Postactivation depression of the Hoffmann (H) reflex is associated with a transient period of suppression following activation of the reflex pathway. In soleus, the depression lasts for 100-200 ms during voluntary contraction and up to 10 s at rest. A reflex root evoked potential (REP), elicited after a single pulse of transcutaneous stimulation to the thoracolumbar spine, has been shown to exh...

Group I reflex functions, namely monosynaptic reflex transmission, facilitation of synergists, and direct and disynaptic inhibition, show early post-tetanic potentiation following conditioning with a brief, high frequency, tetanus. Of these reflex functions, monosynaptic transmission always shows low frequency depression. Direct inhibitory pathways, and therefore inhibitory junctions, are insen...

The local anesthetic activities of 1-(morpholino or piperidino)-2-propanol derivatives were investigated. These activities were observed with nerve trunk anesthesia, rabbit's corneal anesthesia and intradermal injection anesthesia. Among these propanol derivatives, No. 24 and No. 25 which possess thioether-type sulfur were the most active and the effective potency was enhanced by increasing the...

The rat monosynaptic reflex shows marked depression in response to repetitive stimulation of low frequency, which is called 'low frequency depression'. The site and the mechanism of this depression was studied and discussed in relation to the characteristic features of the rat spinal cord. 1) The depressive effect of the repetitive stimulation is referable to the motoneurons invaded by the impu...

In cellular studies of habituation, such as in the gill and siphon withdrawal reflex to tactile stimulation of the siphon of Aplysia, a mechanism that has emerged as an explanation for response decrement during habituation is homosynaptic depression at sensory neurons mediating the behavioral response. We have examined the contribution of homosynaptic depression to habituation in sensory neuron...

[Purpose] The soleus H-reflex is depressed at stimulation rates greater than 0.1 Hz. This reflex depression is referred to as postactivation depression. Postactivation depression reflects the reduced efficacy of the Ia-motoneurons synapses when they are evaluated after a previous activation. The aim of this study was to determine whether the recovery of motor functions in the lower extremities ...

In healthy subjects, functionally appropriate modulation of short latency leg muscle reflexes occurs during gait. This modulation has been ascribed, in part, to changes in presynaptic inhibition of Ia afferents. The changes in modulation of quadriceps tendon jerk reflexes during gait of healthy subjects were compared with those of hemi- or paraparetic spastic patients. The spasticity was due to...

BACKGROUND AND PURPOSE Hypoxic effects on neuronal functions vary significantly with experimental conditions, but the mechanism for this is unclear. Adenosine has been reported to play a key role in depression of neuronal activities in the CNS during acute hypoxia. Hence, we examined the effect of acute hypoxia on different spinal reflex potentials and the contribution of adenosine to them. E...

Experiments were performed to find out whether supraspinal inhibitory influences affect spinal interneurones during physiological sleep. Single shock stimulation of the tibial nerve elicits a direct motor action potential from the intrinsic plantar muscles, followed by two reflex action potentials. The early response is due to monosynaptie excitation of the spinal motoneurones, while the late r...