Universität zu Köln

Zill, Sasha N., Dallmann, Chris J., Szczecinski, Nicholas S., Bueschges, Ansgar and Schmitz, Josef (2021). Evaluation of force feedback in walking using joint torques as naturalistic stimuli. J. Neurophysiol., 126 (1). S. 227 - 249. BETHESDA: AMER PHYSIOLOGICAL SOC. ISSN 1522-1598

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Abstract

Control of adaptive walking requires the integration of sensory signals of muscle force and load. We have studied how mechanoreceptors (tibial campaniform sensilla) encode naturalistic stimuli derived from joint torques of stick insects walking on a horizontal substrate. Previous studies showed that forces applied to the legs using the mean torque profiles of a proximal joint were highly effective in eliciting motor activities. However, substantial variations in torque direction and magnitude occurred at the more distal femorotibial joint, which can generate braking or propulsive forces and provide lateral stability. To determine how these forces are encoded, we used torque waveforms of individual steps that had maximum values in stance in the directions of flexion or extension. Analysis of kinematic data showed that the torques in different directions tended to occur in different ranges of joint angles. Variations within stance were not accompanied by comparable changes in joint angle but often reflected vertical ground reaction forces and leg support of body load. Application of torque waveforms elicited sensory discharges with variations in firing frequency similar to those seen in freely walking insects. All sensilla directionally encoded the dynamics of force increases and showed hysteresis to transient force decreases. Smaller receptors exhibited more tonic firing. Our findings suggest that dynamic sensitivity in force feedback can modulate ongoing muscle activities to stabilize distal joints when large forces are generated at proximal joints. Furthermore, use of naturalistic stimuli can reproduce characteristics seen in freely moving animals that are absent in conventional restrained preparations. NEW & NOTEWORTHY Sensory encoding of forces during walking by campaniform sensilla was characterized in stick insects using waveforms of joint torques calculated by inverse dynamics as mechanical stimuli. Tests using the mean joint torque and torques of individual steps showed the system is highly sensitive to force dynamics (dF/dt). Use of naturalistic stimuli can reproduce characteristics of sensory discharges seen in freely walking insects, such as load transfer among legs.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Zill, Sasha N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Dallmann, Chris J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Szczecinski, Nicholas S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bueschges, Ansgar UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmitz, Josef UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-591379
DOI:	10.1152/jn.00120.2021
Journal or Publication Title:	J. Neurophysiol.
Volume:	126
Number:	1
Page Range:	S. 227 - 249
Date:	2021
Publisher:	AMER PHYSIOLOGICAL SOC
Place of Publication:	BETHESDA
ISSN:	1522-1598
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language TIBIAL CAMPANIFORM SENSILLA; GOLGI TENDON ORGANS; STICK INSECT; SENSORY SIGNALS; MUSCLE-ACTIVITY; MOTOR CONTROL; BODY LOAD; AMERICAN COCKROACH; PLATEAU POTENTIALS; SOLEUS MUSCLE Multiple languages Neurosciences; Physiology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59137