Impact of Speller Size on a Visual P300 Brain-Computer Interface (BCI) System under Two Conditions of Constraint for Eye Movement.

The vast majority of P300-based brain-computer interface (BCI) systems are based on the well-known P300 speller presented by Farwell and Donchin for communication purposes and an alternative to people with neuromuscular disabilities, such as impaired eye movement. The purpose of the present work is to study the effect of speller size on P300-based BCI usability, measured in terms of effectiveness, efficiency, and satisfaction under overt and covert attention conditions. To this end, twelve participants used three speller sizes under both attentional conditions to spell 12 symbols. The results indicated that the speller size had, in both attentional conditions, a significant influence on performance. In both conditions (covert and overt), the best performances were obtained with the small and medium speller sizes, both being the most effective. The speller size did not significantly affect workload on the three speller sizes. In contrast, covert attention condition produced very high workload due to the increased resources expended to complete the task. Regarding users' preferences, significant differences were obtained between speller sizes. The small speller size was considered as the most complex, the most stressful, the less comfortable, and the most tiring. The medium speller size was always considered in the medium rank, which is the speller size that was evaluated less frequently and, for each dimension, the worst one. In this sense, the medium and the large speller sizes were considered as the most satisfactory. Finally, the medium speller size was the one to which the three standard dimensions were collected: high effectiveness, high efficiency, and high satisfaction. This work demonstrates that the speller size is an important parameter to consider in improving the usability of P300 BCI for communication purposes. The obtained results showed that using the proposed medium speller size, performance and satisfaction could be improved.

Statistical model choice including variable selection based on variable importance: A relevant way for biomarkers selection to predict meat tenderness.

In this paper, we describe a new computational methodology to select the best regression model to predict a numerical variable of interest Y and to select simultaneously the most interesting numerical explanatory variables strongly linked to Y. Three regression models (parametric, semi-parametric and non-parametric) are considered and estimated by multiple linear regression, sliced inverse regression and random forests. Both the variables selection and the model choice are computational. A measure of importance based on random perturbations is calculated for each covariate. The variables above a threshold are selected. Then a learning/test samples approach is used to estimate the Mean Square Error and to determine which model (including variable selection) is the most accurate. The R package modvarsel (MODel and VARiable SELection) implements this computational approach and applies to any regression datasets. After checking the good behavior of the methodology on simulated data, the R package is used to select the proteins predictive of meat tenderness among a pool of 21 candidate proteins assayed in semitendinosus muscle from 71 young bulls. The biomarkers were selected by linear regression (the best regression model) to predict meat tenderness. These biomarkers, we confirm the predominant role of heat shock proteins and metabolic ones.

A SENtence Supramodal Areas AtlaS (SENSAAS) based on multiple task-induced activation mapping and graph analysis of intrinsic connectivity in 144 healthy right-handers.

We herein propose an atlas of 32 sentence-related areas based on a 3-step method combining the analysis of activation and asymmetry during multiple language tasks with hierarchical clustering of resting-state connectivity and graph analyses. 144 healthy right-handers performed fMRI runs based on language production, reading and listening, both with sentences and lists of over-learned words. Sentence minus word-list BOLD contrast and left-minus-right BOLD asymmetry for each task were computed in pairs of homotopic regions of interest (hROIs) from the AICHA atlas. Thirty-two hROIs were identified that were conjointly activated and leftward asymmetrical in each of the three language contrasts. Analysis of resting-state temporal correlations of BOLD variations between these 32 hROIs allowed the segregation of a core network, SENT_CORE including 18 hROIs. Resting-state graph analysis applied to SENT_CORE hROIs revealed that the pars triangularis of the inferior frontal gyrus and the superior temporal sulcus were hubs based on their degree centrality (DC), betweenness, and participation values corresponding to epicentres of sentence processing. Positive correlations between DC and BOLD activation values for SENT_CORE hROIs were observed across individuals and across regions regardless of the task: the more a SENT_CORE area is connected at rest the stronger it is activated during sentence processing. DC measurements in SENT_CORE may thus be a valuable index for the evaluation of inter-individual variations in language areas functional activity in relation to anatomical or clinical patterns in large populations. SENSAAS (SENtence Supramodal Areas AtlaS), comprising the 32 supramodal sentence areas, including SENT_CORE network, can be downloaded at http://www.gin.cnrs.fr/en/tools/ .

An innovative approach combining Animal Performances, nutritional value and sensory quality of meat.

