scholarly journals The Immobilization of Locomotory Movements in the Earthworm, Lumbricus Terrestris

1938 ◽  
Vol 15 (3) ◽  
pp. 339-357
Author(s):  
H. O. J. COLLIER
Keyword(s):  
Nerve Cord ◽  
Lumbricus Terrestris ◽  
The Body ◽  
Peristaltic Wave ◽  
Time Interval ◽  
Mechanical Stimuli ◽  
Head Region ◽  
Spontaneous Reversal ◽  
The Central Nervous System ◽  
Chemical Stimuli

1. In response to stimuli at the head, a peristaltic wave travelling in any part of the earthworm's body may be arrested. This occurs after an interval of about 0.5 sec., if the nearest part of the wave is 5 cm. from the point of stimulus. This response is of regular occurrence, and it depends on the continuity of the nerve cord between the point of stimulus and the region of the wave. It is therefore named the reflex arrest of peristalsis. 2. The arrest of peristalsis is brought about by the complete cessation of movement of both the elongation phase and the shortening phase of the wave. The shape of the wave is not lost; though it appears that there may be some relaxation of the circular muscles in the region of elongation. 3. The receptors of the reflex lie on the cephalic half of the body. Stimuli applied on the most cephalic one-third of the body may arrest a peristaltic wave cephalic to their point of application. 4. The response may appear in answer to mechanical or to chemical stimuli. It may also appear in response to the absence of contact with the substratum in the head region. In this last case the reflex depends upon the presence of the supraoesophageal ganglion. The response to mechanical stimuli, however, depends neither on the presence of the cephalic one-third of the body, nor on the presence of the tail segments. 5. A similar reflex arrest of anti-peristalsis occurs in response to mechanical or chemical stimuli on the caudal half of the body. The time interval between stimulus and response at 5 cm. from the point of stimulus is about 0.4 sec. The anti-peristaltic wave was not observed to be arrested while travelling in the most cephalic one-third of the body. 6. The arrest of the anti-peristaltic wave is due, too, to a cessation of movement of both phases of the wave, without a loss of its general shape. 7. The receptors for the reflex lie in the caudal half of the body, and the nerve paths from them run in both directions. The reflex does not depend on the presence of either the head or the tail segments. It can be obtained in a worm with the most caudal one-third of the body removed, or in a worm with the most cephalic one-third cut off. 8. The arrest of an anti-peristaltic wave by the development of a peristaltic wave can be observed in the spontaneous reversal of the direction of crawling. This act of behaviour, which is named the spontaneous immobilization of anti-peristalsis, does not depend on the presence of either the most cephalic one-third or the most caudal one-third of the body. Though this act of behaviour need not be considered as a reflex, its performance depends on the continuity of the nerve cord between the new peristaltic wave and the anti-peristaltic wave that is immobilized. 9. The above three acts of behaviour are distinct from each other in their paths in the cord, and the two reflexes are distinct in their receptors. All three play an important part in one or more larger patterns of behaviour. All are conducted in paths separate from those conducting the rapid shortening reflexes. 10. There is little evidence to throw light on the mode of action of these three immobilizations. They may be compared to the "freezing" of movement into posture found in insects and vertebrates. It is to be expected that their mechanism will prove to lie within the central nervous system.

The Giant Nerve-Fibres in the Central Nervous System of Myxicola (Polychaeta, Sabellidae)

1948 ◽  
Vol s3-89 (5) ◽  
pp. 1-45
Author(s):  
J.A. C. NICOL
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Size Structure ◽  
Nerve Cells ◽  
The Body ◽  
Usual Sense ◽  
Fibrous Sheath ◽  
Giant Fibre ◽  
The Central Nervous System

