Exploring the Fundamental Dynamics of Error-Based Motor Learning Using a Stationary Predictive-Saccade Task

The maintenance of movement accuracy uses prior performance errors to correct future motor plans; this motor-learning process ensures that movements remain quick and accurate. The control of predictive saccades, in which anticipatory movements are made to future targets before visual stimulus information becomes available, serves as an ideal paradigm to analyze how the motor system utilizes prior errors to drive movements to a desired goal. Predictive saccades constitute a stationary process (the mean and to a rough approximation the variability of the data do not vary over time, unlike a typical motor adaptation paradigm). This enables us to study inter-trial correlations, both on a trial-by-trial basis and across long blocks of trials. Saccade errors are found to be corrected on a trial-by-trial basis in a direction-specific manner (the next saccade made in the same direction will reflect a correction for errors made on the current saccade). Additionally, there is evidence for a second, modulating process that exhibits long memory. That is, performance information, as measured via inter-trial correlations, is strongly retained across a large number of saccades (about 100 trials). Together, this evidence indicates that the dynamics of motor learning exhibit complexities that must be carefully considered, as they cannot be fully described with current state-space (ARMA) modeling efforts

The mechanisms of “incidental news consumption”: An eye tracking study of news interaction on Facebook

This exploratory study examines how participants incidentally consumed news on social media through an eye tracking analysis of their visual interaction with posts on Facebook. By interaction, we refer to the attention participants gave to news (measured through the time devoted to looking at the content); how they read these news items (measured through ocular movements on the screen); and the way they engaged with this content (measured through forms of participation such as liking, commenting, or sharing news). The data were triangulated through interviews with Facebook users and an analysis of the metrics of posts from Costa Rican news organizations on Facebook from 2017 to 2020. We draw on scholarship in communication studies and multimodal discourse analysis. We argue for a more nuanced approach to what study participants did when they incidentally encountered news on social media that focuses on mechanisms, that is, the specific procedures and operations that shape user interaction with news on Facebook (such as visual fixations on parts of news posts; the visual entry points through which they begin to interact with the news; the sequences that characterize how they navigate content; and the time they spend assessing various multimodal elements).Universidad de Costa Rica/[]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Centro de Investigación en Comunicación (CICOM)UCR::Vicerrectoría de Docencia::Artes y Letras::Facultad de Letras::Escuela de Filología, Lingüística y Literatur

Learning the Optimal Control of Coordinated Eye and Head Movements

Various optimality principles have been proposed to explain the characteristics of coordinated eye and head movements during visual orienting behavior. At the same time, researchers have suggested several neural models to underly the generation of saccades, but these do not include online learning as a mechanism of optimization. Here, we suggest an open-loop neural controller with a local adaptation mechanism that minimizes a proposed cost function. Simulations show that the characteristics of coordinated eye and head movements generated by this model match the experimental data in many aspects, including the relationship between amplitude, duration and peak velocity in head-restrained and the relative contribution of eye and head to the total gaze shift in head-free conditions. Our model is a first step towards bringing together an optimality principle and an incremental local learning mechanism into a unified control scheme for coordinated eye and head movements

Preliminary study of muscle contraction assessment by NIR spectroscopy

NIR spectroscopy allows monitoring of muscle oxygenation and perfusion during contraction. The knowledge of modifications of blood characteristics in body tissues has relevant clinical interest. A compact and reliable device, which makes use of two laser diodes at 750 and 810 nm coupled with the skin surface through optical fibres, was tested. NIR and surface EMG signals during isokinetic contractions were studied. A set of parameters was analysed in order to obtain information about metabolic modifications during muscle fatigue

A PC based method for clinical evaluation of saccadic eye movements

A program is presented which computes saccade parameters and evaluates the amplitude/duration and amplitude/peak velocity relationships, the latency, and precision and symmetry as a function of target offset. Based on statistical methods, it gives a judgement of normality. Data were collected from a population of 76 normal subjects whose ages ranged from 10 to 80 years. Subjects were divided, according to their age, into 7 groups. Several statistical methods were used to find the most significant method to be used for patient comparison. Once the statistical method was tested on patients, an automatic computer program was developed which, based on these statistical methods, gives the examiner the results of the comparison in a simple, comprehensive way that can be easily understood, even by people not familiar with statistical problems. The program is implemented on a MS-DOS personal computer equipped with an input/output device for online acquisition of eye movements

Dimetilarginina simmetrica e nefropatia nel gatto : prime osservazioni

SYMMETRIC DIMETHYLARGININE IN FELINE NEPHROLOGY: PRELIMINARY OBSERVATIONS Chronic kidney disease (CKD) is very common in geriatric cats. Since CKD is an irreversible and progressive disease, early detection and treatment is mandatory. A population of 45 client-owned cats with or at risk of CKD was considered. This study compares the latest renal biomarker, the symmetric dimethylarginine (SDMA) with other clinical and analytical parameters of these cats, especially serum creatinine (sCr), in order to evaluate its diagnostic utility in clinical practice. Most part of the population belongs to IRIS stage 2 (55,6%) and the total population is distributed as follows: 17 (37,8%) with SDMA 14 \u3bcg/dL and sCr > 1,8 mg/dL, 8 (17,7%) with SDMA > 14 \u3bcg/dL and sCr 1,8 mg/dL . SDMA shows a significant relation- ship with body weight (p<0,05), weight loss (p<0,05), IRIS stage (p<0,05), urea (p<0,01), creatinine (p<0,01), white blood cells (p<0,01), red blood cells (p<0,05), hematocrit (p<0,01), hemoglobin (p<0,05) urine specific gravity (p<0,01). Finally, SDMA can be consider a useful biomarker in early detection of feline CKD, but it needs to be considered in association with other renal biomarkers, better to define the renal condition of every patient