This work sets out a methodological approach to assess how to simultaneously control together Animal Performances, nutritional value, sensory quality of meat. Seventy-one young bulls were characterized by 97 variables. Variables of each element were arranged into either 5 homogeneous Intermediate Scores (IS) or 2 Global Indices (GI) via a clustering of variables and analysed together by Principal Component Analysis (PCA). These 3 pools of 5 IS (or 2 GI) were analysed together by PCA to established the links existing among the triptych. Classification on IS showed no opposition between Animal Performances and nutritional value of meat, as it seemed possible to identify animals with a high butcher value and intramuscular fat relatively rich in polyunsaturated fatty acids. Concerning GI, the classification indicated that Animal Performances were negatively correlated with sensory quality. This method appeared to be a useful contribution to the management of animal breeding for an optimal trade-off between the three elements of the triptych.

Sprained ankle syndrome: prevalence and analysis of 639 acute injuries.

The ankle sprain is often thought of as an injury involving only the lateral ankle ligaments. Frequently other structures are also injured. However, the literature describes only some of the associated injuries. The authors feel that a thorough analysis of each structure injured with the inversion and eversion ankle sprain along with the incidence would be invaluable in making an accurate diagnosis and providing appropriate treatment. The authors conducted a prospective study using a standardized evaluation during the initial examination of patients reporting with an ankle sprain. Over a 33-month period, 639 patients were studied at Oakwood Hospital Downriver Center Emergency Room and Occupational Medicine Clinic. Of the 639 patients, 92 had an associated avulsion or compression fracture of the foot or ankle. Of the remaining 547 patients, the anterior talofibular ligament was injured 453 times, the calcaneal fibular ligament was injured 366 times, and the posterior talofibular ligament was injured 187 times. Injuries to the ankle joint capsule were noted in 180 cases, the extensor digitorum brevis was involved in 111 cases, the sinus tarsi was involved in 88 cases, the peroneal tendons in 83 cases, the Achilles tendon in 67 cases, the calcaneal-cuboid ligament in 41 cases, and the syndesmosis was injured in 31 cases. Additionally, neuritis was seen in 80 patients presenting with a sprained ankle. Because of the varied and multiple components to the common sprained ankle, the authors feel that this condition would more appropriately be designated as the sprained ankle syndrome. The findings of this study may aid the examiner in exploring a more knowledgeable approach in evaluation, leading to an accurate diagnosis and appropriate treatment.

Positive and negative psychotropic effects of lamotrigine in patients with epilepsy and mental retardation.

PURPOSE: To describe significant positive or negative psychotropic effects of lamotrigine (LTG) observed in epilepsy patients with mental retardation (MR). METHODS: Seven mentally retarded epilepsy patients, [5 with Lennox-Gastaut syndrome (LGS)] who experienced significant behavioral improvements or worsening after addition of LTG to their medication regimen were studied. RESULTS: LTG produced behavioral improvements in 4 patients. Patient 1, a 14-year-old girl, had LTG added to valproate (VPA) and thioridazine, resulting in diminished lethargy, less hyperactivity, and more appropriate speech. In a 17-year-old boy (patient 2) LTG added to VPA, phenytoin (PHT), and gabapentin (GBP) lessened irritability and hyperactivity. In patient 3, a 41-year-old woman, LTG added to PHT, VPA, and carbamazepine (CBZ) diminished lethargy and enhanced her social interactions. In patient 4, a 27-year-old man, LTG monotherapy diminished irritability and hyperactivity. Adverse behavioral effects were noted in 3 patients. In patient 5, a 43-year-old man, LTG added to PHT, phenobarbital (PB), lorazepam, sertraline, and thioridazine produced irritability, hyperactivity, and poor cooperation. In patient 6, a 29-year-old woman, LTG added to VPA produced frequent screaming, temper tantrums, increased rocking movements, and hyperactivity. In patient 7, a 29-year-old man, LTG added to VPA and PHT resulted in severe exacerbation of baseline behaviors, including self-injurious activity, temper tantrums, and failure to obey simple instructions. CONCLUSIONS: In some patients with epilepsy and MR, LTG has significant positive or negative effects on behavior.

The trabeculum as a drain in aphakic glaucoma.

