Visual Tracking Test Research Articles

USE OF EYE TRACKING TECHNOLOGY TO DETECT MILD COGNITIVE IMPAIRMENT

Abstract Early detection of dementia is key to helping individuals and their families cope. Use of eye tracking technology to measure eye movements could provide an objective and sensitive measure of cognitive impairment (Hodgson et al, 2019; Wang et al, 2020). In this pilot study, we predicted that eye tracking metrics differ between people with diagnosed MCI and those of healthy controls. Eleven veterans (≥ 55 years) being seen at the San Francisco VA Health Care System who either had a confirmed diagnosis of MCI or had subjective memory complaints and scored lower than a 26 on the MoCA participated. Their results were compared to that of a previously collected control sample (n = 41) (Liston et al, 2017). Participants completed a five-minute visual tracking test with 48 trials based on a classic step-ramp visual tracking paradigm that was administered on a PC computer with a camera and eye tracking capability. The visual tracking test yields 10 z-scored eye tracking metrics that are summarized in a single scalar summary score. Receiver operating characteristics (ROC) were computed and compared to the control sample. The summary score of the MCI group (median: -2.2) differed significantly from the healthy control sample (median: 0.0), which yielded a significant sensitivity of the test to presence or absence of MCI (ROC area = 0.94, p < .001). Although we view the results as preliminary due to the small sample size, results suggest that use of eye tracking technology may be a viable option for MCI detection.

Kinematic modelling and experimental testing of a particle-jamming soft robot based on a DEM-FEM coupling method

Particle-jamming soft robots are characterised by high flexibility in motion and high stiffness when executing a task. Regarding particle jamming of soft robots, the discrete element method (DEM)-finite element method (FEM) coupling was used for modelling and control. At first, a real-time particle-jamming soft actuator was proposed by integrating advantages of the driving Pneu-Net and the driven particle-jamming mechanism. Then, DEM and FEM were separately employed to determine the force-chain structure of the particle-jamming mechanism and the bending deformation performance of the pneumatic actuator. Furthermore, the piecewise constant curvature method was adopted for forward and inverse kinematic modelling of the particle-jamming soft robot. Finally, a prototype of the coupled particle-jamming soft robot was prepared, and a visual tracking test platform was established. The adaptive control method was proposed to compensate for the accuracy of motion trajectories. The variable-stiffness performance of the soft robot was verified by conducting stiffness tests and bending tests. The results provide novel theoretical and technical support for the modelling and control of variable-stiffness soft robots.

Using electrooculography with visual stimulus tracking test in diagnosing of ADHD: findings from machine learning algorithms.

Attention deficit hyperactivity disorder (ADHD), one of the most common neurodevelopmental disorders in childhood, is diagnosed clinically by assessing the symptoms of inattention, hyperactivity, and impulsivity. Also, there are limited objective assessment tools to support the diagnosis. Thus, in this study, a new electrooculography (EOG) based on visual stimulus tracking to support the diagnosis of ADHD was proposed. Reference stimulus one-to-one tracking numbers (RSOT) and colour game detection (CGD) were applied to 53 medication-free children with ADHD and 36 healthy controls (HCs). Also, the test was applied six months after the treatment to children with ADHD. Parameters obtained during the visual stimulus tracking test were analyzed and Higuchi fractal dimension (HFD) and Hjorth parameters were calculated for all EOG records. The average test success rate was higher in HCs than in children with ADHD. Based on machine learning algorithms, the proposed system can distinguish drug-free ADHD patients from HCs with an 89.13% classification performance and also distinguish drug-free children from treated children with an 80.47% classification performance. The findings showed that the proposed system could be helpful to support the diagnosis of ADHD and the follow-up of the treatment.

Visuomotor Synchronization: Military Normative Performance.

