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PubMed1999

Factors responsible for the prolongation of school refusal.

Two hundred and one school refusers (< or =18 years old), excluding schizophrenia, were treated at the Department of Neuropsychiatry, Hirosaki University Hospital between April 1975 and March 1995. Of 56 cases of school refusal, 31 did not improve for more than 2 years (group P), and 25 cases had improved in the degree of school refusal and social impairment (group B). The remaining cases were excluded from the analysis for several reasons. There was no significant difference between groups B and P in age at the first psychiatric evaluation as well as the age of onset of school refusal. The duration from school absence to the first evaluation of group P was significantly longer than that of group B. The duration of school refusal significantly and positively correlated with the duration from school absence to the first evaluation. Introversion and nervousness prolonged the duration of school refusal. The non-presence of volition for school attendance, and a low frequency of school attendance during the 1 month prior to the first evaluation influenced the prolongation of school refusal. The 'duration from school absence to the first evaluation', the 'patient's character', the 'non-presence of volition for school attendance' and the 'frequency of school attendance' influenced the prolongation of school refusal. The introduction of treatment within 10 months of the onset of school refusal is an important factor in preventing the prolongation of the school refusal.

Absenteeism↗
PubMed1999

The outcome of artificial urinary sphincter placement after a mean 15-year follow-up in a paediatric population.

OBJECTIVE: To evaluate the long-term outcome in children who had an artificial urinary sphincter (AUS) placed, after a minimum of 10 years of follow-up. PATIENTS AND METHODS: The medical records of patients who had an AUS placed at the Children's Hospital of Michigan were reviewed and a telephone questionnaire was then completed by all patients with an AUS currently in place. RESULTS: Forty-seven children initially had an AUS placed between October 1978 and August 1986; medical records and follow-up were available for 32. After a mean follow-up of 15.4 years, 13 patients had had the AUS removed and 19 currently have an intact AUS. Erosion or infection was responsible for all AUS removals. Possible risk factors for AUS removal were prior AUS erosion, prior bladder neck surgery and a balloon pressure of >70 cmH2O. Eighteen of 19 patients with an intact AUS are dry and seven void volitionally. Revision was the most common reason for additional surgery, but the revision rate has decreased with the most current AS-800 model, to 0.03 revisions per patient-year. Of the 13 patients with an AS-800 model placed after 1987, nine have not required revision. Upper tract changes were mild and uncommon. CONCLUSION: The AUS is a durable and effective surgical option in the management of neurogenic urinary incontinence, and is the only reliable technique that can preserve volitional voiding. With technical improvements to the AUS and a longer follow-up, the revision rate has decreased. Causes of AUS removal may be preventable with improvements in surgical technique and patient selection. AUS placement should be considered as a first choice for the surgical management of neurogenic sphincteric incompetence.

Adolescent↗
PubMed1995

Increase of serum insulin and stable c-peptide concentrations with exhaustive incremental graded exercise during acute hypoxia in sedentary subjects.

Hypoxia was shown to reduce insulin concentrations at rest and during exercise. However, some studies have also demonstrated increases in the hormone associated with arterial desaturation. This study was conducted in order to decide [1] whether acute alveolar hypoxia increased or decreased the circulating insulin levels, and [2] to elucidate whether interactions of insulin with other hormones were of relevance in this respect. Glucose (GLU), insulin (INS), c-peptide (CP), adrenaline and noradrenaline (CATs), atrial natriuretic peptide (ANP) and cortisol (CORT) as well as the capillary blood gases were determined in 15 healthy fasting male volunteers (age: 26.2 +/- 2.8 years, body mass index: 22.4 +/- 2.7 kg.m-2). On two separate test days the subjects breathed, in random order, either normal air (N) or a gas mixture with reduced oxygen content (H; FIO2: 0.14). Measurements were made at rest as well as during an incremental cycle exercise in a supine position (increments of 6 min and 50 W) at 100 W and 150 W, at volitional exhaustion (N: 227 +/- 36 W; H: 200 +/- 32 W) as well as in the 5th min of recovery. Arterial desaturation was seen throughout on H-day. At rest all hormones and GLU were normal and showed no influence of H. During exercise INS remained constant on N-day, increased on H-day and was significantly higher with H than with N, most pronounced at 150 W and at volitional exhaustion with 20%, respectively. For CP and GLU no significant exercise-induced changes were seen on either test day and no influence of H was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed2006

Reproducibility of time at or near VO2max during intermittent treadmill running.

