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PubMed1980

Changes in excitability of tendon tap and Hoffmann reflexes following voluntary contractions.

The effects on the Hoffmann reflex and tendon tap responses in the human soleus and medial gastrocnemius muscles of a brief conditioning volitional contraction have been compared with the objective of distinguishing contributions from the central nervous system and the periphery. The H-wave on successive trials over a 50 sec period following contraction for the most part demonstrated a depression, especially upon the initial trial. The T-wave responses in the first few trials were greater than those in the control period. Using the assumption that responses to tendon taps had been reduced by the amounts reflected in the excitability curve for H-response, it was deducted that a marked enhancement in T-wave excitability had been present at the initial tendon tap and more moderate facilitation thereafter. This is consistent with the post-contraction discharge and increase in stretch sensitivity of spindle receptors seen after contraction of a muscle in experimental animals. It is concluded that such effects on spindles may occur in man, maybe of such force as to detectably influence dynamic movements.

Adult↗
PubMed1992

Dependence of presaccadic cortical potentials on the type of saccadic eye movement.

Premovement cortical potentials were studied with 4 types of saccadic eye movement: (a) visually triggered saccades of normal reaction time (RT; regular saccades); (b) visually triggered saccades of extremely short RT (express saccades); (c) saccades towards predicted target locations (anticipatory saccades); (d) saccades back towards predicted location of fixation point (refixation saccades). With all 4 saccade types a "presaccadic negativity" with the maximum at the vertex (Cz) was observed. A bilaterally symmetrical component contained in this potential (being smallest with almost unconsciously performed refixation saccades and smaller in trained than in naive subjects) appeared to be related mainly to the subjects' volitional effort. In addition, anticipatory and refixation saccades were preceded by an early, widespread contralateral negativity, which we relate to cortical activities that prepare, in general terms, action within or towards the hemifield containing the saccade goal. During the 60 msec before anticipatory saccades, a negativity occurred over the contralateral central lead, which may reflect neural activation in the frontal eye field (FEF) and premotor cortex. In contrast, regular saccades were preceded 30 msec before onset by a negativity over the contralateral parietal cortex, which probably reflects an activation of parietal visuo-motor neurons. No lateralization of the cortical potentials was observed before express saccades, which suggests that these saccades are generated in a reflex-like way mainly by subcortical mechanisms.

Adult↗
PubMed1983

Afferent fibers to the cingular vocalization region in the squirrel monkey.

Three squirrel monkeys (Saimiri sciureus) received horseradish peroxidase injections in the anterior cingulate cortex at the level of the genu of the corpus callosum, a region yielding vocalization when electrically stimulated. Retrogradely labeled neurons were found at the cortical level within the dorsomedial and lateral prefrontal cortex (areas 9 and 10), orbital cortex (area 11), premotor cortex (areas 44, 6b, and 8), frontoparietal operculum, insula, cortex of the superior temporal sulcus, piriform cortex, subiculum, posterior cingulate, and retrosplenial cortex. Subcortical telencephalic projections came from the the claustrum, diagonal band of Broca, nucleus basalis Meynert, nuclei basalis lateralis and accessorius amygdalae, and cells at the periphery of globus pallidus. Diencephalic structures projecting to the anterior cingulate cortex were the thalamic nuclei anterior medialis, anterior ventralis, ventralis anterior, ventralis lateralis pars medialis, medialis dorsalis, pulvinaris medialis, centralis superior lateralis and limitans; the intralaminar nuclei paracentralis, centralis lateralis and parafascicularis; and the midline nuclei periventricularis, parataenialis, centralis superior, centralis inferior, centralis medialis, and reuniens. In the hypothalamus, projections came from the periventricular, lateral and posterior part, as well as the supramamillary nucleus. Midbrain afferent fibers came from the ventral tegmental area of Tsai, medial substantia nigra, reticular formation, area praerubralis, nucleus peripeduncularis, and periaqueductal gray. The most posterior labeled neurons were found in the locus ceruleus, dorsal tegmental nucleus of Gudden, nucleus annularis, nucleus centralis superior Bechterew, nucleus dorsalis raphae and the most dorsomedial part of the nucleus reticularis tegmenti pontis. Some of those projections have functional significance in the light of the hypothesis that the cingular cortex is involved in the volitional control of emotional reactions on the one hand and the influence of primary emotional reactions on intentional behavior on the other.

