Numbers, space and motion, convergent data about their interaction. Behavioral, electrophysiological and TMS evidence

2006/2007In this thesis five studies on the relationship between numbers and space and between numbers and motion are presented. The introduction of the thesis contains a description of works dealing with the link between numbers and spatial attention. This includes some behavioral data exploring shifts of spatial attention induced by numbers, data from hemispatial neglect and neuroimaging data. We further explore space-number relationship across modalities (vision and audition) and discuss how the semantics of numbers are dependent or independent form the used modality. This includes an study on blind population using the auditory modality. In a second part, the possible relationship between numbers and motion is introduced and discussed. Two papers that bring convergent data about it are provided. In the first one, an interference of the perception of motion into a number comparison process is presented. In the second paper, a neural substrate in the intraparietal sulcus is proposed as a focus of intersection between number and motion processes. Finally, a study with neglect patients explore possible compensatory mechanism of motion in their altered spatial representation of numbers. Amounting evidence exists on the relationship between numbers and space (see introduction). Numbers´ semantics would have the form of a mental number line with spatial characteristics. Fischer and collaborators (2003) showed that a lateralized target presented on the left visual field (LVF) is detected faster after low numbers than after high numbers and a target presented on the right visual field (RVF) is detected faster following a high number than after low numbers. The studies presented here explore these shifts of attention induced by numbers in electrophysiological terms. Event related potentials (ERPs) allow to explore the process underlying this effect: we describe it as a conjunction of attentional sensory and cognitive, more controlled, mechanisms. We test the possibility that the effect extends to the auditory modality both in sighted and in blind individuals. And we show interesting differences between the two populations in the way they manipulate a similar left-to-right number representation. Regarding the link between motion and number processes, we show how rightward motion facilitates a process thought to call the core presentation of numbers: number comparison. We also explore the vertical dimension, in which upward motion has the same facilitatory effects in number comparison. We show how selective attention to motion has effects on the number comparison process and that his effect may be independent of space-location effects. Furthermore, using transcranial magnetic stimulation (TMS), we present evidence of possible common neural networks processing numbers and motion. One area of intersection, we show, is the ventral intraparietal sulcus (VIPS). VIPS has been proposed previously as an area processing motion in humans. We show that besides motion it is implied in number comparison processes. Finally, we use the behavioral paradigm from the third paper to explore possible effects of motion perception in number processing in hemispatial neglect. While several papers show their difficulty in the representation of the “left side” of the mental number line or in its access, we show that this difficulty or misrepresentation can be compensated by the external presentation of leftward coherent motion. Therefore, common attentional processes seem to be acting over external and internal representational space. In summary, the present thesis provides evidence of the space number relationship and describe how they interact through electrophysiological methods. Some tentative conclusions about the modality dependencies of the number-space link can be drawn from the comparison between modalities. Besides, when there is no access to the visual modality, in congenital blindness, we show how a left to right mental number line stands, but its manipulation varies. We propose motion as another process operating over number representation and provide direct evidence of this new link. Finally, we show how motion acts as a compensatory mechanism in neglect.XX Cicl

Evaluación preliminar de una prueba de realidad virtual para el diagnóstico de discalculia: procedimiento aritmético.

Tanto la discalculia (DD) como la dislexia suelen ser diagnosticadas durante la infancia durante el ciclo de educación primaria. Una prueba diagnóstica ideal debería abarcar el sistema numérico en su conjunto y orientarse a la especificación de perfiles. El presente estudio pone a prueba 4 de las 12 tareas que forman parte de una prueba de realidad virtual en desarrollo para el diagnóstico de la DD. Las pruebas seleccionadas son pruebas que teóricamente deberían asociarse o disociarse de un factor lingüístico. Además, se comparan los datos obtenidos en un grupo sano con los recogidos en un participante con diagnóstico de TDAH (AT). Los resultados muestran diferencias significativas entre el grupo control y AT, además de diversas correlaciones entre las tareas y la extracción de un factor fonológico en el grupo control. El presente estudio supone una primera evaluación de la sensibilidad a las tareas y una comprobación de la eficacia de las variables introducidas. Se propone la continuación del estudio, además de considerar alternativas para la realización de la prueba. Palabras clave: Discalculia, TDAH, Realidad Virtual. <br /