The purpose of this study was to determine the reproducibility of time at or above 90 % (t (90 % )VO (2max)) and 95 % (t (95 % )VO (2max)) maximal oxygen uptake during an intermittent treadmill run to exhaustion. Twenty-two distance runners (age 38.0 +/- 7.1 yrs) performed two identical incremental and two identical intermittent tests on four separate days. Respiratory exchange was measured continuously throughout each test by an automated open-circuit gas analysis system. The incremental test consisted of increases in treadmill speed every minute until volitional exhaustion. The highest averaged 30-s oxygen uptake (VO (2)) value was defined as VO (2max) and the minimum speed that elicited VO (2max) was defined as vVO (2max). The intermittent test consisted of 30-s work intervals ran at 105 % vVO (2max) interspersed by 30-s relief intervals ran at 60 % vVO (2max) and was continued until volitional exhaustion. The time that VO (2) was at or above 90 % and 95 % of the mean maximum values elicited during the two previous incremental tests was determined for the intermittent tests. The mean t (95 % )VO (2max) was 232 (SD 174) s and 244 (SD 195) s and the mean t (90 % )VO (2max) was 480 (SD 220) s and 488 (SD 252) s, for trial 1 and trial 2, respectively. Reproducibility statistics for t (95 % )VO (2max) and t (90 % )VO (2max), respectively, were: 95 % limits of agreement 12 +/- 227 s and 8 +/- 328 s; coefficient of variation 34.5 % and 24.5 %; and intraclass correlation coefficient 0.80 and 0.75. Statistical power analysis indicated that this level of reproducibility would allow mean differences of 15 - 20 % between intermittent training protocols to attain statistical significance in future experimental research, with sample sizes probably within the resources of most researchers.

Adult↗
PubMed1997

Hypnotic involuntariness and the automaticity of everyday life.

We present a new theory of hypnotic involuntariness based on an integration and extension of recent social and cognitive theories on the automaticity of mundane, intentional behavior. According to this model, experiences of volition and involuntariness-in and out of hypnosis-are constructions or interpretations made possible by the high degree of automaticity that is a characteristic of all complex behavior, including novel behavior. Suggested nonvolitional behaviors are intentional acts that are triggered automatically by situational cues (suggestions) and cue-related sensations. The triggering of both the behaviors and the sensations are enabled by the formation of a generalized response expectancy, which is a cognitive set to respond appropriately to suggestions. Response expectancies are functionally equivalent to implementation intentions taking the form, "emit response x when situation y is encountered." The classification of a response set as either an expectancy or an intention and the experience of the response as volitional or nonvolitional depend on interpretations derived from instructional cues and prior beliefs.

Activities of Daily Living↗
PubMed1997

Determination of peak oxygen uptake during upper body exercise.

The purpose of this study was to determine (1) the repeatability of a currently recommended protocol for determination of VO2 peak during upper body exercise involving a crank rate of 60 rev min-1 (Hale et al. 1988), (2) whether employing a higher crank rate (70 rev min-1) elicits higher VO2 peak values; (3) whether including an additional exercise stage 5 min after volitional exhaustion would elicit higher VO2 peak values. Twenty subjects (mean +/- SD) age, height and body mass were 22.8 +/- 1.8 years, 176 +/- 5.0 cm and 77.5 +/- 4.0 kg, respectively) visited the laboratory on three separate occasions. Subjects performed a different test to determine upper body VO2 peak on each visit. The tests were continuous and incremental in nature and were performed on a Monark cycle ergometer (Model 814E) adapted for arm exercise. Test 1 required subjects to exercise at a crank rate of 60 rev min-1 (60RPM-1). Test 2 was identical to test 1 (60RPM-2) but after 5 min recovery from the test subjects performed a further exercise stage (60RPM-F). Test 3 employed a crank rate of 70 rev min-1 (70RPM). Five minutes after volitional exhaustion a further exercise stage was performed (70RPM-F). The levels of agreement for the 60 rev min-1 protocol were +/-0.50 1 min-1. All VO2 peak values achieved were within these limits. However, a higher VO2 peak was achieved by employing a crank rate of 70 rev min-1 (p < 0.05). The VO2 peak achieved for 60RPM-F was similar to 60RPM whereas the VO2 peak for 70RPM-F tended to be less than that for 70RPM (p = 0.064). The results of this study suggest that the 60 rev min-1 protocol can reliably determine VO2 peak, however it would appear to be more appropriate to employ a 70 rev min-1 protocol as higher values were attained.

