Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DECELERATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,783 records · Page 99Linked to original sources
PubMed2006

[Growth of full term low and adequate birth weight infants during the first two years of life].

OBJECTIVE: To assess the growth pattern of full term low and adequate birth weight infants during the first two years of life and to identify the determinants at the time of the greatest growth deceleration. METHODS: A prospective cohort study was conducted with 148 full term infants in five small towns of the state of Pernambuco, Northeastern Brazil. Newborns were recruited from maternities between January 1993 and January 1994 and their anthropometric measurements were taken at one, two, four, six, 12 and 24 months of life. Risk factors were analyzed using multivariable linear regression. RESULTS: The increment of mean weight-for-age and length-for-age were more evident for low birth weight when compared with adequate weight infants, especially during the first two months after birth. From this point onward it was observed a progressive mean growth deceleration in both indexes up to 12 months of life. All infants had similar weight and length growth patterns. However, adequate birth weight infants remained in an upper level. Socioeconomic variables explained 23% of variation for weight-for-age, followed by 4% for birth weight. Socioeconomic condition was also the factor mostly affecting length-for-age, explaining 28% of its variation, followed by birth weight, maternal height and diarrhea. CONCLUSIONS: The study results suggest that interventions aiming to adequate growth should focus on prenatal care and social and environmental factors during childhood as a way of ensuring full expression of the genetic potential of this population.

Age Factors↗
PubMedDate not supplied

Pulsed tissue Doppler imaging in normal cats and cats with hypertrophic cardiomyopathy.

Myocardial motion was quantified in normal cats (n = 25) and cats with hypertrophic cardiomyopathy (HCM) (n = 23) using the pulsed tissue Doppler imaging (TDI) technique. A physiologic nonuniformity was documented in the myocardial motion of normal cats, which was detected as higher early diastolic velocities, acceleration, and deceleration in the interventricular septum compared with the left ventricular free wall (LVFW). HCM cats exhibited lower early diastolic velocities, acceleration, and deceleration and also prolonged isovolumic relaxation time compared with normal cats. These differences were detected mainly along the longitudinal axis of the heart. A cutoff value of E' in the LVFW along the longitudinal axis >7.2 cm/s discriminated normal from HCM cats with a sensitivity of 92% and a specificity of 87%. The physiologic nonuniformity of myocardial motion during diastole was lost in affected cats. Systolic impairment (decreased late-systolic velocities in most segments along the longitudinal axis and decreased early systolic acceleration in both mitral annular sites) was evident in HCM cats irrespective of the presence of left ventricular outflow tract obstruction and congestive heart failure. Postsystolic thickening was recorded in the LVFW along the longitudinal axis only in affected cats (n = 6) and was another finding indicative of systolic impairment in the HCM of this species. This study identified both diastolic and systolic impairment in cats with HCM compared with normal cats. The study also documents the normal physiologic nonhomogeneity in myocardial motion in cats and the subsequent loss of this feature in the HCM diseased state.

Animals↗
PubMed1991

Behavioral economics of drug self-administration. II. A unit-price analysis of cigarette smoking.

In behavioral economics, the ratio of response requirement to reinforcer magnitude is referred to as unit price. Previous research with nonhuman subjects has demonstrated that (a) comparable amounts of food are consumed at the same unit price even though different response requirements and reinforcer magnitudes comprise that unit price and (b) increases in unit price decrease food consumption in a positively decelerating fashion. The present study assessed the generality of these findings to the cigarette smoking of 5 human volunteers. During approximately 18 3-hr sessions, various combinations of response requirement (fixed-ratio 200, 400, and 1,600) and reinforcer magnitude (1, 2, and 4 puffs per bout) were arranged. Consumption (i.e., the number of puffs) generally was comparable at the same unit price independent of the response requirement and reinforcer magnitude comprising that unit price. In addition, increasing unit price generally decreased consumption in a positively decelerating fashion. These results extend the generality of the unit-price analysis to human cigarette smoking. Moreover, these results further support the position that reinforcer magnitude and response requirement are functionally equivalent and interact to determine consumption. The concept of unit price, by integrating and summarizing the effects of those two operations, provides a more parsimonious explanation of the results than do separate evaluations of the effects of response requirement and reinforcer magnitude.

