scholarly journals Anisotropic distortion in the perceived orientation of stimuli on the arm

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Scinob Kuroki
Keyword(s):  
Line Shape ◽  
Shape Perception ◽  
Frame Of Reference ◽  
The Body ◽  
The Other ◽  
Neural Signals ◽  
Perceptual Distortion ◽  
Braille Display ◽  
The Brain ◽  
Volar Surface

AbstractMechanoreceptors on the skin are heterogeneously distributed, and the sampling of neural signals in the brain can vary depending on the part of the body. Therefore, it can be challenging for the brain to consistently represent stimuli applied to different body sites. Here, we report an example of a regional perceptual distortion of the tactile space. We used a piezoelectric braille display to examine shape perception on the volar surface of the arm and to compare it to that on the palm. We found that the orientation of perceived stimuli on the arm was distorted in certain areas. In particular, an inwardly-inclined line shape was perceived as being more inwardly-inclined than it actually was. On the other hand, an outwardly-inclined line was perceived accurately. When the same stimuli were applied to the palm, this anisotropic bias was not observed. We also found that changing the posture of the arm changed the angle at which this anisotropic distortion occurred, suggesting the influence of the skin frame of reference on this illusion. This study showed a clear example of how the representation of even simple stimuli is complexly distinct when the stimuli are applied to different body sites.

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.

scholarly journals Sensory Reweighting in Targeted Reaching: Effects of Conscious Effort, Error History, and Target Salience

2010 ◽  
Vol 103 (1) ◽  
pp. 206-217 ◽  
Author(s):  
Hannah J. Block ◽  
Amy J. Bastian
Keyword(s):  
Minimum Variance ◽  
The Body ◽  
The Other ◽  
Proprioceptive Information ◽  
Sensory Reweighting ◽  
Sensorimotor Processing ◽  
Important Principle ◽  
Conscious Effort ◽  
Visual Error ◽  
The Brain

When both visual and proprioceptive information are available about the position of a part of the body, the brain weights and combines these sources to form a single estimate, often modeled by minimum variance integration. These weights are known to vary with different circumstances, but the type of information causing the brain to change weights (reweight) is unknown. Here we studied reweighting in the context of estimating the position of a hand for the purpose of reaching it with the other hand. Subjects reached to visual (V), proprioceptive (P), or combined (VP) targets in a virtual reality setup. We calculated weights for vision and proprioception by comparing endpoints on VP reaches with endpoints on P and V reaches. Endpoint visual feedback was manipulated to control completely for the error history seen by subjects. In different experiments, we manipulated target salience, conscious effort, or statistics of the visual error history to see if these cues could cause reweighting. Most subjects could reweight strongly by conscious effort. Changes in target salience reliably caused reweighting, but seen error history alone did not. We also found that experimental weights can be predicted by minimizing the variance of visual and proprioceptive estimates, supporting the idea that minimum variance integration is an important principle of sensorimotor processing.

scholarly journals Distinct neural circuits for control of movement vs. holding still

2017 ◽  
Vol 117 (4) ◽  
pp. 1431-1460 ◽  
Author(s):  
Reza Shadmehr
Keyword(s):  
Body Part ◽  
Oculomotor System ◽  
The Body ◽  
Head Movements ◽  
Fine Tuning ◽  
Neural Integrator ◽  
Neural Signals ◽  
Sensory State ◽  
Control Circuits ◽  
The Brain

In generating a point-to-point movement, the brain does more than produce the transient commands needed to move the body part; it also produces the sustained commands that are needed to hold the body part at its destination. In the oculomotor system, these functions are mapped onto two distinct circuits: a premotor circuit that specializes in generating the transient activity that displaces the eyes and a “neural integrator” that transforms that transient input into sustained activity that holds the eyes. Different parts of the cerebellum adaptively control the motor commands during these two phases: the oculomotor vermis participates in fine tuning the transient neural signals that move the eyes, monitoring the activity of the premotor circuit via efference copy, whereas the flocculus participates in controlling the sustained neural signals that hold the eyes, monitoring the activity of the neural integrator. Here, I review the oculomotor literature and then ask whether this separation of control between moving and holding is a design principle that may be shared with other modalities of movement. To answer this question, I consider neurophysiological and psychophysical data in various species during control of head movements, arm movements, and locomotion, focusing on the brain stem, motor cortex, and hippocampus, respectively. The review of the data raises the possibility that across modalities of motor control, circuits that are responsible for producing commands that change the sensory state of a body part are distinct from those that produce commands that maintain that sensory state.

scholarly journals Modes of pointing to existing spaces and the use of frames of reference

