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Biomedical subjects

M Fleury

Publications and source records attributed to M Fleury.

At least 19 recordsLinked to original sources
PubMed1995

Weight judgment. The discrimination capacity of a deafferented subject.

A weight discrimination study was undertaken to test (i) the capacity of controls and a deafferented subject (deprived of large sensory myelinated fibres from nose down), to discriminate weights with and without vision; (ii) the capacities of observers to discriminate weights while watching the deafferented and control subjects' lifting movements; (iii) the contribution of supplementary sources of sensory information (e.g. vestibular afferents) to the deafferented subject's discrimination capacity. With vision, G.L.'s liminal discrimination of weights was similar to that of the controls. In contrast, precluding vision impaired massively, but not completely, G.L.'s discrimination capacity, so emphasizing the importance of visual kinaesthetic cues in G.L. and incidently the importance of large myelinated sensory function in weight discrimination in controls. Kinematics recordings of G.L.'s lifting movements with vision revealed a significant correlation between weight and peak velocity of the lifting movement. This reflects a specific strategy used by G.L. to generate movements, allowing her to judge the weight of a lifted object visually. Peak velocity rather than amplitude of movement appears to be the main cue for G.L. since there was a lack of correlation between amplitude and weight lifted. For controls, none of the correlations (weight versus amplitude or weight versus velocity) was significant, whether vision was available or not. When watching G.L.'s lifting performance, external observers were able to use similar cues to establish their judgments, but they were far less accurate in doing so when watching control subjects. This suggests that controls were using a strategy different from G.L.'s.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Contribution of proprioception for calibrating and updating the motor space.

The absence of muscular proprioception, whether at a segmental or at a central level, impairs performance in several ways. The contribution of proprioception to movement control and learning is not easily dissociated from that of other sources of sensory information (e.g., vision). Therefore, the rare clinical cases of extensive neuropathy, depriving the brain massively and permanently of its presumed main sources of dynamogenic information from skin and muscles, are of very special interest. Two such patients and controls were tested in experiments investigating (i) force production, (ii) amplitude coding, (iii) spatial reference frames in pointing, and (iv) prismatic adaptation. Overall, our results highlight the key role of proprioceptive afferents for calibrating the spatial motor frame of reference, and the powerful substitutive properties of the central nervous system.

Adult↗
PubMed1995

Is proprioception important for the timing of motor activities?

This study tested whether a deafferented patient demonstrates impaired timing ability compared with four control subjects. By comparing normal subjects with the deafferented patient, some insight was expected on the importance of proprioception in timing of motor behavior. The protocol was set to enhance the strategy of the subjects in using feedbacks. Subjects had to synchronize finger taps with a sound produced at regular intervals. Once synchronized, the bips were muted and the subjects had to continue the tapping at the same pace. Interresponse interval (IRI) variability was measured under two feedback conditions: with and without vision and auditory feedback. The Wing and Kristofferson model (A.M. Wing and A.B. Kristofferson. Percept. Psychophys. 13(3): 455-460, 1973) was used to segment IRI variance into separate components: a central clock and a peripheral motor delay. When the deafferented patient saw and heard the outcome of her tapping movements, there was a greater variability in successive intervals between taps than when vison and hearing were blocked. We interpret this variability as indicating that the subject used auditory and visual feedback to maintain a correct overall rhythm. The patient may easily substitute visual and (or) auditory feedback for her defective proprioception for movement timing. However, this substitution proved to be inefficient in the limited training period provided in this experiment. The results suggest that the proprioceptive contribution to the time-keeping mechanism presumably depends on the presence of an efference copy signal.

Efferent Pathways↗
PubMed1992

Role of afferent information in the timing of motor commands: a comparative study with a deafferented patient.