Afferent Pathways↗
PubMed1996

Influence of lateral destabilization on compensatory stepping responses.

Previous studies of compensatory stepping, in response to postural perturbation, have focussed on forward or backward stepping; however, the ability to step in other directions is of equal functional importance, since the perturbations encountered in daily life may often include a lateral component. The primary objective of this study was to determine how lateral destabilization affects the compensatory stepping response, in terms of: (1) swing-leg selection, (2) preparatory unloading of the swing leg, and (3) spatial and temporal characteristics of the swing trajectory. A novel multi-directional moving platform was used to apply transient perturbations in eight horizontal directions, in 10 healthy young adults. Perturbation magnitude was varied unpredictably over a wide range and subjects were instructed to try not to step, so as to discourage preplanned 'volitional' foot movement. The predominant strategy, seen in 96% of stepping responses to lateral destabilization, was to swing the leg that was unloaded by the perturbation. This strategy allowed a much more rapid foot-lift but required a longer and more complex swing trajectory, compared to responses where the perturbation-loaded leg was swung. When compared to forward and backward steps, the addition of a lateral component to the perturbation led to a 20% (90 ms) reduction in time to foot-off, a 20% (7 cm) increase in step length and a 70% (110 ms) increase in swing duration, on average. The results clearly demonstrate that compensatory stepping responses to non-sagittal perturbations are strongly influenced by biomechanical constraints and affordances that do not affect the forward and backward stepping behaviour that has been studied traditionally. These findings underscore the need to assess postural responses in multiple directions, in order to understand more fully how balance is maintained in the exigencies of everyday life.

Adult↗
PubMed1979

Developmental apraxia: diagnostic considerations.

This study compares the performance of developmentally apraxic children with that of children who have functional articulation disorders on a battery of diagnostic tests. Based on preliminary data, tests which assess auditory attention, auditory discrimination, auditory memory, oral-tactile feedback, and isolated and sequenced volitional oral movements appear to be useful in a differential diagnosis of articulatory defective children and, thus, warrant further study. Implications of these findings are discussed.

Apraxias↗
PubMed1993

Bladder management in children with genitourinary sarcoma.

Between 1977 and 1991, 14 patients were treated for genitourinary sarcoma (mean age, 7.4 years). The primary site was bladder in six patients, prostate in five, and vagina in three. Histological study showed embryonal rhabdomyosarcoma in 12 and leiomyosarcoma in 2 children. Initial therapy included biopsy followed by chemotherapy in all patients. Subsequently, five patients had anterior exenteration, four underwent partial cystectomy, and one patient had a radical prostatectomy; four patients were treated with chemotherapy and external beam pelvic irradiation (4,000 to 6,000 rads) alone. Overall survival for the group is 100% (follow-up 6 to 168 months). Two of four patients undergoing partial cystectomy had bladder augmentation at the time of surgery. All patients having partial cystectomy had negative surgical margins, are tumor free, and have volitional voiding. Two of four patients (50%) initially treated with chemotherapy and radiotherapy alone have had significant bladder deterioration requiring bladder reconstruction. There has been an evolution toward less radical, initial surgical intervention in pediatric genitourinary sarcoma; however, surgical resection continues to be the primary curative modality. Partial cystectomy with or without primary reconstruction may be preferable to exenteration for selected patients. Primary reconstruction at the time of partial cystectomy leaves a functional bladder and excellent long-term results. Children treated with chemotherapy and radiotherapy protocols alone must be monitored for late bladder deterioration.

Adolescent↗
PubMed1976

Dystrophia myotonica. Peripheral nerve involvement and pathogenetic implications.

