Identified nonspiking interneurons in leg reflexes and during walking in the stick insect

1994 ◽  
Vol 174 (6) ◽  
Author(s):  
A. B�schges ◽  
R. Kittmann ◽  
J. Schmitz
Keyword(s):  
Stick Insect ◽  
Nonspiking Interneurons

Modulation of Membrane Potential in Mesothoracic Moto- and Interneurons During Stick Insect Front-Leg Walking

2005 ◽  
Vol 94 (4) ◽  
pp. 2772-2784 ◽  
Author(s):  
Björn Ch. Ludwar ◽  
Sandra Westmark ◽  
Ansgar Büschges ◽  
Joachim Schmidt
Keyword(s):  
Membrane Potential ◽  
Spike Activity ◽  
Membrane Resistance ◽  
Stick Insect ◽  
Signal Transfer ◽  
Motoneuron Pool ◽  
Current Pulses ◽  
Nonspiking Interneurons ◽  
Resistance Decrease ◽  
Synaptic Drive

During walking, maintenance and coordination of activity in leg motoneurons requires intersegmental signal transfer. In a semi-intact preparation of the stick insect, we studied membrane potential modulations in mesothoracic (middle leg) motoneurons and local premotor nonspiking interneurons that were induced by stepping of a front leg on a treadmill. The activity in motoneurons ipsi- and contralateral to the stepping front leg was recorded from neuropilar processes. Motoneurons usually exhibited a tonic depolarization of ≤5 mV throughout stepping sequences. This tonic depolarization depended on membrane potential and was found to reverse in the range of −32 to −47 mV. It was accompanied by a mean membrane resistance decrease of ∼12%. During front-leg stepping, an increased spike activity to depolarizing current pulses was observed in 73% of contralateral flexor motoneurons that were tested. Motoneurons ipsilateral to the walking front leg exhibited phasic membrane potential modulations coupled to steps in accordance with previously published results. Coupling patterns were typical for a given motoneuron pool. Local nonspiking mesothoracic interneurons that provide synaptic drive to tibial motoneurons also contribute to the modulation of membrane potential of tibial motoneurons during front-leg walking. We hypothesize that the tonic depolarization of motoneurons during walking is a cellular correlate of arousal that usually increases effectiveness of phasic excitation in supporting motoneuron firing.

Cooperative Mechanisms Between Leg Joints of Carausius morosusI. Nonspiking Interneurons That Contribute to Interjoint Coordination

1998 ◽  
Vol 79 (6) ◽  
pp. 2964-2976 ◽  
Author(s):  
Dennis E. Brunn
Keyword(s):  
Membrane Potential ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Stick Insect ◽  
Interjoint Coordination ◽  
Antagonistic Muscle ◽  
Nonspiking Interneurons ◽  
Active Motor ◽  
Thoracic Part ◽  
Depressor Muscle