1. A description is given of the main features of the central nervous system of Myxicola infundibulum Rénier. 2. The nerve-cord is double in the first four thoracic segments and single posteriorly. It shows segmental swellings but is not ganglionated in the usual sense in that nerve-cell accumulations are not related directly to such swellings of the cord. 3. A very large axon lies within the dorsal portion of the nerve-cord and extends from the supra-oesophageal ganglia to the posterior end of the animal. It is small in the head ganglia where it passes transversely across the mid-line, increases in diameter in the oesophageal connectives, and expands to very large size, up to 1 mm., in the posterior thorax and anterior abdomen, and gradually tapers off to about 100µ in the posterior body. It shows segmental swellings corresponding to those of the nerve-cord in each segment. It occupies about 27 per cent, of the volume of the central nervous system and 0.3 per cent, of the volume of the animal. The diameter of the fibre increases during contraction of the worm. 4. The giant fibre is a continuous structure throughout its length, without internal dividing membranes or septa. Usually a branch of the giant fibre lies in each half of the nerve-cord in the anterior thoracic segments and these several branches are continuous with one another longitudinally and transversely. 5. The giant fibre is connected with nerve-cells along its entire course; it arises from a pair of cells in the supra-oesophageal ganglia, and receives the processes of many nerve-cells in each segment. There is no difference between the nerve-cells of the giant fibre and the other nerve-cells of the cord. 6. A distinct fibrous sheath invests the giant fibre. A slight concentration of lipoid can be revealed in this sheath by the use of Sudan black. 7. About eight peripheral branches arise from the giant fibre in each segment. They have a complex course in the nerve-cord where they anastomose with one another and receive the processes of nerve-cells. Peripherally, they are distributed to the longitudinal musculature. 8. Specimens surviving 16 days following section of the nerve-cord in the thorax have shown that the giant fibre does not degenerate in front of or behind a cut, thus confirming that it is a multicellular structure connected to nerve-cells in the thorax and abdomen. 9. It is concluded that the giant fibre of M. infundibulum is a large syncytial structure, extending throughout the entire central nervous system and the body-wall of the animal. 10. The giant fibre system of M. aesthetica resembles that of M. infundibulum. 11. Some implications of the possession of such a giant axon are discussed. It is suggested that its size, structure, and simplicity lead to rapid conduction and thus effect a considerable saving of reaction time, of considerable value to the species when considered in the light of the quick contraction which it mediates. The adoption of a sedentary mode of existence has permitted this portion of the central nervous system to become developed at the expense of other elements concerned with errant habits.

scholarly journals Rabies anterograde monosynaptic tracing reveals organization of spinal sensory circuits

2021 ◽  
Author(s):  
Sofia Pimpinella ◽  
Niccolò Zampieri
Keyword(s):  
Sensory Input ◽  
Population Coding ◽  
The Body ◽  
Mechanical Stimuli ◽  
Sensory Afferents ◽  
Laminar Organization ◽  
Somatosensory Information ◽  
Connectivity Patterns ◽  
Somatosensory Neurons ◽  
The Central Nervous System

AbstractSomatosensory neurons detect vital information about the environment and internal status of the body, such as temperature, touch, itch and proprioception. The circuit mechanisms controlling the coding of somatosensory information and the generation of appropriate behavioral responses are not clear yet. In order to address this issue, it is important to define the precise connectivity patterns between primary sensory afferents dedicated to the detection of different stimuli and recipient neurons in the central nervous system. In this study we used a rabies tracing approach for mapping spinal circuits receiving sensory input from distinct, genetically defined, modalities. We analyzed the anatomical organization of spinal circuits involved in coding of thermal and mechanical stimuli and showed that somatosensory information from distinct modalities is relayed to partially overlapping ensembles of interneurons displaying stereotyped laminar organization, thus highlighting the importance of positional features and population coding for the processing and integration of somatosensory information.

The Giant Fibre Reflex of the Earthworm, Lumbricus Terrestris L

1962 ◽  
Vol 39 (2) ◽  
pp. 219-227
Author(s):  
M. B. V. ROBERTS
Keyword(s):  
Nerve Cord ◽  
Lumbricus Terrestris ◽  
The Body ◽  
Muscle Preparation ◽  
Direct Stimulation ◽  
Giant Fibre ◽  
Low Threshold ◽  
Giant Fibres ◽  
Nerve Muscle ◽  
Stimulation Of

1. A nerve-muscle preparation including the longitudinal musculature and the giant fibres in the nerve cord of the earthworm is described. 2. Direct stimulation of the nerve cord with single shocks of increasing intensity results in two types of response: (a) a low threshold, very small twitch, resulting from a single impulse in the median giant fibre, and (b) a higher threshold, slightly larger twitch, resulting from single impulses in the median and lateral giant fibres. Both responses are highly susceptible to fatigue. 3. Stimulation of the body surface evokes a much more powerful contraction which is associated with a burst of impulses in the giant fibre. The strength of the contraction depends upon the number of impulses in the burst and this in turn upon the intensity and duration of the stimulus.

Induction d'une queue et de parapodes surnuméraires par déviation de l'intestin chez les Nereidae (Annélides Polychètes)

Development ◽  
1973 ◽  
Vol 30 (2) ◽  
pp. 329-343
Author(s):  
Par B. Boilly
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Body Wall ◽  
The Body ◽  
The Central Nervous System ◽  
Different Tissues

Supernumerary tail and parapodia induction by deviation of the intestine in nereids (Annelida: Polychaeta) Localized ablation of the intestine has been performed on normal and grafted specimens of the two polychaetes Nereis pelagica L. and Perinereis cultrifera G. with the following results: (1) In the absence of the intestine, segments are not regenerated but parapodia grow on the plane of section. (2) A segmented tail arises where the intestine is deviated; the regenerate we obtain in this case is of the ‘aneurogenic’ type and without anal cirri and parapodia. (3) These results suggest that caudal regeneration results from the association of different tissues (intestine and the body wall) whereas the nerve cord exerts an influence upon the organization of the regenerate. Likewise the caudal regeneration of parapodia is the consequence of the juxtaposition of a dorsal and a ventral body wall in the presence of the central nervous system.

