Pattern of Motor Coordination Underlying Backward Swimming in the Lamprey

2006 ◽  
Vol 96 (1) ◽  
pp. 451-460 ◽  
Author(s):  
Salma S. Islam ◽  
Pavel V. Zelenin ◽  
Grigori N. Orlovsky ◽  
Sten Grillner ◽  
Tatiana G. Deliagina
Keyword(s):  
Spinal Cord ◽  
Motor Coordination ◽  
Anterior Part ◽  
Dorsal Side ◽  
The Body ◽  
Large Area ◽  
Lower Vertebrate ◽  
Complete Transection ◽  
Lateral Body ◽  
Propagating Waves

The main form of locomotion in the lamprey (a lower vertebrate, cyclostome) is forward swimming (FS) based on periodical waves of lateral body flexion propagating from head to tail. The lamprey is also capable of backward swimming (BS). Here we describe the kinematical and electromyographic (EMG) pattern of BS, as well as the effects on this pattern exerted by different lesions of the spinal cord. The BS was evoked by tactile stimulation of a large area in the anterior part of the body. Swimming was attributed to the waves of lateral body undulations propagating from tail to head. The EMG bursts on the two sides alternated, and the EMG in more caudal segments led in phase the EMG in more rostral segments. Main kinematical characteristics of BS strongly differed from those of FS: the amplitude of undulations was much larger and their frequency lower. Also, the maintenance of the dorsal-side-up body orientation ascribed to vestibular postural reflexes (typical for FS) was not observed during BS. A complete transection of the spinal cord did not abolish the generation of forward-propagating waves rostral to the lesion. After a lateral hemisection of the spinal cord, the BS pattern persisted on both sides rostral to the lesion; caudal to the lesion, it was present on the intact side and reduced or abolished on the lesioned side. The role of the spinal cord in generation of different forms of undulatory locomotion (FS and BS) is discussed.

Comparison of the Motor Effects of Individual Vestibulo- and Reticulospinal Neurons on Dorsal and Ventral Myotomes in Lamprey

2003 ◽  
Vol 90 (5) ◽  
pp. 3161-3167 ◽  
Author(s):  
P. V. Zelenin ◽  
E. L. Pavlova ◽  
S. Grillner ◽  
G. N. Orlovsky ◽  
T. G. Deliagina
Keyword(s):  
Spinal Cord ◽  
The Body ◽  
Spinal Motoneurons ◽  
Lower Vertebrate ◽  
Motor Synergies ◽  
Spike Triggered Averaging ◽  
Spinal Segments ◽  
Motor Effects ◽  
The Brain ◽  
Rostral Part

In the lamprey (a lower vertebrate), motor commands from the brain to the spinal cord are transmitted through the reticulospinal (RS) and vestibulospinal (VS) pathways. The axons of larger RS neurons reach the most caudal of approximately 100 spinal segments, whereas the VS pathway does not descend below the 15th segment. This study was carried out to compare functional projections of RS and VS neurons in the rostral spinal segments that the neurons innervate together. To reveal these projections, individual RS or VS neurons were stimulated, and the responses of different groups of spinal motoneurons were recorded in ventral root branches to dorsal and ventral parts of myotomes. The responses were detected using a spike-triggered averaging technique on the background of ongoing motoneuronal activity. Individual RS and VS neurons exerted uniform effects on segmental motor output within this rostral part of the spinal cord. The effects of VS neurons on different groups of motoneurons were weaker and less diverse than those of RS neurons. The results indicate that VS neurons are able to elicit a flexion of the rostral part of the body and to turn the head in different planes without affecting more caudal parts. By contrast, larger RS neurons can elicit head movement only together with movement of a considerable part of the body and thus seem to be responsible for formation of gross motor synergies.