A comparative electrophysioloical study of patients with dystrophia myotonica and control subjects is presented. The study includes estimation of the number of motor axons innervating the extensor digitorum brevis muscle and measurements of the conduction of M- and F-waves along the deep peroneal nerve. There is unequivocal electrophysiological evidence of nerve involvement in the disease. This was indicated by (a) prolongation of the terminal latencies and slowing of the motor conduction of the deep peroneal nerve (P less than 0.001), (b) delayed conduction of the F-wave along the proximal segments of the nerves (P less than 0.02-0.01), (c) reduced number of motor axons innervating the extensor digitorum brevis muscle (P less than 0.001), (d) high amplitude motor unit potentials and discrete EMG activity on the maximal volitional contraction of minimally affected muscles in one patient. However, if the muscle changes were secondary to the nerve involvement occurring in the disease, one would expect that the electrophysiological findings of neuropathy would become more prominent in patients with severe muscle wasting and weakness. Our results showed that in some patients with marked muscle atrophy and weakness there was no evidence of nerve involvement while in other patients with slight to moderate degree of muscle weakness the electrophysiological studies indicated peripheral neuropathy. Therefore, it appears that both the nerves and the muscles are independently affected by the pleiotropic action of the responsible gene and the evidence does not suggest that the muscle atrophy of patients with dystrophia myotonica is entirely neural.

Adolescent↗
PubMed1992

Evidence of subclinical brain influence in clinically complete spinal cord injury: discomplete SCI.

Previous studies of the neurocontrol of movement in spinal cord injury (SCI) subjects revealed that even those without volitional movement may retain some degree of preservation of distal brain influence. We previously defined a discomplete lesion as one which is clinically complete but which is accompanied by neurophysiological evidence of residual brain influence on spinal cord function below the lesion. In order to document the nature and extent of such neurocontrol, we recorded surface EMGs from multiple muscle groups to study patterns of motor unit activity in response to tendon vibration, activation of muscles below the lesion by reinforcement maneuvers above the lesion and by voluntary suppression of plantar withdrawal reflexes. We analyzed data from this brain motor control assessment (BMCA) procedure in order to describe the frequency of occurrence and characteristics of residual control in discomplete SCI subjects, comparing with findings in (clinically and neurophysiologically) complete and in (clinically and neurophysiologically) incomplete SCI subjects. From a group of 139 SCI subjects seen for management of spasticity, 88 had clinically complete lesions. Of these, 74 (84%) were discomplete as defined by responses to the above maneuvers. The selection of management and intervention strategies, whether physiological, pharmacological, behavioral or surgical, should give consideration to the high likelihood that clinically complete subjects may be neurophysiologically incomplete.

Brain↗
PubMed1986

Hemiparkinsonism in monkeys after unilateral internal carotid artery infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).

Infusion of MPTP (0.2-0.8 mg/kg) into the right internal carotid artery of monkeys produces toxin-induced injury to the right nigrostriatal pathway with sparing of other dopaminergic neurones on the infused side and with negligible or little injury to the opposite, untreated side. There are contralateral limb dystonic postures, rigidity, and bradykinesia, but the animals are able to eat and maintain health without drug treatment. Spontaneous motor activity is attended by circling towards the injured side, whereas treatment with L-DOPA/-carbidopa or apomorphine stimulates circling towards the intact side. Dopamine and dopamine metabolite levels are normal in the left caudate and putamen, but markedly depressed on the right (MPTP-treated) side. This animal hemiparkinsonian model will be useful in studies of volitional movement control, drug treatments of Parkinson's disease, and functional efficacy of brain tissue implants.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1982

The origin of left hand preference: pathological and non-pathological influences.

Models of the origin of left hand preference were tested with prospective data. Infants with and without a history of perinatal complications, matched for age, sex and parental handedness, were filmed at 6 weeks of age. Children with a history of perinatal complications lacked the rightward headturning bias of those children without a history of perinatal trauma. Children with a history of perinatal complications were also deviant with reference to the duration of a postural reflex and its degree of lateralization. Perinatal complications may delay the establishment of volitional hand use as well as increase the probability of left-handedness. The data were interpreted as supporting SATZ's (Cortex 8, 121-135, 1972) rather than BAKAN et al.'s (Neuropsychologia 11, 363-366, 1973) model of "pathological" left-handedness.