METABOLIC STUDIES WITH 131I-LABELED THYROXINE. II.

1963 ◽  
Vol 44 (3) ◽  
pp. 475-480 ◽  
Author(s):  
R. Grinberg
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Optic Nerve ◽  
Pituitary Gland ◽  
Time Interval ◽  
Time Intervals ◽  
Pituitary Glands ◽  
The Central Nervous System ◽  
Tentative Explanation

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.

Preparation and In Vitro Evaluation of Resealed Erythrocytes as A New Trend in Treatment of Asthma

2016 ◽  
Vol 6 (3) ◽  
Author(s):  
Mohammed Ibrahim ◽  
Alaa Zaky ◽  
Mohsen Afouna ◽  
Ahmed Samy
Keyword(s):  
In Vitro Release ◽  
Human Erythrocytes ◽  
The Body ◽  
Blood Levels ◽  
Time Interval ◽  
Burst Release ◽  
Prolonged Release ◽  
Nocturnal Asthma ◽  
Carrier Erythrocytes

Carrier erythrocytes are emerging as one of the most promising biological drug delivery systems investigated in recent decades. Beside its biocompatibility, biodegradability and ability to circulate throughout the body, it has the ability to perform extended release system of the drug for a long period. The ultimate goal of this study is to introduce a new carrier system for Salbutamol, maintaining suitable blood levels for a long time, as atrial to resolve the problems of nocturnal asthma medication Therefore in this work we study the effect of time, temperature as well as concentration on the loading of salbutamol in human erythrocytes to be used as systemic sustained release delivery system for this drug. After the loading process is performed the carrier erythrocytes were physically and cellulary characterized. Also, the in vitro release of salbutamol from carrier erythrocytes was studied over time interval. From the results it was found that, human erythrocytes have been successfully loaded with salbutamol using endocytosis method either at 25 Co or at 37 Co . The highest loaded amount was 3.5 mg/ml and 6.5 mg/ml respectively. Moreover, the percent of cells recovery is 90.7± 1.64%. Hematological parameters and osmotic fragility behavior of salbutamol loaded erythrocytes were similar that of native erythrocytes. Scanning electron microscopy demonstrated that the salbutamol loaded cells has moderate change in the morphology. Salbutamol releasing from carrier cell was 43% after 36 hours in phosphate buffer saline. The releasing pattern of the drug from loaded erythrocytes showed initial burst release in the first hour followed by a very slow release, obeying zero order kinetics. It concluded that salbutamol is successfully entrapped into erythrocytes with acceptable loading parameters and moderate morphological changes, this suggesting that erythrocytes can be used as prolonged release carrier for salbutamol.

Characteristics of the dynamics of the central nervous system and att ention function in workers of shoe production

2020 ◽  
pp. 64-68
Author(s):  
F. L. Azizova ◽  
U. A. Boltaboev
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Women Workers ◽  
Functional State ◽  
The Body ◽  
Conflict Of Interests ◽  
Professional Groups ◽  
Universal Device ◽  
The Central Nervous System ◽  
Working Day

The features of production factors established at the main workplaces of shoe production are considered. The materials on the results of the study of the functional state of the central nervous system of women workers of shoe production in the dynamics of the working day are presented. The level of functional state of the central nervous system was determined by the speed of visual and auditory-motor reactions, installed using the universal device chronoreflexometer. It was revealed that in the body of workers of shoe production there is an early development of inhibitory processes in the central nervous system, which is expressed in an increase in the number of errors when performing tasks on proofreading tables. It was found that the most pronounced shift s in auditory-motor responses were observed in professional groups, where higher levels of noise were registered in the workplace. The correlation analysis showed a close direct relationship between the growth of mistakes made in the market and the decrease in production. An increase in the time spent on the task indicates the occurrence and growth of production fatigue.Funding. The study had no funding.Conflict of interests. The authors declare no conflict of interests.

