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.

Nondestructive imaging of the internal microstructure of vessels and nerve fibers in rat spinal cord using phase-contrast synchrotron radiation microtomography

2017 ◽  
Vol 24 (2) ◽  
pp. 482-489 ◽  
Author(s):  
Jianzhong Hu ◽  
Ping Li ◽  
Xianzhen Yin ◽  
Tianding Wu ◽  
Yong Cao ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Synchrotron Radiation ◽  
Phase Contrast ◽  
Three Dimensional ◽  
Nerve Fibers ◽  
The Body ◽  
Rat Spinal Cord ◽  
Nondestructive Imaging ◽  
Synchrotron Radiation Microtomography ◽  
The Brain

The spinal cord is the primary neurological link between the brain and other parts of the body, but unlike those of the brain, advances in spinal cord imaging have been challenged by the more complicated and inhomogeneous anatomy of the spine. Fortunately with the advancement of high technology, phase-contrast synchrotron radiation microtomography has become widespread in scientific research because of its ability to generate high-quality and high-resolution images. In this study, this method has been employed for nondestructive imaging of the internal microstructure of rat spinal cord. Furthermore, digital virtual slices based on phase-contrast synchrotron radiation were compared with conventional histological sections. The three-dimensional internal microstructure of the intramedullary arteries and nerve fibers was vividly detected within the same spinal cord specimen without the application of a stain or contrast agent or sectioning. With the aid of image post-processing, an optimization of vessel and nerve fiber images was obtained. The findings indicated that phase-contrast synchrotron radiation microtomography is unique in the field of three-dimensional imaging and sets novel standards for pathophysiological investigations in various neurovascular diseases.

Neurodevelopment

2020 ◽  
pp. 91-100
Author(s):  
Karl Zilles ◽  
Nicola Palomero-Gallagher
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Neural Tube ◽  
Neural Plate ◽  
Adult Brain ◽  
The Central Nervous System ◽  
Specialized Region ◽  
The Brain ◽  
Rostral Part ◽  
Human Nervous System

The pre- and post-natal development of the human nervous system is briefly described, with special emphasis on the brain, particularly the cerebral and cerebellar cortices. The central nervous system originates from a specialized region of the ectoderm—the neural plate—which develops into the neural tube. The rostral part of the neural tube forms the adult brain, whereas the caudal part (behind the fifth somite) differentiates into the spinal cord. The embryonic brain has three vesicular enlargements: the forebrain, the midbrain, and the hindbrain. The histogenesis of the spinal cord, hindbrain, cerebellum, and cerebral cortex, including myelination, is discussed. The chapter closes with a description of the development of the hemispheric shape and the formation of gyri.

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.

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.

Introduction to the Nervous System

2017 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
The Body ◽  
Conscious Awareness ◽  
Sensory Stimuli ◽  
System P ◽  
Brainstem Stroke ◽  
Primary Deficit ◽  
The Central Nervous System ◽  
The Brain

The primary regions and principal functions of the central nervous system are introduced through the story of Jean-Dominique Bauby who became locked in after suffering a brainstem stroke. Bauby blinked out his story of locked-in syndrome one letter at a time. The primary deficit of locked-in syndrome is in voluntary movement because pathways from the brain to motoneurons in the brainstem and spinal cord are interrupted. Perception is also disturbed as pathways responsible for transforming sensory stimuli into conscious awareness are interrupted as they ascend through the brainstem into the forebrain. Homeostasis, through which the brain keeps the body alive, is also adversely affected in locked-in syndrome because it depends on the brain, spinal cord and autonomic nervous system. Abstract functions such as memory, language, and emotion depend fully on the forebrain and are intact in locked-in syndrome, as clearly evidenced by Bauby’s eloquent words.

scholarly journals Spinobulbar Neurons in Lamprey: Cellular Properties and Synaptic Interactions

2006 ◽  
Vol 96 (4) ◽  
pp. 2042-2055 ◽  
Author(s):  
James F. Einum ◽  
James T. Buchanan
Keyword(s):  
Spinal Cord ◽  
Brain Stem ◽  
Feedback Inhibition ◽  
Inhibitory Synapses ◽  
Medium Size ◽  
Spinal Neurons ◽  
Lower Vertebrate ◽  
Dorsal Cells ◽  
The Brain

An in vitro preparation of the nervous system of the lamprey, a lower vertebrate, was used to characterize the properties of spinal neurons with axons projecting to the brain stem [i.e., spinobulbar (SB) neurons)]. To identify SB neurons, extracellular electrodes on each side of the spinal cord near the obex recorded the axonal spikes of neurons impaled with sharp intracellular microelectrodes in the rostral spinal cord. The ascending spinal neurons ( n = 144) included those with ipsilateral (iSB) (63/144), contralateral (cSB) (77/144), or bilateral (bSB) (4/144) axonal projections to the brain stem. Intracellular injection of biocytin revealed that the SB neurons had small- to medium-size somata and most had dendrites confined to the ipsilateral side of the cord, although about half of the cSB neurons also had contralateral dendrites. Most SB neurons had multiple axonal branches including descending axons. Electrophysiologically, the SB neurons were similar to other lamprey spinal neurons, firing spikes throughout long depolarizing pulses with some spike-frequency adaptation. Paired intracellular recordings between SB and reticulospinal (RS) neurons revealed that SB neurons made either excitatory or inhibitory synapses on RS neurons and the SB neurons received excitatory input from RS neurons. Mutual excitation and feedback inhibition between pairs of RS and SB neurons were observed. The SB neurons also received excitatory inputs from primary mechanosensory neurons (dorsal cells), and these same SB neurons were rhythmically active during fictive swimming, indicating that SB neurons convey both sensory and locomotor network information to the brain stem.