Adolescent↗
PubMed1996

Labour analgesia. A risk-benefit analysis.

The pain associated with labour can be severe. The ideal labour analgesic does not exist and systemic opioids provide little relief. Nausea, vomiting and sedation are common adverse effects of systemic opioids. Paracervical block can relieve only the pain of the first stage of labour. The duration of analgesia obtained using paracervical block is limited and repeat blocks increase the risk of direct fetal injection. Epidural analgesia effectively relieves labour pain. The insertion of an epidural catheter can provide continuous analgesia throughout labour. In addition, the catheter can be used to provide surgical anaesthesia, should operative delivery be required. Epidural local anaesthetics commonly produce maternal hypotension and motor blockade. However, opioids potentiate the effect of epidural local anaesthetics. Thus, concomitant epidural opioid injection allows the use of lower concentrations of local anaesthetics, decreasing the frequency and severity of hypotension and motor blockade. Epidural analgesia has other, potentially catastrophic, adverse effects but, with safe clinical practice, these problems are extremely rare. Intrathecal injection of opioids or local anaesthetics also effective labour analgesia. However, no single intrathecal drug or drug combination reliably provides analgesia for the duration of labour. Many clinicians use both intrathecal and epidural analgesia as a combined spinal-epidural technique. This approach provides the rapid onset of intrathecal drugs and the flexibility of continuous epidural block. Fetal heart rate decelerations occasionally follow the use of any of the above labour analgesic techniques. Most studies of the aetiology of fetal heart rate decelerations have focused on factors unique to each analgesic technique. However, the similar timing and appearance of fetal bradycardia suggests a common cause. Induction of maternal analgesia may transiently alter the balance between factors encouraging and inhibiting uterine contraction. A temporary increase in the uterotonic effects of endogenous or exogenous oxytocin may then produce a tetanic uterine contraction with subsequent decrease fetal oxygen delivery and resultant fetal bradycardia. Regardless of aetiology, these bradycardias are transient and should not produce maternal or fetal morbidity. Much controversy surrounds the effects of analgesia, especially epidural block, on the course and outcome of labour. Various studies have reported that epidural analgesia slows labour, increases the incidence of malposition of the fetal head, increases the need for forceps delivery and increases the risk of caesarean delivery. Most of the studies reporting these effects are retrospective and nonrandomised. More careful studies suggest that specific anaesthetic techniques (i.e. local anaesthetic-opioid mixtures) or obstetrical management can limit or eliminate these 'risks' of epidural labour analgesia.

Adult↗
PubMedDate not supplied

Neurological sequelae of boxing.