The accuracy of the motor system in synchronizing simultaneous movements initiations was tested in two conditions: (1) when the motor commands were triggered by an external signal (reactive condition), and (2) when subjects self-paced their movement onsets (self-paced condition). The task consisted of initiating simultaneously ipsilateral finger extension and heel raising. Eight normal subjects and a deafferented patient were tested. In the reactive condition, both normal subjects and the deafferented patient exhibited a precession of finger initiation over heel raising. This delay corresponds to the difference observed in the reaction time of the two limbs when measured independently. It reflects the difference in conduction times of the efferent pathways, as if the two motor commands were released simultaneously through a common triggering signal in the motor cortex. In contrast, in the self-paced condition normal subjects showed precession of heel over finger onsets, suggesting that synchrony is based upon the evaluation of afferent information. Unlike normal subjects, the patient showed no heel precession in the self-paced condition. These findings suggest that reactive and self-paced responses are produced through two different control modes and that afferent information contributes to the timing of motor commands in the self-paced mode.

Adult↗
PubMed1992

Mirror drawing in a deafferented patient and normal subjects: visuoproprioceptive conflict.

Results on a mirrow drawing task showed that a deafferented patient had no problem completing the pattern, whereas normal subjects needed more than four trials to attain a similar performance. The results suggest the presence of integrated visual and proprioceptive maps. The inversion of visual coordinates requires the need for a recalibration. Without proprioception, the task is more like a simple visual tracking task.

Adult↗
PubMed1992

Comparative effects of two topical antiseptics (chlorhexidine vs KMn04) on bacterial skin flora in atopic dermatitis.

In order to determine the efficacy and tolerance of two topical antiseptics, chlorhexidine vs KMn04 (diluted at 1:20,000), we compared their bacteriological and clinical effects in a randomized trial on 20 children with Atopic Dermatitis (AD) treated with topical steroids (desonide). After treatment, a clinical improvement was noted in the two groups, though without statistical differences. In vivo: Before treatment, Staphylococcus aureus (S.A.) density was high and predominant in both groups. After treatment, the decrease in S.A. was greater in the chlorhexidine group than in the KMn04 group, without significant difference. In vitro: At the clinical dilution used, there was a statistical difference (p < 0.05) between the number of killed bacteria in the chlorhexidine group (-3 log) and the number in the KMn04 group (-1 log). This study confirms the role and importance of the choice of a topical antiseptic in the treatment of AD.

Administration, Cutaneous↗
PubMed1992

[Attentional requirements for preparing to return a serve in tennis].

Recent studies demonstrated that athletes use more efficient strategies than novices in sports with high perceptual requirements (Abernethy and Russel, 1984; Goulet et al., 1989; Starkes, 1987b). The aim of the present study was to investigate the attentional cost of information processing preceding action in tennis players of different calibers. The dual-task paradigm was used. The primary task consisted of identifying the type of serve (flat, slice, or top-spin) presented on 16-mm file. The secondary task was a manual response to an auditory probe. Results demonstrated that attentional requirements during information processing do not differ between experts and novices. Nevertheless, the experts' results on the primary task are significantly higher than those of novices, whether the primary task is performed alone or simultaneously with the secondary task. The attentional cost of information processed during the ritual phase of the serve is significantly higher than the costs for processing information from the preparation and execution of the serve. It appears, therefore, that attentional input effort is maximal before identification of the most important cues necessary for adequate performance.

Adult↗
PubMed1991

Kinematics of aiming in direction and amplitude: a developmental study.

The patterns of aimed movements to visual targets were analyzed in children aged 6, 8 and 10. Tasks with direction and/or amplitude requirements were used. The tasks were performed both with and without vision. Peak velocity, acceleration and deceleration and their relative temporal occurrence were evaluated. Overall, the 6- and 10-year-olds exhibited higher peak velocity and acceleration when performing the pure directional task than when performing tasks with an amplitude or stopping requirement. On the contrary, 8-year-olds showed similar peak acceleration and velocity across all three tasks. Similarly, when performing the pure directional task, the 6- and 10-year-olds reached their peak velocity and acceleration relatively later in time than the 8-year-olds. Vision of movement increased the peak velocity in all experimental tasks and peak acceleration was increased only in the pure directional task. Thus, movement kinematics varied according to the task requirements and age. Eight-year-olds showed greater propensity to feedback control in all tasks, suggesting an over-inhibition in their approach patterns, whereas 10-year-olds tended to use feedforward processes, with a shortened deceleration phase.