Cognitive processes such as perception and reasoning are preceded and dependent on attention. Because of the close overlap between neural circuits of attention and eye movement, attention may be objectively quantified with recording of eye movements during an attention-dependent task. Our previous work demonstrated that performance scores on a circular visual tracking task that requires dynamic synchronization of the gaze with the target motion can be impacted by concussion, sleep deprivation, and attention deficit/hyperactivity disorder. The current study examined the characteristics of performance on a standardized predictive visual tracking task in a large sample from a U.S. Military population to provide military normative data. The sample consisted of 1,594 active duty military service members of either sex aged 18-29 years old who were stationed at Fort Hood Army Base. The protocol was reviewed and approved by the U.S. Army Medical Research and Materiel Command Institutional Review Board. Demographic, medical, and military history data were collected using questionnaires, and performance-based data were collected using a circular visual tracking test and Trail Making Test. Differences in visual tracking performance by demographic characteristics were examined with a multivariate analysis of variance, as well as a Kolmogorov-Smirnov test and a rank-sum test. Associations with other measures were examined with a rank-sum test or Spearman correlations. Robust sex differences in visual tracking performance were found across the various statistical models, as well as age differences in several isolated comparisons. Accordingly, norms of performance scores, described in terms of percentile standings, were developed adjusting for age and sex. The effects of other measures on visual tracking performance were small or statistically non-significant. An examination of the score distributions of various metrics suggested that strategies preferred by men and women may optimize different aspects of visual tracking performance. This large-scale quantification of attention, using dynamic visuomotor synchronization performance, provides rigorously characterized age- and sex-based military population norms. This study establishes analytics for assessing normal and impaired attention and detecting changes within individuals over time. Practical applications for combat readiness and surveillance of attention impairment from sleep insufficiency, concussion, medication, or attention disorders will be enhanced with portable, easily accessible, fast, and reliable dynamic eye-tracking technologies.

Surgeons Maintain Better Focus Working 12-Hour Shifts Compared to 24-Hour Calls

In this quality improvement project, we analyzed surgeon focus and attention utilizing a visual tracking device. We hypothesized that surgeons maintained better focus working 12-hour shifts compared to 24-hour calls. A prospective, quality improvement project was performed on surgery residents, medical students, and attending physicians working at a busy, tertiary referral, safety-net hospital with Level 1 trauma and burn centers. A visual tracking system was used to measure visual attention before and after a 12-hour, in-house shift and a 24-hour, surgical in-house call. A pupil tracker was utilized to measure attention impairment. Individual performance was rated on a scale of 0 to 6: Severely Impaired- 0; Impaired- 1; Low Average- 2; Average- 3; Above Average- 4; High Average- 5; Superior- 6. Data were analyzed for homogeneity. The Wilcoxon Ranked Sum was used to assess for statistically significant differences between focus scores in the same group of individuals before and after shifts and/or calls. The Mann-Whitney U test was used to compare differences in focus between 12 and 24 hour in-house shifts and/or calls. A total of 21 surgeons provided a total of 61 visual tracking tests for analysis. Results were found to be nonhomogeneous. The project population was 46% men with a median age of 31 years IQR (28-33). General surgery residents accounted for 48 tests, medical students for 2, and attending surgeons for 11. Average hours of self-reported sleep before the shift/call was 6 (IQR; 6-7). There was almost no overall change in focus in individuals before and after a 12-hour, in-house shift -0.06 (SD 1.9), while after a 24- hour, in-house call, focus decreased by almost 2 full grades -1.8 (SD 1.6) (p = 0.013). There was no statistically significant difference in focus found between 12-hour day shift and 12-hour night shift. Twelve-hour shifts appear to preserve focus in surgeons better compared with 24- hour, in-house calls. More research is needed to establish the optimal time of surgeon focus maintenance and shift duration.

A combined stepping and visual tracking task predicts cognitive decline in older adults better than gait or visual tracking tasks alone: a prospective study.

