An Electrotherapy Based on the Natural Sequence of Motor Unit Action Potentials: A Laboratory Trial

1988 ◽  
Vol 2 (2) ◽  
pp. 125-138 ◽  
Author(s):  
GL Kidd ◽  
JA Oldham
Keyword(s):  
Motor Unit ◽  
Fatigue Resistance ◽  
Motor Units ◽  
Normal Subjects ◽  
Dominant Hand ◽  
Normal Muscle ◽  
Laboratory Trial ◽  
Analysis Of Results ◽  
The Difference ◽  
The Right

An electrotherapy based on a computer analysis of results obtained by analytical electromyography has been put to laboratory trial. Twenty-seven normal subjects received comparative regimes of electrotherapy each of which occupied three continuous hours each day for seven weeks. A comparison of the effectiveness on increasing fatigue resistance to voluntary effort of the first dorsal interosseus in the right, dominant hand was made. All electrotherapies employed had a mean frequency of stimulation of approximately 10Hz. The difference between them was found in the changes of pattern of stimulation which was exactly based on the changing patterns of discharge of slow motor units in normal muscle as it was progressively fatigued. The ability of the electrotherapies to induce fatigue resistance of the muscle was directly related to the extent of fatigue of the motor unit from which the pattern of discharge, which formed the basis of the technique, had been extracted. Electrotherapies with patterns randomized from naturally occurring patterns are shown to be without effect on increasing the fatigue resistance of normal muscle. The significance of the results from the points of view of rehabilitation and of signal analysis are discussed.

Site of impulse initiation in tendon organs of cat soleus muscle

1985 ◽  
Vol 54 (6) ◽  
pp. 1383-1395 ◽  
Author(s):  
J. E. Gregory ◽  
D. L. Morgan ◽  
U. Proske
Keyword(s):  
Motor Unit ◽  
Soleus Muscle ◽  
Motor Units ◽  
Impulse Generator ◽  
Golgi Tendon Organs ◽  
Cross Adaptation ◽  
Tendon Organs ◽  
The Right ◽  
Tendon Organ ◽  
Stimulation Of

A continuing controversy surrounds the question of whether Golgi tendon organs are examples of receptors in which impulses may be generated at more than one site. This paper reports a systematic examination of a number of models incorporating single or multiple impulse generators and of the compatibility of their predictions with experimental observations. Two phenomena, in particular, that must be accounted for are nonlinear summation and cross-adaptation. When two motor units each with a direct effect on the tendon organ are stimulated together, the rate of discharge is greater than either individual rate but is less than their sum. In cross-adaptation a conditioning response elicited by one motor unit contraction produces adaptation of the discharge associated with stimulation of a second motor unit. A model with a central impulse generator can be modified to account for nonlinear summation by postulating a nonlinear transformation in the generator current-to-impulse rate conversion. Experiments measuring summation of responses to stimulation of three inputs produced results that did not support this model. Another variation of the model, which had a nonlinearity in the tension-to-current step and cross-connections (mechanical or neural) between tendon strands stressed by contracting muscle fibers, was able to account for the observations. A second model that provided the right predictions was a multiple impulse generator with cross-connections. Which of the two models best fits the experimental observations can be decided by comparing the calculated summation coefficients and cross-adaptation coefficients. A central impulse generator predicts a negative correlation, the multiple impulse generator a positive correlation. All of the observations were made using tendon organs of cat soleus muscle. Responses were recorded to stimulation of filaments of ventral root. In a comparison between 20 pairs of responses from six tendon organs the correlation between summation and cross-adaptation coefficients was found to be significantly positive. We conclude that the tendon organ model that accurately predicts all of the experimental observations incorporates multiple generators.

