Reduction of the muscle activity associated with self-imposed electrical stimulation of mixed nerves supplying lower limb muscles in man.

Similarly to brief hammer taps self-imposed on the limb segments, self-triggered electrical stimulation delivered to the tibial, femoral or peroneal nerves are associated with anticipatory reduction in the muscle activity (RMA) of the target leg muscles. The anticipatory RMA starts shortly before the expected perturbation and lasts until the onset of the impact. The purpose of the present work is to study to what extent the selective activation of the different homonymous and heteronymous afferents could modify the central programs and the associated time and space distribution of the anticipatory RMA pattern in the target leg muscles.

Anticipatory reduction of the muscle activity associated with self-triggered electrical stimulation of mixed nerves and mecanical taps on muscle tendons.

Brief hammer taps self-imposed on the Achilles tendon or self-triggered electrical single-pulse stimulation delivered to the tibial nerve in the middle of the popliteal fossa are associated with an anticipatory reduction in the muscle activity (RMA) of the reflex-bearing soleus. The anticipatory RMA starts shortly prior tothe onset of the perturbation and lasts until the consequent T- or H-responses. When the amplitudes of the control T- and H-reflexes in a resting state are the same and equal to 50% of Hmax, then the anticipatory RMA patterns revealed with mechanical and electrical stimulation are similar.

Contribution of a Ia muscle afferent activation to the rise of H reflexes and somatosensory evoked potentials in man.

Electrical stimuli were applied to the tibial nerve in the popliteal fossa in man in order to investigate how information is transferred from group I muscle afferents to motoneurons and to the somatosensory cortex. For control purposes, identical stimuli were applied to the skin beside the electrode above the nerve. The somatosensory evoked potential (SEP) to skin stimulation alone had a peak latency which was 5 ms longer than the SEP to transcutaneous nerve stimulation.

Association between muscle architecture and quadriceps femoris H-reflex.

The purpose of the present study was to establish the relationship between muscle architecture and H-reflex recordings in quadriceps femoris muscle. H-reflexes were elicited in human quadriceps femoris muscle over a broad area of skin to document the shape and amplitude of the H-potentials. This, in combination with recording monopolar and bipolar H-potentials, was performed to determine the location and method for measuring maximum-amplitude H-reflexes.

Self-generated rapid taps directed to the opposite forearm in man: anticipatory reduction in the muscle activity of the target arm.

A brief hammer tap applied passively (by the experimenter) to the forearm elicits a short-latency reflex response in the forearm flexors and extensors. When the same tap is performed actively (by the subject) using the opposite forearm, the reflex response is preceded by a short-lasting anticipatory reduction in the muscle activity appearing around the impact. This anticipatory reduction is interpreted as an alternative mode of feedforward motor control associated with damping of kinetic impulses generated within the bimanual system.