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Hand muscle reflexes following air puff stimulation
G Deuschl1, E Feifel, B Guschlbauer
1Department of Neurology, University of Freiburg, Germany.
Experimental Brain Research
|January 1, 1995
Summary
This study reveals that gentle air puffs on fingers trigger unique hand muscle reflexes, identified as cutaneous long-latency reflexes (cLLR I and cLLR II), originating from skin receptors.
Area of Science:
- Neuroscience
- Human Physiology
- Somatosensory System
Background:
- Hand muscle reflexes are typically studied via muscle stretch or nerve stimulation.
- The role of pure cutaneous stimulation in eliciting hand reflexes was less understood.
Purpose of the Study:
- To investigate and characterize reflexes evoked by direct cutaneous stimulation of the fingers.
- To identify the afferent pathways responsible for these cutaneous reflexes.
Main Methods:
- Air puffs were applied to the palmar and nail bed regions of the first, second, and fifth fingers during voluntary hand muscle contraction.
- Electromyography (EMG) of thenar, first dorsal interosseous, and hypothenar muscles was recorded.
- Cutaneous nerve blockade was used to confirm the origin of the reflexes.
Main Results:
- A consistent reflex pattern emerged, featuring two excitatory components (cutaneous long-latency reflex I and II) and an intervening inhibitory phase.
- Reflex responses were largest in the muscles controlling the stimulated finger.
- The size of the reflexes varied with stimulation intensity, location (palmar vs. nail bed), and finger displacement.
- Blockade of cutaneous nerve branches abolished the reflexes, confirming cutaneous receptor involvement.
Conclusions:
- Cutaneous stimulation of the fingers elicits distinct long-latency reflexes in hand muscles.
- These reflexes are mediated solely by cutaneous afferents under the tested conditions.
- The findings provide insights into the somatosensory processing of tactile input in the hand.