Adult↗
PubMed1996

Influence of Destabilization on the Temporal Characteristics of lquot;Volitionalrquot; Stepping.

Previous work suggests that there may be fundamental differences between compensatory stepping responses evoked by postural perturbation and visually cued "volitional" stepping (e.g., gait initiation). In contrast to visual cueing, postural destabilization evokes an array of sensory inputs that are intrinsically linked to the mobilization of rapid compensatory responses. The hypothesis examined in this study was that this fundamental difference would lead to distinct changes in the temporal characteristics of the stepping response. Six healthy young adults were instructed to step quickly in response to either visual cueing or anterioposterior platform motion. Both forward and backward stepping responses were characterized, using measures of vertical ground reaction force. A stereotypical temporal patterning of the stepping response occurred in both stimulus conditions and both directions of stepping, and anticipatory postural adjustments were evident in all trials. However, postural destabilization led to a more rapid initiation and execution of the temporal pattern, in comparison with visually cued responses. The most pronounced effect was seen in the duration of the response, which was reduced by a factor of two, with approximately proportional foreshortening of both the preparatory and swing phases. The results suggest that sensory information conveying a state of instability has a distinct influence on the characteristics of a subsequent stepping reaction. The persistence of the anticipatory postural adjustments suggests that the failure to see this element of the response in previous studies may reflect fundamental differences between volitional and unplanned compensatory stepping.

Journal Article↗
PubMed1989

The anatomy of the ego.

There is a curious behavior observed in the human split-brain experiments in which the subject demonstrates a reflexive and obligatory ownership of the actions initiated by the silent right brain even though the speaking self is ignorant of that volition. If you add to this observation the results of another experiment, revealing the existence of a boundary to the verbal mental system in the intact brain, then--with the knowledge of certain facts about cerebral laterality--you may come to a startling conclusion: There exists a governing mental system that occupies the verbally dominant hemisphere and is responsible for mental unity, volition, and consciousness. I contend that this anatomical brain agency is the substrate for the ego. If this is true, then it can be seen that the ego, in its development, function, and integrity, is intimately involved in the brain dynamics of obligatory unity, cerebral dominance, and laterality.

Cerebral Cortex↗
PubMed2003

A comparison of the cycling performance of cyclists and triathletes.

The aim of this study was to compare the cycling performance of cyclists and triathletes. Each week for 3 weeks, and on different days, 25 highly trained male cyclists and 18 highly trained male triathletes performed: (1) an incremental exercise test on a cycle ergometer for the determination of peak oxygen consumption (VO2peak), peak power output and the first and second ventilatory thresholds, followed 15 min later by a sprint to volitional fatigue at 150% of peak power output; (2) a cycle to exhaustion test at the VO2peak power output; and (3) a 40-km cycle time-trial. There were no differences in VO2peak, peak power output, time to volitional fatigue at 150% of peak power output or time to exhaustion at VO2peak power output between the two groups. However, the cyclists had a significantly faster time to complete the 40-km time-trial (56:18 +/- 2:31 min:s; mean +/- s) than the triathletes (58:57 +/- 3:06 min:s; P < 0.01), which could be partially explained (r = 0.34-0.51; P < 0.05) by a significantly higher first (3.32 +/- 0.36 vs 3.08 +/- 0.36 l x min(-1)) and second ventilatory threshold (4.05 +/- 0.36 vs 3.81 +/- 0.29 l x min(-1); both P < 0.05) in the cyclists compared with the triathletes. In conclusion, cyclists may be able to perform better than triathletes in cycling time-trial events because they have higher first and second ventilatory thresholds.

Adult↗
PubMed2003

Simulated tennis matchplay in a controlled environment.

