Intersegmental and local interneurons in the metathorax of the stick insect Carausius morosus that monitor middle leg position

1994 ◽  
Vol 72 (3) ◽  
pp. 1208-1219 ◽  
Author(s):  
D. E. Brunn ◽  
J. Dean
Keyword(s):  
Longitudinal Direction ◽  
Stick Insect ◽  
Proprioceptive Information ◽  
Joint Angles ◽  
Local Interneuron ◽  
Starting Position ◽  
Metathoracic Ganglion ◽  
Adequate Stimulus ◽  
Swing Movement ◽  
Made In

1. In the stick insect, proprioceptive information from the middle leg is used to define the target for the swing movement of the adjacent rear leg ("targeting behavior"). To investigate the underlying neural circuits, intracellular recordings were made in the ganglion controlling the rear leg, the metathoracic ganglion, while systematically moving the tarsus of the middle leg. 2. Several intersegmental interneurons and one local interneuron were identified as possible contributors to the targeting behavior. The intersegmental interneurons code the position of the middle leg tarsus in a highly simplified manner: test movements of the middle leg in the dorsal, lateral, and caudal directions from the standard starting position at right angles to the thorax elicit phasic-tonic responses in three different intersegmental neurons. The response in each interneuron actually reflects the movement and position at only one joint of the middle leg: for the neurons responding primarily to movement in the caudal, dorsal, and lateral test directions, the adequate stimulus is movement at the subcoxal joint, the coxa-trochanter joint, and the femur-tibia joint, respectively. 3. The metathoracic local interneuron integrates information from ipsilateral middle and rear legs in such a way as to provide an approximate measure of the distance between the two tarsi in the longitudinal direction. It is depolarized in a phasic-tonic manner both by caudal movements of the ipsilateral middle leg and by rostral movements of the ipsilateral rear leg. The adequate stimulus in each case is the change in the angle at the subcoxal joint of the leg moved. Depolarization of this neuron activates retractor motoneurons, which is consistent with a role in terminating the swing movement. 4. Altogether the results indicate first, that the targeting behavior could be controlled by very few intersegmental channels and, second, that the nervous system encodes the position of the middle leg tarsus in terms of joint angles rather than in abstract, body-centered coordinates.

Cooperative Mechanisms Between Leg Joints of Carausius morosusII. Motor Neuron Activity and Influence of ConditionalBursting Interneuron

1998 ◽  
Vol 79 (6) ◽  
pp. 2977-2985 ◽  
Author(s):  
Dennis E. Brunn ◽  
Antje Heuer
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Lucifer Yellow ◽  
Companion Paper ◽  
Stick Insect ◽  
Neuron Activity ◽  
Local Interneuron ◽  
Metathoracic Ganglion ◽  
Thoracic Part ◽  
Swing Movement

Brunn, Dennis E. and Antje Heuer. Cooperative mechanisms between leg joints of Carausius morosus. II. Motor neuron activity and influence of conditional bursting interneuron. J. Neurophysiol. 79: 2977–2985, 1998. The activity of the motor neuron pools of the protractor coxae muscle and of the thoracic part of the depressor trochanteris muscle during forward walking in the stick insect was investigated, and a spiking local interneuron, able to produce “endogenous bursting” and innervating both motor neuron pools, was identified. Extracellular recordings of the motor neurons innervating the protractor and the thoracic depressor of front, middle, and rear legs, respectively, were made with oil-hook electrodes from the peripheral nerves nl2c and nl4a while the animals were walking on a styrofoam treadwheel. The corresponding leg movements were registered and phase histograms were created with the software Spike2. Intracellular recordings were made in the neuropile of the metathoracic ganglion with glass electrodes filled with the dye Lucifer yellow. In all three legs measured (front, middle, and rear), both motor neuron pools increased their activity during the swing movement. The increase in the activity of the protractor motor neurons started at the end of the stance ∼100 ms before reaching the posterior extreme position (PEP), and the activity of the large-sized depressor motor neurons increased as soon as the tarsus was lifted at the PEP. A local spiking interneuron was identified that excited both motor neuron pools. In 4 of 23 recordings the interneuron started to burst in synchrony with protractor and thoracic depressor motor neurons. During bursting a depolarizing stimulus reinforced and a hyperpolarizing stimulus inhibited the activity of both motor neuron pools. Thus we conclude that the thoracic part of the depressor trochanteris muscle might be a component of the neuromuscular system that shapes the swing movement. The two proximal joints, subcoxal and coxa-trochanter, connected mechanically via the thoracic part of the depressor trochanteris muscle, are also connected neurally by segmental and intersegmental spiking interneurons (this paper) and by nonspiking local interneurons (see companion paper).