The brain lateralization and development of math functions: progress since Sperry, 1974

In 1974, Roger Sperry, based on his seminal studies on the split-brain condition, concluded that math was almost exclusively sustained by the language dominant left hemisphere. The right hemisphere could perform additions up to sums less than 20, the only exception to a complete left hemisphere dominance. Studies on lateralized focal lesions came to a similar conclusion, except for written complex calculation, where spatial abilities are needed to display digits in the right location according to the specific requirements of calculation procedures. Fifty years later, the contribution of new theoretical and instrumental tools lead to a much more complex picture, whereby, while left hemisphere dominance for math in the right-handed is confirmed for most functions, several math related tasks seem to be carried out in the right hemisphere. The developmental trajectory in the lateralization of math functions has also been clarified. This corpus of knowledge is reviewed here. The right hemisphere does not simply offer its support when calculation requires generic space processing, but its role can be very specific. For example, the right parietal lobe seems to store the operation-specific spatial layout required for complex arithmetical procedures and areas like the right insula are necessary in parsing complex numbers containing zero. Evidence is found for a complex orchestration between the two hemispheres even for simple tasks: each hemisphere has its specific role, concurring to the correct result. As for development, data point to right dominance for basic numerical processes. The picture that emerges at school age is a bilateral pattern with a significantly greater involvement of the right-hemisphere, particularly in non-symbolic tasks. The intraparietal sulcus shows a left hemisphere preponderance in response to symbolic stimuli at this age

Verb generation for presurgical mapping: Gaining specificity

Verb generation is among the most frequently used tasks in presurgical mapping. Because this task involves many processes, the overall brain effects are not specific. While it is necessary to identify the whole network involving noun comprehension or semantic retrieval and lexical selection to produce the verb, isolation of those components is also crucial. Here, we present data from four patients undergoing presurgical brain mapping. The study implied a reanalysis of magnetoencephalography data with a recategorization of the used items. It aimed to extract the task component that relies on the inferior frontal gyrus (IFG). The task could be applied with higher specificity when targeting frontal areas. For that, we based item classification on the selection demands imposed by the noun. It is a robust finding that the IFG carries out this selection and that a quantitative index can be calculated for each noun, which depends on the selection effort (Proceedings of the National Academy of Sciences of the United States of America, 1997; 94(26):14792–14797, Proceedings of the National Academy of Sciences of the United States of America, 1998; 95(26):15855–15860). Data showed focality and specificity, with a correlation between this derived index and source activations in the inferior frontal gyrus for all patients. Strikingly, we detected when the right‐hemisphere homologue area was involved in the selection process in two patients showing reorganization or language right lateralization. The present data are a step towards a dissection of broad specific tasks frequently used in presurgical protocols

Propuesta de intervención para el uso de las metodologías de aprendizaje basadas en ejercicios de indagación y argumentación

En este trabajo se presenta una intervención en el aula que pretende desarrollar destrezas de la práctica científica como la argumentación y la indagación, en el contexto de los nuevos materiales bioplásticos. Esta propuesta didáctica se llevó a cabo con alumnos de 1º bachillerato al trabajar las reacciones de polimerización. Para ello partimos del problema medioambiental que supone el uso de materiales plásticos, estudiaremos los nuevos materiales plásticos biodegradables que se han desarrollado desde la química, haremos trabajos prácticos (TP) con este tipo de materiales como la plastificación del almidón o la desnaturalización de la caseína, y comprobaremos qué plásticos de los que usamos habitualmente es más biodegradable. El objetivo de esta experiencia ha sido fomentar las destrezas propias del trabajo científico y permitir el papel activo del alumno trabajando en el contexto de descubrimiento, de la comprobación de hipótesis y de su validación tras el análisis de los resultados.<br /

