To evaluate attentional processes to visual stimuli that do not require motor response, a study with evoked potentials was carried out on 17 children with attention deficit disorder predominantly inattentive (ADDH-I) and 15 controls between the ages of 7 and 11 years. The latency and localization of sources of the early visual evoked potentials P100 and N100 were analyzed during the performance of a visual oddball task (20% horizontal and 80% vertical lines) where the vertical lines did not require motor response. The results indicate that ADDH-I group process visual information that does not require motor response with a greater increase in brain activity and through the ventral temporal pathway, while the control group does so by means of the dorsal parietal stream. This neurobiological process of visual information processing by ventral temporal pathway of ADDH-I group could be due to alterations in emotional processes that directly influence visual recognition or as consequence of deficit in the control of attentional processes by the dorsal parietal pathway.

Para evaluar los procesos atencionales a estímulos visuales que no requieren repuesta motora, se llevó a cabo un estudio con potenciales evocados a 17 niños con trastornos del déficit de atención/ hiperactividad (TDAH-I) con predominio inatento y a 15 controles de edades entre 7 y 11 años. Se analizó la latencia y localización de fuentes de los potenciales evocados visuales tempranos P100 y N100 durante la realización de una tarea oddball visual (20% rayas horizontales y 80% verticales) en que las rayas verticales no exigían respuesta motora. Los resultados indican que los niños con TDAH-I procesan la información visual que no requiere respuesta motora con un mayor aumento de la actividad cerebral y mediante la vía temporal ventral mientras que el grupo control lo hace mediante la vía parietal dorsal. Este proceso neurobiológico de procesamiento de la información visual vía temporal ventral de los niños con TDAH-I podría deberse a alteraciones en los procesos emocionales que influyen directamente en el reconocimiento visual o a un déficit en el control de los procesos atencionales por parte de la vía parietal dorsal.

Los monoterpenos y otros compuestos orgánicos volátiles emitidos por la vegetación (emisiones biogénicas) juegan un papel significativo en la química troposférica por su participación en la formación de oxidantes fotoquímicos (p.e. ozono troposférico). Es así como la estimación de emisiones biogénicas resulta útil para establecer valores aproximados de la concentración, fundamental en la elaboración de programas de mejoramiento de calidad del aire. El objetivo del trabajo consistió en estimar las emisiones biogénicas de monoterpenos en el Parque Nacional Natural Tayrona, seleccionado por contar con áreas de vegetación autóctona de la región tropical con escasa o nula intervención antropogénica. Se aplicaron sensores remotos para la clasificación de cobertura vegetal, obteniendo la distribución espacial de la vegetación típica e identificando las familias de mayor dominancia. Las emisiones de monoterpenos se calcularon en 3,54 x 10(4) kg d-1, representadas 60% por la familia Leguminosae, 37,4% por la familia Euphorbiaceae, 2,4% por la familia Anacardiaceae y menos de 1% por las familias Rubiaceae y Polygonaceae. Durante las horas de sol en el área del parque (de las 6 a las 18 horas) se registraron las mayores temperaturas diarias y las más altas tasas de emisión de monoterpenos (59,6%); la cuarta parte de las emisiones ocurren entre las 10 y las 15 horas (24,2%), periodo en el que la radiación solar presenta máximos diarios y establece condiciones críticas para la formación de oxidantes fotoquímicos. La influencia de los vientos en la distribución espacio-temporal de las emisiones en el ambiente y la información de la rosa de vientos, evidencia que el 26% de las masas de aire proceden del N y el 15% del NE en el último trimestre del año, situación que podría favorecer la dispersión de monoterpenos a centros urbanos próximos al parque natural, pudiendo alterar la química atmosférica local con la formación de oxidantes fotoquímicos.

Monoterpenes and other volatile organic compounds emitted by vegetation (biogenic emissions) play a significant role in tropospheric chemistry because of their participation in the formation of photochemical oxidants (i.e. troposfheric ozone). This is how the estimation of biogenic emissions is useful for determining approximate values of monoterpenes concentration, which is essential in developing programs to improve air quality. The aim of this work was to estimate biogenic emissions of monoterpenes in the Tayrona National Park, that was selected because of the presence of native vegetation of the tropics with little or no human interference. Remote sensing was applied for classification of vegetation, coverage obtaining the spatial distribution of the typical vegetation and identifying the most dominant families. Monoterpenes emissions were estimated at 3.54 x 104 kg d-1, represented 60% of the Leguminosae family, 37.4% of the Euphorbiaceae family, 2.4% of the Anacardiaceae family and less than 1% of Rubiaceae and Polygonaceae families. During daylight hours in the park area (from 6:00 a.m. to 6:00 p.m.) the highest daily temperatures were registered and the highest emission rates of monoterpenes (59.6%); one fourth of the emissions occur between 10:00 a.m. and 3:00 p.m. (24.2%), period in which solar radiation presents daily maximums and establishes critical conditions for the formation of photochemical oxidants. The influence of winds on the spatial-temporal distribution of emissions shows that 26% of the air mass come from the N and 15% of NE in the last quarter of year, a situation that could favor the spread of monoterpenes to urban centers near the natural park, which could alter the local atmospheric chemistry with the formation of photochemical oxidants.