Investigations for the biological control in Fiji of the coconut stick-insect Graeffea crouanii (Le Guillou)

1968 ◽  
Vol 57 (4) ◽  
pp. 567-604 ◽  
Author(s):  
R. W. Paine
Keyword(s):  
Pacific Islands ◽  
Narrow Range ◽  
Solomon Islands ◽  
Pupal Stage ◽  
Stick Insect ◽  
Small Island ◽  
Sago Palm ◽  
Significant Damage ◽  
In Captivity ◽  
Made In

The stick-insect Graeffea crouanii (Le Guillou) is a pest of coconuts of local and sporadic importance in the south Pacific and there have been recent outbreaks on Taveuni Island, in the Fiji group. As there appear to be virtually no parasites of the nymphal stages, a preliminary search was made in 1960 for parasites of other palm-feeding Phasmatids in Melanesia. This revealed the presence of Tachinidae parasitising species of the genera Ophicrania and Megacrania, and in 1963–64 these were studied in the Solomon Islands. The Tachinidae comprise at least two species of Mycteromyiella: M. laetifica (Mesnil) attacking both O. leveri Günth. and a species of Megacrania in the western Solomons, and M. phasmatophaga Crosskey attacking 0. leveri and some other Phasmatid hosts on Guadalcanal. The early stages of both species of Mycteromyiella are briefly described and compared, with notes on their bionomics. There was no evidence of any egg parasite attacking Ophicrania in the Solomons.O. leveri, which is very closely related to G. crouanii, has never caused significant damage to coconuts in the Solomon Islands, except on the small island of Savo, from which its Tachinid parasites appear to be absent. It is concluded that Mycteromyiella, especially M. laetifica, which appears to be fairly specific, may be an important factor in the control of O. leveri in the Solomons.The principal hosts of O. leveri are the sago palm (Metroxylon salomonense) and species of arecoid palms in the forest, on all of which the insect has better scope for concealment than on coconuts. Collections of nearly 6,000 examples of O. leveri from sago palm on Kolombangara island, in the western Solomons, in August 1963-February 1964 showed an average parasitism by Mycteromyiella laetifica of 28 per cent. Eggs of the Tachinid are laid on nymphs of all instars as well as on adults. The host-survival rate was about 30 per cent, for nymphs and 50 per cent, for adults.A small number of parasitised specimens of O. leveri from Kolombangara were released on Savo, but there was no evidence six months later that M. laetifica had become established there.Breeding trials at Honiara showed that O. leveri could be reared successfully in captivity but not M. laetifica, which shows reluctance to mate in cages and has a narrow range of environmental tolerance in the pupal stage, in which a mortality of at least 70 per cent, seems unavoidable under the conditions practicable for transportation of this stage by air.Between October 1963 and March 1964 nearly 960 puparia of M. laetifica were sent to Fiji. About half of them were used for breeding trials, which showed that the Tachinid could be reared through G. crouanii in captivity but could not be maintained. The rest were released on Taveuni, but a further outbreak of G. crouanii during 1965 yielded no evidence that M. laetifica had become established.Material of M. phasmatophaga, which has a more restricted choice of environment than M. laetifica, but also a somewhat greater potentiality for killing its host, was obtained by exposing O. leveri on seedling coconut palms planted in the forest at Honiara. Quantities were insufficient for transmission to Fiji; 150 parasitised hosts were released on Savo but samples of O. leveri collected there six months later gave no indication of its establishment.Despite this initial failure, it is considered that Mycteromyiella could bring about the control of G. crouanii in Fiji and other affected Pacific islands, and the means by which this might be achieved are discussed.

