Quantitative Characterization of Smooth Pursuit Eye Movements in School-Age Children Using a Child-Friendly Setup

Purpose: It could be argued that current studies investigating smooth pursuit development in children do not provide an optimal measure of smooth pursuit characteristics, given that a significant number have failed to adjust their setup and procedures to the child population. This study aimed to characterize smooth pursuit in children using child-friendly stimuli and procedures. Methods: Eye movements were recorded in 169 children (4–11 years) and 10 adults, while a customized, animated stimulus was presented moving horizontally and vertically at 6°/s and 12°/s. Eye movement recordings from 43 children with delayed reading, two with nystagmus, two with strabismus, and two with unsuccessful calibration were excluded from the analysis. Velocity gain, proportion of smooth pursuit, and the number and amplitude of saccades during smooth pursuit were calculated for the remaining participants. Median and quartiles were calculated for each age group and pursuit condition. ANOVA was used to investigate the effect of age on smooth pursuit parameters. Results: Differences across ages were found in velocity gain (6°/s P 0.05). Conclusions: Using child-friendly methods, children over the age of 7 to 8 years demonstrated adultlike smooth pursuit. Translational Relevance: Child-friendly procedures are critical for appropriately characterizing smooth pursuit eye movements in children

Infantile nystagmus: an optometrist's perspective

Infantile nystagmus (IN), previously known as congenital nystagmus, is an involuntary to-and-fro movement of the eyes that persists throughout life. IN is one of three types of early-onset nystagmus that begin in infancy, alongside fusion maldevelopment nystagmus syndrome and spasmus nutans syndrome. Optometrists may also encounter patients with acquired nystagmus. The features of IN overlap largely with those of fusion maldevelopment nystagmus syndrome, spasmus nutans syndrome, and acquired nystagmus, yet the management for each subtype is different. Therefore, the optometrist’s role is to accurately discern IN from other forms of nystagmus and to manage accordingly. As IN is a lifelong condition, its presence not only affects the visual function of the individual but also their quality of life, both socially and psychologically. In this report, we focus on the approaches that involve optometrists in the investigation and management of patients with IN. Management includes the prescription of optical treatments, low-vision rehabilitation, and other interventions such as encouraging the use of the null zone and referral to support groups. Other treatments available via ophthalmologists are also briefly discussed in the article

Correlation of internal representations in feed-forward neural networks

Feed-forward multilayer neural networks implementing random input-output mappings develop characteristic correlations between the activity of their hidden nodes which are important for the understanding of the storage and generalization performance of the network. It is shown how these correlations can be calculated from the joint probability distribution of the aligning fields at the hidden units for arbitrary decoder function between hidden layer and output. Explicit results are given for the parity-, and-, and committee-machines with arbitrary number of hidden nodes near saturation.Comment: 6 pages, latex, 1 figur

Effect of Stimulus Type and Motion on Smooth Pursuit in Adults and Children

PURPOSE: This study presents a two-degree customized animated stimulus developed to evaluate smooth pursuit in children and investigates the effect of its predetermined characteristics (stimulus type and size) in an adult population. Then, the animated stimulus is used to evaluate the impact of different pursuit motion paradigms in children. METHODS: To study the effect of animating a stimulus, eye movement recordings were obtained from 20 young adults while the customized animated stimulus and a standard dot stimulus were presented moving horizontally at a constant velocity. To study the effect of using a larger stimulus size, eye movement recordings were obtained from 10 young adults while presenting a standard dot stimulus of different size (1° and 2°) moving horizontally at a constant velocity. Finally, eye movement recordings were obtained from 12 children while the 2° customized animated stimulus was presented after three different smooth pursuit motion paradigms. Performance parameters, including gains and number of saccades, were calculated for each stimulus condition. RESULTS: The animated stimulus produced in young adults significantly higher velocity gain (mean: 0.93; 95% CI: 0.90-0.96; P = .014), position gain (0.93; 0.85-1; P = .025), proportion of smooth pursuit (0.94; 0.91-0.96, P = .002), and fewer saccades (5.30; 3.64-6.96, P = .008) than a standard dot (velocity gain: 0.87; 0.82-0.92; position gain: 0.82; 0.72-0.92; proportion smooth pursuit: 0.87; 0.83-0.90; number of saccades: 7.75; 5.30-10.46). In contrast, changing the size of a standard dot stimulus from 1° to 2° did not have an effect on smooth pursuit in young adults (P > .05). Finally, smooth pursuit performance did not significantly differ in children for the different motion paradigms when using the animated stimulus (P > .05). CONCLUSIONS: Attention-grabbing and more dynamic stimuli, such as the developed animated stimulus, might potentially be useful for eye movement research. Finally, with such stimuli, children perform equally well irrespective of the motion paradigm used