Gesture ◽  
2011 ◽  
Vol 11 (3) ◽  
pp. 271-307 ◽  
Author(s):  
Olivier Le Guen
Keyword(s):  
Frame Of Reference ◽  
Point Of View ◽  
The Body ◽  
The Other ◽  
Frames Of Reference ◽  
Spatial Relationships ◽  
External Cues ◽  
The Status ◽  
Systematic Framework

This paper aims at providing a systematic framework for investigating differences in how people point to existing spaces. Pointing is considered according to two conditions: (1) A non-transposed condition where the body of the speaker always constitutes the origo and where the various types of pointing are differentiated by the status of the target and (2) a transposed condition where both the distant figure and the distant ground are identified and their relation specified according to two frames of reference (FoRs): the egocentric FoR (where spatial relationships are coded with respect to the speaker’s point of view) and the geocentric FoR (where spatial relationships are coded in relation to external cues in the environment). The preference for one or the other frame of reference not only has consequences for pointing to real spaces but has some resonance in other domains, constraining the production of gesture in these related domains.

Recent Contributions to the Pathology of Nervous Diseases

1867 ◽  
Vol 13 (61) ◽  
pp. 44-58 ◽  
Author(s):  
H. M.
Keyword(s):  
Physical Method ◽  
The Body ◽  
The Other ◽  
Physiological Basis ◽  
Natural Laws ◽  
Positive Science ◽  
Positive Method ◽  
Holy Ground ◽  
The Brain ◽  
Structure And Functions

When we reflect that the sciences of astronomy, physics, and chemistry have only recently got rid of the metaphysical spirit, we cannot wonder much that physiology is not yet entirely emancipated from the pernicious thraldom. It was plainly impossible that physiology should be cultivated in the spirit of the positive method of investigation while the sciences upon the advance of which itsadvance is dependent were not sciences at all, but clouds of idle andshifting fancies. But there has been another and weighty reason why the science dealing with the structure and functions of the organism has remained so long in a metaphysical bondage: because psychology, the last stronghold and the forlorn hope of the meta physical method, is an important branch of it. Metaphysicians have for at least two thousand years been supremely self-satisfied to evolve, from the unfathomable depths of the inner consciousness, ingenious mazes of vague and ill-defined words which they have dignified with the name of mental philosophy; and the consequence has been that the physiologist, when he came in the course of his inquiries to the brain, contented himself with the anatomical de scription of it, and never dreamed of studying its functions as the mental organ. By a prescriptive right, sanctioned by the authority of generations, mind belonged to the metaphysician; and it naturally seemed sacrilegious to venture a scientific step in such holy ground. Not only so, but the mischievous influence of the metaphysical spirit spread beyond the department of psychology, and infected more or less strongly all physiological inquiries. However, this state of things could not last in face of the active progress of positive science; the or ans and functions of the body became objects of positive investigation, and even the brain no longer escaped scientific study. So it has come to pass that the germs of a mental science having a physiological basis have appeared, and now threaten to disturb the ancient ascendancy of metaphysical mental philosophy. The present position of matters is this: there are two systems of philosophy dealing with the same subject, but not having the slightest connection one with the other, and cultivated according to different methods by different men-metaphysical mental philosophy and positive mental science. A man might be deeply learned in all the wisdom of the former, and yet entirely ignorant of the very meaning of the simplest facts of the latter. It is hardly worth while considering seriously at the present day which of these rival systems is likely to prevail over the other; one of them is the latest issue of the advance of positive science, has its foundations deep rooted in the relations of natural laws, and exhibits a promising growth; while the other has moved in an everlasting circle, has no better foundations than the clouds and conceits of men's thoughts, and exhibits symptoms of active decay. Now and then it is skilfully galvanized into a spasmodic semblance of life, but each artificially excited convulsion is plainly the fore runner of an increase of the inevitable paralysis. Much remains to be done, however, before we can claim acceptance for a positive mental science. Not only is our knowledge of the structure and functions of the brain very defective, but there is nothing like exact information to be had regarding its pathology. It has been the fashion to give the name of some disease to a group of symptoms, without attempting to connect these with particular diseased states of the nervous centres. The pathology of all the diseases of the nervous system is, it must be confessed, in a most unsatisfactory condition.