It is unclear whether motor-cognitive dual tasks predict cognitive decline better than either motor or cognitive tasks alone. To examine the utility of the novel motor-cognitive dual-task test [Stepping Trail Making Test (S-TMT)], as a predictor of cognitive decline, and compare its predictive performance with single motor or cognitive tests. This 2-year population-based prospective study included 626 adultsaged ≥70 years from Takashimadaira, Itabashi, Tokyo. The S-TMT measured the time taken to step on 16 numbers in order. Gait speed and TMT-A were assessed with standardized methods as single motor and cognitive tasks, respectively. A decline in the Mini-Mental State Examination score by ≥ 3 points over 2years was defined as a significant cognitive decline. Over 2years, 97 (15.5%) experienced cognitive decline. After adjusting for confounders, binary logistic regression models showed no significant associations between gait speed, TMT-A time tertiles, and risk of cognitive decline, but participants in the longest tertile of S-TMT time were more likely to develop cognitive decline than those of the shortest tertile (odds ratio 2.14; 95% confidence interval 1.17-3.90). Only the addition of the S-TMT time to the covariates model significantly improved the reclassification indices for predicting cognitive decline (net reclassification improvement: 0.31, P < 0.01; integrated discrimination improvement: 0.01, P = 0.02). Only the S-TMT was significantly associated with cognitive decline and improved reclassification indices, indicating that it is more useful for predicting cognitive decline than individual gait speed or visual tracking tests alone.

Vision‐Based Three‐Dimensional Reconstruction and Monitoring of Large‐Scale Steel Tubular Structures

A four‐ocular vision system is proposed for the three‐dimensional (3D) reconstruction of large‐scale concrete‐filled steel tube (CFST) under complex testing conditions. These measurements are vitally important for evaluating the seismic performance and 3D deformation of large‐scale specimens. A four‐ocular vision system is constructed to sample the large‐scale CFST; then point cloud acquisition, point cloud filtering, and point cloud stitching algorithms are applied to obtain a 3D point cloud of the specimen surface. A point cloud correction algorithm based on geometric features and a deep learning algorithm are utilized, respectively, to correct the coordinates of the stitched point cloud. This enhances the vision measurement accuracy in complex environments and therefore yields a higher‐accuracy 3D model for the purposes of real‐time complex surface monitoring. The performance indicators of the two algorithms are evaluated on actual tasks. The cross‐sectional diameters at specific heights in the reconstructed models are calculated and compared against laser rangefinder data to test the performance of the proposed algorithms. A visual tracking test on a CFST under cyclic loading shows that the reconstructed output well reflects the complex 3D surface after correction and meets the requirements for dynamic monitoring. The proposed methodology is applicable to complex environments featuring dynamic movement, mechanical vibration, and continuously changing features.

New Tools and Methods in Selection of Air Traffic Controllers Based on Multimodal Psychophysiological Measurements

Comprehensive multimodal psychophysiological measurements and smart data analysis based on wearable and low-cost technologies could enhance traditional air traffic controller (ATC) selection process. Many recent studies in neuro-cognitive science and stress resilience illustrated effectiveness of these multimodal measurements and appropriate metrics in comprehensive assessment of ATCs' mental states, such as cognitive workload, cognitive decline, attention deficit, fatigue, emotional and behavioural problems, etc. Accordingly, this article is focused on innovation efforts in ATC selection protocols based on a set of comprehensive stimuli and corresponding multimodal psychophysiological measurements. The concept of enhancement of ATC selection process presented in this article includes complex physiological, oculometric and speech measurements and appropriate metrics. From these multimodal measurements during specific stimulation tasks, which include different versions of acoustic startle stimuli, airblasts, semantically relevant aversive images and sounds, different versions of Stroop tests, visual tracking test, a complex set of multimodal-multidimensional features is computed as predictors of ATC candidates' future performance, like: stress resilience, workload capacity, attention, visual performance, working memory etc. Such cost-effective, more objective, non-invasive preliminary measurements, lasting no longer than 45 minutes may have good discriminative power and might be used in ATC selection processes as enhancement of current selection procedures. Comprehensive analysis of presented multimodal features during different experimental conditions might also be very useful in selection processes of other stressful professional jobs, like first responders, pilots, astronauts etc.

