Related Experiment Video
Updated: May 9, 2026

An Emerging Target Paradigm to Evoke Fast Visuomotor Responses on Human Upper Limb Muscles
Published on: August 25, 2020
Withdrawal reflexes in the upper limb adapt to arm posture and stimulus location
Carrie L Peterson1, Zachary A Riley, Eileen T Krepkovich
1Sensory Motor Performance Program, Rehabilitation Institute of Chicago, 345 East Superior Street, Chicago, Illinois, 60611, USA; Edward Hines, Jr., VA Hospital, Hines, IL, USA.
Introduction:
Withdrawal reflexes in the leg adapt in a context-appropriate manner to remove the limb from noxious stimuli, but the extent to which withdrawal reflexes adapt in the arm remains unknown.
Methods:
We examined the adaptability of withdrawal reflexes in response to nociceptive stimuli applied in different arm postures and to different digits. Reflexes were elicited at rest, and kinetic and electromyographic responses were recorded under isometric conditions, thereby allowing motorneuron pool excitability to be controlled.
Results:
Endpoint force changed from a posterior-lateral direction in a flexed posture to predominantly a posterior direction in a more extended posture [change in force angle (mean ± standard deviation) 35.6 ± 5.0°], and the force direction changed similarly with digit I stimulation compared with digit V (change = 22.9 ± 2.9°).
Conclusions:
The withdrawal reflex in the human upper limb adapts in a functionally relevant manner when elicited at rest.
Related Concept Videos
Somatic Spinal Reflexes
One of the most well-known somatic spinal reflexes is the stretch reflex, which is activated by the sudden stretching of a muscle. This reflex involves the activation of specialized sensory receptors called muscle spindles, which are located in the muscle tissue and detect changes in the length and speed of muscle contractions. When a muscle is suddenly...
Reflex Activity
A reflex exam is a diagnostic procedure performed by a healthcare professional to evaluate the functionality of a patient's...
Indirect Motor Pathways
The vestibulospinal tract originates in the vestibular nuclei of the brainstem. The vestibular system detects changes in...
Somatosensation