Benjamin Libet’s Big Experiment

2019 ◽  
pp. 186-199
Author(s):  
Alan J. McComas
Keyword(s):  
Electrical Activity ◽  
Neural Activity ◽  
The Body ◽  
The Other ◽  
Sensory Stimulus ◽  
Conscious Awareness ◽  
Evoked Responses ◽  
Temporal Reference ◽  
The Mind ◽  
The Brain

This chapter describes Benjamin Libet’s finding that electrical activity in the brain precedes conscious awareness. Libet’s work had shown that, no matter how brief it was, a sensory stimulus evoked responses in the cortex that lasted hundreds of milliseconds. He also suggested that, just as the somatosensory cortex was able to refer sensations to a particular point on the opposite side of the body (“spatial reference”) so it could refer sensations to an earlier moment—the time when impulse activity had first been initiated in the cortex following the stimulus (“temporal reference”). These were important conclusions and inevitably became the subjects of debate following their publication. But Libet was soon to deliver a greater surprise when he discovered that a decision only entered consciousness when the underlying neural activity was already far advanced. Rather than the mind controlling the brain—thought by thought—it was the other way round and “free will,” seemingly so self-evident, was an illusion.

VI. Experiments made with a view to ascertain the principle on which the action of the heart depends, and the relation which subsists between that organ and the nervous system

1815 ◽  
Vol 105 ◽  
pp. 65-90 ◽  
Keyword(s):  
Nervous System ◽  
The Body ◽  
The Other ◽  
Modus Operandi ◽  
Spinal Marrow ◽  
Difference Of Opinion ◽  
The Subject ◽  
The Brain ◽  
General Opinion ◽  
Nervous Influence

The following experiments were begun with a view to as­ certain the manner in which certain poisons act in destroying life. I soon found that, in order to make any considerable progress in such an inquiry, it is necessary to ascertain how far the powers of the nervous and sanguiferous systems di­rectly depend on each other. There seems never to have been any difference of opinion respecting the direct depend­ence of the nervous on the sanguiferous system. When the powers of circulation are increased or diminished, the nervous system always suffers a corresponding change, nor can the latter, under any circumstances, continue to perform its functions after the former are destroyed. I speak of the warm blooded animals. In cold blooded animals the process of dying is so slow, that the functions of the nervous system abate very gradually, after the circulation has wholly ceased. The converse of the above proposition is by no means so generally admitted. It is evident that certain changes of the nervous, produce corresponding changes in the sanguiferous, system ; yet, while some assert, that the action of the heart depends as immediately on the brain, as that of the latter does on the heart, others maintain, that the nervous power may be wholly destroyed without impairing the vigour of this organ. This point it is necessary to determine, before we can trace with precision the modus operandi of poisons. The following inquiry therefore may be divided into two parts. In the first, I shall endeavour to ascertain how far the power of the heart is influenced by the state of the nervous system; in the other, by what steps certain poisons destroy the powers of both. This I shall reserve for another paper, and here confine my­self to the first part of the subject. Till the time of Haller, it seems to have been the general opinion, that the muscles derive their power from the nervous system. He taught, that the power of the muscles depends on their mechanism, that the nervous influence is merely a stimulus which calls it into action, and consequently that those muscles, the heart for example, which act only by the appli­cation of one peculiar stimulus, unconnected with the nervous system, are wholly independent of it. This opinion seemed confirmed by its being generally admitted, that the action of the heart continues after it is removed from the body, and that it cannot be influenced by stimulating the brain, or spinal marrow, or the nerves which terminate in it. Haller and his followers maintain, that there are two distinct vital powers, one of the nervous and another of the sanguiferous system.

scholarly journals Heavy Metals in Liver, Kidney, Brain and Muscle Slender-Billed Gull (Chroicocephalus Genei) From the Chahnimeh Water Reservoirs Sistan and Coast Oman Sea (Iran)

2021 ◽  
Author(s):  
Reza Dahmardeh Behrooz ◽  
Joanna Burger
Keyword(s):  
Heavy Metals ◽  
Gender Differences ◽  
Adverse Effects ◽  
Brain Tissue ◽  
The Body ◽  
The Other ◽  
Water Reservoirs ◽  
Oman Sea ◽  
The Brain ◽  
Sea Coast

Abstract The concentrations of four heavy metals nickel (Ni), cadmium (Cd), lead (Pb) and zinc (Zn) were determined in liver, kidney, muscle and brain tissues of 20 slender-billed gulls (Chroicocephalus genei) from the Chahnimeh water reservoirs of Sistan and the Oman Sea coast of Iran. There were significant differences between nickel Ni, Cd, Pb and Zn concentrations observed in the liver and brains of birds from the Oman Sea coast than in liver and brains of gulls from the Chahnimeh water reservoirs (P < 0.05). Higher levels of Pb, Cd and Zn were found in the brain and liver of gulls than in the kidney and muscles tissues. There were significant gender differences in heavy metals in liver and brain tissue. In gulls from the coast of Oman Sea, all four elements (Cd, Pb, Ni and Zn) were positively correlated with levels in all organs, and except for muscle, the elements were positively correlated with the other elements in the other tissue (except Ni in brain). Thus, the pathways and sources of entry for the elements are similar, and the pathways for accumulation of these elements, and the reactions of different organs of the body to these elements, are very similar. Also, 40% of gulls in Oman Sea coast had levels of lead in the brain that were above the adverse effects levels, Ni concentrations in liver of slender-billed gull in Oman Sea coast (100 %) and Chahnimeh water reservoirs (90 %) were above toxic levels, and 80% of Ni concentration in kidneys in gulls from the Oman Sea coast and Chahnimeh water reservoirs were higher than the toxicity levels.