Child↗
PubMed1990

Timing and accuracy of visually directed movements in children: control of direction and amplitude components.

The reaction times (RTs), movement times (MTs), and final accuracy of hand movements directed towards visual goals were measured in 6-, 8-, and 10-year-old children, using tasks in which direction and amplitude components of movement were distinctly required. The tasks were performed with and without visual feedback of the limb. RTs decreased with age, and were shorter in directional than in amplitude task, in all ages. MTs were the longest at age 8 in both tasks, equally short at ages 6 and 10 in the directional task, the shortest at age 10, and intermediate at age 6, when amplitude had to be regulated. In the amplitude task, the target distance generally affected MTs under both visual conditions, but to a lower degree at age 10 than in the two younger groups. Movement accuracy, which was in all cases higher with visual feedback, showed different developmental trends among the two spatial components: directional accuracy was not different among the three groups of age, whereas amplitude accuracy showed a nonmonotonic development in the nonvisual condition, with an increase between age 6 and age 10, and the lowest level at age 8. In the visual condition, amplitude accuracy did not change with age. The specification of direction seems therefore to predominantly load the preparatory stage of the response. Amplitude specification seems to be more dependent on on-going regulations and to undergo a longer and more complex development, with a critical period around age 8 when a greater propensity for a feedback-based control appears on the two components. With increasing age, amplitude tends to be specific to a greater extent by a feedforward process.

Attention↗
PubMed1990

[Metabolic fatigue and the performance of visual tasks].

The aim of this study was to analyse the effects of different types of metabolic fatigue, induced by anaerobic alactacid, anaerobic lactacid, sub-maximal aerobic, and maximal aerobic efforts, on the performance of a sensory task (peripheral threshold detection), a sensory-motor task (coincidence-anticipation), and a cognitive task (recall in central vision). Each of three experimental groups performed one of the above-mentioned tasks under all types of fatigue. Running bouts on a treadmill were used to induce the different types of fatigue. Results show that performance in peripheral vision improves with all types of effort. For coincidence-anticipation, only constant error is affected by anaerobic alactacid and maximal aerobic efforts; the former producing a change in behavior from lateness to anticipation, whereas the latter significantly reduces lateness. Finally, performance in the cognitive task is significantly disturbed by the maximal aerobic exercise. It is suggested that, while sensory and adaptive behaviors improve with previous physical work, cognitive behavior is handicapped by highly demanding activities, that is, activities requiring aerobic maximal efforts.

Adult↗
PubMed1989

[Efficacy of uvulopalatopharyngoplasty (UPPP) and modifications in sleep structure in the sleep apnea syndrome (SAS)].

Thirty-four patients (32 male, 2 female; mean age 53 +/- 7 years) with confirmed sleep apnea syndrome (SAS) were studied before and after uvulopalatopharyngoplasty (UPPP). Clinical symptoms were tiredness, excessive daytime sleepiness and snoring. All patients were overweight. Patients underwent a thorough physical and oropharyngeal examination and polysomnography before and 3 months after surgery. On the basis of post-operative results, patients are divided into 3 groups: --group 1: 16 cured patients: apnea index (A.I./h) 38 +/- 17 before and 4.4 +/- 4 apneas/h sleep after surgery. Improved nocturnal hypoxemia: mean minimum oxyhemoglobin saturation (SAO2) before and after UPPP in NREM sleep 83 +/- 4% v. 90 +/- 4% in REM sleep 76 +/- 11% v. 85 +/- 7%. Uninterrupted sleep is restored; --group 2: 8 improved patients: A.I./h of 64 +/- 11 before and 20 +/- 6 after UPPP: improved nocturnal hypoxemia: mean minimum SAO2 in NREM sleep 74 +/- 10% before and 86 +/- 6% after UPPP: in REM sleep 59 +/- 9% before and 79 +/- 6% after UPPP, lower amount and percentage of fragmented sleep; --group 3: 10 non-improved patients: A.I./h unchanged 55 +/- 22% before and 50 +/- 20% after UPPP. Persistent nocturnal hypoxemia: mean minimum SAO2 in NREM sleep 76 +/- 13 before and 81 +/- 12% after UPPP: in REM sleep 63 +/- 16% before and 65 +/- 24% after UPPP. Sleep remains fragmented. In this last group patients are more overweight and all suffer from severe SAS with greater nocturnal oxyhemoglobin desaturation. Surgical treatment by UPPP is shown to be effective for 70% of our patients. Better results are obtained when SAS is less severe and overweight less important.