Birth Injuries↗
PubMed1988

Open-field behavior is not related to treadmill performance in exercising rats.

We examined the association between open-field behavior and treadmill performance in 39 adult male Sprague-Dawley rats. Three daily, five-minute trials were conducted in an open field of 49 19 cm squares. The objectivity of the open-field test was established by intraclass correlations (R) for observer agreement on total squares traversed (R = .99) and a subjective behavioral rating scale for anxiety (R = .92). As expected, total squares were inversely correlated (r = -.86) with the subjective anxiety ratings. An independent observer also rated animals on treadmill performance across six daily, five-minute trials of level running at 15 m/min. Performance ratings were objective (rs = .89) and reproducible (R = .91). A volitional endurance run at 30 m/min on level grade was also conducted on a subsequent day. Extreme groups of low anxious (N = 7) and high anxious (N = 7) animals were then identified from convergent responses on total square traversals and the subjective behavioral ratings that were reproducible (R = .72 to .78) of trials two and three of the open-field test. Repeated measures ANOVA showed no group differences (p greater than 0.10) on mean treadmill performance across trials. Endurance was also the same for each group (p greater than 0.05). Our findings indicate that the open-field test is objective and reliable, and it does not reveal a selection bias effect on treadmill performance or endurance. Thus, open-field behavior can be used as a dependent or subject-matching variable in studies of adult male Sprague-Dawley rats when motor-driven treadmill running is a behavioral intervention or outcome measure.

Animals↗
PubMed1987

Exercise-induced changes in functional residual capacity.

We used a helium-rebreathe technique in nine healthy subjects to determine the effects of exercise intensity and duration on end-expiratory lung volume (EELV). The rebreathe functional residual capacity (FRC) technique was shown: (a) to be similar to that measured in the body plethysmograph, at rest; (b) to agree closely with volitionally induced changes in EELV as determined by inductance plethysmography, at rest; (c) to be reproducible within subjects between trials conducted at rest or exercise on different days (r = 0.96, coefficient of variation +/- 3%); (d) to correlate significantly with coincident changes in end-expiratory esophageal pressure from rest to exercise, with increasing exercise intensity and over time at a constant exercise load. Exercise-induced reductions in EELV occurred in all subjects, averaging 0.3 L (-0.1 to -0.7 L) in light exercise and 0.79 L (-0.5 to -1.2 L) in heavy or maximum exercise. This reduction in EELV accounted for slightly more than one-half of the increase in VT during light exercise and slightly less than one-half of the increased VT in heavy exercise. In heavy prolonged exercise lasting 8-15 min, EELV fell in the initial 2 min and was either sustained at this reduced level or fell further with exercise duration to exhaustion. We found that FRC was reduced even in very light exercise when changes in TE and VE from rest were minimal; further reductions in EELV occurred as end-inspiratory lung volume increased and expiratory time shortened with increasing exercise intensity and duration. Based on these types of changes we speculate that active expiration during exercise in humans may be controlled by a combination of locomotor-related feed-forward and lung volume related feed-back mechanisms.

Adult↗
PubMed1996

Control of breathing in man; insights from the 'locked-in' syndrome.

Control of breathing was studied in a patient with a lesion in the ventral pons; no volitional behaviour, including voluntary breathing acts, was possible (locked-in syndrome, LIS). Spontaneous breathing via a tracheostomy maintained a normal PETCO2 of 39-40 mmHg. Variability of ventilatory parameters awake was similar to that seen in five tracheostomized control subjects during stage IV sleep but much smaller than during resting wakefulness. Emotion associated with laughter caused disturbances of breathing. The ventilatory response to CO2 was normal and was associated with 'hunger for air' when the PETCO2 was 49-50 mmHg. Mechanical ventilation to reduce PETCO2 by as little as 1 mmHg resulted in apnoea when the ventilator was disconnected; breathing resumed when PETCO2 crossed the threshold of 39-40 mmHg. These results demonstrate the functional dependence of the human medullary respiratory oscillator on a threshold level of PCO2 in the absence of cortico-bulbar input, even during wakefulness. The absence of such input may explain the regularity of breathing.

