scholarly journals Invariance of Oscillator Interneurone Activity During Variable Motor Output by Locusts

1989 ◽  
Vol 141 (1) ◽  
pp. 231-239
Author(s):  
H. REICHERT ◽  
C. H. F. ROWELL
Keyword(s):  
Action Potentials ◽  
Motor Output ◽  
Motor Patterns ◽  
Sensory Inputs ◽  
Motor Neurones ◽  
Depressor Muscle ◽  
Premotor Interneurones ◽  
Centre Of Rotation ◽  
Flight Motor ◽  
Oscillator Output

Simultaneous intracellular recordings were made in locusts from (a) flight motor neurones and (b) output interneurones of the flight oscillator. The insects were mounted with the head at the centre of rotation of an artificial horizon. During fictive flight, these animals responded to simulated deviations from course with the changes in motor output appropriate to course-correction manoeuvres, as previously described. In the motor neurone of depressor muscle MN98 (mesothoracic second basalar) these changes take the form of systematic variation in amplitude in the cyclical depolarization seen in the neurone in flight which, in turn, leads to variation in the number of action potentials per cycle (from 0–3) and in the latency of the first spike (up to 19 ms difference). These changes are closely related to the perceived movement of the horizon. The oscillator output, as recorded in metathoracic interneurone 511, shows, in contrast, very little change. The fraction of its variation which is correlated with horizon movement is vanishingly small (e.g. for number of action potentials per burst r2 = 0.008). The exteroceptive sensory inputs which modify motor output during steering do not, therefore, affect the oscillator appreciably. Thus, by exclusion, the motor patterns of compensatory steering are due exclusively to summation of the oscillator drive with the sensory inputs. This takes place in the motor neurones and especially in the premotor interneurones, as previously described.

Reflex Organization in the Swimmeret System of the Lobster

1969 ◽  
Vol 51 (3) ◽  
pp. 547-563
Author(s):  
W. J. DAVIS
Keyword(s):  
Sensory Feedback ◽  
Motor Command ◽  
Homarus Americanus ◽  
Motor Output ◽  
Motor Patterns ◽  
Motor Neurones ◽  
Output Pattern

1. The intrasegmental feedback reflexes in the swimmeret system of the lobster Homarus americanus were activated while recording the responses from the swimmeret nerves and muscles. 2. Two main sources of sensory feedback were identified; proprioceptors in the coxal region of the swimmeret, and sensory setae on the edges of the two rami of each swimmeret. The reflexes activated by these inputs are described. 3. Reflexive feedback from the powerstroke movement to the powerstroke excita tory motor neurones is positive, further reinforcing the movement. Intrasegmental reflexes capable of independently initiating or terminating the powerstroke activity are absent, however. Therefore the powerstroke movement of each cycle can begin and end only in response to a purely central nervous motor command. It follows that the intrasegmental swimmeret reflexes are incapable of contributing to the periodicity seen in the motor output pattern which underlies swimmeret beating. 4. In addition to strengthening the powerstroke, the intrasegmental reflexes strengthen the linkage between the powerstroke and the returnstroke within each movement cycle. The reflexes may also reinforce the reciprocity between excitor and inhibitor axon activity to the main powerstroke and returnstroke muscles. 5. It is shown, however, that these three features of the motor output pattern are programmed into the CNS independently of the sensory feedback. The intrasegmental reflexes thus act as subservient amplifying devices for cyclic motor patterns which are produced independently by purely central nervous mechanisms.

scholarly journals Motor Patterns During Walking on a Slippery Walkway

2010 ◽  
Vol 103 (2) ◽  
pp. 746-760 ◽  
Author(s):  
Germana Cappellini ◽  
Yuri P. Ivanenko ◽  
Nadia Dominici ◽  
Richard E. Poppele ◽  
Francesco Lacquaniti
Keyword(s):  
Motor Output ◽  
Emg Activity ◽  
Head Orientation ◽  
Cycle Duration ◽  
Horizontal Shear ◽  
Motor Patterns ◽  
Spatiotemporal Organization ◽  
Surface Conditions ◽  
Gait Kinematics ◽  
Slippery Surface