Changes in diaphragm motor unit EMG during fatigue

1990 ◽  
Vol 68 (5) ◽  
pp. 1917-1926 ◽  
Author(s):  
G. C. Sieck ◽  
M. Fournier
Keyword(s):  
Motor Unit ◽  
Fatigue Test ◽  
Motor Units ◽  
Evoked Force ◽  
Slow Twitch ◽  
The Right ◽  
Fast Twitch ◽  
Multiple Units ◽  
Motor Unit Emg ◽  
Stimulation Of

Fatigue-related changes in the waveform and root-mean-square (rms) values of evoked motor unit electromyographic (EMG) responses were studied in the right sternocostal region of the cat diaphragm. Motor units were isolated by microdissection and stimulation of C5 ventral root filaments and then classified as fast-twitch fatigable (FF), fast-twitch fatigue intermediate (FInt), fast-twitch fatigue resistant (FR), or slow-twitch (S) based on standard physiological criteria. The evoked EMG responses of S and FR units showed very little change during the fatigue test. The evoked EMG waveform and rms values of FF and FInt units displayed variable changes during the fatigue test. When changes were observed, they typically included a prolongation of the EMG waveform, a decrease in peak amplitude, and a decrease in rms value. The changes in EMG amplitude and rms values were not correlated. In more fatigable units, the decrease in force during the fatigue test generally exceeded the decrease in EMG rms values. Changes in the evoked force and EMG responses of multiple units innervated by C5 or C6 ventral roots were also examined during the fatigue test. The decrease in diaphragm force during the fatigue test closely matched the force decline predicted by the proportionate contribution of different motor unit types. However, the observed reduction in diaphragm EMG rms values during the fatigue test exceeded that predicted based on the aggregate contribution of different motor unit types. It was concluded that changes in EMG do not reflect the extent of diaphragm fatigue.

Physiological responses of rat plantaris motor units to overload induced by surgical removal of its synergists

1988 ◽  
Vol 60 (6) ◽  
pp. 2138-2151 ◽  
Author(s):  
A. E. Olha ◽  
B. J. Jasmin ◽  
R. N. Michel ◽  
P. F. Gardiner
Keyword(s):  
Motor Unit ◽  
Fatigue Resistance ◽  
Motor Units ◽  
High Threshold ◽  
Surgical Removal ◽  
Type I ◽  
Myofibrillar Atpase ◽  
Force Output ◽  
Cross Sectional ◽  
Single Motor Units

1. Rat plantaris muscles were subjected to chronic overload by the surgical removal of the soleus and most of the gastrocnemius muscles. Twelve to 16 wk later whole muscle and motor unit (ventral root dissection technique) contractile properties as well as histochemistry were determined. 2. Motor units were categorized as fast, fatigable (FF), fast, intermediate fatigue-resistant (FI), fast, fatigue-resistant (FR), and slow (S) based on contractile characteristics. Muscle fibers were identified as type I and type II according to myofibrillar ATPase staining. 3. Whole muscles demonstrated increases in wet weight, tetanic force, proportion of type I fibers, and mean cross-sectional areas of both type I and II fibers, as a result of chronic overload. 4. Tetanic tension increased by the same relative magnitude in all motor units whereas twitch tension remained unchanged. A significant change in the proportions of the motor unit types occurred in overloaded muscles, such that the latter contained higher proportions of FF and S units, and lower proportions of FI and FR units, than normal muscles. 5. The fatigue profile of a composite constructed from a summation of motor unit responses revealed that the overloaded plantaris displayed fatigue resistance similar to that of the normal plantaris for a given absolute force output. 6. Glycogen-depleted fibers of hypertrophied single motor units demonstrated uniform myofibrillar ATPase and SDH staining characteristics suggesting that metabolic adaptations among fibers of the same unit were similar after 12-16 wk of overload. 7. The finding that overload caused a uniform increase in the tetanic strength of all motor units, whereas alterations in fatigue resistance varied in degree and direction among unit types, demonstrate that these two properties are not controlled in parallel in this model. The smallest units maintain or even increase their fatigue resistance during the hypertrophic process, whereas high threshold units actually decrease in fatigue resistance.