Adult↗
PubMed1990

The effects of acute exercise and increased atmospheric pressure on the hemostatic mechanism and plasma catecholamine levels.

The hemostatic response to acute exercise and increased atmospheric pressure was studied in 20 healthy male subjects (18-35 yr of age) exercised to volitional exhaustion on a cycle ergometer in a hyperbaric chamber at 3 atmospheres absolute (ATA). As a means of comparison, 6 of the 20 subjects were exercised in the same manner at 1 ATA. Similar increases in fibrinolytic activity (FA), Factor VIII activity (VIII:C), von Willebrand factor antigen (vWF:Ag) and plasma catecholamine levels were observed following acute exercise at 1 ATA and at 3 ATA. There were no changes in the levels of plasminogen, antithrombin III, Protein C or Fibrinopeptide A (FPA) with exercise either at 1 ATA or at 3 ATA. In addition, there were no changes in plasma catecholamine levels or any of the hemostatic variables measured when atmospheric pressure was increased from 1 ATA to 3ATA without exercise. These findings demonstrate that increasing atmospheric pressure from 1 ATA to 3 ATA does not alter the exercise-induced changes in hemostasis. Therefore, exercise or physical exertion at 3 ATA for a time period not to exceed 30 min does not perturb the hemostatic mechanism and increase the risk of bleeding or thrombosis.

Adolescent↗
PubMed1990

Central action of an inhibitor of brain dopa-decarboxylase, NSD-1015, on cyanamide-induced alcohol drinking in rats.

A cannula for repeated intracerebroventricular (ICV) infusion was implanted stereotaxically in 16 male Sprague-Dawley rats. Subsequently, an alcohol preference test was given to each animal to establish its preferred concentration in the presence of water. After the alcohol solution was removed, 15 mg/kg cyanamide was injected subcutaneously for 4 days to maximize volitional intake of the single preferred solution of alcohol, which ranged from 7-15% in these animals. The L-aromatic amino acid decarboxylase inhibitor, NSD-1015 (3-hydroxybenzylhydrazine dihydrochloride) was then given ICV twice daily in a volume of 5.0 microliters in the following doses: 0.005, 0.01, 0.1 and 1.0 micrograms. NSD-1015 in all doses attenuated the g/kg alcohol intake of the rats; however, this decline was significant only at the lowest dose, which was pharmacologically specific, since neither food nor water intakes were altered by the treatment. Following the ICV infusions of NSD-1015, alcohol drinking returned essentially to postcyanamide levels. Further, during the interval of administration of NSD-1015, the cyanamide-induced decline in food consumption was reversed. These observations are in agreement with previous findings obtained under similar experimental conditions with the L-aromatic amino acid decarboxylase inhibitor, benserazide (Ro4-4602). They suggest that central decarboxylation or other effects of this drug on limbic system structures involved in the intake of alcohol could comprise a part of the mechanism underlying the induction of drinking. Further support is also provided for the involvement of brain dopamine and/or serotonin in the specific pattern of alcohol consumption in the rat.

Alcohol Drinking↗
PubMed1992

Selective reduction by the 5-HT antagonist amperozide of alcohol preference induced in rats by systemic cyanamide.

This investigation was undertaken to determine the effect of a unique psychotropic agent on the volitional drinking of alcohol induced pharmacologically in the rat by an inhibitor of aldehyde dehydrogenase. Following administration of cyanamide in a dose of 10 mg/kg twice daily for 3 days, the pattern of drinking of ethyl alcohol was determined in each of 12 Sprague-Dawley rats by means of a standard preference test for 3-30% alcohol vs. water. Then, each rat was offered water and its maximally preferred concentration of alcohol, which ranged from 7-15%. After a 4-day predrug test, either the saline control vehicle or the diphenylbutylpiperazinecarboxamide derivative, amperozide, was administered subcutaneously. The injections of amperozide were given b.i.d. at 1600 and 2200 h over 3 days in a dose of 0.5, 1.0, or 2.5 mg/kg. The intake of alcohol during the sequence of amperozide injections was significantly reduced in a dose-dependent manner in terms of both absolute g/kg and proportion of alcohol to water intake, whereas the saline control vehicle was without any effect on alcohol consumption. Although the highest dose of amperozide reduced the total intake of fluid due to the sharp decline in alcohol drinking, neither the consumption of food nor level of body weight was affected by any dose of the drug either during or after its administration. Because amperozide acts centrally on the synaptic activity of dopaminergic and serotonergic neurons in limbic system structures, it is envisaged that the drug ameliorates the aberrant drinking of alcohol by virtue of a direct effect on either one or both of these classes of neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1993