Mechanism of the Crystallization of High Polymers

1954 ◽  
Vol 27 (2) ◽  
pp. 374-384 ◽  
Author(s):  
G. Schuur
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Amorphous Material ◽  
Crystalline Polymer ◽  
Longitudinal Direction ◽  
Crystalline Material ◽  
Current View ◽  
X Ray ◽  
Made In ◽  
High Polymers

Abstract The crystallization of higher polymers is a phenomenon which is not yet fully understood, one of the main difficulties being to explain how the spherulites arise. An attempt will be made in this paper to draw a clearer picture of the mechanism of crystallization and thus to account for the origin of spherulites. It will then be seen how several other phenomena involved in the crystallization of natural rubber can be shown to be logically interrelated. The current view is that a crystalline polymer consists of a continuous amorphous phase containing small crystalline regions, the crystallites. The evidence as to the size of these crystallites, however, is at present inconclusive, because only the lower limit of their size can be measured by means of x-ray examination. The reason is that, owing to the absence of reflections of a higher order, the effect of irregularities in the crystallites and of the heat motion of the molecules cannot be measured separately. Another doubtful question is whether the small angle interference maxima are to be interpreted as a measure of mean distances between the crystallites. To do this, Wallner has to resort to the assumption that the crystallites are unstable, whereas it is presumed, on the evidence of the mechanical properties of the high polymers, that a crystallite is stable and permanent. Hoffmann found 82 ± 7 per cent of crystalline material in polychlorotrifluoroethylene and Buckley, Cross, and Ray found as much as 95 per cent in polymethylene. Such high percentages make it doubtful whether the crystalline phase can be discontinuous at all. In this article any volume of material in which the molecules lie parallel is called a crystallite. The direction in which the molecules are oriented is termed the longitudinal direction of the crystallite. It is immaterial to the argument whether a crystallite consists of several crystallites, aligned in parallel separated by a small amount of amorphous material, or of a single crystallite containing large irregularities.

scholarly journals Isotropic Points on Glaciers

1986 ◽  
Vol 32 (112) ◽  
pp. 363-365 ◽  
Author(s):  
J. F. Nye
Keyword(s):  
Strain Rate ◽  
Pattern Classification ◽  
Transverse Direction ◽  
Transverse Velocity ◽  
Longitudinal Direction ◽  
Stationary Points ◽  
Star Pattern ◽  
Isotropic Point ◽  
Made In

AbstractTwo isotropic points measured by Meier and others (1985) on Columbia Glacier, Alaska, are examined. The pattern classification of the upper one is on the borderline between monstar and lemon, and this is traced to the fact that the variation of strain-rate in the longitudinal direction is approximately equal to that in the transverse direction, contrary to the assumption made in Nye (1983). The conditions for the lower isotropic point to have the star pattern, as observed, are believed to be typical for a glacier that ends in an ice cliff, like this one, which calves icebergs. Where, as in this case, there is only a small transverse velocity, the isotropic points on a glacier must nearly coincide with stationary points for the speed, and these are almost always either maxima or saddles, alternating. The maxima correspond to lemon or monstar patterns, and the saddles to star patterns.