Friction and gravity represent two basic physical constraints of terrestrial locomotion that affect both motor patterns and the biomechanics of bipedal gait. To provide insights into the spatiotemporal organization of the motor output in connection with ground contact forces, we studied adaptation of human gait to steady low-friction conditions. Subjects walked along a slippery walkway (7 m long; friction coefficient ≃ 0.06) or a normal, nonslippery floor at a natural speed. We recorded gait kinematics, ground reaction forces, and bilateral electromyographic (EMG) activity of 16 leg and trunk muscles and we mapped the recorded EMG patterns onto the spinal cord in approximate rostrocaudal locations of the motoneuron (MN) pools to characterize the spatiotemporal organization of the motor output. The results revealed several idiosyncratic features of walking on the slippery surface. The step length, cycle duration, and horizontal shear forces were significantly smaller, the head orientation tended to be stabilized in space, whereas arm movements, trunk rotations, and lateral trunk inclinations considerably increased and foot motion and gait kinematics resembled those of a nonplantigrade gait. Furthermore, walking on the slippery surface required stabilization of the hip and of the center-of-body mass in the frontal plane, which significantly improved with practice. Motor patterns were characterized by an enhanced (roughly twofold) level of MN activity, substantial decoupling of anatomical synergists, and the absence of systematic displacements of the center of MN activity in the lumbosacral enlargement. Overall, the results show that when subjects are confronted with unsteady surface conditions, like the slippery floor, they adopt a gait mode that tends to keep the COM centered over the supporting limbs and to increase limb stiffness. We suggest that this behavior may represent a distinct gait mode that is particularly suited to uncertain surface conditions in general.

Temperature Dependence of the Neural Control of the Moth Flight System

1970 ◽  
Vol 53 (3) ◽  
pp. 629-639
Author(s):  
JAMES L. HANEGAN ◽  
JAMES EDWARD HEATH
Keyword(s):  
Temperature Dependence ◽  
Neural Control ◽  
Motor Pattern ◽  
Motor Output ◽  
Flight Pattern ◽  
Flight System ◽  
Warm Up ◽  
Thoracic Ganglia ◽  
Flight Motor

1. The transition from the warm-up motor pattern to the flight motor pattern in the saturnid moth H. cecropia, is described. 2. The transition from warm-up to flight was found to be dependent on the temperature of the thoracic ganglia. 3. A model to account for the two different motor output patterns and the transition of the warm-up pattern to the flight pattern is proposed.

An Arthropod Muscle Innervated by Nine Excitatory Motor Neurones

1980 ◽  
Vol 88 (1) ◽  
pp. 249-258
Author(s):  
CHRISTINE E. PHILLIPS
Keyword(s):  
Action Potentials ◽  
Motor Neurone ◽  
Muscle Fibres ◽  
Relaxation Rates ◽  
Motor Neurones ◽  
The Individual ◽  
Contraction And Relaxation ◽  
High Degree ◽  
Individual Motor ◽  
Indirect Stimulation

The anatomical and physiological organization of the locust metathoracic flexor tibiae was examined by a combination of intracellular recording and electron microscopy. Nine excitatory motor neurones, three fast, three intermediate and three slow innervate the muscle; each is uniquely identifiable using a combination of physiological response and soma location. A simple spatial distribution of inputs to the muscle from the individual motor neurones was not found. Individual muscle fibres responded to as many as seven of the motor neurones in various combinations. The muscle fibres are heterogeneous, ranging from slow (tonic) to fast (phasic) in a continuum from predominantly phasic proximally to tonicdistally. This is demonstrated by contraction and relaxation rates to directand indirect stimulation, as well as contraction elicited by action potentials in a single flexor motor neurone. The fast and slow contractile properties of the muscle fibres are matched by appropriate ultrastructures. Such a high degree of complexity of neuromuscular innervation as that found in the metathoracic flexor tibiae has not previously been described for an arthropod muscle.