Retrieval behavior and thermodynamic properties of symmetrically diluted Q-Ising neural networks

The retrieval behavior and thermodynamic properties of symmetrically diluted Q-Ising neural networks are derived and studied in replica-symmetric mean-field theory generalizing earlier works on either the fully connected or the symmetrical extremely diluted network. Capacity-gain parameter phase diagrams are obtained for the Q=3, Q=4 and $Q=\infty$ state networks with uniformly distributed patterns of low activity in order to search for the effects of a gradual dilution of the synapses. It is shown that enlarged regions of continuous changeover into a region of optimal performance are obtained for finite stochastic noise and small but finite connectivity. The de Almeida-Thouless lines of stability are obtained for arbitrary connectivity, and the resulting phase diagrams are used to draw conclusions on the behavior of symmetrically diluted networks with other pattern distributions of either high or low activity.Comment: 21 pages, revte

Prilagodba usnih organa kod nekih podzemnih holevina (Cholevinae) (Coleoptera, Leiodidae)

Cholevinae are a group of beetles with many cave representatives that are mainly detritivorous or saprophagous. Some species show modifications of the mouthparts on account of their dietary niche, being adapted to a semi-aquatic way of life, or on account of the degree of adaptation to the life in caves. Differences are obvious also among the genera, and cave species that are at the same level of adaptation. The main modifications concern the shape and structure of the different parts, as well as their length and the disposal of hairs, bristles and setae. The adaptation to an aquatic dietary niche has modified the mandibles, which acquired a spoon-like form to bring water near the mouth, the lacinia taking on the role of stirring and the galea of filtering the organic particles with its fine and very dense hairs. The apparent uniformity of the subterranean environmental conditions and of the trophic resources, together with the scarcity of the latter, might mistakenly lead to the conclusion of a one-way evolution for the underground colonizers. The observed differences between the mouthparts of the studied species can be good material for taxonomists, who can include some of these features in their studies, often difficult due to the homogenous morphology of many inhabitants of the underground. As a contribution to the comparative study of the mouthparts at some representatives of cholevin beetles, we can also highlight the effect of adaptation to cave life on the mouthparts and the evidence of a divergent evolution in a relatively constant environment in terms of climate and food input.Holevine su skupina kornjaša s mnogo podzemnih predstavnika koji su pretežno detritivorni ili saprofagni. Neke vrste pokazuju modifikacije usnih organa zbog svoje prehrambene niše, prilagođavajući se poluakvatičkom načinu života, ili zbog stupnja adaptacije na život u špilji. Razlike su očite i među rodovima i špiljskim vrstama koje su na istom stupnju adaptacije. Glavne modifikacije tiču se oblika i strukture različitih dijelova, kao i njihove duljine, i rasporeda dlaka, čekinja i seta. Prilagodba na akvatičku prehrambenu nišu modificirala je čeljusti, koje su dobile oblik žlice kojom se voda prinosi ustima; lacinia preuzima ulogu miješanja, a galea filtriranja organskih čestica svojim finim i vrlo gustim dlačicama. Očita jednoličnost uvjeta u podzemnom okolišu, te izvora hrane, zajedno s njenom rijetkošću, mogu pogrešno upućivati na jednosmjernu evoluciju stanovnika podzemlja. Uočene razlike između usnih organa proučavanih vrsta mogu biti dobar materijal za taksonomiste koji neke od tih osobina mogu uključiti u svoj rad, obično težak zbog homogene morfologije mnogih stanovnika podzemlja. Kao doprinos komparativnoj studiji usnih organa nekih predstavnika holevina, na temelju usnih organa naglašavamo efekt prilagodbe na špiljski život te dokaz divergentne evolucije u relativno konstantnom okolišu, u smislu klime i dotoka hrane