Properties of self-reinnervated motor units of medial gastrocnemius of cat. II. Axotomized motoneurons and time course of recovery

1986 ◽  
Vol 55 (5) ◽  
pp. 947-965 ◽  
Author(s):  
R. C. Foehring ◽  
G. W. Sypert ◽  
J. B. Munson
Keyword(s):  
Electrical Properties ◽  
Motor Unit ◽  
Fatigue Resistance ◽  
Time Course ◽  
Muscle Fibers ◽  
Motor Units ◽  
Input Resistance ◽  
Medial Gastrocnemius ◽  
Muscle Properties ◽  
Fast Twitch

This study tested the hypothesis that functional connection to muscle is necessary for expression of normal motoneuron electrical properties. Also examined was the time course of self-reinnervation. Properties of individual medial gastrocnemius (MG) motor units were examined following section and reanastomosis of the MG nerve. Stages examined were 3-5 wk (prior to reinnervation, no-re), 5-6 wk (low-re), 9-10 wk (med-re), and 9 mo (long-re, preceding paper) after nerve section. Motor units were classified on the basis of their mechanical response as type fast twitch, fast fatiguing (FF), fast twitch with intermediate fatigue resistance (FI), fast twitch, fatigue resistant (FR), or slow twitch, fatigue resistant (S) (11, 24). Motoneuron electrical properties were measured. Muscle fibers were classified using histochemical methods as type fast glycolytic (FG), fast oxidative glycolytic (FOG), or slow oxidative (SO) (60). Prior to functional reinnervation, MG motoneurons exhibited increased input resistance, decreased rheobase, decreased rheobase/input resistance, and decreased axonal conduction velocity. There was no change in mean afterhyperpolarization (AHP) half-decay time. Normal relationships between motoneuron electrical properties were lost. These data are consistent with dedifferentiation of motoneuron properties following axotomy (35, 47). At 5-6 wk after reanastomosis, motor-unit tensions were small, and motoneuron membrane electrical properties were unchanged from the no-re stage. There were no differences in motoneuron electrical properties between cells that elicited muscle contraction and those that did not. Motor-unit types were first recognizable at the med-re stage. The proportions of fast and slow motor units were similar to normal MG. Within the fast units, there were fewer type-FF units and more type-FI and type-FR units than normal, reflecting a general increase in fatigue resistance at this stage. Neither motoneuron membrane electrical properties nor muscle contractile properties had reached normal values, although both were changed in that direction from the low-re stage. Normal relationships between muscle properties, between motoneuron properties, and between motoneuron and muscle properties were re-established. The correspondence between motor-unit type and motoneuron type was similar to normal or 9 mo reinnervated MG. Muscle-unit tetanic tensions became larger with time after reinnervation. Most of the increase in muscle tension beyond the med-re stage could be accounted for by increase in muscle fiber area. There was an increased proportion of SO muscle fibers observed in the med-re muscles, as at the long-re stage.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Drawing with the Non-dominant Hand: Implications for the Study of Construction

1998 ◽  
Vol 25 (4) ◽  
pp. 306-309 ◽  
Author(s):  
Sherma Zacharias ◽  
Andrew Kirk
Keyword(s):  
Neurological Disease ◽  
Right Hemisphere ◽  
Normal Subjects ◽  
Elderly Subjects ◽  
Dominant Hand ◽  
Left Hand ◽  
Right Hand ◽  
Left And Right ◽  
The Right ◽  
Right And Left Hand

ABSTRACT:Background:Constructional impairment following left vs. right hemisphere damage has been extensively studied using drawing tasks. A confounding factor in these studies is that right-handed patients with left hemisphere damage (LHD) are often forced by weakness to use their non-dominant (left) hand or hemiparetic dominant hand. Qualitative differences in the drawing characteristics of left and right hand drawings by normal subjects have not previously been characterized. The present study was undertaken to determine the qualitative differences between left and right hand drawings of normal subjects.Methods:Thirty right-handed, elderly subjects without a history of neurological disease were asked to draw, from memory, seven objects using the right and left hand. Half of the subjects were randomly assigned to draw with the left hand first, and half the right hand first. Right and left hand drawings were compared using a standardized scoring system utilized in several previous studies of drawing in focal and diffuse neurological disease. Each drawing was scored on eighteen criteria. Right and left hand drawing scores were then compared using the t-test for paired samples or the Wilcoxon matched-pairs testResults:Drawings made using the left hand were found to be significantly simpler, more tremulous and of poorer overall quality than drawings made by the same subjects using the right hand.Conclusions:The deficits found in left versus right hand drawings of normals are similar to those found in patients with LHD, suggesting that much of the drawing impairment seen following LHD is due to an elementary motor disturbance related to use of the non-dominant hand.