The aim of this study was to develop an exercise protocol to simulate tennis matchplay on a 'category 2' surface. Match analyses were used to form the basis for the design of the protocol. The protocol involved playing against a tennis ball serving machine. Part A of the protocol comprised 92 min 46 s of simulated tennis matchplay; Part B consisted of continuous hitting to the point of 'volitional fatigue' or when the required hitting frequency for two consecutive ball feeds could no longer be maintained. Ten elite tennis players (5 males, 5 females) volunteered to participate in the study, which was performed on an indoor tennis court (Matchplay, En-Tout-Cas). Their age, body mass and estimated maximal oxygen uptake were as follows: males, 21.7 +/- 1.0 years, 73.6 +/- 2.6 kg and 58.0 +/- 1.7 ml x kg(-1) x min(-1), respectively; females, 21.9 +/- 1.3 years, 62.3 +/- 2.0 kg and 42.2 +/- 0.7 ml x kg x min(-1), respectively (mean +/- sx). Heart rate, change in body mass and time to volitional fatigue were monitored. The heart rate responses of the participants to the simulated matchplay (range: 140-157 beats x min(-1), 73-81% peak heart rate) were consistent with the results of previous studies, for 'actual' matchplay. This protocol was successful in simulating similar physiological responses in Part A to 'actual' matchplay on a 'category 2' surface, in a controlled environment; it was also a sensitive evaluation tool of skilled performance in Part B. The current protocol may be used as a baseline protocol for studying the influence of, for example, training and dietary intervention on performance.

Adult↗
PubMed2005

Tennis ball diameter: the effect on performance and the concurrent physiological responses.

The aim of this study was to examine the influence of a pressurized tennis ball 6% greater in diameter (Type 3) than a standard sized (Type 2) ball on performance and the physiological responses to the Loughborough Intermittent Tennis Test (LITT) (Davey et al., 2002). Eight competitive tennis players (males, n = 4, age 24.8+/-3.5 years, body mass 81.3+/-3.1 kg, height 1.74+/-0.02 m, estimated VO2max 54.4+/-2.6 ml x kg(-1) min(-1); females, n = 4, age 26.3+/-3.1 years, body mass 67.0+/-6.7 kg, height 1.68 + 0.02 m, estimated VO2max 49.9+/-3.3 ml kg(-1) min(-1); mean+/-s(x)) completed two main trials of the LITT with either the Type 2 or Type 3 tennis balls to the point of volitional fatigue. The mean time to volitional fatigue was 29.5% greater during the Type 3 trials than during the Type 2 trials (56.9+/-6.4 min vs 40.1+/-3.7 min; P < 0.05). The mean percentage accuracy and mean percentage consistency recorded for the entire LITT were greater for the Type 3 than the Type 2 trials (9.2+/-1.5 vs 4.0+/-0.3% and 61.1+/-0.6 vs 51.3+/-0.6%, respectively; P < 0.01). A significantly lower mean heart rate and blood lactate concentration were observed during the Type 3 than during the Type 2 trials. There was a clear effect of ball diameter on tennis performance and certain physiological responses.

Adult↗
PubMed2005

The impact of mild closed head injury on involuntary saccadic adaptation: evidence for the preservation of implicit motor learning.

OBJECTIVE: Mild closed head injury (CHI) can impair performance on volitional saccades (fast eye movements), with poorer saccade accuracy being one of the principal deficits. Assessing a patient group with known deficits of volitional saccades, the authors investigated whether mild CHI similarly impairs the implicit adaptation of visually-guided (reflexive) saccades, an important process which maintains saccadic accuracy. METHODS: Within 2 weeks following mild CHI, 30 patients and 30 matched controls were compared on a computerized paradigm, which artificially induced saccadic adaptation. In response to an initial stimulus, subjects made a saccade during which the stimulus was displaced centripetally causing the initial (primary) saccade to be inaccurate. While these intra-saccadic changes remained unnoticed by the subjects, the displacements gradually caused adaptive saccadic hypometria. RESULTS: No differences in adaptation were found between the CHI group and the controls (F(1, 29) = 0.51, p = 0.48). This finding indicates that mild CHI does not impair implicit reflexive saccade adaptation and suggests that cerebellar function and functions of deeper brain structures such as the thalamus, superior colliculus and the basal ganglia may be largely preserved following mild CHI. The current results support the notion that the profile of oculomotor function after mild CHI reflects a centripetal gradient of impairment and relates closely to the functional integrity of the injured brain.

Adaptation, Physiological↗
PubMed2004

Nightly enteral nutrition support of elderly hip fracture patients: a pilot study.

