The Origin of the Interoceptive Pathway

Author(s):  
A. D. (Bud) Craig

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.

2017 ◽  
Vol 24 (2) ◽  
pp. 482-489 ◽  
Author(s):  
Jianzhong Hu ◽  
Ping Li ◽  
Xianzhen Yin ◽  
Tianding Wu ◽  
Yong Cao ◽  
...  

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.


1997 ◽  
Vol 78 (2) ◽  
pp. 960-976 ◽  
Author(s):  
Fredrik Ullén ◽  
Tatiana G. Deliagina ◽  
Grigori N. Orlovsky ◽  
Sten Grillner

Ullén, Fredrik, Tatiana G. Deliagina, Grigori N. Orlovsky, and Sten Grillner. Visual pathways for postural control and negative phototaxis in lamprey. J. Neurophysiol. 78: 960–976, 1997. The functional roles of the major visuo-motor pathways were studied in lamprey. Responses to eye illumination were video-recorded in intact and chronically lesioned animals. Postural deficits during spontaneous swimming were analyzed to elucidate the roles of the lesioned structures for steering and postural control. Eye illumination in intact lampreys evoked the dorsal light response, that is, a roll tilt toward the light, and negative phototaxis, that is a lateral turn away from light, and locomotion. Complete tectum-ablation enhanced both responses. During swimming, a tendency for roll tilts and episodes of vertical upward swimming were seen. The neuronal circuitries for dorsal light response and negative phototaxis are thus essentially extratectal. Responses to eye illumination were abolished by contralateral pretectum-ablation but normal after the corresponding lesion on the ipsilateral side. Contralateral pretectum thus plays an important role for dorsal light response and negative phototaxis. To determine the roles of pretectal efferent pathways for the responses, animals with a midmesencephalichemisection were tested. Noncrossed pretecto-reticular fibers from the ipsilateral pretectum and crossed fibers from the contralateral side were transected. Eye illumination on the lesioned side evoked negative phototaxis but no dorsal light response. Eye illumination on the intact side evoked an enhanced dorsal light response, whereas negative phototaxis was replaced with straight locomotion or positive phototaxis. The crossed pretecto-reticular projection is thus most important for the dorsal light response, whereas the noncrossed projection presumably plays the major role for negative phototaxis. Transection of the ventral rhombencephalic commissure enhanced dorsal light response; negative phototaxis was retained with smaller turning angles than normal. Spontaneous locomotion showed episodes of backward swimming and deficient roll control (tilting tendency). Transections of different spinal pathways were performed immediately caudal to the brain stem. All spinal lesions left dorsal light response in attached state unaffected; this response presumably is mediated by the brain stem. Spinal hemisection impaired all ipsiversive yaw turns; the animals spontaneously rolled to the intact side. Bilateral transection of the lateral columns impaired all yaw turns, whereas roll control and dorsal light response were normal. After transection of the medial spinal cord, yaw turns still could be performed whereas dorsal light response was suppressed or abolished, and a roll tilting tendency during spontaneous locomotion was seen. We conclude that the contralateral optic nerve projection to the pretectal region is necessary and sufficient for negative phototaxis and dorsal light response. The crossed descending pretectal projection is most important for dorsal light response, whereas the noncrossed one is most important for negative phototaxis. In the most rostral spinal cord, fibers for lateral yaw turns travel mainly in the lateral columns, whereas fibers for roll turns travel mainly in the medial spinal cord.


2015 ◽  
Vol 2015 ◽  
pp. 1-3 ◽  
Author(s):  
David J. Kopsky ◽  
Jan M. Keppel Hesselink ◽  
Roberto Casale

Baclofen 5% cream can be used for the treatment of neuropathic pain. We describe an unusual case of a neuropathic pain patient with spinal cord injury. A 71-year-old woman with a partial spinal cord injury lesion at L4 complained of tingling, pins and needles, and burning in her legs. She scored her pain as 6 before adding baclofen 5% cream to her pain medication (pregabalin 450 mg, acetaminophen 3000 mg, and diclofenac 150 mg daily). One month later she experienced complete pain relief, though experienced increased difficulties in walking, leading to frequent falls. Her steadier walking without stumbling and falling was more important to her than pain reduction. Thus she decided to stop using baclofen. This unusual case report discusses two important issues that relate to pain medicine and rehabilitation in patients with painful spinal cord lesions: (1) the presence of wide areas of sensory loss “covered” by the presence of painful sensations and (2) pathological sensations that can be used and integrated in the body schema to create an improved spatiovisual orientation and thus mobility. Both these aspects have to be taken into account when treating pain and design rehabilitation programs.


2003 ◽  
Vol 90 (5) ◽  
pp. 3161-3167 ◽  
Author(s):  
P. V. Zelenin ◽  
E. L. Pavlova ◽  
S. Grillner ◽  
G. N. Orlovsky ◽  
T. G. Deliagina

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.


2021 ◽  
Vol 1 (Volume 1 No 2) ◽  
pp. 153-164
Author(s):  
Daswara Djajasasmita ◽  
Hindung Sa'adah ◽  
Miftahudin

The carotid artery consists of two carotid arteries, namely the dextra communist artery and the sinistra, the main blood vessels in the neck that supply blood to the brain, the basal ganglia, which have the function of regulating the motor functions of the body. The communal carotid arteries blocked flow can cause brain ischemia. It is due to hypoxia due to a lack of oxygen supply carried by the brain, resulting in motor body function disorders, incredible blockages in the carotid arteries that supply blood to the brain, and neurons as regulators of motor functions. The research is a literature study that has relevance to the formulation of the problem meets the criteria and research objectives to determine the effect of the length of the blockage of the arteries of the carotid artery of the communist to the motor function of the Wistar strain rats. The results of a literature review or literature studies in some previous scientific research journals indicate if the blockage of the arteries of the communal carotid arteries affects the disruption of motor function caused by hypoxia and damage to neurons and brain tissue in motor neurons. The conclusion is that the blockage and the duration of blockage of the communal carotid arteries affect motor function.


Author(s):  
Peggy Mason

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.


Author(s):  
Brian A. Crum ◽  
Eduardo E. Benarroch ◽  
Robert D. Brown

Neurological disorders of the brain, spine, and peripheral nervous system are examined. Symptoms and signs related to disorders of the cerebral cortex may lead to alterations in cognition and consciousness. Unilateral neurologic symptoms involving a single neurologic symptom commonly localize to the cerebral cortex. Abnormalities of speech and language are localized to the dominant cerebral hemisphere, whereas abnormalities of the nondominant hemisphere may lead to visuospatial deficits, confusion, or neglect of the contralateral side of the body. The hypothalamus is important in many functions that affect everyday steady-state conditions, including temperature regulation, hunger, water regulation, sleep, endocrine functions, cardiovascular functions, and regulation of the autonomic nervous system. Cortical and subcortical abnormalities may also lead to visual system deficits, usually homonymous visual defects of the contralateral visual field. Sensory levels, signs of anterior horn cell involvement, and long-tract signs in the posterior columns or corticospinal tract suggest a spinal cord lesion.


Author(s):  
Daniel J. Wallace ◽  
Janice Brock Wallace

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.


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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