Desarrollo de la inhibición: comparación de medidas neuropsicológicas y de seguimiento de ojos

Inhibition is the ability to stop an automatic response when a stimulus is presented. It is one main component of executive function models. Few studies have evaluated the development of this ability’s in children between five and eight years of age using eye tracking measures. The first objective of this exploratory study is to evaluate the performance difference of younger compared to older children. The second objective is to evaluate if inhibition assessed via three different neuropsychological tests develops at a similar rate as inhibition assessed via two eye tracking tasks. Forty-six children aged 5.7 to 8.4 years completed both types of tests. Results show that one neuropsychological test was sensitive to the children’ increasing inhibition ability, while both eye tracking tests were. Additionally, scores from one eye tracking task correlated with scores from one neuropsychological test. Possible explanations of moderate relations between tasks are discussed.La inhibición es la capacidad de detener una respuesta automática. Es una de las funciones ejecutivas principales. Pocos estudios han evaluado su desarrollo en niños de cinco a ocho años utilizando pruebas de seguimiento de ojos. Este estudio exploratorio tiene, como primer objetivo, evaluar la diferencia de rendimiento entre los más jóvenes y los mayores. El segundo objetivo es evaluar si la inhibición se desarrolla a un ritmo similar en tres pruebas neuropsicológicas y dos pruebas de seguimiento de ojos. Cuarenta y seis niños, de 5 años y 8 meses a 8 años y 5 meses, realizaron ambos tipos de pruebas. Los resultados muestran que una de las pruebas neuropsicológicas y ambas pruebas de seguimiento de ojos fueron sensibles a la mejora de la inhibición. Además, resultados de una prueba de seguimiento de ojos y de una prueba neuropsicológica estaban correlacionados. Se discuten las explicaciones posibles de las relaciones entre las tareas

Antimicrobial susceptibility patterns of eampylobacter coli isolates from swine and humans

An increase in resistance to various antimicrobial agents has been reported in many countries for Campylobacter species. In order to study their resistance profiles to various antimicrobial agents, strains ofC. coli isolated from slaughtered pigs and from human patients were examined for resistance to quinolones and other antimicrobial agents by agar dilution technique. Resistance to tetracycline was common for human (53 %) and swine (68 %) isolates. Higher level of resistance to streptomycine was found in swine isolates (67 %) than in human (24 %) isolates. Human isolates were more frequently found to be resistant to enrofloxacin and ciprofloxacin (18 and 24 %) than swine isolates (7 and II %). Sixty one percent C. coli from swine were resistant to erythromycine while only 12 %of C. coli of human origin were resistant. Emergence of resistance to macrolides, tetracyclines and quinolones is of interest in regard with possible dissemination of genetic resistance determinants to humans

A neural network perspective on learning and development /

This manuscript-based thesis explores the relationship between learning and development. The first manuscript reviews the important empirical regularities identified in human discrimination shift learning, including a qualitative age-related change in performance observed in childhood. Leading theoretical accounts of the empirical data are discussed, suggesting that none provides a comprehensive interpretation. The manuscript presents the novel, spontaneous overtraining interpretation. It hypothesizes that age-related changes in human shift learning stem from differences in amount of processing. Successful neural network simulations of the reversal and nonreversal shift tasks and of the optional shift task are reported as tests of the hypothesis.The second manuscript reports simulations of additional discrimination shift tasks. These are the intradimensional and extradimensional shift tasks, in which novel stimuli are introduced in the relearning phase. Preschoolers and adults exhibit the same pattern of behavior in this variant of shift learning. Simulation results show that the spontaneous overtraining hypothesis captures this effect.The third chapter reports an empirical validation of the shift learning model. If the shift learning performance of adults is a consequence of more extensive processing, it follows that adults in whom such processing is prevented should perform as preschoolers. Sixty adults took part in a shift learning experiment with a Brown-Peterson task as a cognitive load. Results mirror those observed with preschoolers. As a control, 40 adults performed the shift learning experiment without the cognitive load. These results replicate the typical adult performance. Overall, these experiments lend additional support to the model developed in Manuscript 1.The final manuscript is a theoretical discussion of the relationship between learning and development. Two classes of neural networks are discussed, and their underlying assumptions about learning and development are highlighted. These are static architecture and generative architecture networks. It is argued that only generative algorithms, such as used in the shift learning simulations, qualify as developmental models. Both classes of networks are further contrasted with respect to innateness. The comparison suggests that only generative networks can acquire genuinely new representations. The manuscript proposes a novel formulation of Piaget's constructivism from the generative neural network perspective