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

Büschges A, Kittmann R, Schmitz J. Identified nonspiking interneurons in leg reflexes and during walking in the stick insect. Journal of Comparative Physiology, A - Sensory Neural and Behavioral Physiology. 1994;174(6):685-700.In the stick insect Carausius morosus identified nonspiking interneurons (type E4) were investigated in the mesothoracic ganglion during intra- and intersegmental reflexes and during searching and walking. In the standing and in the actively moving animal interneurons of type E4 drive the excitatory extensor tibiae motoneurons, up to four excitatory protractor coxae motoneurons, and the common inhibitor 1 motoneuron (Figs. 1-4). In the standing animal a depolarization of this type of interneuron is induced by tactile stimuli to the tarsi of the ipsilateral front, middle and hind legs (Fig. 5). This response precedes and accompanies the observed activation of the affected middle leg motoneurons. The same is true when compensatory leg placement reflexes are elicited by tactile stimuli given to the tarsi of the legs (Fig. 6). During forward walking the membrane potential of interneurons of type E4 is strongly modulated in the step-cycle (Figs. 8-10). The peak depolarization occurs at the transition from stance to swing. The oscillations in membrane potential are correlated with the activity profile of the extensor motoneurons and the common inhibitor 1 (Fig. 9). The described properties of interneuron type E4 in the actively behaving animal show that these interneurons are involved in the organization and coordination of the motor output of the proximal leg joints during reflex movements and during walking

Intracellular recordings from nonspiking interneurons in a semiintact, tethered walking insect

Schmitz J, Büschges A, Kittmann R. Intracellular recordings from nonspiking interneurons in a semiintact, tethered walking insect. J.Neurobiol. 1991;22(9):907-921.Nonspiking interneurons were investigated in a tethered, walking insect, Carausius morosus, that was able to freely perform walking movements. Experiments were carried out with animals walking on a lightweight, double-wheel treadmill. Although the animal was opened dorsally, the walking system was left intact. Intracellular recordings were obtained from the dorsal posterior neuropil of the mesothoracic ganglion. Nonspiking interneurons, in which modulations of the membrane potential were correlated with the walking rhythm, were described physiologically and stained with Lucifer Yellow. Interneurons are demonstrated in which membrane potential oscillations mirror the leg position or show correlation with the motoneuronal activity of the protractor and retractor coxae muscles during walking. Other interneurons showed distinct hyperpolarizations at certain important trigger points in the step cycle, for example, at the extreme posterior position. Through electrical stimulation of single, nonspiking interneurons during walking, the motoneuronal activity in two antagonistic muscles-protractor and retractor coxae-could be reversed and even the movement of the ipsilateral leg could be influenced. The nonspiking interneurons described appear to be important premotor elements involved in walking. They receive, integrate, and process information from different leg proprioceptors and drive groups of leg motoneurons during walking

The calibration procedure of the LINC-NIRVANA ground and high layer WFS

LINC-NIRVANA (LN) is a MCAO module currently mounted on the Rear Bent Gregorian focus of the Large Binocular Telescope (LBT). It mounts a camera originally design to realize the interferometric imaging focal station of the LBT. LN follows the LBT strategy having two twin channels: a double Layer Oriented multi-conjugate adaptive optics system assists the two arms, supplying high order wave-front correction. In order to counterbalance the field rotation a mechanical derotation is applied for the two ground wave-front sensors, and an optical (K-mirror) one for the two high layers sensors, fixing the positions of the focal planes with respect to the pyramids aboard the wavefront sensors. The derotation introduces a pupil images rotation on the wavefront sensors changing the projection of the deformable mirrors on the sensor consequently. The soft real-time computer load the matrix corresponding to the needed at one degree step. Calibrations were performed in daytime only and using optical fibers