Glaucoma of the aphakic patient is often difficult to treat. The authors present a new surgical technique which uses a portion of the trabeculum as a drain placed in the anterior chamber. Thirty eyes (19 aphakic and 11 pseudophakic) in 28 patients presenting refractory glaucoma were operated on by the same surgeon. Sixteen eyes had already undergone glaucoma surgery, 17 presented vitreous in the anterior chamber. The average postoperative follow-up was 18 months. Eighteen eyes (60%) needed no further treatment, 6 eyes (20%) were stabilized with a local treatment, 6 eyes (20%) remained hypertonic. This new surgical technique, which uses a portion of the trabeculum as a drain, allows for long-lasting filtration in the aphakic or pseudophakic patient with refractory glaucoma.

[Trabeculo-intendation. A new surgical treatment of glaucoma of the aphakic eye]. / La trabéculo-indentation. Nouveau traitement chirurgical du glaucome de l'aphake.

INTRODUCTION: Glaucoma of the aphakic patient is often difficult to treat. Classical surgical management is limited by poor quality conjunctiva and by the presence of the vitreous gel opposite the fistula. We present a new surgical technique which uses a portion of the trabeculum as a drain placed in the anterior chamber. MATERIAL AND METHODS: Thirty eyes (19 aphakic and 11 pseudophakic) in 28 patients presenting refractory glaucoma were operated on by the same surgeon. Sixteen eyes had already undergone glaucoma surgery, 17 presented vitreous in the anterior chamber. Average post-operative follow-up was 18 months. RESULTS: Eighteen eyes (60%) needed no further treatment, 6 eyes (20%) were stabilized with a local treatment, 6 eyes (20%) remained hypertonic. CONCLUSION: This new surgical technique, which uses a portion of the trabeculum as a drain, allows for long lasting filtration in the aphakic or pseudophakic patient with refractory glaucoma.

[Sensitivity of the retinal pigment epithelium to spindle poisons]. / Sensibilité du cytosquelette de l'épithélium pigmentaire rétinien aux poisons du fuseau mitotique.

PURPOSE: The function of RPE is well known in PVR. Pharmacological agents have been extensively studied both experimentally and clinically. Few reports have detailed the interactions of antimitotic drugs on the microtubule network. The aim of this study is to visualize by indirect immunofluorescence the effects of colchicine and paclitaxel on the microtubule network of cultured pig RPE cells in interphase. METHODS: Pigs were killed at the slaughter-house, their eyes were enucleated. RPE cells were isolated and cultured. RPE cells were plated onto glass cover-slips at a density of 2,000,000 cells/ml, cultured and treated with the drugs during 4 and 24 hours at 37 degrees C at different concentrations. Immunofluorescence reaction was developped using antitubulin and fluoresceinated anti-mouse antibodies. The cytoskeletons were visualized employing a Zeiss photomicroscope equipped with epiilumination, a 63 x lens and appropriate filters for fluoresceine. RESULTS: The cytoplasmic microtubules of RPE cells were disrupted in a concentration and time-dependant manner by colchicine. Between 10 and 100 nm Veveral degrees of depolymarization of the microtubule network were observed. Paclitaxel between 1 micron and 10 microns was found to induce several degrees of microtubule "bundling" after 4 and 24 hours of incubation. Actin network was modified neither by colchicine and paclitaxel used in the same conditions. CONCLUSIONS: The results show that low doses of antimitotic drugs inhibit the microtubule network formation by depolymerization (colchicine) or stabilize it (paclitaxel). These actions inhibit cell division, which is one of the mechanisms implicated in PVR.

[Treatment of choroid melanoma by Gamma-Knife radiosurgery]. / Traitement du mélanome choroïdien par radiochirurgie Gamma-Knife.

Conservative treatment of uveal melanomas by Gamma Knife Radiosurgery is based on the use of cross fire technique with 201 Cobalt60 sources. A following of 13 months is available for the first case operated by Gamma-Knife Surgery in France. Technical baselines and one year preliminary results are reported. The diagnosis of uveal melanoma T3NOMO was established by converging results of clinical examination, angiography and echography. The definition of the target was based on stereotactic MRT examination. We delivered a dose of 50 Gys to the marginal isodose (50%). Today, one year after treatment the tumor decreased, the visual function was preserved. There were no side effect or complication.

Effects of strabismus surgery on refraction in children.

We assessed 115 eyes of 59 children with esotropia 2-3 months postoperatively to evaluate the effects of strabismus surgery on refraction. Three variables were measured: spherical equivalent, and cylinder power and axis. The mean changes in spherical equivalent were non-significant. The axis of postoperative astigmatism moved towards 'with-the-rule', thus improving refraction. The amount of recession and the consequent changes in cylinder power were inversely related. The results showed a significant change in cylinder axis after recession of the inferior oblique. Recession-tucking procedures led to the largest changes in cylinder power.