Adult↗
PubMed1989

[A new case of allo-anti-LWab].

A patient admitted to hospital for hip replacement was found incompatible in pretransfusion testing due to allo-anti-LWab antibody, as well as anti-JKb, anti-E and anti-IH antibodies. The patient had a rare phenotype LW(a-b-ab-). The antibodies were acquired though pregnancy and/or transfusion. This newly discovered anti-LWab allowed us to study and emphasize the relevant serological and transfusional aspects related to incompatibility caused by "public" antibodies in association with other alloantibodies. We attempted to update the LW system in the light of Sistonen and Tippett's recent discoveries. We collected the required compatible units of blood through autologous donations and a Central Canadian Red Cross Registry for rare donors.

Aged↗
PubMed1989

[Delayed hemolytic transfusion reaction caused by an anti-U].

Delayed hemolytic transfusion reactions due to anti-U are rare, only two (2) cases having been reported in the literature. We now report a third case: a multiparous black woman without any transfusion history was admitted to hospital for severe microlytic anemia (31 g/l). The patient was group AB negative, the direct antiglobulin test was negative and an anti P1 cold allo-antibody was present in her serum. Five A, Rh negative, P2 packed red cells were cross-marched with the sample obtained at admission on January 8, 1988. She was transfused on January 8, 9, 10, 11 and 12. On the 12th of January her hemoglobin level reached 125 g/l. On January 13, the patient presented clinical signs of hemolysis and her hemoglobin fell to 60 g/l within 24 hours. On January 15, the direct antiglobulin test was positive and an antibody found in her serum was reactive with all the red cells of the commercial panel. The sample was referred to our red cell serology reference laboratory. The phenotype of the pre-transfusion sample was found to be Fy(a-b-) M, N, S-s-U-. An anti-U was detected in the eluate and the serum. The patient was transfused with two (2) units of O-P2, U-red cells obtained from the American Red Cross, Syracuse, and her hemoglobin reached 90 g/l within 48 hours. This is the third reported case of a delayed hemolytic transfusion reaction due to anti-U. This case illustrates the need to perform cross-matches with samples obtained within 48 hours of the scheduled transfusion for patients who have been transfused with blood in the preceding 3 months. Also, this case emphasises the need to recruit U negative blood donors for the Canadian rare donor file.

Anemia↗
PubMed1989

[Stability in shooting: the effect of expertise in the biathlon and in rifle shooting].

The aim of this study is to compare the body-gun stability of biathletes and rifle shooters up to the firing of a shot, when shooting in standing position. Eight subjects are tested: two experts and two novices in rifle shooting, two experts and two novices in biathlon. Electromyographic (EMG) activity of the tibialis anterior, gastrocnemius and deltoid muscles, as well as rifle oscillation and centre-of-pressure displacements were recorded during a set of ten shots per subject. The results revealed that expert biathletes seem to use a different strategy than expert rifle shooters, each of them adapting to the characteristics of their respective discipline. No significant pattern emerged from tests with novice rifle shooters, as their scores correlated only weakly with the various parameters measured in this study.

Adult↗
PubMed1988

[Analysis of advance visual indices in receiving a tennis serve].

The aim of this study is to analyse the differential visual patterns of expert and non-expert tennis players preparing to return a tennis serve. Two 16 mm films were used for testing purposes; 27 services were delivered and recorded on each film. The subjects had to identify verbally the type of serve delivered. During film viewing, eye movements were recorded by an Eye Mark Recorder NAC V. Results revealed that the expert players seem to use cues from the general position of the body during the ritual phase and cues from the racquet position during the execution phase.

Adult↗