scholarly journals Lessons from behavioral lateralization in olfaction

2021 ◽  
Author(s):  
Matthias Cavelius ◽  
Théo Brunel ◽  
Anne Didier
Keyword(s):  
Brain Connectivity ◽  
Sensory Information ◽  
The Body ◽  
The Other ◽  
Behavioral Data ◽  
Future Research ◽  
Brain Lateralization ◽  
Complex Picture ◽  
Psychiatric Conditions ◽  
The Brain

AbstractSensory information, sampled by sensory organs positioned on each side of the body may play a crucial role in organizing brain lateralization. This question is of particular interest with regard to the growing evidence of alteration in lateralization in several psychiatric conditions. In this context, the olfactory system, an ancient, mostly ipsilateral and well-conserved system across phylogeny may prove an interesting model system to understand the behavioral significance of brain lateralization. Here, we focused on behavioral data in vertebrates and non-vertebrates, suggesting that the two hemispheres of the brain differentially processed olfactory cues to achieve diverse sensory operations, such as detection, discrimination, identification of behavioral valuable cues or learning. These include reports across different species on best performances with one nostril or the other or odorant active sampling by one nostril or the other, depending on odorants or contexts. In some species, hints from peripheral anatomical or functional asymmetry were proposed to explain these asymmetries in behavior. Instigations of brain activation or more rarely of brain connectivity evoked by odorants revealed a complex picture with regards to asymmetric patterns which is discussed with respect to behavioral data. Along the steps of the discussed literature, we propose avenues for future research.

Of the functions of some parts of the brain; and of the relations between the brain and nerves of motion and sensation

1837 ◽  
Vol 3 ◽  
pp. 283-284
Keyword(s):  
Medulla Oblongata ◽  
The Body ◽  
The Other ◽  
Spinal Nerves ◽  
Close Resemblance ◽  
Internal Position ◽  
Voluntary Motion ◽  
Pass Through ◽  
The Brain ◽  
Source Of Error

The author commences his paper by an enumeration of some of the sources of difficulty and of error which have impeded the progress of discovery in the physiology of the brain; the first impediment to which, he observes, “is in the nature of the inquiry, since extraordinary and contradictory results must be expected from experimenting on an organ so fine as that must be which ministers to sensibility and motion, and which is subject to change on every impression conveyed through the senses.”Another cause of fallacy is the dependence of the brain on the condition of the circulation within it: but the most frequent source of error is the obscurity which hangs over the whole subject; for although the brain be divided naturally into distinct masses, not one of these grand divisions has yet been distinguished by its functions; and hence we may account for the failure of all attempts to explain the phenomena which attend injury of the brain. The principle, now universally admitted, that nerves have distinct functions, and not a common quality, is pursued by the author in his investigation of the structure of the brain, in which he follows the nerves into that organ, and observes the tracts of nervous matter from which they take their origin. He concludes from his inquiries that both sensibility and motion belong to the cerebrum; that two columns descend from each hemisphere; that one of these, the anterior, gives origin to the anterior roots of the spinal nerves, and is dedicated to voluntary motion; and that the other, which from its internal position is less known, gives origin to the posterior roots of the spinal nerves, and to the sensitive root of the fifth nerve, and is the column for sensation. He further shows that the columns for motion, which come from different sides of the cerebrum, join and decussate in the medulla oblongata; that the columns of sensation also join and decussate in the medulla oblongata; and lastly, that these anterior and posterior columns bear, in every circumstance, a very close resemblance to one another, in as much as the sensorial expansions of both are widely extended in the hemispheres; for they pass through similar bodies towards the base of the bruin, and both concentrate and decussate in the same manner; thus agreeing in every respect, except in the nervous filaments to which they give origin. Hence he explains the phenomena of the loss of sensibility as well as the power of motion of one side of the body, consequent on injuries of the other side of the brain. The Society then adjourned over Whitsun Week to the 29th of May.

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