Properties of self-reinnervated motor units of medial gastrocnemius of cat. I. Long-term reinnervation

1986 ◽  
Vol 55 (5) ◽  
pp. 931-946 ◽  
Author(s):  
R. C. Foehring ◽  
G. W. Sypert ◽  
J. B. Munson
Keyword(s):  
Electrical Properties ◽  
Muscle Contraction ◽  
Motor Unit ◽  
Fatigue Resistance ◽  
Muscle Fibers ◽  
Motor Units ◽  
Contractile Properties ◽  
Medial Gastrocnemius ◽  
Unit Type ◽  
Fast Twitch

This work tested whether the membrane electrical properties of cat motoneurons, the contractile properties of their muscle units, and the normal relationships among them would be restored 9 mo after section and resuture of their muscle nerve. Properties of medial gastrocnemius (MG) motor units were examined 9 mo following section and resuture of the MG nerve in adult cats. Motoneuron electrical properties and muscle-unit contractile properties were measured. Motor units were classified on the basis of their contractile properties as type fast twitch, fast fatiguing (FF), fast twitch with intermediate fatigue resistance (FI), fast twitch, fatigue resistant (FR), or slow twitch, fatigue resistant (S) (8, 20). Muscle fibers were classified as type fast glycolytic (FG), fast oxidative glycolytic (FOG), or slow oxidative (SO) on the basis of histochemical staining for myosin adenosine triphosphatase, nicotinamide adenine dinucleotide diaphorase, and alpha-glycerophosphate dehydrogenase (48). Following 9 mo self-reinnervation, the proportions of each motor-unit type were the same as in normal control animals. Motoneuron membrane electrical properties [axonal conduction velocity, afterhyperpolarization (AHP) half-decay time, rheobase, and input resistance] also returned to control levels in those motoneurons that made functional reconnection with the muscle (as determined by ability to elicit measurable tension). The relationships among motoneuron electrical properties were normal in motoneurons making functional reconnection. Approximately 10% of MG motoneurons sampled did not elicit muscle contraction. These cells' membrane electrical properties were different from those that did elicit muscle contraction. Contractile speed and fatigue resistance of reinnervated muscle units had recovered to control levels at 9 mo postoperation. Force generation did not recover fully in type-FF units. The reduced tensions were apparently due to failure of recovery of FG muscle fiber area. Following reinnervation, relationships between motoneuron electrical and muscle-unit contractile properties were similar to controls. This was reflected in a degree of correspondence between motor-unit type and motoneuron type similar to normal units (84 vs. 86%, as defined by Ref. 61). There was a significantly increased proportion of type-SO muscle fibers and a decrease in the fast muscle fibers (especially type FOG) in 9 mo reinnervated MG. Together with the unchanged proportions of motor-unit types, this led to an estimate of average innervation ratios being increased in type-S motor units and decreased in type-FR units.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptations of rat lateral gastrocnemius motor units in response to voluntary running

1995 ◽  
Vol 78 (5) ◽  
pp. 1673-1678 ◽  
Author(s):  
K. L. Seburn ◽  
P. Gardiner
Keyword(s):  
Motor Unit ◽  
Fatigue Resistance ◽  
Wheel Running ◽  
Motor Units ◽  
Lateral Gastrocnemius ◽  
Tetanic Force ◽  
Direct Demonstration ◽  
Voluntary Running ◽  
Normal Functional ◽  
Tetanic Tension

