The interpretation of changes in the soleus H reflex is problematic in the face of reflex gain changes, a nonlinear input/output relationship for the motoneuron pool, and a nonhomogeneous response of different motoneurons to afferent inputs. By altering the stimulus intensity to maintain a constant reflex output, threshold tracking allows a relatively constant population of alpha-motoneurons to...

The masseteric jaw closure reflex was utilized as a model system with which to gauge the functional activity of central noradrenergic neurons. This system was chosen because it is a simple monosynaptic reflex the neuronal substrate of which receives a dense noradrenergic input. The modulatory effects of norepinephrine (NE) on this response in the intact, chloral hydrate-anesthetized rat were st...

The blink reflex and its equivalent glabella tap reflex are behavioural motor responses normally found in neonates and in the physiological startle reflex. Historically, it was described by Overend in 1896 and soon afterwards by McCarthy and by Bekhterev who disputed its origins. Kugelberg in 1952 recorded the early-latency R1 and the late-latency R2 electromyographic responses from orbicularis...