Temporal features of directional tuning by spinocerebellar neurons: relation to limb geometry

1996 ◽  
Vol 75 (4) ◽  
pp. 1647-1658 ◽  
Author(s):  
G. Bosco ◽  
R. E. Poppele
Keyword(s):  
Goodness Of Fit ◽  
Sagittal Plane ◽  
Cell Activity ◽  
Local Maximum ◽  
The Other ◽  
Movement Direction ◽  
Proprioceptive Information ◽  
Joint Angles ◽  
Directional Tuning ◽  
Directional Bias

1. We showed previously that neurons in the dorsal spinocerebellar tract (DSCT) may encode whole-limb parameters of movement and posture rather than localized proprioceptive information. Neurons were found to respond to hindlimb movements in the sagittal plane with maximum activity for foot placements in one direction and minimum activity for placements in the opposite direction. In contrast, movement direction is not specifically encoded by response activity when movement are restricted to a single joint. 2. We now describe the spatiotemporal characteristics of DSCT directional sensitivity for the responses of 267 neurons to small amplitude (0.5 cm) perturbations of the cat hindlimb. A small platform attached to the left hind foot was perturbed along four or eight directions in the sagittal plane, eliciting significant responses in 261 (98%) of the cells. The responses typically consisted of a sequence of peaks and troughs in poststimulus spike density lasting 150 ms or more following limb perturbation. 3. Peaks of activity in particular poststimulus intervals were broadly tuned for the direction of the perturbation, as determined by fitting the firing rates recorded in response to each perturbation direction to a cosine model. The parameters of the cosine model, namely the amplitude of modulation, the direction of maximum response, and the goodness of fit to the model, were computed for each 4 ms poststimulus interval. The parameters all showed the same tendency to wax and wane with respect to poststimulus time. For each period during which the cell activity was highly correlated with tuning model, the tuning indicated a different best direction. Thus each cell's directional tuning could be characterized by a set of tuning maxima associated with specific poststimulus times, when the amplitude of the tuning reached a local maximum and the fit to the cosine model was highly significant (R2 > 0.85). 4. Directions of the tuning maxima for the total population of cells were not uniformly distributed within particular poststimulus intervals. There was a statistically significant directional bias for upward directed perturbations in the poststimulus interval between 20 and 40 ms, followed by a period of downward bias from 45 to 55 ms. Between 60 and 85 ms, the distribution of tuning maxima was significantly skewed backward, whereas a very strong bias for the forward direction was present at about 100 ms. 5. Because the tuning was determined from responses to a very small perturbations of the limb in a given posture, it was not clear whether the responses were related to specific joint angles or muscle lengths, or whether they somehow represented the kinematics of the whole limb. To address this point, we examined the responses of 95 cells in two animals that were each tested in two different limb positions. One position was an approximation of the normal standing position. The other position consisted of a shortening of the limb axis (with major changes in all joint angles) in one animal, or a rotation of the limb axis backward (with little change in joint angles) in the other. 6. We compared each cell's responses to the same perturbations applied in the two limb positions and found they could be identical, scaled in time or magnitude, or completely different in the two positions. A greater percentage of cells with different responses was found in the experiment with the limb axis rotated. In the other experiment, in which there were major differences in joint angles in the two positions, the responses were mostly the same or scaled in time in the two positions. We also determined the population directional biases for the two positions in each experiment, and found that phase differences between the vectors representing population biases for the two positions were minimized when they were measured relative to the orientation of the limb axis (limb coordinates) rather than to the extrinsic vertical (lab coordinates). 7.

An atlas of the thoracic ganglia in the stick insect, Carausius morosus

1991 ◽  
Vol 331 (1260) ◽  
pp. 101-121 ◽  
Keyword(s):  
Single Unit ◽  
Present Report ◽  
Stick Insect ◽  
Functional Specialization ◽  
Carausius Morosus ◽  
Thoracic Ganglia ◽  
The Third ◽  
Metathoracic Ganglion ◽  
The Subject ◽  
Left And Right

