Universität zu Köln

Stolz, Thomas, Diesner, Max, Neupert, Susanne, Hess, Martin E., Delgado-Betancourt, Estefania, Pflueger, Hans-Joachim and Schmidt, Joachim (2019). Descending octopaminergic neurons modulate sensory-evoked activity of thoracic motor neurons in stick insects. J. Neurophysiol., 122 (6). S. 2388 - 2414. BETHESDA: AMER PHYSIOLOGICAL SOC. ISSN 1522-1598

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Abstract

Neuromodulatory neurons located in the brain can influence activity in locomotor networks residing in the spinal cord or ventral nerve cords of invertebrates. How inputs to and outputs of neuromodulatory descending neurons affect walking activity is largely unknown. With the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and immunohistochemistry, we show that a population of dorsal unpaired median (DUM) neurons descending from the gnathal ganglion to thoracic ganglia of the stick insect Carausius morosus contains the neuromodulatory amine octopamine. These neurons receive excitatory input coupled to the legs' stance phases during treadmill walking. Inputs did not result from connections with thoracic central pattern-generating networks, but, instead, most are derived from leg load sensors. In excitatory and inhibitory retractor coxae motor neurons, spike activity in the descending DUM (desDUM) neurons increased depolarizing reflexlike responses to stimulation of leg load sensors. In these motor neurons, descending octopaminergic neurons apparently functioned as components of a positive feedback network mainly driven by load-detecting sense organs. Reflexlike responses in excitatory extensor tibiae motor neurons evoked by stimulations of a femur-tibia movement sensor either are increased or decreased or were not affected by the activity of the descending neurons, indicating different functions of desDUM neurons. The increase in motor neuron activity is often accompanied by a reflex reversal, which is characteristic for actively moving animals. Our findings indicate that some descending octopaminergic neurons can facilitate motor activity during walking and support a sensory-motor state necessary for active leg movements. NEW & NOTEWORTHY We investigated the role of descending octopaminergic neurons in the gnathal ganglion of stick insects. The neurons become active during walking, mainly triggered by input from load sensors in the legs rather than pattern-generating networks. This report provides novel evidence that octopamine released by descending neurons on stimulation of leg sense organs contributes to the modulation of leg sensory-evoked activity in a leg motor control system.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Stolz, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Diesner, Max UNSPECIFIED UNSPECIFIED UNSPECIFIED Neupert, Susanne UNSPECIFIED UNSPECIFIED UNSPECIFIED Hess, Martin E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Delgado-Betancourt, Estefania UNSPECIFIED UNSPECIFIED UNSPECIFIED Pflueger, Hans-Joachim UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmidt, Joachim UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-125362
DOI:	10.1152/jn.00196.2019
Journal or Publication Title:	J. Neurophysiol.
Volume:	122
Number:	6
Page Range:	S. 2388 - 2414
Date:	2019
Publisher:	AMER PHYSIOLOGICAL SOC
Place of Publication:	BETHESDA
ISSN:	1522-1598
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language UNPAIRED MEDIAN NEURONS; TIBIAL CAMPANIFORM SENSILLA; EFFERENT NEUROMODULATORY NEURONS; CENTRAL PATTERN GENERATORS; FEMORAL CHORDOTONAL ORGAN; INTER-LEG COORDINATION; CENTRAL-NERVOUS-SYSTEM; SYNAPTIC-TRANSMISSION; DUM NEURONS; SUBESOPHAGEAL GANGLION Multiple languages Neurosciences; Physiology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/12536