Visual Eye movement-vestibular ocular balance assessment in the diagnosis of central and peripheral vertigo

Objective To explore the role of visual oculomotor-vestibular eye balance function in the diagnosis of central and peripheral vertigo. Methods From January 2015 to June 2016, one hundred and sixty-two patients with central vertigo who were treated at Kailuan General Hospital were enrolled in the study, including 124 males and 38 females, aged (64.09±10.98) years old; there were 166 cases of peripheral vertigo, 75 males and 91 females, aged (52.13±12.20) years old.Spontaneous nystagmus test, gaze test, position test, saccade test, smooth visual tracking test, visual single-speed test, visual sinus test, swivel chair rotation-emergency stop test using infrared video nystagmus and static balance posture instrument, open-closed eye hard plate erect test, open-closed eye sponge soft bottom erect test balance function electrophysiological test were conducted. Results The detection rate of pathological spontaneous nystagmus and pathological gaze nystagmus was higher in the central vertigo group than that in the peripheral vertigo group (χ2=5.674, 16.458, P<0.05). The occurrence rate of positional nystagmus was higher in peripheral vertigo group than that in central vertigo group (χ2=48.896, P<0.001). The abnormal rate of scanning test, stable visual tracking test, visual movement single speed and sinusoidal test, and static balance posture test were higher in the central vertigo group than those in the peripheral vertigo group (χ2=137.169, 166.972, 150.877, 150.877, 27.273, P<0.001), while the abnormal rate of rotating chair sudden stop test was higher in the central vertigo group than that in the peripheral vertigo group (χ2=51.000, P<0.001). The abnormal results were mainly scanned underflush and slow scan in central vertigo group (χ2=103.846, 4.296, P<0.05), stable visual tracking curve (χ2=147.389, 4.296, P<0.05) in type III-IV, and the gain of nystagmus decreased unilaterally and bilaterally (χ2=47.531, 44.477, 52.529, 53.255, P<0.001). Anomalies of proprioception in reverse and vertical nystagmus and static balance posture were induced by rotating chair sudden stop test (χ2=11.847, 23.778, P<0.001), while peripheral vertigo group showed unilateral decrease of nystagmus gain induced by rotating chair sudden stop test.(χ2=79.771, P<0.001). Conclusion The patients with peripheral vertigo have obvious body position spontaneous vestibular response and vestibular oculomotor system dysfunction, while the patients with central vertigo mainly have visual and oculomotor system dysfunction, and may be accompanied by vestibular oculomotor system and vestibular spinal reflex dysfunction. Key words: Vertigo; Videonystagmography; Static equilibrium posture

Prediction of ophthalmological problems in 6.5 year‐old prematurely born children

PurposeThe aim of the study was to describe the ophthalmological outcome at 6.5 years and to identify possible predictive factors visual problems at this age.MethodsThis is a prospective, population‐based study, including all infants born ≤32 weeks gestational age (GA) in Uppsala County, Sweden, during 2004 to 2007. The children were screened for ROP in the neonatal period, visual tracking test were performed at 4 months tests of, and at 2.5 years, ophthalmological, visuospatial and cognitive testing were performed. At 6.5 years, 84 prematurely born and 64 children born at term participated in ophthalmological and visual testing. Of the preterm children, 24 (29%) had ROP and 9 had IVH 3‐4 and/or PVL in the neonatal period.ResultsMean visual acuity (VA) did not differ between preterm and full‐term children, but a “subnormal” VA of ≤0.8 was more common in the preterm than the control group (31% versus 14%) (p &lt; 0.05). No prematurely born child was blind, but two had VA &lt; 0.5. A contrast sensitivity of &lt; 0.5 was more common (36% versus 19%, p &lt; 0.05) and strabismus was also more common in the pre‐terms (8% versus 0%, p &lt; 0.05). Within the preterm group, logistic regression analyses revealed GA, ROP, PVL/IVH, and mild cognitive disability (Bayley III test), to be predictive factors for ophthalmological and visual problems at 6.5 years age.ConclusionsPrematurely born children had an increased prevalence of ophthalmological problems at 6.5 years age. Treated ROP and early neurological problems were risk factors for later ophthalmological dysfunctions. This study also showed that reduced cognitive function at 2.5 years appeared to predict such problems.