The present report describes the neuroanatomy of the three thoracic ganglia in the stick insect, Carausius morosus , the subject of numerous behavioural and neurobiological studies. The structure of the ganglia is summarized in an atlas of the major features. The results are compared with published descriptions of other insects and arthropods. Numerous similarities with locusts encourage the use of a common nomenclature even where minor differences make homology uncertain pending detailed investigation. Five out of the nine longitudinal tracts described in locusts can be readily identified in the stick insect. Three major tracts (LDT, DIT, VIT) and two smaller tracts (MDT, DMT) are compact and well defined. The VMT and MVT are also prominent but these two tracts are not clearly separated except near the rostral margin of the neuropile. An eighth tract, the VLT, is much less distinct: it is represented by scattered fibres in neuropile lateral to the DIT. The iLVT apd oLVT, the two parts of the ninth tract, are quite inconspicuous: in some, but not all, preparations they can be identified as two thin bands running along the ventral and ventrolateral margins of the ganglion. As in locusts, six dorsal commissures (DCI-DCVI) and five ventral commissures (VCI, vVCII, dVCII, SMC, PVC) connecting the left and right hemiganglia have been named although the two most dorsal commissures, DCII and DCIV, are often subdivided. The VCII is retained as a single unit with dorsal and ventral parts. Of the dorsal-ventral tracts only the transverse tract (TT) and the circle tract (CT) are well-defined. Roots of lateral nerves are left unnamed pending more detailed study but several conspicuous branches are included in the drawings as guides to orientation in the lateral neuropile. The ventral association centre (VAC) and several other neuropile divisions are described. Pro- and mesothoracic ganglia derive from single neuromeres. The metathoracic ganglion results from the fusion of the third thoracic and the first abdominal neuromeres: each part contains its own set of commissures and dorsoventral tracts. The results underline the qualitative similarities of the thoracic ganglia in insects; they provide a basis for more precise descriptions of identified neurons and functional specialization within the ganglia of the stick insect.

Reference Frames for Spinal Proprioception: Limb Endpoint Based or Joint-Level Based?

2000 ◽  
Vol 83 (5) ◽  
pp. 2931-2945 ◽  
Author(s):  
G. Bosco ◽  
R. E. Poppele ◽  
J. Eian
Keyword(s):  
Regression Model ◽  
Neuronal Activity ◽  
Reference Frames ◽  
Joint Angle ◽  
Cell Activity ◽  
Proprioceptive Information ◽  
Joint Angles ◽  
Indicator Variable ◽  
Mechanical Constraints ◽  
Foot Position

Many sensorimotor neurons in the CNS encode global parameters of limb movement and posture rather than specific muscle or joint parameters. Our investigations of spinocerebellar activity have demonstrated that these second-order spinal neurons also may encode proprioceptive information in a limb-based rather than joint-based reference frame. However, our finding that each foot position was determined by a unique combination of joint angles in the passive limb made it difficult to distinguish unequivocally between a limb-based and a joint-based representation. In this study, we decoupled foot position from limb geometry by applying mechanical constraints to individual hindlimb joints in anesthetized cats. We quantified the effect of the joint constraints on limb geometry by analyzing joint-angle covariance in the free and constrained conditions. One type of constraint, a rigid constraint of the knee angle, both changed the covariance pattern and significantly reduced the strength of joint-angle covariance. The other type, an elastic constraint of the ankle angle, changed only the covariance pattern and not its overall strength. We studied the effect of these constraints on the activity in 70 dorsal spinocerebellar tract (DSCT) neurons using a multivariate regression model, with limb axis length and orientation as predictors of neuronal activity. This model also included an experimental condition indicator variable that allowed significant intercept or slope changes in the relationships between foot position parameters and neuronal activity to be determined across conditions. The result of this analysis was that the spatial tuning of 37/70 neurons (53%) was unaffected by the constraints, suggesting that they were somehow able to signal foot position independently from the specific joint angles. We also investigated the extent to which cell activity represented individual joint angles by means of a regression model based on a linear combination of joint angles. A backward elimination of the insignificant predictors determined the set of independent joint angles that best described the neuronal activity for each experimental condition. Finally, by comparing the results of these two approaches, we could determine whether a DSCT neuron represented foot position, specific joint angles, or none of these variables consistently. We found that 10/70 neurons (14%) represented one or more specific joint-angles. The activity of another 27 neurons (39%) was significantly affected by limb geometry changes, but 33 neurons (47%) consistently elaborated a foot position representation in the coordinates of the limb axis.