OBJECTIVES: Assess whether postoperative nightly enteral nutrition support improves outcomes of elderly patients with an acute hip fracture DESIGN: Randomized controlled trial. SETTING: A University and a Department of Veteran's Affairs Hospital SUBJECTS: Adults >64 years of age who underwent surgical repair of an acute hip fracture. INTERVENTIONS: Subjects randomized to the control (Ctrl) group received standard care while the treatment (Tx) group received standard care plus up to 1,375 Kcal [5,755 kJ/d] of nasoenteral tube feedings each night. When tube feedings had to be discontinued, Tx subjects were asked to drink an equivalent amount of the nutritional supplement each night. MEASURES OF OUTCOME: Rate of postoperative complications and 6-month postoperative survival. RESULTS: Fifty-seven patients were randomized to the Tx (n = 27, mean age 75.9 +/- 7.4 yrs) or Ctrl groups (age 81.7 +/- 7.7 yrs). All subjects had reduced volitional nutrient intakes after surgery. During the first week subsequent to surgery, there was no difference between the treatment and control groups in the amount of nutrients that they volitionally consumed during the day. However, the treatment subjects had a greater total daily nutrient intake (Median 5,866 (IQR 5,024 to 7,335) kJ/d vs. 3,965 (IQR 2,968 to 4,664) kJ/d, p < 0.001). However, by the second postoperative week this difference was no longer statistically significant. Intolerance to the tube feedings developed commonly. There was no difference between the groups in the rate of postoperative life-threatening complications or mortality within six months subsequent to surgery. CONCLUSIONS: This study failed to confirm findings from a prior study of improved postoperative survival with nutrition support. However, it was conducted on multiple hospital wards which may have contributed to the higher rate of tube-related problems and less nutrient delivery signifying the need for further study.

Aged↗
PubMed2006

Attention to arrows: pointing to a new direction.

It was long believed that central arrows needed to be spatially predictive to produce a shift in spatial attention. Recent evidence indicates, however, that central spatially nonpredictive directional cues, like arrows, will trigger reflexive shifts in attention. We asked what this recent discovery means for past studies that used predictive directional cues such as arrows. Our findings indicate that predictive arrows produce attention effects that greatly exceed the individual or summed effects of reflexive orienting to nonpredictive arrows and volitional orienting to predictive numbers. This suggests that the especially large effect produced by predictive arrows reflects an interaction between reflexive and volitional orienting. Given the broad application of the predictive arrow cueing paradigm in both past and current research, the present data shed new light on a wide range of investigations, from psychophysical studies of basic attention to behavioural and neuroimaging studies of cognition and social development.

Analysis of Variance↗
PubMed2006

Extraction of motor activity from the cervical spinal cord of behaving rats.

Injury at the cervical region of the spinal cord results in the loss of the skeletal muscle control from below the shoulders and hence causes quadriplegia. The brain-computer interface technique is one way of generating a substitute for the lost command signals in these severely paralyzed individuals using the neural signals from the brain. In this study, we are investigating the feasibility of an alternative method where the volitional signals are extracted from the cervical spinal cord above the point of injury. A microelectrode array assembly was implanted chronically at the C5-C6 level of the spinal cord in rats. Neural recordings were made during the face cleaning behavior with forelimbs as this task involves cyclic forelimb movements and does not require any training. The correlation between the volitional motor signals and the elbow movements was studied. Linear regression technique was used to reconstruct the arm movement from the rectified-integrated version of the principal neural components. The results of this study demonstrate the feasibility of extracting the motor signals from the cervical spinal cord and using them for reconstruction of the elbow movements.

Animals↗
PubMed1999

Distribution and latency of muscle responses to transcranial magnetic stimulation of motor cortex after spinal cord injury in humans.