Modifications of Locomotor Pattern Underlying Escape Behavior in the Lamprey

2008 ◽  
Vol 99 (1) ◽  
pp. 297-307 ◽  
Author(s):  
Salma S. Islam ◽  
Pavel V. Zelenin
Keyword(s):  
Spinal Cord ◽  
Escape Behavior ◽  
Sensory Information ◽  
The Body ◽  
Descending Pathways ◽  
Long Distance ◽  
Lower Vertebrate ◽  
Dorsal Roots ◽  
Tactile Stimuli ◽  
Undulatory Locomotion

Two forms of undulatory locomotion in the lamprey (a lower vertebrate) have been described earlier: fast forward swimming (FFS) used for long distance migrations and slow backward swimming (SBS) used for escape from adverse tactile stimuli. In the present study, we describe another form of escape behavior: slow forward swimming (SFS). We characterize the kinematic and electromyographic patterns of SFS and compare them with SBS and FFS. The most striking feature of SFS is nonuniformity of shape and speed of the locomotor waves propagating along the body: close to the site of stimulation, the waves slow down and the body curvature increases several-fold due to enhanced muscle activity. Lesions of afferents showed that sensory information critical for elicitation of SFS is transmitted through the dorsal roots. In contrast, sensory signals that induce SBS are transmitted through the dorsal roots, lateral line nerves, and trigeminal nerves. Persistence of SFS and SBS after different lesions of the spinal cord suggests that the ascending and descending pathways, necessary for induction of SBS and SFS, are dispersed over the cross section of the spinal cord. As shown previously, during FFS (but not SBS) the lamprey maintains the dorsal-side-up body orientation due to vestibular postural reflexes. In this study we have found that the orientation control is absent during SFS. The role of the spinal cord and the brain stem in generation of different forms of undulatory locomotion is discussed.

Fasciola gigantica: surface topography of the adult tegument

2001 ◽  
Vol 75 (1) ◽  
pp. 43-50 ◽  
Author(s):  
T. Dangprasert ◽  
W. Khawsuk ◽  
A. Meepool ◽  
C. Wanichanon ◽  
V. Viyanant ◽  
...  
Keyword(s):  
Anterior Part ◽  
Ventral Side ◽  
Ventral Surface ◽  
Dorsal Side ◽  
Fasciola Gigantica ◽  
The Body ◽  
Lateral Aspect ◽  
Tegumental Surface ◽  
Type 3

Adult Fasciola gigantica are leaf-shaped with tapered anterior and posterior ends and measure about 35 mm in length and 15 mm in width across the mid section. Under the scanning electron microscope its surface appears rough due to the presence of numerous spines and surface foldings. Both oral and ventral suckers have thick rims covered with transverse folds and appear spineless. On the anterior part of the ventral surface of the body, the spines are small and closely-spaced. Each spine has a serrated edge with 16 to 20 sharp points, and measures about 20 μm in width and 30 μm in height. In the mid-region the spines increase in size (up to 54 μm in width and 58 μm in height) and number, especially towards the lateral aspect of the body. Towards the posterior end the spines progressively decrease in both size and number. The tegumental surface between the spines appears highly corrugated with transverse folds alternating with grooves. At higher magnifications the surface of each fold is further increased with a meshwork of small ridges separated by variable-sized pits or slits. There are three types of sensory papillae on the surface. Types 1 and 2 are bulbous, measuring 4–6 μm in diameter at the base with nipple-like tips, and the type 2 also have short cilia. Type 3 papillae are also bulbous and of similar size but with a smooth surface. These sensory papillae usually occur in clusters, each having between 2 and 15 units depending on the region of the body. Clusters of papillae on the lateral aspect (usually types 1 and 2) and around the suckers (type 3) tend to be more numerous and larger in size. The dorsal side of the body exhibits similar surface features, but the spines and papillae appear less numerous and are smaller. Corrugation and invaginations of the surface are also less extensive than on the ventral side of the body.