Blunt trauma to the head results in acceleration of the brain within the skull. This takes 2 forms: linear or translational acceleration which produces focal lesions, and rotational acceleration which results in 'sheering stresses' with stretching of nerves and bridging veins. Deceleration of the brain within the skull occurs when the head strikes a stationary object (e.g. floor, ring post). Cerebrovascular events are not infrequently encountered. The most common vascular sequalae is the subdural haematoma, which is also the most frequent cause of death in boxers. Epidural bleeds rare, and are generally due to deceleration of the brain. Subarachnoid bleeds have been rarely reported, but, like intraparenchymal haemorrhages, they do occur. Sudden flexion/extension of the neck is suggested as the mechanism of the occasional brainstem haemorrhage reported in boxing. Thrombosis of the internal carotid artery can occur secondary to direct blows to the neck or stretching of the contralateral carotid artery. The best known sequalae of boxing is traumatic encephalopathy--the 'punch drunk' syndrome. This is most common in second-rate and slugging type fighters. Severity correlates with the length of a boxer's career and total number of bouts, with an incidence of approximately 18%. Three stages of clinical deterioration are seen, the encephalopathy may be progressive or may remain clinically stable at any level. The first stage consists of affective disturbances with psychiatric symptoms being most marked. During the second stage an accentuation of the psychiatric symptoms occurs and signs/symptoms of Parkinsonism develop. The final stage consists of a decrease in general cognitive function together with pyramidal tract disease. Generally 2 to 3 years elapse between the first and final stages. Neuropathological studies reveal abnormalities of the septum pellucidum, scarring of the cerebellar and cerebral cortices, and loss of pyramidal neurons in the substantia nigra with neurofibrillary tangles in the absence of senile plaques. A 'groggy state' can occur in some fighters with confusion, impaired active attention and alteration of consciousness. During this period the boxer is at greater risk to suffer brain injury as defensive reflexes are frequently lost. Other neurological syndromes have been reported in addition to the 'groggy state'. These include a midbrain syndrome, headaches and cervical spinal injuries. Additionally, boxing appears to be a significant risk factor for the development of meningiomas.(ABSTRACT TRUNCATED AT 400 WORDS)

Athletic Injuries↗
PubMed1992

Biomechanics of sprint running. A review.

Understanding of biomechanical factors in sprint running is useful because of their critical value to performance. Some variables measured in distance running are also important in sprint running. Significant factors include: reaction time, technique, electromyographic (EMG) activity, force production, neural factors and muscle structure. Although various methodologies have been used, results are clear and conclusions can be made. The reaction time of good athletes is short, but it does not correlate with performance levels. Sprint technique has been well analysed during acceleration, constant velocity and deceleration of the velocity curve. At the beginning of the sprint run, it is important to produce great force/power and generate high velocity in the block and acceleration phases. During the constant-speed phase, the events immediately before and during the braking phase are important in increasing explosive force/power and efficiency of movement in the propulsion phase. There are no research results available regarding force production in the sprint-deceleration phase. The EMG activity pattern of the main sprint muscles is described in the literature, but there is a need for research with highly skilled sprinters to better understand the simultaneous operation of many muscles. Skeletal muscle fibre characteristics are related to the selection of talent and the training-induced effects in sprint running. Efficient sprint running requires an optimal combination between the examined biomechanical variables and external factors such as footwear, ground and air resistance. Further research work is needed especially in the area of nervous system, muscles and force and power production during sprint running. Combining these with the measurements of sprinting economy and efficiency more knowledge can be achieved in the near future.

Acceleration↗
PubMed1996

Biomechanics of overhand throwing with implications for injuries.

Proper throwing mechanics may enable an athlete to achieve maximum performance with minimum chance of injury. While quantifiable differences do exist in proper mechanics for various sports, certain similarities are found in all overhand throws. One essential property is the utilisation of a kinetic chain to generate and transfer energy from the larger body parts to the smaller, more injury-prone upper extremity. This kinetic chain in throwing includes the following sequence of motions: stride, pelvis rotation, upper torso rotation, elbow extension, shoulder internal rotation and wrist flexion. As each joint rotates forward, the subsequent joint completes its rotation back into a cocked position, allowing the connecting segments and musculature to be stretched and eccentrically loaded. Most notable is the external rotation of the shoulder, which reaches a maximum value of approximately 180 degrees. This biomechanical measurement is a combination of true glenohumeral rotation, trunk hyperextension and scapulothoracic motion. Near the time of maximum shoulder external rotation (ERmax), shoulder and elbow musculature eccentrically contract to produce shoulder internal rotation torque and elbow varus torque. Both the shoulder and the elbow are susceptible to injury at this position. At ball release, significant energy and momentum have been transferred to the ball and throwing arm. After ball release, a kinetic chain is used to decelerate the rapidly moving arm with the entire body. Shoulder and elbow muscles produce large compressive forces to resist joint distraction. Both joints are susceptible to injury during arm deceleration.

