title: Measurements of excitatory postsynaptic potentials in the stretch reflex of normal subjects and spastic patients.
abstract: The patellar tendon was tapped by random impulses of triangular waveform and motor unit spikes were recorded from the quadriceps femoris muscle. The cross-correlogram of the taps and the motor unit spikes revealed a primary correlation kernel, the width of which was interpreted as an indicator of the mean time-to-peak of excitatory postsynaptic potentials (EPSPs) elicited monosynaptically in an alpha-motoneurone by the triangular taps. The mean time-to-peak was 7.6 +/- 1.3 ms in normal subjects and 9.0 +/- 1.8 ms in spastic patients (P less than 0.005). The prolonged time-to-peak of EPSP in spastic patients is consistent with the hypothesis that as a result of degeneration of the corticomotoneuronal tract the Ia axons sprout and form more synaptic contacts on distal portions of the dendrites of alpha-motoneurones.
mesh_terms: D000125:Achilles Tendon / Q000294:innervation; D004576:Electromyography; D005071:Evoked Potentials; D006801:Humans; D007866:Leg / Q000294:innervation; D008465:Mechanoreceptors / Q000503:physiopathology*; D009046:Motor Neurons / Q000502:physiology; D009128:Muscle Spasticity / Q000503:physiopathology*; D009132:Muscles / Q000294:innervation*; D012018:Reflex / Q000502:physiology*; D013569:Synapses / Q000502:physiology*