A canonical ensemble approach to graded-response perceptrons

Perceptrons with graded input-output relations and a limited output precision are studied within the Gardner-Derrida canonical ensemble approach. Soft non- negative error measures are introduced allowing for extended retrieval properties. In particular, the performance of these systems for a linear and quadratic error measure, corresponding to the perceptron respectively the adaline learning algorithm, is compared with the performance for a rigid error measure, simply counting the number of errors. Replica-symmetry-breaking effects are evaluated.Comment: 26 pages, 10 ps figure

Iron Status and Analysis of Efficacy and Safety of Ferric Carboxymaltose Treatment in Patients with Inflammatory Bowel Disease

Background and Aims:We analyzed iron deficiency and the therapeutic response following intravenous ferric carboxymaltose in a large single-center inflammatory bowel disease (IBD) cohort. Methods: 250 IBD patients were retrospectively analyzed for iron deficiency and iron deficiency anemia. A subgroup was analyzed regarding efficacy and side effects of iron supplementation with ferric carboxymaltose. Results: In the cohort (n = 250), 54.4% of the patients had serum iron levels 60 mu g/dl, 61.6% had ferritin >100 ng/ml, and 90.7% reached Hb >12/13 g/dl at follow-up (p < 0.0001 for all parameters vs. pretreatment values). The most frequent adverse event was a transient increase of liver enzymes with male gender as risk factor (p = 0.008, OR 8.62, 95% CI 1.74-41.66). Conclusions: Iron deficiency and anemia are frequent in IBD patients. Treatment with ferric carboxymaltose is efficious, safe and well tolerated in iron-deficient IBD patients. Copyright (C) 2011 S. Karger AG, Base

Evidence for spatially-responsive neurons in the rostral thalamus

Damage involving the anterior thalamic and adjacent rostral thalamic nuclei may result in a severe anterograde amnesia, similar to the amnesia resulting from damage to the hippocampal formation. Little is known, however, about the information represented in these nuclei. To redress this deficit, we recorded units in three rostral thalamic nuclei in freely-moving rats (the parataenial nucleus, the anteromedial nucleus and nucleus reuniens). We found units in these nuclei possessing previously unsuspected spatial properties. The various cell types show clear similarities to place cells, head direction cells, and perimeter/border cells described in hippocampal and parahippocampal regions. Based on their connectivity, it had been predicted that the anterior thalamic nuclei process information with high spatial and temporal resolution while the midline nuclei have more diffuse roles in attention and arousal. Our current findings strongly support the first prediction but directly challenge or substantially moderate the second prediction. The rostral thalamic spatial cells described here may reflect direct hippocampal/parahippocampal inputs, a striking finding of itself, given the relative lack of place cells in other sites receiving direct hippocampal formation inputs. Alternatively, they may provide elemental thalamic spatial inputs to assist hippocampal spatial computations. Finally, they could represent a parallel spatial system in the brain

Synchronous versus sequential updating in the three-state Ising neural network with variable dilution

The three-state Ising neural network with synchronous updating and variable dilution is discussed starting from the appropriate Hamiltonians. The thermodynamic and retrieval properties are examined using replica mean-field theory. Capacity-temperature phase diagrams are derived for several values of the pattern activity and different gradations of dilution, and the information content is calculated. The results are compared with those for sequential updating. The effect of self-coupling is established. Also the dynamics is studied using the generating function technique for both synchronous and sequential updating. Typical flow diagrams for the overlap order parameter are presented. The differences with the signal-to-noise approach are outlined.Comment: 21 pages Latex, 12 eps figures and 1 ps figur