Arm↗
PubMed1985

Traumatic laceration of the ascending aorta: angiographic assessment.

Radiographic evaluation of ascending aortic injuries is rare because they are almost always immediately fatal. We report three cases of ascending aortic laceration studied by angiography, with a review of the literature and discussion of mechanisms of injury. The type of deceleration trauma resulting in ascending aortic laceration differs from the usual driver deceleration injury in that no attenuation of force on the victim occurs at the time of impact. Traction-torsion forces on the aorta at points of fixation and increased intraluminal aortic pressure are the likely mechanisms of rupture. Adequate angiographic evaluation of these patients requires visualizing the entire aortic arch from aortic valve to diaphragm.

Adolescent↗
PubMed1991

Value of CT in determining the need for angiography when findings of mediastinal hemorrhage on chest radiographs are equivocal.

The role of CT in determining the need for angiography in patients with possible thoracic vascular injury resulting from blunt trauma is controversial. During a 24-month period, we prospectively evaluated the results of CT to screen 90 patients with a history of decelerating thoracic trauma for evidence of mediastinal hemorrhage or great vessel abnormality. All patients either had equivocally abnormal mediastinal contours on chest radiographs (64%) or had technically suboptimal chest radiographs owing to body habitus or restriction to the supine projection (36%). Patients with unequivocal signs of mediastinal hemorrhage on chest radiographs underwent immediate arteriography without prior CT. Thoracic CT was interpreted as normal in 63 (77%) patients and no further imaging was performed. Five patients had technically suboptimal CT studies, and CT scans were interpreted as equivocal in six. These 11 patients had normal arteriograms. Sixteen CT scans (18%) demonstrated evidence of mediastinal hemorrhage and/or great vessel contour abnormality. Four (27%) of 15 patients who underwent arteriography had injury to the great vessels. One patient refused to undergo angiography. In 11 patients with CT evidence of mediastinal hemorrhage, major vascular injury was not seen on arteriography. These results suggest a valuable role for CT in determining the need for arteriography to detect potential great vessel injury in patients with blunt decelerating thoracic trauma and equivocally abnormal mediastinal contours on chest radiographs.

Adult↗
PubMedDate not supplied

[Postoperative changes in diastolic function of the left ventricle in patients with aortic valve stenosis].

INTRODUCTION: Diastolic dysfunction in valvular aortic stenosis frequently precedes systolic dysfunction. The purpose of this study was to examine the changes in left ventricular diastolic function after aortic valve replacement. METHODS: Seventy eight patients with significant isolated valvular aortic stenosis were enrolled in the study. The echocardiographic examination was performed with ACUSON-XP 10 imaging system. Complete M-mode, 2-dimensional and Doppler echocardiographic results were obtained. In 48 patients right and left heart catheterisation was performed. Left ventricular diastolic function was evaluated by pulse Doppler recording of inflow velocity on the tips of the mitral valve leaflets. Forty two underwent aortic valve replacement. They were followed up 6-12 months postoperatively. RESULTS: Abnormal patterns of left ventricular diastolic filling were noticed in almost all patients (Table 1). Most prominent changes were found in subjects with marked and diffuse hypertrophy (Table 2). After aortic valve replacement decrease in left ventricular size, mass, pressures and improvement in systolic Function (Table 3). Twelve months after the operation late diastolic filling velocity was lower (A = 64 +/- 15 cm/s, Avti = 7.1 +/- 1.8 cm), early diastolic filling velocity was higher (E = 83 +/- 14 cm/s, Evti = 10.3 +/- 1.4 cm), deceleration time (DT = 123 +/- 14 ms) and isovolumetric relaxation time (IRT = 66 +/- 6 ms) were longer in patients with preoperative moderate hypertrophy (Table 4). In patients with severe left ventricular hypertrophy changes in diastolic function were slower. We found decrease in early diastolic filling velocity (A = 44 +/- 6 cm/s, Avti = 4.6 +/- 04 cm), increase in late diastolic filling velocity (E = 67 +/- 14 cm/s, Evti = 9.4 +/- 1.7 cm), with prolongation of deceleration (DT = 131 +/- 18 ms) and isovolumetric relaxation time (IRT = 94 +/- 23 ms) (Table 5). DISCUSSION: In adults with significant sympthomatic aortic valve stenosis, aortic valve replacement is therapy of choice. Replacement of the diseased aortic valve with a prosthetic valve yields relief of left ventricular outflow obstruction. Myocardial remodeling with regression of mass transpires as the heart adapts to the new level of afterload. In patients with moderate left ventricular hypertrophy improvement in diastolic function during the first year after aortic valve replacement is visible, while in patients with extreme myocardial hypertrophic changes it was slower.