The Effect of Hearing Aid Noise Reduction on Listening Effort in Hearing-Impaired Adults

The purpose of the present study was to evaluate the effect of a noise-reduction (NR) algorithm on the listening effort hearing-impaired participants expend on a speech in noise task. Twelve hearing-impaired listeners fitted with behind-the-ear hearing aids with a fast-acting modulation-based NR algorithm participated in this study. A dual-task paradigm was used to measure listening effort with and without the NR enabled in the hearing aid. The primary task was a sentence-in-noise task presented at fixed overall speech performance levels of 76% (moderate listening condition) and 50% (difficult listening condition) correct performance, and the secondary task was a visual-tracking test. Participants also completed measures of working memory (Reading Span test), and processing speed (Digit Symbol Substitution Test) ability. Participants' speech recognition in noise scores did not significantly change with the NR algorithm activated in the hearing aid in either listening condition. The NR algorithm significantly decreased listening effort, but only in the more difficult listening condition. Last, there was a tendency for participants with faster processing speeds to expend less listening effort with the NR algorithm when listening to speech in background noise in the difficult listening condition. The NR algorithm reduced the listening effort adults with hearing loss must expend to understand speech in noise.

Predictive visual tracking: specificity in mild traumatic brain injury and sleep deprivation.

We tested whether reduced cognitive function associated with mild traumatic brain injury (mTBI) and sleep deprivation can be detected and distinguished using indices of predictive visual tracking. A circular visual tracking test was given to 13 patients with acute mTBI (recruited within 2 weeks of injury), 127 normal control subjects, and 43 healthy subjects who were fatigued by 26-hour sleep deprivation. Eye movement was monitored with video-oculography. In the mTBI-related portion of the study, visual tracking performance of acute mTBI patients was significantly worse than normal subjects (p < 0.001). In the sleep-deprivation-related portion of the study, no change was detected between the two baseline measures separated by 2 to 3 weeks, but the 26-hour sleep deprivation significantly degraded the visual tracking performance (p < 0.001). The mTBI subjects had substantially worse visual tracking than sleep-deprived subjects that could also be identified with different visual tracking indices, indicating possible different neurophysiological mechanisms. Results suggest that cognitive impairment associated with mTBI and fatigue may be triaged with the aid of visual tracking measures.

The effect of sports vision exercises on the visual skills of university students

Vision is one of the most important special senses and is the primary source of external information. The role of vision in our everyday lifestyles is immense and adequate visual skills are needed for simple tasks which include reading and writing, that are especially important for students. Stress is an important factor which most students deal with, and along with other external factors, could adversely affect the ability to effectively perform many visual skills. This study aims to determine if sports vision exercises could improve visual skills and thereby enhance motor and cognitive performance. A 169 second year physiology students (18-22 years of age) participated in the study. The students were divided into control (n=78) and experimental groups (n=91) and pre and post sports vision tests were conducted. This included testing visual skills such as visual acuity, eye dominance, focusing, tracking, vergence, sequencing, eye-hand coordination, visualization and reflex. The results showed a significant improvement in the sequencing and eye-hand coordination tests in the experimental group, whilst a non-significant improvement (control group) was observed in the visual acuity, visualization, tracking, vergence and reflex tests. The improvements (except for focusing) were greater in the experimental group than in the control group. The study clearly showed that correct sports vision training can improve certain visual skills and lead to an enhancement of motor and cognitive learning and performance. Sports vision exercises are therefore an efficient method of improving certain visual skills and possibly minimizing any defects caused by stress.

Effects of Differences in Manipulation and Supporting Legs and Moving Target Speed on a Visual Tracking Test Using Center of Pressure