scholarly journals Columnas Compuestas de Hormigón y Acero SRC, Sujetas a Flexocompresión Biaxial

2018 ◽  
Vol 3 (1) ◽  
pp. 281
Author(s):  
Jorge Ricardo Vintimilla Jaramillo ◽  
Luis Tinerfe Hernández Rodríguez
Keyword(s):  
Axial Compression ◽  
Bending Strength ◽  
Longitudinal Direction ◽  
Biaxial Bending ◽  
Load Curve ◽  
Composite Columns ◽  
Interaction Diagram ◽  
European Code ◽  
Made In

The work presented is based on experimental and theoretical analysis of SRC composite columns subjected to biaxial bending and axial compression, where the specification of American and European code criteria are used to calculate de load bending strength. The computer program to calculate the interaction diagram of biaxial bending and axial compression with inclined neutral axis is made in the software Matlab by using the fiber method, besides, the strength of the specimen is calculated. Users can design new frame sections and check the exist sections. To obtain the displacements and load curve, to calculate load contours and determination of the interaction family curves of the modeled sections. The destructive performance of the round and rectangle composite columns are made in the structures laboratory of EPN to obtain the results such as the buckling displacement at strong, weak and longitudinal direction measured with LVDT´S. Subsequently, the theoretical and experimental analysis results are made to demonstrate the reliability of the numeric model.Keywords: Composite Columns, Concrete, Steel

The Function of the Brain of Octopus in Tactile Discrimination

1957 ◽  
Vol 34 (1) ◽  
pp. 131-142
Author(s):  
M. J. WELLS ◽  
J. WELLS
Keyword(s):  
Mode Of Action ◽  
Sensory System ◽  
Sensory Nerves ◽  
Proprioceptive Information ◽  
Tactile Discrimination ◽  
Nerve Impulses ◽  
The Difference ◽  
Scanning Mechanism ◽  
The Brain ◽  
Made In

The results of fifty-three experiments in which octopuses were trained to make tactile discriminations between the members of pairs of Perspex cylinders are reported. Grooves cut into these otherwise smooth cylinders varied in number and arrangement. The proportion of errors made in distinguishing such objects depends upon the difference between the proportions of groove on the objects concerned, and is not affected by the pattern or orientation of the grooves. It has thus been possible to measure the similarity to Octopus of the objects used and to predict the errors that will be made in any such discrimination. When these results are considered in the light of the known nervous arrangements in the arms, it is possible to present a hypothesis about the mode of action of the peripheral tactile sensory system and the function of the brain. It is necessary to suppose that the latter distinguishes frequencies of nerve impulses in the sensory nerves from the arms; it is not necessary to postulate any projection of the sensory field or scanning mechanism involving the use of proprioceptive information.

scholarly journals Isotropic Points on Glaciers

1986 ◽  
Vol 32 (112) ◽  
pp. 363-365 ◽  
Author(s):  
J. F. Nye
Keyword(s):  
Strain Rate ◽  
Pattern Classification ◽  
Transverse Direction ◽  
Transverse Velocity ◽  
Longitudinal Direction ◽  
Stationary Points ◽  
Star Pattern ◽  
Isotropic Point ◽  
Made In

AbstractTwo isotropic points measured by Meier and others (1985) on Columbia Glacier, Alaska, are examined. The pattern classification of the upper one is on the borderline between monstar and lemon, and this is traced to the fact that the variation of strain-rate in the longitudinal direction is approximately equal to that in the transverse direction, contrary to the assumption made in Nye (1983). The conditions for the lower isotropic point to have the star pattern, as observed, are believed to be typical for a glacier that ends in an ice cliff, like this one, which calves icebergs. Where, as in this case, there is only a small transverse velocity, the isotropic points on a glacier must nearly coincide with stationary points for the speed, and these are almost always either maxima or saddles, alternating. The maxima correspond to lemon or monstar patterns, and the saddles to star patterns.

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