Reticulospinal neurons controlling forward and backward swimming in the lamprey

2011 ◽  
Vol 105 (3) ◽  
pp. 1361-1371 ◽  
Author(s):  
P. V. Zelenin
Keyword(s):  
Spinal Cord ◽  
Postural Control ◽  
Motor Coordination ◽  
Vestibular Stimulation ◽  
Firing Frequency ◽  
The Body ◽  
Body Orientation ◽  
Locomotor Rhythm ◽  
Reticulospinal Neurons ◽  
Implanted Electrodes

Most vertebrates are capable of two forms of locomotion, forward and backward, strongly differing in the patterns of motor coordination. Basic mechanisms generating these patterns are located in the spinal cord; they are activated and regulated by supraspinal commands. In the lamprey, these commands are transmitted by reticulospinal (RS) neurons. The aim of this study was to reveal groups of RS neurons controlling different aspects of forward (FS) and backward (BS) swimming in the lamprey. Activity of individual larger RS neurons in intact lampreys was recorded during FS and BS by chronically implanted electrodes. It was found that among the neurons activated during locomotion, 27% were active only during FS, 3% only during BS, and 70% during both FS and BS. In a portion of RS neurons, their mean firing frequency was correlated with frequency of body undulations during FS (8%), during BS (34%), or during both FS and BS (22%), suggesting their involvement in control of locomotion intensity. RS activity was phasically modulated by the locomotor rhythm during FS (20% of neurons), during BS (29%), or during both FS and BS (16%). The majority of RS neurons responding to vestibular stimulation (and presumably involved in control of body orientation) were active mainly during FS. This explains the absence of stabilization of the body orientation observed during BS. We discuss possible functions of different groups of RS neurons, i.e., activation of the spinal locomotor CPG, inversion of the direction of propagation of locomotor waves, and postural control.

Identification of interneurons with contralateral, caudal axons in the lamprey spinal cord: synaptic interactions and morphology

1982 ◽  
Vol 47 (5) ◽  
pp. 961-975 ◽  
Author(s):  
J. T. Buchanan
Keyword(s):  
Spinal Cord ◽  
Motor Coordination ◽  
Contralateral Side ◽  
Müller Cell ◽  
The Body ◽  
Intracellular Stimulation ◽  
Muller Cell ◽  
Axon Branch ◽  
Dorsal Cells ◽  
Stimulation Of

1. As part of a continuing investigation of the organization of the spinal cord of the lamprey, propriospinal interneurons with axons projecting contralaterally and caudally (CC interneurons) were surveyed with intracellular recordings. 2. CC interneurons were identified by recording their axon spikes extracellularly in the spinal cord during intracellular stimulation of the cell body. The axon projections of Cc interneurons were confirmed after intracellular injection and development of horseradish peroxidase. 3. Intracellular stimulation of CC interneurons produced synaptic potentials in myotomal motoneurons, lateral interneurons and other CC interneurons that lay caudally on the opposite side of the spinal cord. Most CC interneurons were inhibitory, but some were excitatory. 4. CC interneurons were divided into three classes on the basis of reticulospinal Muller cell inputs. CC1 interneurons were excited by the ipsilateral Muller cell B1 and the contralateral Mauthner cell. CC1 interneurons were inhibitory. They were excited polysynaptically by ipsilateral sensory dorsal cells and were inhibited by contralateral dorsal cells. They were distinguished morphologically by having no rostral axon branch and no contralateral dendrites. CC1 interneurons were phasically active during fictive swimming with their peak depolarizations preceding those of myotomal motoneurons by about 0.15 cycle. 5. CC2 interneurons were also inhibitory, but they were distinguished from CC1 interneurons by their excitation from the ipsilateral Muller cells B2-4 nd by their thin rostral and thicker caudal axonal branches on the contralateral side of the spinal cord. 6. CC3 interneurons were excitatory, and they were inhibited by the ipsilateral Muller cell I1. CC3 interneurons could have contralateral dendrites and bifurcating axons, and they had lower average axonal conduction velocities than CC1 and CC2 interneurons. 7. Inhibitory CC interneurons may be important for motor coordination in the lamprey. Movements of the lamprey body during reflexes and swimming consist of contraction and relaxation of myotomal muscles on opposite sides of the body. By being coactive with ipsilateral myotomal motoneurons, inhibitory CC interneurons could contribute to the inhibition of contralateral motoneurons during these movements.