Adolescent↗
PubMed2004

[Renoprotective effect of ramipril in children with chronic renal failure--the experience of one centre].

The objective of our study was to evaluate the changes of blood pressure (BP), urinary protein excretion (PRT/Cr) and renal function (GFR) after long-term administration of ACE inhibitor, ramipril. This prospective trial, a part of the European Multicentric Escape Study, included 14 patients (5 girls and 9 boys), mean-age 11 years, with congenital renal malformations. The basic inclusion criteria were stable chronic renal failure (CRF) and mean arterial pressure (MAP) above 50 percentile defined by 24-hour ABPM or earlier antihypertensive medication. The patients were studied 6 months before and up to 36 months after the introduction of ramipril therapy. The dosage of ramipril ranged from 4.7 to 7.7 mg/ m2 SBA, mean 37.8 (+/- 4.03) mg/m2 SBA. The patients were controlled every two months for BP, proteinuria and GFR, while 24-hour ABPM was performed in 6 months. The significant decrease of regular and 24-hour ambulatory blood pressure (ABP), systolic, diastolic and MAP, was found within the first months of treatment, while ramipril-induced reduction of proteinuria and slowing down of GFR were delayed. BP did not differ significantly among patients, but antiproteinuric effect and influence on GFR showed large individual variations. Antiproteinuric and antihypertensive effects of ramipril correlated with underlying proteinuria, GFR and blood pressure. However, there was no constant relationship between changes of proteinuria and BP. Ramipril has been shown to: lower BP significantly, decrease proteinuria slowly, and significantly decelerate GFR after 18 months of treatment. Considering favorable preliminary results of lower BP, decrease of proteinuria and decelerated GFR, an optimal renal protection by long-term therapy with ACE inhibitors may be expected in children with CRF caused by congenital renal malformations.

Adolescent↗
PubMed1992

Effect of glycemic control on growth velocity in children with IDDM.

OBJECTIVE: To determine the effect of glycemic control on growth velocity in children with insulin-dependent diabetes mellitus. RESEARCH DESIGN AND METHODS: One hundred twenty-two children with insulin-dependent diabetes mellitus were studied over a 5-yr period. Every 4 mo, glycemic control was assessed by measuring total glycosylated hemoglobin (GHb), pubertal status was determined by physical examination, and height was measured with a stadiometer. Height measurements were normalized for age and sex by converting them to tau scores (the number of SD above or below the mean for age and sex). Alterations in growth velocity were determined by the change in tau scores (delta tau) between visits (i.e., no change in tau score = normal growth velocity; decrease in tau score = growth deceleration; and increase in tau score = growth acceleration). RESULTS: A linear relationship was seen between GHb levels and the change in tau scores (r = -0.117, P = 0.001). GHb values less than 8% were associated with growth acceleration (delta tau = +0.10 +/- 0.03), and the greatest growth deceleration occurred when GHb was greater than 16% (delta tau = -0.07 +/- 0.03). The level of GHb at which growth suppression occurred (mean delta tau became negative) was dependent on pubertal status: Tanner stage 1 greater than or equal to 10%, Tanner stages 2 and 3 greater than or equal to 8%, Tanner stages 4 and 5 greater than or equal to 16%. CONCLUSIONS: Linear growth velocity in children with insulin-dependent diabetes mellitus is heavily related to metabolic control. Children who are prepubertal or in the early stages of puberty are the most vulnerable to growth suppression. Once puberty is well established, growth suppression does not occur until marked hyperglycemia (GHb greater than 16%) exists.