The human limbs are paired organs, each capable of independent movement. Functional laterality is found in the upper limbs when writing letters or throwing a ball, etc. This study aimed to examine the effects of differences in manipulation leg (ML), defined as the leg used when kicking a ball and supporting leg (SL), as the contralateral leg, and moving target speed on a visual tracking test using center of pressure (COP). We included 20 healthy male students (age, 22.0 ± 4.9 years; height, 172.4 ± 3.2 cm, and weight, 66.2 ± 5.0 kg) without lower limb or eye disorders. During the tracking test, subjects pursued a target moving on the Y-axis by COP. We selected 0.083 and 0.050 Hz frequencies to examine the effect of different target speeds. An evaluation variable was defined as total errors between moving targets and COP over 30 s. It was assumed that individuals with smaller errors would be superior during tracking tests. A significant difference was found between means for bilateral and unilateral stance (ML or SL) at both frequencies but not between ML and SL, and in all standing conditions, 0.083 Hz showed a smaller error than 0.050 Hz. In conclusion, regardless of the speed of the moving target, performance of the visual tracking test was superior in bilateral than unilateral stance, and there was no difference between ML and SL. Regardless of stance, test performance reduced with faster target speed, particularly with unilateral stance (about 29%).

The effects of sports vision exercises on the visual skills of university students

Vision is one of the most important special senses and is the primary source of external information. The role of vision in our everyday lifestyles is immense and adequate visual skills are needed for simple tasks which include reading and writing, that are especially important for students. Stress is an important factor which most students deal with, and along with other external factors, could adversely affect the ability to effectively perform many visual skills. This study aims to determine if sports vision exercises could improve visual skills and thereby enhance motor and cognitive performance. A 169 second year physiology students (18-22 years of age) participated in the study. The students were divided into control (n=78) and experimental groups (n=91) and pre and post sports vision tests were conducted. This included testing visual skills such as visual acuity, eye dominance, focusing, tracking, vergence, sequencing, eye-hand coordination, visualization and reflex. The results showed a significant improvement in the sequencing and eye-hand coordination tests in the experimental group, whilst a non-significant improvement (control group) was observed in the visual acuity, visualization, tracking, vergence and reflex tests. The improvements (except for focusing) were greater in the experimental group than in the control group. The study clearly showed that correct sports vision training can improve certain visual skills and lead to an enhancement of motor and cognitive learning and performance. Sports vision exercises are therefore an efficient method of improving certain visual skills and possibly minimizing any defects caused by stress.Key words: Sports vision exercises, visual skills, students.

Deficiency of chemokine receptors CCR1, CCR5 AND CX3CR1 causes defective osteoclast differentiation and defective bone remodeling

oc/oc fetal liver cells after conditioning with irradiation or busulfan. Here, we hypothesized that transplantation without prior conditioning could reverse osteopetrosis and rescue oc/oc mice. Oc/oc and control mice were injected iv at day 1 after birth with normal or lineage depleted (lin−) BM cells (1 or 5×106). More than 85% of oc/ oc mice injected with 5×106 lin-cells survived long term (up to a year), while the other oc/oc groups died at 3–4 w. Engraftment, as determined by % donor cells in peripheral blood (PB) was 4–5% at 3, 6, 12 and 20 w. Several mice were sacrificed at 3–4 w for thorough analysis. Histopathology of femurs revealed 40–50% reversal of osteopetrosis at 3 w but almost complete reversal at 4 w. Micro-CT of femurs and calvariae confirmed these findings. BM cells were harvested and in vitro differentiated to osteoclasts. While the number of osteoclasts formed from BM cells of control mice and oc/oc mice was the same, bone resorption did not occur by cells generated from oc/oc mice. Osteoclasts from transplanted oc/oc mice resorbed bone although it was only 5% as compared to the controls. Confocal microscopy revealed that resorption was only associated with osteoclasts which were at least partially derived from fusion of donor cells in oc/oc mice. Lineage analysis of BM, PB and spleen did not show any evidence for selective recruitment of cells to the osteoclast lineage. Analysis of PB at 9 months revealed that the block in B-cell development in oc/oc mice was partially reversed. Assessment of vision with a visual drum tracking test showed that blindness was prevented in transplanted oc/oc mice. Our findings are of biological significance as they show that coupling of bone resorption and formation can be shifted by only a small fraction of normal cells in this severe disease model. Furthermore, they are clinically significant and encouraging for the continued development of stem cell based gene therapy of IMO. Conflict of interest: None declared.