Resumo A aquisição ao longo da vida de competências cognitivas moldam a biologia do cérebro. No entanto, existem períodos críticos para o cérebro processar melhor as informações adquiridas. Objetivos: Discutir o período crítico de aquisição cognitiva, o conceito de reserva cognitiva e o modelo HAROLD (Redução da Assimetria Hemisférica em Idosos). Métodos: Sete mulheres que aprenderam a ler e escrever após a idade de 50 anos (ex-analfabetos) e cinco mulheres com 10 anos de escolaridade regular (controles) foram submetidas a um teste de reconhecimento de palavras enquanto a atividade cerebral estava sendo registrada mediante magnetoencefalografia. As palavras foram ouvidas com o emprego de dois tubos plásticos conectados a cada orelha e as gravações foram feitas com um magnetômetro de cabeça inteira com 148 bobinas de registro. Resultados: Ambos os grupos tiveram desempenho semelhante na identificação das palavras-alvo. Análise do número de fontes de atividade no hemisfério esquerdo e no hemisfério direito revelou diferenças significativas entre os dois grupos, mostrando que os ex-analfabetos tiveram menor assimetria cerebral funcional no desempenho da tarefa. Conclusões: Estes resultados devem ser interpretados com cautela, pois os grupos são pequenos. No entanto, reforçam o conceito que os indivíduos com baixa escolaridade tendem a usar o cérebro para processar informações de uma forma diferente do que indivíduos com nível educacional elevado ou que tenham o adquirido na época regular. Finalmente, o recrutamento de ambos os hemisférios para reconhecer as palavras ocorreu mais intensamente no grupo de ex-analfabetos e pode ser interpretado como um sinal de maior dificuldade na tarefa.

Abstract The lifelong acquisition of cognitive skills shapes the biology of the brain. However, there are critical periods for the best use of the brain to process the acquired information. Objectives: To discuss the critical period of cognitive acquisition, the concept of cognitive reserve and the HAROLD (Hemispheric Asymmetry Reduction in Older adults) model. Methods: Seven women who learned how to read and to write after the age of 50 (ex-illiterates) and five women with 10 years of regular schooling (controls) were submitted to a language recognition test while brain activity was being recorded using magnetoencephalography. Spoken words were delivered binaurally via two plastic tubs terminating in ear inserts, and recordings were made with a whole head magnetometer consisting of 148 magnetometer coils. Results: Both groups performed similarly on the task of identifying target words. Analysis of the number of sources of activity in the left and right hemispheres revealed significant differences between the two groups, showing that ex-illiterate subjects exhibited less brain functional asymmetry during the language task. Conclusions: These results should be interpreted with caution because the groups were small. However, these findings reinforce the concept that poorly educated subjects tend to use the brain for information processing in a different way to subjects with a high educational level or who were schooled at the regular time. Finally, the recruiting of both hemispheres to tackle the language recognition test occurred to a greater degree in the ex-illiterate group where this can be interpreted as a sign of difficulty performing the task.

Ictal onset localization is a important factor in presurgical evaluation of epilepsy. This paper describes the localization of a seizure onset recorded by magnetoencephalography (MEG) from a 12-year-old male patient who suffered from complex partial drug-resistant seizures. MRI revealed a 20mm diameter lesion located in left hippocampus. Scalp EEG showed left temporal theta waves. Interictal MEG registrations detected isolated spike-wave activity posterior and inferior to the MRI lesion. Ictal MEG showed continuous spike-wave activity (2 Hz). Dipole localization sited seizure onset in the inferior left temporal gyrus, the same localization of the interictal MEG activity. This ictal activity spreads bilaterally to frontal areas. Intrasurgical electrocorticography recording confirmed interictal MEG results.

La localización del inicio de las crisis es un factor importante para la evaluación prequirúrgica de la epilepsia. En este trabajo se describe la localización del inicio de una crisis registrada mediante magnetoencefalografía (MEG) en un niño de 12 años que presenta crisis parciales complejas farmacorresistentes. La RM muestra una lesión de 20mm de diámetro en el hipocampo izquierdo. EEG de superficie con ondas theta temporales izquierdas. Registro MEG interictal con punta-onda aislada posterior e inferior a la lesión de la RM. Registro MEG ictal con punta-onda (2 Hz). La localización de los dipolos indica el inicio de la crisis en la circunvolución temporal inferior en la misma localización que la actividad interictal MEG. Esta actividad ictal se propaga bilateralmente a áreas frontales. El registro corticográfico intraquirúrgico confirma los resultados de la localización interictal mediante MEG.