Adolescent↗
PubMed1994

The relationship between subjective knee scores, isokinetic testing, and functional testing in the ACL-reconstructed knee.

It is important to examine the functional relationships between commonly performed clinical tests and to resolve inconsistencies in previous investigative results. The purpose of this study was to determine if a correlation exists between three commonly performed clinical tests: isokinetic isolated knee concentric muscular testing, the single-leg hop test, and the subjective knee score in anterior cruciate ligament reconstructed knees. To determine if a relationship exists would be beneficial to clinicians in determining patient progression, treatment modification, and return-to-sport objective parameters. Several investigators have analyzed two of these parameters, but no one has investigated three parameters to date. Additionally, this study explored the concept of limb acceleration and deceleration during high-speed isokinetics and its relationship to function. Fifty patients were randomly selected (29 males) with a mean age of 23.7 years (range 15-52). The subjects completed a subjective knee score questionnaire that rated symptoms (pain, swelling, giving way) and specific sport function and completed an overall knee score assessment. The patients were then evaluated performing three one-legged functional tests: 1) hop for distance, 2) timed hop, and 3) cross-over triple hop. Isokinetic testing was performed on a Biodex dynamometer at 180, 300, and 450 degrees/sec for knee extension/flexion. The patients' mean value of the self-assessed knee rating was 86 points. Sixty-four percent of the patients exhibited normal limb symmetry (within 85%) on all three single-leg hop tests. Sixteen percent exhibited quadriceps strength at least 90% of the contralateral limb isokinetically. A positive correlation was noted between isokinetic knee extension peak torque (180, 300 degrees/sec) and subjective knee scores, and the three hop tests (p < 0.001). A statistical trend was noted between knee extension acceleration and deceleration range at 180 and 300 degrees/sec for the timed hop test and triple cross-over hop (r = 0.48, r = 0.49, r = 0.51, r = 0.49). No positive correlations were found for isokinetic test results for the knee flexors.

Adolescent↗
PubMed1995

Effect of a helium-neon laser on cutaneous inflammation.

A Helium-Neon (He-Ne) laser with a wavelength of 632.8 nm is known to have photobiological effects and is widely used for reducing the pain of herpes zoster and accelerating wound healing, however the cellular mechanism and effect of the He-Ne laser are poorly understood. The present study was designed to examine the influence of He-Ne laser irradiation on irritant and allergic contact dermatitis of the mouse ear and on histamine release from rat peritoneal mast cells. Irradiation was applied with a He-Ne laser (12.2 J/cm2) at 1 h, 10 min, 5 min and 0 min before, and 5 min, 6 hs and 24 hs after a challenge of an irritated contact dermatitis (ICD) or allergic contact dermatitis (ACD) was made on the right ears of ICR-mice. Twenty-four hours after the challenge, the swelling of the ear was measured with a dial thickness gauge, and the anti-inflammatory effect of He-Ne laser irradiation was expressed as an ear thickness ratio (ETR). Although the laser did not decelerate the ETR from ICD, the allergic response was decelerated. Irradiation at 5 min after the challenge of contact dermatitis increased the thickness ratio. Next, the influence of the He-Ne laser on histamine release from Wistar-rat peritoneal mast cells was observed. The spontaneous histamine release was inhibited by laser irradiation, while substance P and compound 48/80-induced histamine release were not inhibited. From these results, it can be suggested that He-Ne laser irradiation has an anti-inflammatory effect on cutaneous inflammation.

Animals↗
PubMed1987

Fetal heart rate pattern before and after paracervical anesthesia. A prospective study.

