Proprioception From a Spinocerebellar Perspective

2001 ◽  
Vol 81 (2) ◽  
pp. 539-568 ◽  
Author(s):  
G. Bosco ◽  
R. E. Poppele

This review explores how proprioceptive sensory information is organized at spinal cord levels as it relates to a sense of body position and movement. The topic is considered in an historical context and develops a different framework that may be more in tune with current views of sensorimotor processing in other central nervous system structures. The dorsal spinocerebellar tract (DSCT) system is considered in detail as a model system that may be considered as an end point for the processing of proprioceptive sensory information in the spinal cord. An analysis of this system examines sensory processing at the lowest levels of synaptic connectivity with central neurons in the nervous system. The analysis leads to a framework for proprioception that involves a highly flexible network organization based in some way on whole limb kinematics. The functional organization underlying this framework originates with the biomechanical linkages in the limb that establish functional relationships among the limb segments. Afferent information from limb receptors is processed further through a distributed neural network in the spinal cord. The result is a global representation of hindlimb parameters rather than a muscle-by-muscle or joint-by-joint representation.

Author(s):  
J. Eric Ahlskog

As a prelude to the treatment chapters that follow, we need to define and describe the types of problems and symptoms encountered in DLB and PDD. The clinical picture can be quite varied: problems encountered by one person may be quite different from those encountered by another person, and symptoms that are problematic in one individual may be minimal in another. In these disorders, the Lewy neurodegenerative process potentially affects certain nervous system regions but spares others. Affected areas include thinking and memory circuits, as well as movement (motor) function and the autonomic nervous system, which regulates primary functions such as bladder, bowel, and blood pressure control. Many other brain regions, by contrast, are spared or minimally involved, such as vision and sensation. The brain and spinal cord constitute the central nervous system. The interface between the brain and spinal cord is by way of the brain stem, as shown in Figure 4.1. Thought, memory, and reasoning are primarily organized in the thick layers of cortex overlying lower brain levels. Volitional movements, such as writing, throwing, or kicking, also emanate from the cortex and integrate with circuits just below, including those in the basal ganglia, shown in Figure 4.2. The basal ganglia includes the striatum, globus pallidus, subthalamic nucleus, and substantia nigra, as illustrated in Figure 4.2. Movement information is integrated and modulated in these basal ganglia nuclei and then transmitted down the brain stem to the spinal cord. At spinal cord levels the correct sequence of muscle activation that has been programmed is accomplished. Activated nerves from appropriate regions of the spinal cord relay the signals to the proper muscles. Sensory information from the periphery (limbs) travels in the opposite direction. How are these signals transmitted? Brain cells called neurons have long, wire-like extensions that interface with other neurons, effectively making up circuits that are slightly similar to computer circuits; this is illustrated in Figure 4.3. At the end of these wire-like extensions are tiny enlargements (terminals) that contain specific biological chemicals called neurotransmitters. Neurotransmitters are released when the electrical signal travels down that neuron to the end of that wire-like process.


2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Behdad Tahayori ◽  
David M. Koceja

Part of the development and maturation of the central nervous system (CNS) occurs through interactions with the environment. Through physical activities and interactions with the world, an animal receives considerable sensory information from various sources. These sources can be internally (proprioceptive) or externally (such as touch and pressure) generated senses. Ample evidence exists to demonstrate that the sensory information originating from large diameter afferents (Ia fibers) have an important role in inducing essential functional and morphological changes for the maturation of both the brain and the spinal cord. The Ia fibers transmit sensory information generated by muscle activity and movement. Such use or activity-dependent plastic changes occur throughout life and are one reason for the ability to acquire new skills and learn new movements. However, the extent and particularly the mechanisms of activity-dependent changes are markedly different between a developing nervous system and a mature nervous system. Understanding these mechanisms is an important step to develop strategies for regaining motor function after different injuries to the CNS. Plastic changes induced by activity occur both in the brain and spinal cord. This paper reviews the activity-dependent changes in the spinal cord neural circuits during both the developmental stages of the CNS and in adulthood.


2021 ◽  
Vol 15 ◽  
Author(s):  
Brandon L. Brown ◽  
Rachel M. Zalla ◽  
Courtney T. Shepard ◽  
Russell M. Howard ◽  
Jonathan A. Kopechek ◽  
...  

The nervous system coordinates pathways and circuits to process sensory information and govern motor behaviors. Mapping these pathways is important to further understand the connectivity throughout the nervous system and is vital for developing treatments for neuronal diseases and disorders. We targeted long ascending propriospinal neurons (LAPNs) in the rat spinal cord utilizing Fluoro-Ruby (FR) [10kD rhodamine dextran amine (RDA)], and two dual-viral systems. Dual-viral tracing utilizing a retrograde adeno-associated virus (retroAAV), which confers robust labeling in the brain, resulted in a small number of LAPNs being labeled, but dual-viral tracing using a highly efficient retrograde (HiRet) lentivirus provided robust labeling similar to FR. Additionally, dual-viral tracing with HiRet lentivirus and tracing with FR may preferentially label different subpopulations of LAPNs. These data demonstrate that dual-viral tracing in the spinal cord employing a HiRet lentivirus provides robust and specific labeling of LAPNs and emphasizes the need to empirically optimize viral systems to target specific neuronal population(s).


Although GABA and piperidine-4-sulphonic acid depolarize I a afferent terminations in the cat spinal cord by activation of bicuculline-sensitive GABA receptors, no evidence was obtained for a bicuculline-sensitive alteration by either gabamimetic of the electrical threshold of rubrospinal terminations in the spinal intermediate nucleus. The terminal axonal arborizations in the spinal cord of neurons in the red nucleus thus do not have GABA receptors similar to those on the cell bodies. The results are discussed in relation to the depolarizing action of GABA on some central neurons, and on neurons with peripheral cell bodies, and to probable differences in the intracellular chloride content of neurons having peripheral or central cell bodies, and thus of different embryological origin. A presynaptic depolarizing inhibitory process mediated by GABA appears to be confined to the terminals of primary afferent fibres in the mammalian central nervous system.


