respect to the strength and distribution of callosal connectivity with the former having more powerful and widespread callosal connections with a number of motor fields of the opposite cortex than the latter. These anatomical results support the proposition of the SMA being a bilaterally organized system, possibly contributing to bimanual coordination.

Animals↗
PubMed1994

Temporal coordination in bimanual actions.

The issue of bimanual temporal coordination in human subjects is discussed for three selected movement paradigms: (i) simple, symmetric, bimanual finger movements, (ii) bimanual unloading, and (iii) a complex bimanual pull and grasp task. Temporal synchronization was found for all three experiments and was least variable for the first experiment. In the second experiment, synchronization concerned unloading with the index finger of one hand (electromyographic activation of the first dorsal interosseus muscle) and the postural adjustment of the load-bearing index finger of the other hand (electromyographic deactivation of the first dorsal interosseus muscle). In the third experiment, a goal-related temporal invariance was observed, even in the absence of visual guidance. Possible neural mechanisms for the observed temporal coordination of the three types of bimanual movements are discussed, as well as the concepts of goal invariance and motor equivalence.

Fingers↗