Brunn, Dennis E. Cooperative mechanisms between leg joints of Carausius morosus. I. Nonspiking interneurons that contribute to interjoint coordination. J. Neurophysiol. 79: 2964–2976, 1998. Three nonspiking interneurons are described in this paper that influence the activity of the motor neurons of three muscles of the proximal leg joints of the stick insect. Interneurons were recorded and stained intracellularly by glass microelectrodes; motor neurons were recorded extracellularly with oil-hook electrodes. The motor neurons innervate the two subcoxal muscles, the protractor and retractor coxae, and the thoracic part of the depressor trochanteris muscle. The latter spans the subcoxal joint before inserting the trochanter, thus coupling the two proximal joints mechanically. The three interneurons are briefly described here. First, interneuron NS 1 was known to become more excited during the swing phase of the rear and the stance phase of the middle leg. When depolarized it excited several motor neurons of the retractor coxae. This investigation revealed that it inhibits the activity of protractor and thoracic depressor motor neurons when depolarized as well. In a pilocarpine-activated animal, the membrane potential showed oscillations in phase with the activity of protractor motor neurons, suggesting that NS 1 might contribute to the transition from swing to stance movement. Second, interneuron NS 2 inhibits motor neurons of protractor and thoracic depressor when depolarized. In both a quiescent and a pilocarpine-activated animal, hyperpolarizing stimuli excite motor neurons of both muscles via disinhibition. In one active animal the disinhibiting stimuli were sufficient to generate swing-like movements of the leg. In pilocarpine-activated preparations the membrane potential oscillated in correlation with the motor neuronal activity of the protractor coxae and thoracic depressor muscle. Hyperpolarizing stimuli induced or reinforced the protractor and thoracic depressor bursts and inhibited the activity of the motor neurons of the retractor coxae muscle, the antagonistic muscle of the protractor. Therefore interneuron NS 2 can be regarded as an important premotor interneuron for the switching from stance to swing and from swing to stance. Finally, interneuron NS 3 inhibits the spontaneously active motor neurons of both motor neuron pools in the quiescent animal. During pilocarpine-induced protractor bursts, depolarizing stimuli applied to the interneuron excited several protractor motor neurons with large action potentials and one motor neuron of the thoracic depressor. No oscillations of the membrane potentials were observed. Therefore this interneuron might contribute to the generation of rapid leg movements. The results demonstrated that the two proximal joints are coupled not only mechanically but also neurally and that the thoracic part of the depressor appears to function as a part of the swing-generating system.

Premotor Interneurons in the Local Control of Stepping Motor Output for the Stick Insect Single Middle Leg

2009 ◽  
Vol 102 (3) ◽  
pp. 1956-1975 ◽  
Author(s):  
Géraldine von Uckermann ◽  
Ansgar Büschges
Keyword(s):  
Stance Phase ◽  
Stick Insect ◽  
Motor Output ◽  
Chordotonal Organ ◽  
Locomotor System ◽  
State Dependent ◽  
Nonspiking Interneurons ◽  
Leg Kinematics ◽  
Control Regime

In insect walking systems, nonspiking interneurons (NSIs) play an important role in the control of posture and movement. As such NSIs are known to contribute to state-dependent modifications in processing of proprioceptive signals from the legs. For example, NSIs process a flexion of the femur-tibia (FTi) joint signaled by the femoral chordotonal organ (fCO) such that the stance phase motor output is reinforced in the active locomotor system. This phenomenon representing a reflex reversal is the first part of the “active reaction” (AR) and was hypothesized to functionally represent a major control feature by which sensory feedback supports stance generation. As NSIs are known to contribute to the AR, the question arises, whether they serve similar functions during stepping and whether the AR is generally part of the control system for walking. We studied these issues in vivo, in a single leg preparation of Carausius morosus with the leg kinematics being confined to changes in one plane, along the coxa-trochanteral and the FTi-joint. Following kinematic analysis, identified NSIs (E1-E8, I1, I2, and I4) were recorded intracellularly during single leg stepping at different velocities. We detected clear similarities between the activity pattern of NSIs during single leg stepping and their responses to fCO-stimulation during the generation of the AR. This strongly supports the notion that the motor output generated during the AR reflects part of the control regime for stepping. Furthermore, our experiments revealed that alterations in stepping velocity result from modifications in the activity of the premotor NSIs involved in stance phase generation.

Outbreak of the stick insect, Ramulus mikado (Phasmatodea, Phasmatidae), in the Akashina area of Japan (Azumino City, Nagano Prefecture)

2021 ◽  
Vol 24 (2) ◽  
pp. 196-200
Author(s):  
Koki Yano ◽  
Takahisa Ozaki ◽  
Tomoya Suzuki ◽  
Haruka Yamazaki ◽  
Masayoshi Nasuno ◽  
...  
Keyword(s):  
Stick Insect ◽  
Nagano Prefecture

Space constancy in form perception by the stick insect

1996 ◽  
Vol 83 (7) ◽  
pp. 323-324 ◽  
Author(s):  
L. Frantsevich ◽  
L. Frantsevich
Keyword(s):  
Stick Insect ◽  
Form Perception ◽  
Space Constancy
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