Noninvasive transcranial magnetic stimulation (TMS) of the motor cortex was used to evoke electromyographic (EMG) responses in persons with spinal cord injury (n = 97) and able-bodied subjects (n = 20, for comparative data). Our goal was to evaluate, for different levels and severity of spinal cord injury, potential differences in the distribution and latency of motor responses in a large sample of muscles affected by the injury. The spinal cord injury (SCI) population was divided into subgroups based upon injury location (cervical, thoracic, and thoracolumbar) and clinical status (motor-complete versus motor-incomplete). Cortical stimuli were delivered while subjects attempted to contract individual muscles, in order to both maximize the probability of a response to TMS and minimize the response latency. Subjects with motor-incomplete injuries to the cervical or thoracic spinal cord were more likely to demonstrate volitional and TMS-evoked contractions in muscles controlling their foot and ankle (i.e., distal lower limb muscles) compared to muscles of the thigh (i.e., proximal lower limb muscles). When TMS did evoke responses in muscles innervated at levels caudal to the spinal cord lesion, response latencies of muscles in the lower limbs were delayed equally for persons with injury to the cervical or thoracic spinal cord, suggesting normal central motor conduction velocity in motor axons caudal to the lesion. In fact, motor response distribution and latencies were essentially indistinguishable for injuries to the cervical or thoracic (at or rostral to T10) levels of the spine. In contrast, motor-incomplete SCI subjects with injuries at the thoracolumbar level showed a higher probability of preserved volitional movements and TMS-evoked contractions in proximal muscles of the lower limb, and absent responses in distal muscles. When responses to TMS were seen in this group, the latencies were not significantly longer than those of able-bodied (AB) subjects, strongly suggestive of "root sparing" as a basis for motor function in subjects with injury at or caudal to the T11 vertebral body. Both the distribution and latency of TMS-evoked responses are consistent with highly focal lesions to the spinal cord in the subjects examined. The pattern of preserved responsiveness predominating in the distal leg muscles is consistent with a greater role of corticospinal tract innervation of these muscles compared to more proximal muscles of the thigh and hip.

Adolescent↗
PubMed1979

Proximal limb movements in response to microstimulation of primate dentate and interpositus nuclei mediated by brain-stem structures.

The cerebellar dentate and interpositus nuclei and the area of their efferent fibres have been stimulated in Cebus monkeys, using a movable microcathode. Responses consisted of eye and face movements and a stereotyped flexion of proximal parts of extremities. Very few distal limb movements were seen. The activation of proximal muscles was studied most closely. It consisted of the limited number of 5 movements: arm flexion and shoulder elevation in the forelimb and hip flexion, knee flexion and dorsiflexion of the ankle in the hindlimb. With currents of up to 100 microamperemeter these movements were elicited more readily from the interpositus and the area of efferent fibres of both nuclei as compared to the dentate nucleus. Responses were more often seen in forelimb than in hindlimb muscles, without apparent somatotopy in either nucleus. Combined forelimb-hindlimb movements were elicited from 42 per cent of effective points. Lesions placed at various locations of cerebellar output pathways demonstrated that the responses were mediated by the descending branch of brachium conjunctivum and did not require the activation of structures anterior to and including the red nucleus. The responses are interpreted to represent adjustments in flexor posture that may serve to modify maintained antigravity tonus during the initiation of volitional movements. This function, mediated by brain-stem structures, is considered to be closely associated with the activity of the lateral and intermediate cerebellum during initiation and conduction of volitional movements, which is mediated mainly through the cerebral cortex. It is stressed that control over both flexor posture and discrete distal movements is inherent in the initiation of voluntary movements.

Animals↗
PubMed1996

Diagonistic dyspraxia. Clinical characteristics, responsible lesion and possible underlying mechanism.

We present three patients who showed, in addition to signs of callosal interruption, a variety of abnormal motor behaviour of the left hand dissociated from conscious volition, in the absence of pathological grasping phenomena. The abnormal movements of the left hand consisted of (i) antagonistic movements to the right; (ii) non-antagonistic, irrelevant movements to the right; (iii) symmetric movements to the right in which the left hand sometimes preceded the right, and (iv) occasional inability to move at will during a bimanual task. From these observations and a review of previous publications, we propose that, in most right-handed subjects; diagonistic dyspraxia could be defined as abnormal motor behaviour of the left hand activated by voluntary movements of the right hand. Motor phenomena similar to diagonistic dyspraxia but attributable to impulsive groping movements induced by medial frontal lobe pathology should be excluded from diagonistic dyspraxia. Comparison of MRIs of the three patients with those of five patients who developed no diagonistic dyspraxia following an infarction of the corpus callosum, with or without medial hemispheric involvement, revealed that damage to the ventral part of the posterior end of the body of the corpus callosum was crucial for the development of diagonistic dyspraxia. Since the commissural fibres between the superior parietal lobules pass through the caudal part of the body of the corpus callosum, and also since there is accumulating evidence that the human superior parietal lobule is concerned with selection of movement based on the integration of visual and/or somatosensory information, we infer that diagonistic dyspraxia is produced by a disconnection of the right superior parietal lobule from the left which is dominant for volitional control of movement in most right-handed subjects.

Apraxias↗