This study investigated the effects of 12 wk of voluntary wheel running on motor units from rat lateral gastrocnemius. Motor units were isolated via ventral root splitting (L5) from active or sedentary rats and were classified into slow, fast-fatigue-resistant, and fast-fatigable (FF) units. An overall increase in mean motor unit tetanic tension (35%) was accompanied by a decrease in mean motor unit fatigue resistance (-10%). These adaptations were localized in the fast unit population but varied among fast motor unit subtypes. The overall increase in tetanic force was due primarily to increases in fast-fatigue-resistant units (300%), whereas changes in fatigue resistance (-43%) were confined to FF units. However, the changes seen with activity may have been partly obscured by classifying fast motor units based on fatigability, since a significant increase in tetanic force accompanied by a decreased twitch one-half relaxation time was apparent in units falling in the midrange of the tetanic force continuum and included a number of FF units. These data provide direct demonstration of nonuniform motor unit adaptations subsequent to increases in normal functional activity.

scholarly journals Inter- and Intra-individual Variations in Foveal Outer Nuclear Layer Thickness and Their Associations with Clinical Characteristics in a Healthy Chinese Population

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Jia Yu ◽  
Lei Li ◽  
Chunhui Jiang ◽  
Qing Chang ◽  
Qi Zhao
Keyword(s):  
Chinese Population ◽  
Clinical Characteristics ◽  
Linear Models ◽  
Outer Nuclear Layer ◽  
Normal Subjects ◽  
Individual Variations ◽  
Actual Degree ◽  
Healthy Chinese ◽  
The Difference ◽  
The Right

Purpose. To evaluate foveal outer nuclear layer (ONL) thickness and the difference thereof between bilateral eyes and their possible associations with clinical characteristics in a healthy Chinese population. Materials and Methods. Normal subjects were enrolled. Generalized linear models were used to assess the associations of foveal ONL thickness with sex, age, and spherical equivalents (SEs) and the associations of the difference in foveal ONL thickness between bilateral eyes with sex, age, and difference in SEs between bilateral eyes. Results. Totally, 304 subjects were included. The average foveal ONL thickness was 103.19 ± 14.25 (range 70–151) μm in the right eye and 103.90 ± 14.63 (range 69–155) μm in the left eye. The mean difference in foveal ONL thickness between right and left eyes was −0.71 ± 4.36 (range −13 to +12) μm. Men had slightly greater foveal ONL thickness values in both right and left eyes compared with women (both P<0.05); however, some women had a thicker foveal ONL than that of men (85/198 vs. 46/106 in the right eye; 79/198 vs. 52/106in the left eye). Age and SEs were not associated with foveal ONL thickness in either eye (all P>0.05). Sex, age, and difference in SEs between bilateral eyes were not associated with the difference in foveal ONL thickness between bilateral eyes (all P>0.05). Conclusions. Foveal ONL thickness showed wide variation in a normal Chinese population but little difference between bilateral eyes. Both these parameters could not be adjusted by sex, age, SEs, or the SEs difference between bilateral eyes. Thus, in those diseases involving only one eye, the difference or ratio of foveal ONL thickness between the affected eye and normal fellow eye may reflect the actual degree of the disease, rather than the foveal ONL thickness in the affected eye alone.

Effects of chronic spinalization on ankle extensor motoneurons. III. Composite Ia EPSPs in motoneurons separated into motor unit types

1994 ◽  
Vol 71 (4) ◽  
pp. 1480-1490 ◽  
Author(s):  
S. Hochman ◽  
D. A. McCrea
Keyword(s):  
Electrical Properties ◽  
Motor Unit ◽  
Rise Time ◽  
Motor Units ◽  
Input Resistance ◽  
Half Width ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Mean Values ◽  
The Difference