Processing of proprioceptive signals by ascending interneurones in the terminal abdominal ganglion of the crayfish

1999 ◽  
Vol 202 (21) ◽  
pp. 2975-2984
Author(s):  
H. Aonuma ◽  
P.L. Newland ◽  
T. Nagayama
Keyword(s):  
Action Potentials ◽  
Chordotonal Organ ◽  
Simultaneous Application ◽  
Proprioceptive Input ◽  
Proprioceptive Stimulation ◽  
Motor Neurones ◽  
Tail Flip ◽  
Local Circuits ◽  
Proprioceptive Inputs ◽  
Subthreshold Level

Intersegmental interneurones are crucial for the appropriate coordination of the activity of local circuits located in different body segments. We have analysed the synaptic inputs to ascending intersegmental interneurones from a proprioceptor in the tailfan of the crayfish. Twenty identified interneurones responded during stimulation of the exopodite-endopodite chordotonal organ. Of these 20 interneurones, three were excited phaso-tonically, nine were excited phasically and eight were inhibited. All received convergent exteroceptive inputs from water-motion- or touch-sensitive hairs on the uropods. The effects of simultaneous exteroceptive and proprioceptive stimulation depended upon the identity of an interneurone. For interneurones that were inhibited by proprioceptive stimulation, suprathreshold exteroceptive responses were reduced to a subthreshold level by simultaneous proprioceptive stimulation. In contrast, for interneurones that were excited by proprioceptive stimulation, the simultaneous application of subthreshold proprioceptive and exteroceptive stimulation elicited action potentials. Two of the interneurones that receive proprioceptive input (NE-1 and RC-8) are known to be presynaptic to giant interneurones that mediate and coordinate the tail-flip. Many of the other interneurones that receive proprioceptive inputs in the tailfan are known to excite abdominal extensor motor neurones. Thus, proprioceptive input to these intersegmental interneurones could serve two roles: first, to extend the abdomen during postural movements or prior to escape and, second, to drive the tail-flip escape response.

scholarly journals Retracing your footsteps: developmental insights to spinal network plasticity following injury

2018 ◽  
Vol 119 (2) ◽  
pp. 521-536 ◽  
Author(s):  
C. Jean-Xavier ◽  
S. A. Sharples ◽  
K. A. Mayr ◽  
A. P. Lognon ◽  
P. J. Whelan
Keyword(s):  
Spinal Cord ◽  
Neuronal Excitability ◽  
Weight Bearing ◽  
Rhythmic Activity ◽  
Motor Output ◽  
Parallel Mechanisms ◽  
Sensory Afferents ◽  
Motor Patterns ◽  
Network Function ◽  
Cord Injury

During development of the spinal cord, a precise interaction occurs between descending projections and sensory afferents, with spinal networks that lead to expression of coordinated motor output. In the rodent, during the last embryonic week, motor output first occurs as regular bursts of spontaneous activity, progressing to stochastic patterns of episodes that express bouts of coordinated rhythmic activity perinatally. Locomotor activity becomes functionally mature in the 2nd postnatal wk and is heralded by the onset of weight-bearing locomotion on the 8th and 9th postnatal day. Concomitantly, there is a maturation of intrinsic properties and key conductances mediating plateau potentials. In this review, we discuss spinal neuronal excitability, descending modulation, and afferent modulation in the developing rodent spinal cord. In the adult, plastic mechanisms are much more constrained but become more permissive following neurotrauma, such as spinal cord injury. We discuss parallel mechanisms that contribute to maturation of network function during development to mechanisms of pathological plasticity that contribute to aberrant motor patterns, such as spasticity and clonus, which emerge following central injury.

scholarly journals Action-potential broadening and endogenously sustained bursting are substrates of command ability in a feeding neuron of Pleurobranchaea

1980 ◽  
Vol 43 (3) ◽  
pp. 669-685 ◽  
Author(s):  
R. Gillette ◽  
M. U. Gillette ◽  
W. J. Davis
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Motor Output ◽  
Buccal Ganglion ◽  
Short Pulses ◽  
Motor Network ◽  
Single Axon ◽  
Network Output ◽  
Bilateral Pair ◽  
Potential Activity

