At any moment, each of these specialized brain neurons might be receiving multiple messages from multiple sources, but is only selectively responding to certain information about the timing or frequency of the impulses it is receiving. Related Stories.
Methods for measuring sympathetic nervous system activity. Heart rate variability (HRV), the beat-to-beat variation in heart rate, is an indirect method of measuring autonomic nervous system activity, with contributions from both the sympathetic and parasympathetic nervous systems.ine electrodes are used to record 'bursts' of activity from multiple or single afferent and efferent nerve axons in the skin and muscle. The common peroneal nerve is typically chosen for this method (because it is easily accessible) and measures the efferent postganglionic muscle sympathetic nerve activity (MSNA).
Muscle Fiber Excitation. The events already described (calcium entry, cross-bridge cycling) occur when a muscle fiber is excited to fire an action potential. An action potential is triggered in a muscle fiber when it is depolarized due to excitation at its synapse, the neuromuscular junction.Each muscle fiber has one neuromuscular junction, receiving input from just one somatic efferent neuron.Ch binds to nicotinic receptors in a specialized region of the muscle fiber known as the motor endplate. ACh binding allows Na + ions to enter the cell, causing a depolarizing excitatory postsynaptic potential (EPSP) that is above threshold and triggers an action potential.