scholarly journals Spatiotemporal contribution of neuromesodermal progenitor-derived neural cells in the elongation of developing mouse spinal cord

2020 ◽  
Author(s):  
Mohammed R Shaker ◽  
Ju-Hyun Lee ◽  
Kyung Hyun Kim ◽  
Veronica Jihyun Kim ◽  
Joo Yeon Kim ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neural Tube ◽  
Dorsal Side ◽  
Lineage Tracing ◽  
The Body ◽  
Lumbar Spinal Cord ◽  
Genetic Lineage ◽  
Mouse Development ◽  
Axial Elongation

ABSTRACTDuring vertebrate development, the posterior end of the embryo progressively elongates in a head-to-tail direction to form the body plan. Recent lineage tracing experiments revealed that bi-potent progenitors, called neuromesodermal progenitors (NMPs), produce caudal neural and mesodermal tissues during axial elongation. However, their precise location and contribution to spinal cord development remain elusive. Here we used NMP-specific markers (Sox2 and BraT) and a genetic lineage tracing system to localize NMP progeny in vivo. NMPs were initially located at the tail tip, but were later found in the caudal neural tube, which is a unique feature of mouse development. In the neural tube, they produced neural stem cells (NSCs) and contributed to the spinal cord gradually along the AP axis during axial elongation. Interestingly, NMP-derived NSCs preferentially contributed to the ventral side first and later to the dorsal side at the lumbar spinal cord level, which may be associated with atypical junctional neurulation in mice. Our current observations detail the contribution of NMP progeny to spinal cord elongation and provide insights into how different species uniquely execute caudal morphogenesis.

scholarly journals FETAL ANATOMY OF THE HUMAN SPINAL CORD

2020 ◽  
Vol 19 (3) ◽  
pp. 5-12
Author(s):  
V. Shkolnikov
Keyword(s):  
Spinal Cord ◽  
White Matter ◽  
Glial Cells ◽  
Motor Neurons ◽  
Gray Matter ◽  
The Body ◽  
Diagnostic Methods ◽  
Large Area ◽  
Intrauterine Development ◽  
Human Spinal Cord

Due to the development and improvement of medical technologies and diagnostic methods, in recent years, the interest of neuromorphologists, neuropathologists, neurosurgeons and reproductive specialists in the histogenesis of the structures of the central nervous system, in particular, the spinal cord, has increased. In the process of macro- and microscopic examination of the spinal cord of human fetuses of 20-21 weeks of intrauterine development, the topography of the thickenings in relation to the parts of the spinal column was established according to our own method, the morphometric parameters of the structures of the spinal cord segments and the regularities of cytoarchitectonics were determined. In 20-21 week old fetuses, the ratio of the length of the spine to the parietococcygeal length of the fetus is 65.0%, and the ratio of the length of the spinal cord to the parietococcygeal length of the fetus is 54.0 %. The border between the cervical and thoracic spine is projected onto a conditional line that connects the spine of the scapula. The border between the thoracic and lumbar regions of the spine is the line between the upper three quarters and the lower one quarter of the body length. The border between the lumbar and sacral parts runs along a conventionally drawn line that connects the posterior lower iliac spines, and the border of the transition of the sacral to the coccygeal is the level of the lower third of the gluteal region. The structure of the gray matter of the spinal cord segments in this age period corresponds to that in people of mature age – the presence of anterior, lateral and posterior horns. A large area of gray matter is observed in the cervical and lumbar segments, a smaller area in the thoracic and sacral segments. The structuredness of the white matter of the spinal cord segments in this age period corresponds to that in adults – the presence of anterior, lateral and posterior cords. The cervical and lumbar segments have a large area of white matter, and in magnitude they are the same. The nuclei of radial glial cells are relatively equal in size in all segments. The thickness of the matrix layer varies throughout the entire spinal cord, but reaches its greatest size in the ventral parts. The sizes of the nuclei of neuroblasts also fluctuate: the nuclei of motor neurons have large sizes, and the smaller ones are inserted and vegetative. The nuclei of glial cells have relatively identical sizes of different segments of the spinal cord, but 2-3 times less than the nuclei of neuroblasts.