A prospective study of the fetal heart rate pattern during labor before and after paracervical blockade (PCB) was performed. The material comprised 469 women in labor, or 28% of 1673 women delivered during a 6-month period. The majority of the anesthesias (87%) were administered by specially trained midwives. Bupivacain (Marcain) was the anesthetic used. The injections were made at four different points at a cervical diameter of 3-9 cm. The concentration of the anesthetic was 0.25 or 1.25% generally in 10 ml of normal saline. A second PCB was administered in 54 patients at least one hour after the preceding one. Fetal heart rate (FHR) was recorded via a scalp electrode and the pattern studied 15 min before and 30 min after the injection of the anesthetic. Bradycardia was defined as a persistent deceleration exceeding 3 min and occurring within 30 min of the PCB. Variability and acceleration pattern persisted independently of the PCB. Following PCB, decelerations of all types increased, while the basal rhythm decreased by on average 1.5 beats/min. Following PCB fetal bradycardia occurred in 1.9%. The bradycardia persisted on average for 6.5 min with a lowest average FHR of 73 beats/min. Retrospectively, 6 out of 9 infants exhibited recognized risk factors for bradycardia. All infants with bradycardia scored 9-10/5 min, according to the Apgar rating scale and all had a normal development with regard to growth, motor and speech development at the age of 2 years. There were no significant differences in vaginal operative deliveries between the PCB and the non-PCB group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1987

Fetal heart rate changes during diabetic ketosis.

A case of diabetic ketosis during pregnancy is presented in which the fetal heart rate tracing demonstrated tachycardia complicated by late and severe variable decelerations. Intravenous administration of insulin resulted in prompt abolition of the deceleration patterns. The implications of these findings are discussed.

Adult↗
PubMedDate not supplied

Body sway stabilization in human posture.

Electromyographic (emg) responses and joint movements of the leg were analysed in subjects standing with eyes closed on a sinusoidally moving treadmill (0.16 Hz or 0.33 Hz, amplitude 33 cm). Activity in antagonistic leg muscles was reciprocally modulated, with a predominant gastrocnemius activation during deceleration of forward movement and tibialis anterior activation during deceleration of backward movement of the treadmill. In these phases, it was necessary to compensate for sway induced by body inertia. The match between treadmill movement and emg activity was better for the gastrocnemius than for the tibialis anterior muscle. The characteristic pattern of leg muscle emg activity is suggested to be modulated predominantly by vestibulo-spinal reflexes partly because treadmill movements did not evoke muscle strength, and partly because patients with loss of vestibular function showed basic alterations in the emg pattern and could only compensate for the slow sinus while standing unsupported.

Adult↗
PubMed1997

P300 event-related-potential amplitudes and evoked cardiac responses during hypnotic alteration of somatosensory perception.

Ten highly hypnotizable women and 10 women with low hypnotizability were tested in a somatosensory target detection task to evaluate the effects of hypnotic alterations of somatosensory perception on P3 peak amplitude and evoked cardiac response. Stimulus detection task consisted of standard and target electric stimuli delivered with a fixed foreperiod. The P3 peak amplitude of ERPs recorded from frontal, central and temporo-parieto-occipital (posterior) scalp sites and phasic heart rate deceleration response were compared in four conditions: (1) normal attention in waking state, (2) hypnotic obstructive hallucination, (3) hypnotic attention, (4) hypnotic passive attention. High hypnotizable subjects demonstrated significant suppression of P3 peak amplitude to target stimuli in the left frontal and posterior scalp sites during hypnotic obstructive hallucination as compared to a normal attention condition. In this condition P3 suppression was paralleled by a smaller anticipatory heart rate deceleration response to probe stimulus onset. The P3 peak to standard stimuli was found significantly greater in low hypnotizable subjects than for those with high hypnotizability regardless of condition. These findings demonstrate that hypnotically induced obstructive hallucination to somatosensory stimuli involve alterations in neural and autonomic responses and are consistent with a trait conception of hypnotizability.

Adult↗