Assessment of the Biochemical Status of Workers Manufacturing Ethylbenzene and Styrene

2020 ◽  
pp. 40-43
Author(s):  
RR Galimova ◽  
ET Valeeva ◽  
GV Timasheva ◽  
AB Bakirov
Keyword(s):  
Catalase Activity ◽  
Free Radical Oxidation ◽  
The Body ◽  
Atherogenic Index ◽  
Radical Oxidation ◽  
Professional Groups ◽  
Biochemical Status ◽  
The Central Nervous System ◽  
Hepatic Protein Synthesis ◽  
Increased Activity

Introduction: Production of ethylbenzene and styrene (EBS) is one of the most important stages in organic synthesis. The products have general toxic, hepatotoxic, irritating and narcotic effects on the human body. Severe exposures to EВS can induce pronounced disorders of the central nervous system such as styrene sickness and encephalopathy and of peripheral blood such as leukopenia and lymphocytosis. Materials and methods: We studied homeostasis indices in 376 workers of the main professional groups engaged in the production of EBS including equipment operators, repairmen, and instrumentation and automation fitters. Results: We established an increase in lipid peroxidation by the level of malondialdehyde amid an increase in catalase activity and a decrease in blood retinol and α-tocopherol levels. We also noted an increased activity of indicator enzymes including ALT, AST, GGT, and alkaline phosphatase. Significant changes in lipid metabolism in the form of cholesterolemia, triglyceridemia, a higher atherogenic index, and lower cholesterol of non-atherogenic blood serum lipids demonstrating atherogenic changes in the body were revealed. Conclusions: The earliest prenosological disorders in the body of the examined workers included an impaired hepatic protein synthesis, the development of cytolysis processes and a change in the integrity and functional activity of the liver cell in individuals, an imbalance in the oxidant-antioxidant system, one of the reasons of which was the adverse occupational exposure to hazardous chemicals. An increase in catalase activity is a protective compensatory reaction during the activation of free radical oxidation processes.

Neural Stem Cells to Glial Cells an Important Factor for Brain Injury

2020 ◽  
Author(s):  
Prithiv K R Kumar
Keyword(s):  
Stem Cells ◽  
Central Nervous System ◽  
Nervous System ◽  
Neural Stem Cells ◽  
Glial Cells ◽  
Brain Injuries ◽  
The Body ◽  
The Central Nervous System ◽  
Near Future

Stem cells have the capacity to differentiate into any type of cell or organ. Stems cell originate from any part of the body, including the brain. Brain cells or rather neural stem cells have the capacitive advantage of differentiating into the central nervous system leading to the formation of neurons and glial cells. Neural stem cells should have a source by editing DNA, or by mixings chemical enzymes of iPSCs. By this method, a limitless number of neuron stem cells can be obtained. Increase in supply of NSCs help in repairing glial cells which in-turn heal the central nervous system. Generally, brain injuries cause motor and sensory deficits leading to stroke. With all trials from novel therapeutic methods to enhanced rehabilitation time, the economy and quality of life is suppressed. Only PSCs have proven effective for grafting cells into NSCs. Neurons derived from stem cells is the only challenge that limits in-vitro usage in the near future.

Healthy Gut, Healthy Brain: The Gut Microbiome in Neurodegenerative Disorders

2020 ◽  
Vol 20 (13) ◽  
pp. 1142-1153 ◽  
Author(s):  
Sreyashi Chandra ◽  
Md. Tanjim Alam ◽  
Jhilik Dey ◽  
Baby C. Pulikkaparambil Sasidharan ◽  
Upasana Ray ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Neurodegenerative Disorders ◽  
The Body ◽  
Therapeutic Approaches ◽  
Cns Disorders ◽  
Physiological Conditions ◽  
Pathological Conditions ◽  
The Central Nervous System ◽  
Present Understanding ◽  
Lateral Sclerosis

Background: The central nervous system (CNS) known to regulate the physiological conditions of human body, also itself gets dynamically regulated by both the physiological as well as pathological conditions of the body. These conditions get changed quite often, and often involve changes introduced into the gut microbiota which, as studies are revealing, directly modulate the CNS via a crosstalk. This cross-talk between the gut microbiota and CNS, i.e., the gut-brain axis (GBA), plays a major role in the pathogenesis of many neurodegenerative disorders such as Parkinson’s disease (PD), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS) and Huntington’s disease (HD). Objective: We aim to discuss how gut microbiota, through GBA, regulate neurodegenerative disorders such as PD, AD, ALS, MS and HD. Methods: In this review, we have discussed the present understanding of the role played by the gut microbiota in neurodegenerative disorders and emphasized the probable therapeutic approaches being explored to treat them. Results: In the first part, we introduce the GBA and its relevance, followed by the changes occurring in the GBA during neurodegenerative disorders and then further discuss its role in the pathogenesis of these diseases. Finally, we discuss its applications in possible therapeutics of these diseases and the current research improvements being made to better investigate this interaction. Conclusion: We concluded that alterations in the intestinal microbiota modulate various activities that could potentially lead to CNS disorders through interactions via the GBA.

Sign in / Sign up

Export Citation Format

Share Document