Amperozide, a 5-HT2 antagonist, attenuates craving for cocaine by rats.

Amperozide, a novel 5-HT2 receptor antagonist with little affinity for the dopamine receptor, suppresses the intake of alcohol in rats without affecting food intake or inducing other side effects. Because of these actions, amperozide was examined for its efficacy on the oral preference by the rat for a solution of cocaine. In this study, rats were selected for their voluntary consumption of at least 10 mg/kg of cocaine per day in a two-choice paradigm. A solution of 0.02% to 0.06% cocaine plus 0.03% saccharin in water was offered to each animal simultaneously with a solution of only 0.03% saccharin in water. The consumption of food and both fluids, as well as body weight, was recorded daily for three successive periods: 4 days of pretreatment baseline; 3 days during injections of either amperozide or the saline vehicle solution; and 4 days postinjections. Amperozide was administered SC twice daily in a dose of 0.5, 1.0, or 2.5 mg/kg. The volitional intake of cocaine was significantly reduced not only during the 3-day period of injections of amperozide but also during the 4-day posttreatment period. Amperozide exerted little or no effect on the intake of food or on body weight. Radioligand binding experiments confirmed that amperozide has at least a twentyfold greater affinity for 5-HT2 receptors in the frontal cortex of the rat, as compared to striatal DA1 and DA2 receptors, with the proportion value similar to that of the 5-HT2 receptor antagonist, ritanserin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

5-HT2 receptor blockade by amperozide suppresses ethanol drinking in genetically preferring rats.

Previously, it was shown that the unique diphenylbutylpiperazinecarboxamide derivative, amperozide (FG 5606), inhibits the volitional drinking of ethanol induced in the rat by the inhibitor of aldehyde dehydrogenase, cyanamide. In this study, the efficacy of this long-acting psychotropic agent and potent 5-hydroxytryptamine2 (5-HT2) receptor antagonist was examined in the genetic line of ethanol-preferring (P) and -nonpreferring (NP) rats. In both lines, the pattern of drinking of ethyl alcohol was determined by a standard preference test for 3-30% ethanol vs. water. Then, the maximally preferred concentration of ethanol was determined for each individual, which ranged from 9-15% for P rats and 9-13% for NP animals. After a 4-day predrug test, either the saline control vehicle or amperozide was administered SC b.i.d. at 1600 and 2200 h. The drug was given over a 3-day period in one of three doses: 0.5, 1.0, or 2.5 mg/kg. The intake of ethanol of P rats was reduced significantly in a dose-dependent manner in terms of both absolute g/kg and proportion of ethanol to water during injections of amperozide. The same doses of amperozide had no effect on the low intake of ethanol in NP rats. The saline control vehicle also did not alter the consumption of ethanol of P or NP rats. Further, neither the consumption of food nor level of body weight was affected by amperozide either during or after its administration. These results demonstrate that in the individual predisposed genetically to drink ethanol amperozide exerts a palliative effect on the aberrant preference for ethanol consumed in a pharmacologically significant amount. Presently, dopaminergic and serotonergic synapses in the brain are implicated in the genetic differences in the patterns of ethanol consumption that distinguish the P from the NP line of rats. Because amperozide influences the functional activity of both dopaminergic and serotonergic neurons in the mesolimbic system, it is envisaged that the drug attenuates ethanol drinking by way of its direct action on these neurons.

Alcohol Drinking↗