1. In this paper we continue an examination of changes in composite Ia excitatory postsynaptic potentials (EPSPs) in ankle extensor motoneurons after 6-wk (L1-L2) spinal cordotomy. The ratio of rheobase to input resistance was used to divide motoneurons into three groups approximating fast-fatigable (FF), fast fatigue-resistant (FR), and slow (S) motor units in barbiturate-anesthetized cats. Homonymous monosynaptic Ia EPSPs evoked by low-strength [1.2 times threshold (T)] electrical stimulation and heteronymous EPSPs evoked by 2T stimulation were compared between groups of motoneurons in unlesioned and chronic spinal preparations. 2. The distribution of motor unit types of triceps surae and plantaris (PL) motoneurons according to the present classification scheme agrees well with that obtained elsewhere using mechanical typing. Chronic spinalization resulted in an increased proportion of type FF motoneurons in PL and type FR motoneurons in lateral gastrocnemius (LG) motoneurons. There was a numeric but insignificant increase in the proportion of fast medial gastrocnemius motor units. 3. Membrane time constant (tau m) and estimated total cell capacitance were significantly reduced in FF and S motoneurons in chronic spinal preparations. FF motoneurons from chronic spinal animals also had a reduced afterhyperpolarization duration. Mean values of membrane electrical properties in FR motoneurons were unaltered after spinalization. 4. Homonymous Ia EPSP changes after chronic spinalization occurred preferentially in type FR and S motor units. Amplitudes increased 69% in type FR and 38% type S motor units but were unchanged in type FF units. Furthermore, the amplitudes of heteronymous Ia EPSPs in type FF and S units in the chronic spinal preparation were almost double those in unlesioned preparations. 5. Homonymous EPSP 10-90% rise times decreased 25% in type FR motor units and 15% in type S motor units and were unchanged in type FF motor units. Homonymous EPSP half-width decreased in all three motoneuron groups. Normalization of EPSP rise time and half-width to tau m reduced the difference between EPSP shape indexes in unlesioned and chronic spinal preparations in type FF and S motoneurons but less so in type FR motoneurons. Normalized EPSP shape indexes in some type FR units were shorter after chronic spinalization than any in unlesioned preparations. 6. The increased amplitude and decreased rise time of Ia EPSPs in type FR motoneurons after spinalization occurred without changes in the electrical properties of type FR motor units.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Software-Assisted Depth Analysis of Optic Nerve Stereoscopic Images in Telemedicine

2016 ◽  
Vol 2016 ◽  
pp. 1-5
Author(s):  
Tian Xia ◽  
Shriji N. Patel ◽  
Ben C. Szirth ◽  
Anton M. Kolomeyer ◽  
Albert S. Khouri
Keyword(s):  
Optic Nerve ◽  
Intraclass Correlation ◽  
Normal Subjects ◽  
Stereo Pair ◽  
Depth Analysis ◽  
The Difference ◽  
The Right ◽  
A Prospective Study ◽  
High Degree ◽  
Cup To Disc Ratio

Background. Software guided optic nerve assessment can assist in process automation and reduce interobserver disagreement. We tested depth analysis software (DAS) in assessing optic nerve cup-to-disc ratio (VCD) from stereoscopic optic nerve images (SONI) of normal eyes.Methods. In a prospective study, simultaneous SONI from normal subjects were collected during telemedicine screenings using a Kowa 3Wx nonmydriatic simultaneous stereoscopic retinal camera (Tokyo, Japan). VCD was determined from SONI pairs and proprietary pixel DAS (Kowa Inc., Tokyo, Japan) after disc and cup contour line placement. A nonstereoscopic VCD was determined using the right channel of a stereo pair. Mean, standard deviation,t-test, and the intraclass correlation coefficient (ICCC) were calculated.Results. 32 patients had mean age of40±14years. Mean VCD on SONI was0.36±0.09, with DAS0.38±0.08, and with nonstereoscopic0.29±0.12. The difference between stereoscopic and DAS assisted was not significant (p=0.45). ICCC showed agreement between stereoscopic and software VCD assessment. Mean VCD difference was significant between nonstereoscopic and stereoscopic (p<0.05) and nonstereoscopic and DAS (p<0.005) recordings.Conclusions. DAS successfully assessed SONI and showed a high degree of correlation to physician-determined stereoscopic VCD.

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