¿Plásticos sí o plásticos no? Trabajando prácticas científicas con estudiantes de bachillerato

The project was developed with 1st year high school students is presented in relation to the subject of plastics, its main applications and the environmental problems that derive from its use. Starting from a teaching collaboration of the university teaching center, a sequence of activities was designed to develop scientific competence through argumentation, inquiry and modeling practices. Data were collected through audio and video recording, which were transcribed and analyzed. The results obtained show high levels of performance of the skills involved in the scientific practice studied and a high degree of involvement and interest on the part of the students, based on the active role they have developed in the work guided through questions. Presentamos un proyecto desarrollado con alumnado de 1º de Bachillerato en relación al tema de los plásticos, sus principales aplicaciones y los problemas medioambientales que se derivan de su uso. Partiendo de una colaboración docente del centro-docentes de universidad, se diseñó una secuencia de actividades para desarrollar la competencia científica a través de las prácticas de argumentación, indagación y modelización. Se recogieron datos a través de la grabación de audio y video, que fueron transcritos y analizados. Los resultados obtenidos muestran altos niveles de desempeño de las destrezas implicadas en la práctica científicas trabajadas y un alto grado de implicación e interés por parte de los estudiantes, basados en el papel activo que han desarrollado en el trabajo guiado a través de preguntas

Numbers in the Blind's “Eye”

Background: Although lacking visual experience with numerosities, recent evidence shows that the blind perform similarly to sighted persons on numerical comparison or parity judgement tasks. In particular, on tasks presented in the auditory modality, the blind surprisingly show the same effect that appears in sighted persons, demonstrating that numbers are represented through a spatial code, i.e. the Spatial-Numerical Association of Response Codes (SNARC) effect. But, if this is the case, how is this numerical spatial representation processed in the brain of the blind? Principal Findings: Here we report that, although blind and sighted people have similarly organized numerical representations, the attentional shifts generated by numbers have different electrophysiological correlates (sensorial N100 in the sighted and cognitive P300 in the blind). Conclusions: These results highlight possible differences in the use of spatial representations acquired through modalities other than vision in the blind population

A MEG Study on the Processing of Time and Quantity: Parietal Overlap but Functional Divergence

A common magnitude system for the processing of time and numerosity, supported by areas in the posterior parietal cortex, has been proposed by some authors. The present study aims to investigate possible intersections between the neural processing of non-numerical (time) and numerical magnitudes in the posterior parietal lobe. Using Magnetoencephalography for the comparison of brain source activations during the processing of duration and numerosity contrasts, we demonstrate parietal overlap as well as dissociations between these two dimensions. Within the parietal cortex, the main areas of overlap were bilateral precuneus, bilateral intraparietal sulci, and right supramarginal gyrus. Interestingly, however, these regions did not equivalently correlated with the behavior for the two dimensions: left and right precuneus together with the right supramarginal gyrus accounted functionally for durational judgments, whereas numerosity judgments were accounted by the activation pattern in the right intraparietal sulcus. Present results, indeed, demonstrate an overlap between the neural substrates for processing duration and quantity. However, the functional relevance of parietal overlapping areas for each dimension is not the same. In fact, our data indicates that the same parietal sites rule differently non-numerical and numerical dimensions, as parts of broader networks

Perspectivas de la empresa y la economía mexicana frente a la reestructuración productiva

1 archivo PDF (404 páginas)Este texto se presenta una reflexión de investigadores de la UAM, así como de otras Instituciones de Educación Superior respecto al marco en el que se han desenvuelto las empresas mexicanas en los últimos años, así como del desarrollo en algunos de sus sistemas organizacionales. PALABRAS CLAVE: Mexico Economic policy 1970-1994

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio