Age-related changes in ERPs associated with context-based and response-based interference

Age-related differences in information processing have often been explained through deficits in older adults' ability to ignore irrelevant stimuli and suppress inappropriate responses through inhibitory control processes. Functional imaging work on young adults by Nelson and colleagues (2003) has indicated that inferior frontal and anterior cingulate cortex playa key role in resolving interference effects during a delay-to-match memory task. Specifically, inferior frontal cortex appeared to be recruited under conditions of context interference while the anterior cingulate was associated with interference resolution at the stage of response selection. Related work has shown that specific neural activities related to interference resolution are not preserved in older adults, supporting the notion of age-related declines in inhibitory control (Jonides et aI., 2000, West et aI., 2004b). In this study the time course and nature of these inhibition-related processes were investigated in young and old adults using high-density ERPs collected during a modified Sternberg task. Participants were presented with four target letters followed by a probe that either did or did not match one of the target letters held in working memory. Inhibitory processes were evoked by manipulating the nature of cognitive conflict in a particular trial. Conflict in working memory was elicited through the presentation of a probe letter in immediately previous target sets. Response-based conflict was produced by presenting a negative probe that had just been viewed as a positive probe on the previous trial. Younger adults displayed a larger orienting response (P3a and P3b) to positive probes relative to a non-target baseline. Older adults produced the orienting P3a and 3 P3b waveforms but their responses did not differentiate between target and non-target stimuli. This age-related change in response to targetness is discussed in terms of "early selection/late correction" models of cognitive ageing. Younger adults also showed a sensitivity in their N450 response to different levels of interference. Source analysis of the N450 responses to the conflict trials of younger adults indicated an initial dipole in inferior frontal cortex and a subsequent dipole in anterior cingulate cortex, suggesting that inferior prefrontal regions may recruit the anterior cingulate to exert cognitive control functions. Individual older adults did show some evidence of an N450 response to conflict; however, this response was attenuated by a co-occurring positive deflection in the N450 time window. It is suggested that this positivity may reflect a form of compensatory activity in older adults to adapt to their decline in inhibitory control.

Bone speed of sound in overweight and normal-weight girls and adolescents

Over the last two decades, the prevalence of obesity in the general population has been steadily increasing. Obesity is a major issue in scientific research because it is associated with many health problems, one of which is bone quality. In adult females, adiposity is associated with increased bone mineral density, suggesting that there is a protective effect of fat on bone. However, the association between adiposity and bone strength during childhood is not clear. Thus, the purpose of this study was to compare bone strength, as reflected by speed of sound (SOS), of overweight and obese girls and adolescents with normal-weight age-matched controls. Data from 75 females included normal-weight girls (G-NW; body fat:::; 25%; n = 21), overweight and obese girls (GOW; body fat ~ 28%; n = 19), normal-weight adolescents (A-NW, body fat:::; 25%; n = 13) and overweight and obese adolescents (A-OW; body fat ~ 28%; n = 22). Nutrition was assessed with a 24-hour recall questionnaire and habitual physical activity was measured for one week using accelerometry. Using quantitative ultrasound (QUS; Sunlight Omnisense™), bone SOS was measured at the distal radius and mid-tibia. No differences were found between groups in daily total energy, calcium or vitamin D intake. However, all groups were below the recommended daily calcium intake of 1300 mg (Osteoporosis Canada, 2008). Adolescents were significantly less active than girls (14.7 ± 0.6 vs. 6.3 ± 0.6% active for G and A, respectively). OW accumulated significantly less minutes of moderate-to-very vigorous physical activity per day (MVPA) than NW in both age groups (114 ± 6 vs. 57 ± 5 min/day for NW and OW, i respectively). Girls had significantly lower radial SOS (3794 ± 87 vs. 3964 ± 64 mls for G-NW and A-NW, respectively), and tibial SOS (3678 ± 86 vs. 3878 ± 52 mls for G-NW and A-NW, respectively) than adolescents. Radial SOS was similar in the two adiposity groups within each age group. However, tibial SOS was lower in the two overweight groups (3601 ± 75 mls vs. 3739 ± 134 mls for G-OW and A-OW, respectively) compared with the age-matched normal-weight controls. Body fat percentage negatively correlated with tibial SOS in the study sample as a whole (r = -0.30). However, when split into groups, percent bo~y fat correlated with tibial SOS only in the A-OW group (r = -0.53). MVPA correlated with tibial SOS (r = 0.40), once age was partialed out. In conclusion, in contrast withthe higher bone strength characteristic of obese adult women, overweight and obese girls and adolescents are characterized by low tibial bone strength, as assessed with QUS. The differences between adiposity groups in tibial SOS may be at least partially due to the reduced weight-bearing physical activity levels in the overweight girls and adolescents. However, other factors, such as hormonal influences associated with high body fat may also playa role in reducing bone strength in overweight girls. Further research is required to reveal the mechanisms causing low bone strength in overweight and obese children and adolescents.

Living between two cultures : personality and adaptation in Chinese immigrant youth /

The aim of the present study was to examine the relationship between shyness and acculturation modes of Chinese immigrant youth in Canada and whether shyness moderates the relationship between acculturation and adaptation. In addition, I examined whether shyness, in conjunction with sociability, moderates the relationship between acculturation and adaptation. Ninety-nine young Chinese immigrants (42 men), ranging in age from 16 to 26 years old, completed a questionnaire that assessed their demographic information, acculturation modes, shyness, sociability, psychological adaptation Oife satisfaction, self-esteem, and depression), and socio-cultural adaptation. Results showed that Chinese orientation was significantly and negatively correlated with age, generation status, English proficiency, and length of residence in Canada. In contrast, Canadian orientation was significantly and positively correlated with generation status, English proficiency, and length of residence in Canada. Canadian orientation was also significantly and negatively correlated with shyness and positively correlated with sociability and psychological and socio-cultural adaptation. Participants who were shyer were more likely to have poorer psychological and socio-cultural adaptation, and to report lower life satisfaction and self-esteem and higher depression. Results from hierarchical multiple regression analyses indicated that Chinese immigrant youth who were separated had higher scores on shyness than those who were integrated and assimilated. There were no significant differences in shyness between youth who were separated and youth who were marginalized, nor were there differences between youth who were integrated and those who were assimilated. Furthermore, integrated Chinese youth reported significantly higher scores in sociability than those who were separated and marginalized but not significantly higher than those who were assimilated.' Shyness did not moderate the relationship between acculturation modes and psychological and socio-cultural adaptation. Unfortunately, the hypothesis to examine if shyness, in combination with sociability, moderated the relationship between acculturation and psychological adaptation could not be tested in the present study because of limitations in cell sizes. The findings suggested that how Chinese immigrant youth acculturate in the receiving country might not be the crucial factor in determining their adaptation. Instead, other factors, such as personality characteristics and nature of the acculturating group, may playa more crucial role. Shyness may have important ramifications for the acculturation and adaptation of young Chinese immigrants to a new society.

Mechanisms underlying Retinoic acid-induced chemoattraction in molluscan neurons

Retinoic acid, a derivative of vitamin A, is known to play diverse roles in development and regeneration. Previous research in the mollusc Lymnaea stagnalis has shown that a gradient of all-trans retinoic acid attracts the growth cones of cultured neurons. The present study investigates the sub-cellular mechanisms within the growth cones of Lymnaea pedal A neurons which mediate the attractive response to a gradient of alltrans retinoic acid. In this study, the mechanism of growth cone turning is shown to be local, as neurites mechanically isolated from their cell body retain the capacity to turn towards an exogenous gradient of all-trans retinoic acid. The turning response is dependent on the initiation of protein synthesis and calcium influx, but does not appear to involve signaling through protein kinase C (PKC). The retinoid X receptor (RXR), which classically functions as a transcription factor, was also shown to be involved in the turning response, functioning locally through a non-genomic pathway. These data show, for the first time in any species, that all-trans retinoic acid's chemotropic action involves a local mechanism involving non-genomic signaling through the RXR. As retinoic acid is known to playa role in regeneration, understanding the mechanisms underlying retinoic acid signaling may lead to further advances in regenerative neuroscience.

Role of family eating practices on daily nutrient intakes, dietary patterns and measures of body composition in peri-adolescents

Although family eating practices (FEPs) playa role in the formation of eating practices in children, there is a lack of evidence regarding the role of FEPs on obesity (DB) risk. The purpose of this thesis was to assess the role of child, mother 'and father eating practices (CEPs; MEPS; FaEPs) on nutrient intakes, dietary patterns and body composition. Data were collected on approximately 2,400 peri-adolescents (s250 with complete covariate data). Dietary patterns were assessed using scores that reflected how closely participants followed DASH and Health Canada (HC) recommendations. In girls, poor CEPs, MEPs and FaEPs were associated with increased BMI and risk of overweight and poor dietary patterns according to DASH, and DASH and HC, respectively. In boys, poor CEPs and FaEPs were associated with increased monounsaturated and trans fat, and Vitamin C intakes, respectively. These findings suggest FEPs are associated with DB risk, particularly in girls.

Erwinia amylovora bacteriophage resistance

It has been proposed that phages can be used commercially as a biopesticide for the control of fire blight caused by the phytopathogen Erwinia amylovora. The aim of these studies was to investigate two common bacterial resistance mechanisms, lysogeny and exopolysaccharide production and their influence on phage pathogenesis. A multiplex real-time PCR protocol was designed to monitor and quantify Podoviridae and Myoviridae phages. This protocol is compatible with known E. amylovora and Pantoea agglomerans rtPCR primers/probes which allowed simultaneous study of both phage and bacterial targets. Using in vitro positive phage selection, bacteriophage insensitive derivatives were isolated within sensitive populations of E. amylovora. Prophage screening with real-time PCR and mitomycin C induction determined that the insensitive derivatives harboured the temperate Podoviridae phage ΦEaTlOO. Lysogenic conversion resulted in resistance to secondary homologous phage infections. Prophage screening of environmental samples of E. amylovora and P. agglomerans collected from various locations in Canada, United States and Europe did not demonstrate lysogeny. Therefore, lysogeny is rare or absent while these bacterial species reside on the plant. Recombineering was used to construct exopolysaccharide deficient E. amylovora mutants. The EPS amylovoran mutants became resistant to Podoviridae and certain Siphoviridae phages. Increasing amylovoran production increased phage population growth, presumably by increasing the total number of bacterial cell surface receptors which promoted increased phage infections. In contrast, amylovoran did not playa role in Myoviridae infections, nor did production of the EPS levan for any phage pathogenesis.

Electrophysiological investigations of the timing of face processing

As important social stimuli, faces playa critical role in our lives. Much of our interaction with other people depends on our ability to recognize faces accurately. It has been proposed that face processing consists of different stages and interacts with other systems (Bruce & Young, 1986). At a perceptual level, the initial two stages, namely structural encoding and face recognition, are particularly relevant and are the focus of this dissertation. Event-related potentials (ERPs) are averaged EEG signals time-locked to a particular event (such as the presentation of a face). With their excellent temporal resolution, ERPs can provide important timing information about neural processes. Previous research has identified several ERP components that are especially related to face processing, including the N 170, the P2 and the N250. Their nature with respect to the stages of face processing is still unclear, and is examined in Studies 1 and 2. In Study 1, participants made gender decisions on a large set of female faces interspersed with a few male faces. The ERP responses to facial characteristics of the female faces indicated that the N 170 amplitude from each side of the head was affected by information from eye region and by facial layout: the right N 170 was affected by eye color and by face width, while the left N 170 was affected by eye size and by the relation between the sizes of the top and bottom parts of a face. In contrast, the P100 and the N250 components were largely unaffected by facial characteristics. These results thus provided direct evidence for the link between the N 170 and structural encoding of faces. In Study 2, focusing on the face recognition stage, we manipulated face identity strength by morphing individual faces to an "average" face. Participants performed a face identification task. The effect of face identity strength was found on the late P2 and the N250 components: as identity strength decreased from an individual face to the "average" face, the late P2 increased and the N250 decreased. In contrast, the P100, the N170 and the early P2 components were not affected by face identity strength. These results suggest that face recognition occurs after 200 ms, but not earlier. Finally, because faces are often associated with social information, we investigated in Study 3 how group membership might affect ERP responses to faces. After participants learned in- and out-group memberships of the face stimuli based on arbitrarily assigned nationality and university affiliation, we found that the N170 latency differentiated in-group and out-group faces, taking longer to process the latter. In comparison, without group memberships, there was no difference in N170 latency among the faces. This dissertation provides evidence that at a neural level, structural encoding of faces, indexed by the N170, occurs within 200 ms. Face recognition, indexed by the late P2 and the N250, occurs shortly afterwards between 200 and 300 ms. Social cognitive factors can also influence face processing. The effect is already evident as early as 130-200 ms at the structural encoding stage.

El español de los inmigrantes de los Andes bolivianos en el Norte Grande de Chile : convergencias y divergencias dialectales en el marco de una situación de contacto

Cette thèse a été financée par le Conseil de recherches en sciences humaines du Canada (numéro de référence 767-2010-1310)

Entorno : recursos para el conocimiento de Chiclana y la Bahía de Cádiz.

Se presenta la memoria de un proyecto educativo que persigue el conocimiento del medio más cercano al alumnado de Educación Primaria y al profesorado del Colegio de Educación Infantil y Primaria Maestra Carmen Seudofeito en Chiclana de la Frontera, Cádiz. Se pretende desarrollar en el profesorado y alumnado un conocimiento directo y activo del entorno de Chiclana y la Bahía de Cádiz, con recursos que les permitan interpretar este entorno y generalizar lo aprendido a entornos más amplios. Los objetivos principales son: 1. Recopilar, restaurar, elaborar, mantener y editar recursos didácticos sobre el entorno de Chiclana y la Bahía de Cádiz, y en menor medida, de Andalucía. Estos recursos tiene cinco tipos de formato: un jardín botánico escolar, una maqueta en relieve 1:10000 del término de Chiclana, colecciones de diapositivas de elaboración propia, láminas murales, láminas personales. 2. Usar estos recursos con el alumnado, tanto en el centro como en visita de estudios. Valorar su utilidad y hacer las correcciones que correspondan. 3. Incorporar la informática en la elaboración, edición y exposición de estos recursos. El proceso consta de varias fases: se realizan cuidados sobre labores agrícolas para crear y mantener un jardín botánico; se actualiza la maqueta del relieve del término municipal de Chiclana y se completa el manto de arbolado de muchas de sus áreas; se realizan láminas murales con diseño propio sobre el barrio de La Banda, sobre el término municipal y sobre la Bahía de Cádiz; elaboración y actualización de láminas plastificadas cuyos temas fueron: el patio y sus plantas y animales, el patio y los ecosistemas del jardín botánico escolar, el barrio de La Banda, la ciudad de Chiclana, el acantilado, las dunas y la playa de la Barrosa, la Bahía de Cádiz; láminas dibujadas cuyos temas fueron: las lagunas chiclaneras, aves y plantas, los huertos, las salinas, la bahía, el acantilado, plantas del pinar de la Barrosa, planos del jardín botánico de San Fernando, planos de los parques urbanos de La Soledad y de la Huerta del Rosario, rutas al parque de Grazalema, rutas al parque de los Alcornocales; por último se realizan salidas a la naturaleza en autobús de un día hasta cuarto curso y de un día o más para el alumnado de quinto o sexto curso. Los resultados obtenidos fueron de aceptación en docentes del centro y del colegio vecino, pero no consiguió atraer a todo el profesorado al que estaba dirigido, este hecho nos hizo repensar el proyecto hacia la elaboración, no tanto de guías, sino de nuevos recursos para quien estuviera realmente interesado. Los materiales utilizados fueron: maderas, materiales para tareas agrícolas, transparencias, plastificados, pinturas, software informático, diapositivas, discos, disquetes, láminas y mapas de relieve.

Reserva Natural Parcial de la r??a de Villaviciosa : itinerarios did??cticos en la naturaleza. Gu??a del alumno nivel I

Los itinerarios en la naturaleza constituyen una de las herramientas fundamentales de la Educaci??n Ambiental. El trabajo en el campo permite combinar actividades de observaci??n, investigaci??n, interpretaci??n, etc. integrando y poniendo en pr??ctica los conocimientos te??ricos adquiridos en el aula a trav??s de diferentes ??reas formales de conocimiento; por ello se plantea este material para conocer la Reserva Natural Parcial de la r??a de Villaviciosa. La gu??a adem??s de informaci??n plantea una serie de cuestiones a responder agrupadas en cap??tulos que se refieren a las distintas etapas descritas en el itinerario: la playa, un puntal de arena, las dunas, el canal y un dique. A trav??s de ilustraciones, cuadros, listas a relacionar, etc. se van conociendo los aspectos geol??gicos, la flora y fauna de este espacio natural; la gu??a concluye con un espacio para anotaciones y orientaciones para observaciones al estilo de un cuaderno de campo.

Reserva Natural Parcial de la r??a de Villaviciosa : itinerarios did??cticos en la naturaleza. Gu??a del alumno nivel II

El itinerario por este espacio natural de la r??a de Villaviciosa pretende que los alumnos conozcan las caracter??sticas de los ambientes costeros, su singularidad y la necesidad de su conservaci??n; a lo largo del mismo se pueden observar los ecosistemas asturianos de acantilado, de playa y de dunas se persigue el conocimiento de su origen, los procesos que en ellos se desarrollan de forma natural, las causas de su estado actual de degradaci??n y las normas de comportamiento que se deben tener cuando se utilicen de cara a su conservaci??n. La gu??a ofrece una serie de orientaciones de cara a la salida y una propuesta de actividades a realizar en las distintas paradas del camino.

Alejandro Mieres : diseñar el paisaje : paisaje de arena.

Para conocer la obra del pintor y escultor Alejandro Mieres, este material ofrece por un lado una reflexión sobre el reflejo del paisaje en el arte y del arte en el paisaje. Se hace un repaso histórico de los movimientos artísticos y su tratamiento del paisaje; así como una biografía de este autor y una descripción de las etapas de su obra. Finalmente se realiza una propuesta de taller sobre la última etapa del pintor vinculada a la experimentación sobre la arena; así se presentan actividades a realizar en el museo Jovellanos donde está parte de su obra, en las calles del entorno y en la cercana playa trabajando directamente sobre la arena.

Un recorrido por la costa de los dinosaurios.

Resumen basado en la publicación

La costa occidental asturiana.

Resumen basado en la publicación

La región de Cabo Peñas.

Estos materiales han sido realizados al amparo del Convenio de colaboración entre la Consejería de Educación y Ciencia del Principado de Asturias y la Universidad de Oviedo (BOPA, n. 180, sábado, 3 de agosto de 2002). Precede al tít.: Itinerarios por la naturaleza