Reflexion on Reflexes: modulation during gait.

Abstract

Walking is a highly automatic performance. It appears simple but in fact, complex mechanisms underlie this process. This complexity is revealed when the automaticity disappears and walking becomes a conscious activity, requiring attention, for example in the case of sickness or trauma. In such cases, walking is impaired and has to be relearned. Understanding normal locomotion is essential for developing and applying therapeutic approaches to movement disorders. In experiments with animals it is observed that the automaticy of walking is due to the presence of neuronal circuits in the spinal cord. It is thought that this also applies for human. One step can be divided into a swing and stance phase. Therefore, flexion and extension reflexes are used. These reflexes are used by the circuits in the spinal cord for a smooth continuation of the locomotor pattern. This process might be disturbed in trauma. Therefore, a better continuation of this process after trauma could result in a better recovery of the walking pattern. To make this possible, a better understanding of the underlying mechanisms is needed. In this thesis the focus is on the understanding of the function of reflexes during locomotion. It was observed that the brains are more involved in the control of reflexes in humans than in cats. Reflexes can be suppressed when they are evoked by the subjects themselves. Like in cats, a similar mechanism seems to underlie the neural control of reflexes in arms and legs. Also the position of various parts of the body, such as the head, has influence on the reflexes. These results give a better understanding of the mechanisms used during walking. Possibly, they are usable for rehabilitation and training for recovery of the walking pattern after trauma.