Daytime variation in performance and tiredness/sleepiness ratings in patients with insomnia, narcolepsy, sleep apnea and normal controls

Daytime tiredness or sleepiness and deficits in cognitive performance are common complaints in sleep disordered patients. Till now there are few studies comparing patients from different diagnostic groups of sleep disorders in the same experimental protocol. We studied the time course of cognitive functions and subjective alertness in a parallel group design with four groups of patients [narcolepsy, untreated or treated obstructive sleep apnea (OSA), or psychophysiological insomnia] and a control group of subjects without sleep complaints. Each group consisted of 10 subjects, matched for age and gender. After a night with polysomnography, subjects were studied for 10 h from 08:00 hours to 18:00 hours at 20 min intervals under standardized environmental conditions. Four psychological tests were applied, (1) a critical flicker fusion (CFF) test to measure optical fusion threshold (alertness); (2) a paper-and-pencil visual line tracking test (selective attention); (3) a visual analog scale (VAS) for tiredness/sleepiness; and (4) the Tiredness Symptoms Scale (TSS), a 14 items check list. Each test session lasted for 8 min, followed by a 12 min pause. The level and time course of cognitive performance and self-rating data were analysed with hierarchical linear mixed effects models. Cognitive tests showed decrements in alertness and selective attention in untreated patients with insomnia, narcolepsy, and sleep apnea. Narcoleptic patients and untreated OSA had a lower CFF threshold than controls, and for narcoleptic patients the time course differed from that of all other groups. In the visual tracking test the performance of all groups of patients was worse compared with normal controls. Self-rated tiredness/sleepiness was significantly more pronounced in the three groups of untreated patients than in control subjects.

Modeling of motor control on manual tracking for developing a handmovement-compensation technique

Skillful motor control by humans is achieved by the appropriate motor commands generating from the central nervous system. An internal model in the cerebellum may contribute to the realization of accurate motor control. In this work, a model of human motor control of manual tracking to move a visible target was constructed based on experimental data from a visual tracking test with normal healthy adults and with patients with cerebellar ataxia. A compensation method to improve the motor function of patients was also developed by using the model.

MODELING AND ANALYSIS OFHAND MOVEMENT FOR IMPROVING MOTORFUNCTION

Skillful motor control of human is achieved by the appropriate motor commands generating from the central nerve system. Internal model in the cerebellum may have great contribution for realizing accurate motor control. In this paper, the model for human motor control on manual tracking to moving visual target was constructed based on the experimental data of the visual tracking test for three groups; normal healthy adults, patients with cerebellar ataxia and patients with Parkinson disease. Relationship between the model parameters and movement disorders were investigated. Furthermore, the compensation method for improving the motor function of patients were also considered.

Slow-Release Caffeine: A New Response to the Effects of a Limited Sleep Deprivation

The aim of this study is to assess the interest of the intake of a new galenic form of caffeine called "slow-release" caffeine (SR caffeine) during a decrease of vigilance due to a limited sleep deprivation. The controlled method used compared three doses of SR caffeine (150, 300 and 600 mg) with a placebo. Tests were performed 2, 9 and 13 hours after each treatment. Wakefulness level was assessed subjectively through questionnaires and analog visual scales, and objectively with the Multiple Sleep Latency Test. Performance level was also assessed regularly with an attention test, a grammatical reasoning test, a spatial recognition test, a mathematical processing test, a visual tracking test, a memory search test, and a dual task. The motor activity was evaluated by wrist actimeter and safety of treatment was observed by regular clinical examination. NA. Twenty-four young and healthy volunteers (12 men and 12 women) participated in a 32-hour sleep deprivation. NA. The results show a significant effect of slow-release caffeine vs. placebo, and on vigilance and performance when subjects became tired. The effects of SR caffeine lasted 13 hours after treatment. SR caffeine 300 and 600 mg are efficacious doses but the optimal dose (maximum effect without any side effects) for both men and women is after all 300 mg. Globally, there is no difference between placebo and caffeine during the recovery night period. SR caffeine (300 mg) seems to be an efficient and safety substance to maintain a good level of vigilance and performance during limited sleep deprivation.