2015 ◽  
Vol 12 (2) ◽  
pp. 168-188 ◽  
Author(s):  
Laurent Sakka ◽  
Jean Gabrillargues ◽  
Guillaume Coll

Abstract BACKGROUND The spinal meninges have received less attention than the cranial meninges in the literature, although several points remain debatable and poorly understood, like their phylogenesis, their development, and their interactions with the spinal cord. Their constancy among the chordates shows their crucial importance in central nervous system homeostasis and suggests a role far beyond mechanical protection of the neuraxis. OBJECTIVE This work provides an extensive study of the spinal meninges, from an overview of their phylogenesis and embryology to a descriptive and topographic anatomy with clinical implications. It examines their involvement in spinal cord development, functioning, and repair. METHODS This work is a review of the literature using PubMed as a search engine on Medline. RESULTS The stages followed by the meninges along the phylogenesis could not be easily compared with their development in vertebrates for methodological aspects and convergence processes throughout evolution. The distinction between arachnoid and pia mater appeared controversial. Several points of descriptive anatomy remain debatable: the functional organization of the arterial network, and the venous and lymphatic drainages, considered differently by classical anatomic and neuroradiological approaches. Spinal meninges are involved in neurodevelopment and neurorepair producing neural stem cells and morphogens, in cerebrospinal fluid dynamics and neuraxis functioning by the synthesis of active molecules, and the elimination of waste products of central nervous system metabolism. CONCLUSION The spinal meninges should be considered as dynamic functional formations evolving over a lifetime, with ultrastructural features and functional interactions with the neuraxis remaining not fully understood.


Author(s):  
Kathryn L. Lovell ◽  
Margaret Z. Jones

Caprine β-mannosidosis, an autosomal recessive defect of glycoprotein catabolism, is associated with a deficiency of tissue and plasma -mannosidase and with tissue accumulation and urinary excretion of oligosaccharides, including the trisaccharide Man(β1-4)GlcNAc(βl-4)GlcNAc and the disaccharide Man(β1-4)GlcNAc. This genetic disorder is evident at birth, with severe neurological deficits including a marked intention tremor, pendular nystagmus, ataxia and inability to stand. Major pathological characteristics described in Nubian goats in Michigan and in Anglo-Nubian goats in New South Wales include widespread cytoplasmic vacuolation in the nervous system and viscera, axonal spheroids, and severe myelin paucity in the brain but not spinal cord or peripheral nerves. Light microscopic examination revealed marked regional variation in the severity of central nervous system myelin deficits, with some brain areas showing nearly complete absence of myelin and other regions characterized by the presence of 25-50% of the control number of myelin sheaths.


2018 ◽  
Vol 23 (1) ◽  
pp. 10-13
Author(s):  
James B. Talmage ◽  
Jay Blaisdell

Abstract Injuries that affect the central nervous system (CNS) can be catastrophic because they involve the brain or spinal cord, and determining the underlying clinical cause of impairment is essential in using the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), in part because the AMA Guides addresses neurological impairment in several chapters. Unlike the musculoskeletal chapters, Chapter 13, The Central and Peripheral Nervous System, does not use grades, grade modifiers, and a net adjustment formula; rather the chapter uses an approach that is similar to that in prior editions of the AMA Guides. The following steps can be used to perform a CNS rating: 1) evaluate all four major categories of cerebral impairment, and choose the one that is most severe; 2) rate the single most severe cerebral impairment of the four major categories; 3) rate all other impairments that are due to neurogenic problems; and 4) combine the rating of the single most severe category of cerebral impairment with the ratings of all other impairments. Because some neurological dysfunctions are rated elsewhere in the AMA Guides, Sixth Edition, the evaluator may consult Table 13-1 to verify the appropriate chapter to use.


1963 ◽  
Vol 44 (3) ◽  
pp. 475-480 ◽  
Author(s):  
R. Grinberg

ABSTRACT Radiologically thyroidectomized female Swiss mice were injected intraperitoneally with 131I-labeled thyroxine (T4*), and were studied at time intervals of 30 minutes and 4, 28, 48 and 72 hours after injection, 10 mice for each time interval. The organs of the central nervous system and the pituitary glands were chromatographed, and likewise serum from the same animal. The chromatographic studies revealed a compound with the same mobility as 131I-labeled triiodothyronine in the organs of the CNS and in the pituitary gland, but this compound was not present in the serum. In most of the chromatographic studies, the peaks for I, T4 and T3 coincided with those for the standards. In several instances, however, such an exact coincidence was lacking. A tentative explanation for the presence of T3* in the pituitary gland following the injection of T4* is a deiodinating system in the pituitary gland or else the capacity of the pituitary gland to concentrate T3* formed in other organs. The presence of T3* is apparently a characteristic of most of the CNS (brain, midbrain, medulla and spinal cord); but in the case of the optic nerve, the compound is not present under the conditions of this study.


1985 ◽  
Vol 55 ◽  
Author(s):  
F. Terry Hambrecht

ABSTRACTNeural prostheses which are commercially available include cochlear implants for treating certain forms of deafness and urinary bladder evacuation prostheses for individuals with spinal cord disorders. In the future we can anticipate improvements in bioelectrodes and biomaterials which should permit more sophisticated devices such as visual prostheses for the blind and auditory prostheses for the deaf based on microstimulation of the central nervous system.


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