Experimental tolerance to perfluorodecalin used in prolonged intraocular tamponade.

The authors report the results of an experimental study of a series of 16 rabbit eyes that underwent prolonged tamponade by a liquid perfluorocarbon (LPFC). After vitreous compression by C3F8, a complete gas/LPFC exchange is performed and left in place for 48 h, 12 days and 21 days. Study of the retina by light and electron microscopy showed numerous lesions: vacuolization in the nerve fiber layer, progressive defects of the outer photoreceptor segments and presence of pseudomyelinic bodies in the inner plexiform layer. The axonal fiber loss is shown by a specific marker. The analysis of the results underlines the mechanical toxicity of LPFCs used in prolonged tamponade, which are too heavy for the neurosensory retina.

[Experimental tolerability of perfluorodecalin in prolonged intraocular tamponade]. / Tolérance expérimentale de la perfluorodécaline en tamponnement prolongé intraoculaire.

BACKGROUND: Perfluorocarbon liquids are used in vitreoretinal surgery due to their high specific gravity. Studies of retinal tolerance to prolonged tamponade with these liquids are discordant. Our experimental study uses a highly purified perfluorodecalin molecule (DKline) for prolonged retinal tamponade. The retinal lesions observed are described and analyzed. MATERIAL AND METHODS: [corrected] Twenty pigmented rabbit eyes were studied. 1.2 to 1.5 ml of DKline were injected into the vitreous cavity after pneumatic compression. Histological and ultrastructural studies were performed after tamponade lasting 48 hours (5 eyes), 12 days (6 eyes), 21 days (5 eyes) and controls (4 eyes). RESULTS: After 48 hours: vacuolization of the nerve fiber layer is observed without ultrastructural changes; undulation of the photoreceptor outer segments is seen. After 12 days: vacuolization and undulation increase, with modifications in the junction between photoreceptors and the pigment epithelium. After 21 days: major vacuolization is seen, with disorganization of the photoreceptor architecture. The inner limiting membrane is respected and no surface proliferation is observed. CONCLUSION: DKline used in prolonged tamponade induces histological lesions as early as 48 hours; they increase with time. The nerve fiber and photoreceptor outer segment layers are the most severely affected. These lesions appear to be mainly of mechanical origin. Prolonged retinal tamponade with DKline would not seem possible.

Ocular findings in trigonocephaly.

BACKGROUND: Trigonocephaly, caused by premature closure of the metopic suture, is a rare form of craniosynostosis. The aim of this study was to assess the visual outcome in children operated on for trigonocephaly. METHODS: We present eight cases of children with trigonocephaly surgically corrected by the same craniofacial technique. CT with 3D reconstruction was performed in all cases. Genitori defined three types of trigonocephaly according to the severity of the deformity of the skull base only types II and III were included in this study directed at evaluation of the ocular disorder. A complete eye examination was performed on all children by the same observer, with a follow-up of 2-6 years. RESULTS: 3D-CT reconstruction of the skull base showed that the frontozygomatic region was affected by the deformation. Ocular examination showed considerable astigmatism in most children with late operation. A low degree of strabismus was observed in most children. CONCLUSION: This study demonstrated that reconstructive surgery should be performed by the age of 6 months, given the immaturity of the visual system up to that time. Close cooperation between neurosurgeons, pediatricians and ophthalmologists is of paramount importance in order to prevent this bone deformation exerting an adverse effect on visual development. The ophthalmologist must possess a basic understanding of the various craniosynostoses.

Refractive error and ocular motility in plagiocephaly.

Plagiocephaly, which is caused by premature closure of one of the coronal sutures, leads to fronto-orbital asymmetry. The aim of this work was to study the repercussions of orbital deformation on the visual system. Twenty-one patients presenting with plagiocephaly at birth and operated on by the same craniofacial technique (bilateral approach with translation and advancement of the entire involved orbits) were included in the study. All of the patients were examined by clinical anthropometry with three-dimensional reconstruction and underwent complete eye examination by the same observer. Follow-up after craniofacial surgery ranged from 15 months to 4 years. In the last few years, three-dimensional reconstruction has shown that the anatomic region affected by the deformation is the frontozygomatic region and has thus made it possible to advance to another theory on the origins of ocular problems. The severe effect of orbital anomalies on the development of the visual system (binocular vision, strabismus with amblyopia, refractive errors) has been emphasized in the literature. The present study shows that the scheduling of reconstructive surgery is fundamental and must not exceed 6 months, given the immaturity of the visual system up until this time. This means that the ophthalmologist must be able to recognize the various craniostenoses in order to schedule reconstructive surgery as soon as possible. Cooperation between the neurosurgeon and the ophthalmologist is of paramount importance if the pathogenic effects of this bone deformation are to be stopped and proper visual development preserved.

