Long-lasting afterdischarge of alpha-motoneurons after muscle vibration or electrical stimulation of group I afferent fibers in the anemically decerebrated cat.
Experiments were performed on anemically decerebrated cats. Motoneuronal activity in the spinal cord was intracellularly or extracellulary recorded and muscle vibration or electrical stimulation of the peripheral nerve was applied for 1 s every 2 s. Such stimulation elicited monosynaptic responses and afterdischarge, a response which lasts after cessation of the stimuli. Stimulus frequencies from 50 to 200 Hz were effective in eliciting the afterdischarge, while frequencies higher or lower than this range of stimulation were ineffective. The interspike intervals of the motoneuron afterdischarge were almost constant and did not correspond to the stimulus frequency. The mean intervals obtained from the motoneurons examined ranged from 70 to 120 ms. Power spectrum analysis of the membrane potential ripples recorded immediately after stimulation revealed increased activity at 38 and 62 Hz components. Since the spike interval of the afterdischarge in this motoneuron was 80 ms, the interval was almost equal to 5- and 3-fold the cyclic time of the increased frequency components. This indicates that the interval of afterdischarge was determined by the specifically increased frequency components of the membrane potential ripples.
Wada
N
N
Department of Physiology, School of Medicine, Chiba University, Japan.
Nakajima
Y
Y
Homma
S
S
D000818:Animals; D002415:Cats; D003655:Decerebrate State; D004558:Electric Stimulation; D008564:Membrane Potentials; D009046:Motor Neurons / Q000502:physiology*; D014732:Vibration