Effects of vertical linear accelerations on motor controls in the cat.

Experiments have been performed to examine the effects of vertical linear accelerations on motor control in the cat. Examination of electromyographic activity in 2 opposing pairs of muscles in the neck and hindlimb of alert cats undergoing sudden, unexpected falls has demonstrated that electrical activation of all muscles tested occurred in 2 distinct phases. The earlier was otolith-dependent, whereas the later activity apparently did not originate in the labyrinth. Smooth landings from short falls were not possible in the absence of either phase of the response. Observation of the head and neck of the above cats while falling demonstrated a stereotyped pattern of movement, consisting of a lack of rotation of the bead and a progressive dorsiflexion of the neck. It was unaltered by loss of 8th nerve function, and therefore loss of the earlier phase of emg activity in the neck muscles, and could be predicted by an elementary mathematical model based on simple physical principles. [...]L'objectif de cette thèse est d'examiner les effets d'accélérations verticales linéaires sur le contrôle de la motricité chez le chat. L'activité électromyographique de deux paires de muscles antagonistes situés soit dans le cou soit dans une des pattes arrière de chats éveillés a été mesurée. Cette expérience s'effectue en laissant tomber les chats en chute libre. [...