1. The ventral white cells (VWC's) of the buccal ganglion of Pleurobranchaea, so named for their position and color, are a bilateral pair of neuron somata. Each sends a single axon out its contralateral stomatogastric nerve and has a dendritic field originating close to the soma. 2. The vwcs exhibit spontaneous episodes of prolonged depolarization (duration 1--4 min) accompanied by repetitive action-potential activity and separated by regular intervals of 3--30 min. Such prolonged burst episodes can be triggered by short pulses of depolarizing current. During the repetitive activity of the spontaneous bursts or that driven by imposed depolarization, the action potentials progressively broaden to 5--16 times their initial duration. 3. During spontaneous bursting or activity driven by imposed depolarization, the cyclic motor output of the feeding network is initiated or accelerated with a latency corresponding with the development of appreciable VWC spike broadening. When broadening of antidromic VWC spikes is suppressed by imposed hyperpolarization of the soma, the frequency of feeding cycles is significantly lower than when broadened spikes are allowed to develop. When trains of spikes are driven by depolarizing current, the motor output of the feeding network is not initiated until the VWC spikes have broadened to a repeatable "threshold" duration, regardless of the intensity of the depolarizing current. 4. The endogenous production of prolonged burst episodes, triggered by depolarizing current pulses, and progressive spike broadening can be demonstrated in the surgically isolated VWC soma. 5. The paired VWCs are strongly electrically coupled and display highly synchronous activity. They receive synaptic inputs from many previously identified interneurons of the feeding network and are thus reciprocally coupled within the network. 6. These results demonstrate that the capacity of this neuron to generate broadened action potentials during repetitive activity confers the ability to command coordinated motor-network output. The appropriate repetitive activity can be produced endogenously in the form of prolonged bursts of spikes.

scholarly journals Wing Hair Plates in Crickets: Physiological Characteristics and Connections with Stridulatory Motor Neurones

1983 ◽  
Vol 107 (1) ◽  
pp. 21-47 ◽  
Author(s):  
C.J.H. ELLIOTT
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Viscous Drag ◽  
Behavioural Study ◽  
Wing Hair ◽  
Motor Neurones ◽  
Association Area ◽  
The Mean ◽  
Wing Folding ◽  
Stimulation Of

(1) Hairs in the subcostal hair plates of the wings of crickets have a high angular stiffness (5.5μNm rad1) when bent about their base. The mean threshold required to elicit action potentials is 15°. Viscous drag from air movements will not deflect the hairs sufficiently to excite them; this will only occur when the hair is bent by the opposite wing. (2) The hair sensillae project to the ventral association area of the mesothoracic ganglion, but the endings of the stridulatory motor neurones are all in dorsal or lateral neuropiles of the thoracic ganglia. (3) Electrical stimulation of the hair plates evokes reliable EPSPs in opener (M99), closer (M90) and wing folding (M85) motor neurones, after latencies of 4–20 ms, depending on the neurone. Properties of the hairs and motor neurones suggest that these EPSPs in the wing folding muscle (M85) and closer (M90) could play an important role in the control of wing position seen in recent behavioural study.

The Central Nervous Control of Complex Movements in the Uropods of Crayfish

1969 ◽  
Vol 51 (1) ◽  
pp. 135-150
Author(s):  
J. L. LARIMER ◽  
D. KENNEDY
Keyword(s):  
Central Element ◽  
Simultaneous Recording ◽  
Motor Output ◽  
Afferent Feedback ◽  
Rhythmic Pattern ◽  
Nervous Control ◽  
Motor Pathways ◽  
Combined Movements ◽  
Motor Neurones ◽  
Two Sides

1. The control of postural uropod muscles in the crayfish has been investigated by stimulating ‘command’ interneurones isolated from central connectives. Reciprocity is preserved between exciters and inhibitors innervating the same muscle, and between motor axons serving antagonists. 2. The control of combined movements, involving groups of muscles that are neither synergists nor antagonists, was analysed by simultaneous recording. Most command fibres affected several different motor pathways, and different command fibres produced different combinations of output. It is concluded that quite complex movements may be encoded in the connexions of a single central element. 3. In several instances it was shown unequivocally that single central neurones were responsible for releasing the motor output. One identified command neurone produces a stereotyped, rhythmic pattern of activity in several motor pathways. This effect did not depend upon afferent feedback for its form or frequency. 4. Command interneurones often produce asymmetrical responses in the appendages of the two sides. Some of these make connexions only to the ipsilateral motor neurones, others only to contralateral ones, and most make differential connexions on the two sides.

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