The Origin of the Interoceptive Pathway

2014 ◽  
Author(s):  
A. D. (Bud) Craig
Keyword(s):  
Spinal Cord ◽  
Motor Function ◽  
Contralateral Side ◽  
Dorsal Column ◽  
The Body ◽  
Sensory Loss ◽  
Anatomical Basis ◽  
Touch Sensation ◽  
Temperature Sensations ◽  
The Brain

This chapter describes the functional and anatomical characteristics of interoceptive processing at the levels of the primary sensory fiber and the spinal cord. The association of the spinothalamic pathway with pain and temperature had already been described in textbooks for years. The clinical evidence indicated that a knife cut that severed the spinal cord on one side produced a loss of pain and temperature sensations only on the opposite (contralateral) side of the body, as tested with pinprick and a cold brass rod, combined with the loss of discriminative touch sensation and skeletal motor function on the same (ipsilateral) side as the injury to the spinal cord. The anatomical basis for this dissociated pattern of sensory loss is the distinctness of the two ascending somatosensory pathways to the brain-discriminative touch sensation in the uncrossed (ipsilateral) dorsal column pathway, and pain and temperature sensations in the crossed (contralateral) spinothalamic pathway.

Why and How Do We Hurt?

2002 ◽  
Author(s):  
Daniel J. Wallace ◽  
Janice Brock Wallace
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Clinical Situation ◽  
The Body ◽  
Sensory Pathways ◽  
System P ◽  
Chronic Pain Patients ◽  
The Central Nervous System ◽  
Pain Patients ◽  
The Brain

A fibromyalgia patient frequently complains of pain. The pain of fibromyalgia is different from that of a headache, stomach cramp, toothache, or swollen joint. It has been described as a type of stiffness or aching, often associated with spasm. Unlike the other pains mentioned above, fibromyalgia pain responds poorly to aspirin, acetaminophen (Tylenol), or ibuprofen (Advil, Motrin). In fact, studies have suggested that even narcotics such as morphine are minimally beneficial in ameliorating fibromyalgia pain. Why is it that fibromyalgia patients can take codeine, Darvon, Vicodin, or even Demerol for musculoskeletal aches and have only a slight response? What produces “pain without purpose”? In this chapter, we’ll explore what makes fibromyalgia a pain amplification syndrome. Why does the patient hurt in places where there was often no injury and all laboratory tests are normal? What creates what doctors call allodynia, or a clinical situation that results in pain from a stimulus (such as light touch) that normally should not be painful? Fibromyalgia is a form of chronic, widespread allodynia, as well as sustained hyperalgesia, or greater sensitivity than would be expected to an adverse stimulus. The nervous system consists of several components. The brain and spinal cord comprise the central nervous system. Nerves leaving the spinal cord that tell us to move our arms or legs are part of the “motor” aspects of the peripheral nervous system. Additionally, all sorts of information about touch, taste, chemicals, and pressure are relayed through “sensory” pathways back to the spinal cord, where they are processed and sent up to the brain for a response. The autonomic nervous system consists of specialized peripheral nerves. Fibromyalgia is a disorder characterized by an inappropriate neuromuscular reaction that leads to chronic pain. Patients with fibromyalgia usually react normally to acute pain. Our current concepts of the way the body responds to chronic painful stimuli stem from the gate theory, first proposed by Ronald Melzack and Patrick Wall in 1965. Nerve “wires” go from the periphery to the dorsal horn of the spinal cord. These wires are modulated by feedback loops within the nervous system.

William Croone’s theory of muscular contraction

1961 ◽  
Vol 16 (2) ◽  
pp. 158-178 ◽  
Keyword(s):  
Spinal Cord ◽  
Seventeenth Century ◽  
Muscle Contraction ◽  
Muscular Contraction ◽  
The Body ◽  
The Other ◽  
First Person ◽  
Muscular Movement ◽  
The One ◽  
The Brain

In the mid-seventeenth century William Croone had been the earliest among his contemporaries to concern himself with muscular motion. Thus, much of the discussion on muscular movement in the period after 1664 is either a commentary upon Croone’s views or is derived from them, and his influence was thus widespread, especially on the Continent. The background to Croone’s own views is largely that of Greek physiology as represented in the works of Galen. The first person who had a theory of muscle contraction seems to have been Erasistratus. Galen says that Erasistratus of Chios (fl. 290 b.c.) considered that when a muscle is filled with pneuma its breadth increases while its length diminishes and for this reason it is contracted. (1) Galen himself was impressed by the contractility of muscle and by the fact that this contractility depends on the nerve arising from the spinal cord and entering the muscle, where it branches repeatedly and sends its branches into all parts of the muscle. If the nerve, entering the muscle, be cut or injured or merely compressed the muscle loses all movement and sensitivity. (2) Galen considered that a muscle is made up of fibres and flesh. (3) The fibres of the muscle are continuous with those of its tendons at either end. In the body of the muscle itself the fibres are spread apart by the flesh contained in the interspaces between them. Each of these continuous fibres extending through both the tendon and the muscle Galen considers to be made up of finer fibres—on the one hand of inert and insensitive fibres of the same kind as occur in ligaments and, on the other hand, of sensitive fibres which are simply fine extensions of the branches of the nerves. (4) Galen does not, however, seem to offer, as does Erasistratus any mechanism to account for muscle contraction. To Galen the muscle is simply moved by the motor faculty which comes from the brain.

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