scholarly journals Use of galvanic vestibular feedback to control postural orientation in decerebrate rabbits

2012 ◽  
Vol 107 (11) ◽  
pp. 3020-3026 ◽  
Author(s):  
P. V. Zelenin ◽  
L.-J. Hsu ◽  
G. N. Orlovsky ◽  
T. G. Deliagina
Keyword(s):  
Balance Control ◽  
Simple Algorithm ◽  
Vestibular Stimulation ◽  
Dorsal Side ◽  
The Body ◽  
Body Sway ◽  
Lateral Stability ◽  
Postural Perturbation ◽  
Lateral Body ◽  
Postural System

In quadrupeds, the dorsal-side-up body orientation during standing is maintained due to a postural system that is driven by feedback signals coming mainly from limb mechanoreceptors. In caudally decerebrated (postmammillary) rabbits, the efficacy of this system is considerably reduced. In this paper, we report that the efficacy of postural control in these animals can be restored with galvanic vestibular stimulation (GVS) applied transcutaneously to the labyrinths. In standing intact rabbits, GVS causes a lateral body sway towards the positive electrode. We used this GVS-caused sway to counteract the lateral body sway resulting from a mechanical perturbation of posture. Experiments were performed on postmammillary rabbits that stood on the tilting platform with their hindlimbs. To make the GVS value dependent on the postural perturbation (i.e., on the lateral body sway caused by tilt of the platform), an artificial feedback loop was formed in the following ways: 1) Information about the body sway was provided by a mechanical sensor; 2) The GVS current was applied when the sway exceeded a threshold value; the polarity of the current was determined by the sway direction. This simple algorithm allowed the “hybrid” postural system to maintain the dorsal-side-up orientation of the hindquarters when the platform was tilted by ± 20°. Thus, an important postural function, i.e., securing lateral stability during standing, can be restored in decerebrate rabbits with the GVS-based artificial feedback. We suggest that such a control system can compensate for the loss of lateral stability of various etiologies, and can be used for restoration of balance control in patients with impaired postural functions.

The ultrastructure of the epidermis of the redia and cercaria of Parorchis acanthus, Nicoll. A study by scanning and transmission electron-microscopy

Parasitology ◽  
1971 ◽  
Vol 62 (3) ◽  
pp. 479-488 ◽  
Author(s):  
Gwendolen Rees
Keyword(s):  
Electron Micrographs ◽  
Technical Assistance ◽  
Ventral Surface ◽  
The Body ◽  
Muscle Fibres ◽  
Scanning Electron Micrographs ◽  
Large Area ◽  
Transmission Electron ◽  
Parorchis Acanthus ◽  
Scanning Electron

Scanning electron-micrographs have shown the covering of microvilli on the surface of the redia of Parorchis acanthus. In the contracted state the elongated microvilli with bulbous extremities seen in the surface grooves may be the result of compression. The surface of the epidermis of the cercaria is smooth on a large area of the ventral surface and lattice-like with microvilli, laterally, anteriorly, dorsally and on the tail. The spines on the body can be withdrawn into sheaths by the contraction of muscle fibres inserted into the basement lamina below each spine.I would like to express my sincere gratitude to Dr I. ap Gwynn of this department for preparing the scanning electron-micrographs and the School of Engineering Science, University of North Wales, Bangor for the use of their stereoscan. I should also like to thank Mr M. C. Bibby for technical assistance and Professor E. G. Gray and Dr W. Sinclair for assistance with the transmission electron-micrographs.

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