The genetics of retinoblastoma.

Retinoblastoma is a malignant tumor of the eye that affects about one in 20,000 young children and occurs as hereditary and non-hereditary (sporadic) forms. It results from successive loss or inactivation of the two alleles of the Rb1 gene, located in 13q14. A chromosomal deletion in 13q14 is revealed by cytogenetic investigation in about 5% of affected patients. Molecular studies have confirmed that inactivation of both alleles of the Rb1 gene, even by point mutation, is required for tumorigenesis, leading to the concept of antioncogenes or tumor suppressor genes. The protein (p110RB) produced by the Rb1 gene is involved in cell cycle regulation. Absence or abnormal forms of the protein may result in deregulation of the cell cycle and subsequent cell proliferation. Association of p110RB with viral oncoproteins may be a step in tumorigenesis. Differences in penetrance and expressivity among families, could be explained by balanced insertional translocation and by defects of the Rb1 gene, which codes for a shortened Rb protein with partial oncosuppressor function. Techniques allowing analysis of Rb1 mutations can be successfully used to predict or exclude the development of retinoblastoma in newborn infants.

Walker-Warburg syndrome: a report of 3 cases.

Walker-Warburg syndrome is a congenital malformation syndrome of unknown etiology which is characterized by fatal neurological lesions. It was first described by Walker in 1942 as involving agyria, hydrocephalus and eye malformations. Its etiology has been discussed in all of the articles on the subject in the literature, but the majority of the authors describe it as an autosomal recessive syndrome. Ultrasonography plays a key role in detecting a cephalic anomaly by prenatal diagnosis as in our 2 cases. The aim of this article is to report 3 new cases of Walker-Warburg syndrome in two families. Knowledge of this syndrome emphasizes both the need for ultrasonographic observation and genetic counselling for families at risk.

Ocular growth in the fetus. 1. Comparative study of axial length and biometric parameters in the fetus.

The knowledge of ocular growth during fetal life, when compared with other fetal biometric parameters, could not only provide a better definition of malformation syndromes but could also give a better understanding of certain pathological processes in premature babies and in newborns. As the literature concerning prenatal ocular dimensions contains few data, the aim of this study was to measure the axial length of the globe (AL) in fetuses and compare this measurement with their gestational age, weight, height, head circumference (HC) and thoracic circumference (TC) in order to compile a reference table. In the present study, 76 globes from 38 fetuses (18-41 weeks gestational age) from the Department of Pathology (Timone University Hospital, Marseille) were examined. Ultrasonography A and B were used to measure the AL, and a pathological examination determined fetal weight, HC, TC and height. We were interested to find out which of the parameters studied would give the best correlation with ocular growth. Statistical analysis showed that HC remained the most discriminant factor and correlated best with ocular growth. We thus obtained an equation for ocular size according to HC that could serve as a basis for detecting pre- or postnatal ocular defects.

Ocular growth in the fetus. 2. Comparative study of the growth of the globe and the orbit and the parameters of fetal growth.

In a previous study, we showed that the growth of the eye during fetal development compared with the other parameters of the fetus was above all connected to the head circumference, which appeared to be the most discriminant measurement. In a second study, we measured the growth of the orbit of the fetus in order to compare it with the growth of the globe and the cranial circumference. Another 60 eyeballs of 30 fetuses of 18-41 weeks gestational age were examined. The corneal diameter (CD) of the cornea was a measurement added to those used in the method in the previous study, and orbital radiography was carried out: the parameters used were the same as in the previous study measured in relation to the CD, orbital diameter (OD) and the biparietal diameter (BPD). The aim of this study was to show the links between the variations in the measurements and to estimate them in relation to fetal growth. The results confirm those of the previous study, and this study also shows that, in estimating the head circumference, the OD and CD are the most accurate indicators. This study was also concerned with the BPD: the best correlation is obtained with the OD, which can be estimated accordingly from the BPD. Although the OD is not in an area studied by ultrasonography (highly dependent on the sectional plane), this study shows that it should perhaps be reconsidered in the prenatal diagnosis of orbital malformation. It would then be necessary to take into account not only the BPD but also the relationship between the OD and the BPD.