Context-related representation of timing processes in monkey motor cortex.

Precise timing is essential for motor performance, though the neuronal representation of time is unknown. To explore neuronal correlates of timing processes during movement preparation and execution, we compared the activities of neurons recorded in monkey motor cortex during the performance of two tasks requiring correct time estimation in different contextual situations. Despite the fact that both tasks had many common features (e.

Analysis of vertical displacements of the center of gravity in the cat during limb flexion induced by cortical stimulation.

A limb movement and the associated postural adjustment result in a displacement of the center of gravity of the body. The vertical component of this displacement has been calculated from the variations in the sum of vertical forces at each limb. Through these variations, it is possible to measure the vertical acceleration of the center of gravity.

Changes in posturo-kinetic limb responses to cortical stimulation following unilateral neck deafferentation in the cat.

Unilateral neck deafferentation produces in cats a postural asymmetry, characterized by an increase in the extensor activity of the ipsilateral limbs and a decreased activity in the contralateral limbs; moreover, the placing reactions are severely depressed in the ipsilateral limbs. The present experiments were performed to investigate the influence of unilateral section of the cervical dorsal roots C1-C2 or C1-C3 on the postural adjustments occurring during flexion limb movements induced by cortical stimulation in chronically implanted cats. Only weak stimulations were used and motor activity was mainly isometric, to facilitate quantification of responses analyzed by measuring changes in vertical force exerted at the level of each limb in the up-right position of the animal.

[Vertical displacements of the center of gravity in the cat during movement of limb flexion induced by motor cortex stimulation].

A limb movement and the corresponding postural adjustment results in a displacement of the body's center of gravity. The vertical component of this displacement has been calculated by measuring the variations of the sum of vertical forces at each limb. The displacements are upwards and are larger in the case of hindlimb flexion than forelimb flexion.

Biomechanical study of the mechanisms of postural adjustment accompanying learned and induced limb movements in cats and dogs.

Trajectories of the center of pressure and center of gravity projections were studied in dynamic conditions during learned movement and movement evoked by the motor cortex stimulation (induced movement) in dogs and cats. The learned movement began with initial displacement of the center of pressure towards the limb performing movement. It corresponded often with initial increasing of the performing limb pressure on support and it was a reason of initial acceleration of the center of gravity in the opposite direction.