Brain potentials to mathematical syntax problems.

Anterior negativities obtained during sentence processing have never been unambiguously reported in the mathematical domain. The reason for this might be that the tasks explored in the mathematical domain have been far from resembling those typically yielding language-related anterior negativities. To test this hypothesis, we explored three mathematical aspects: Order-relevant information, a parenthesis indicating the onset of an embedded calculation, and violations of the type of symbol displayed. Results yielded parieto-occipital instead of frontal negativities. Late posterior positivities were also found, largely comparable to linguistic P600 in topography, but dissociable in functional terms. Our data suggest that language-related anterior negativities may indeed reflect language-specific resources of the human brain and support recent claims that language and mathematical domains are more independent than previously thought.

Are semantic and syntactic cues inducing the same processes in the identification of word order?

The purpose of this study was to find a common pattern of event-related potential (ERP) fluctuations regardless of the type of information (either semantic or syntactic) determining the presence of a reversed word order. ERPs were recorded while subjects read Spanish transitive sentences in which either semantic or syntactic information determined the actual word order. On the one hand (semantic condition), the order could be reversed by using an inanimate noun in the first noun phrase (NP), together with a verb representing an action that cannot correspond to an inanimate entity. On the other hand (syntactic condition), word order could be manipulated depending on the presence of a preposition preceding the second NP, which confirms the preferred word order, or a determiner, conveying a reversed word order. Interestingly, the inanimate first noun elicited a frontal negativity, which could be interpreted as the detection of an initial difficulty for using that noun as the subject of the sentence. At the point of disambiguation in either condition, a late posterior positivity was observed. The P600/SPS might, therefore, be an indicator of the syntactic processing costs incurred by the variation of word order, reflecting phrase structure reallocation processes common to this operation regardless of the cue used.

The recognition potential during sentence presentation: stimulus probability, background stimuli, and SOA.

Recognition potential (RP) is an electrical brain response that has proved its usefulness for studying semantic processing of isolated words, and appears when subjects view meaningful stimuli embedded in a stream of background images at a high rate of presentation: the rapid stream stimulation paradigm (RSS). The present technical study is aimed at testing the validity of this procedure in the study of words within sentences. For this purpose, we varied word and background probability of appearance, the number of background stimuli preceding each word, and stimulus onset asynchrony. Probability did not have significant effects on RP, but it was found that a minimum number of two background stimuli preceding each word and a high rate (250 ms) of presentation are preferable for enhancing RP amplitude. The RSS paradigm would therefore improve the visibility-and, hence, refine the analysis-of a component that can nevertheless be obtained with more standard paradigms, such as rapid serial visual presentation, devoid of interspersed background stimuli.

Electrophysiological evidence of an early effect of sentence context in reading.

Recognition Potential is an electrophysiological response of the brain that is sensitive to semantic aspects of stimuli. According to its peak values (about 250ms), Recognition Potential appears as a good candidate to reflect lexical selection processes. Consequently, Recognition Potential might be sensitive to contextual information during reading a sentence. In present study, the standard procedures to improve the visibility of Recognition Potential (Rapid Stream Stimulation paradigm) were used in a task in which sentence context was crucial. A parieto-occipital Recognition Potential was observed to peak about 264ms after stimulus onset, followed by a centro-parietal N400 peaking at about 450ms. Recognition Potential was affected by contextual information though, contrary to N400, presenting larger amplitude to contextually congruous words. These results support the assumption that Recognition Potential may reflect lexical selection processes, representing also evidence of context effects on ERP around 250ms after stimulus onset during sentence reading.

Analysis of anxiety variables in dental students.

UNLABELLED: Personality, stress factors, gender and personal circumstances have been studied in dental students and a change in anxiety levels has been discovered over the different academic years that make up the degree course. OBJECTIVES: To analyse the variation in anxiety over the different years and to determine any variation between the genders, in dental students at the Madrid Complutense University. METHOD: Eight scales of the Inventory of Anxiety Situations and Responses were administered to 110 students, of both genders, from the 1st, 3rd and 5th years. RESULTS: Mean scores were obtained for the eight scales, separately by year and for gender. In general the women showed a higher anxiety level in the scales for cognitive, physiological, motor, general and assessment anxiety responses. Anxiety in the 3rd year was higher than in the 1st year. The lowest levels were found in the 5th year. DISCUSSION: High anxiety levels increase the risk of suffering illness and make it necessary to plan educational control strategies bearing in mind the factors which stress men or women and the activities carried out in each academic year.

The recognition potential and repetition effects.

The recognition potential (RP) is an electrical brain response peaking at 250 ms that appears when subjects view meaningful stimuli. Previous RP research was conducted in experimental conditions in which repetition effects could not be totally ruled out as influencing the generation of the RP response. The present study aims to elucidate whether repetition effects affect the topography and waveform of this component. For this purpose semantically correct, orthographically correct, strings of random letters, control and background stimuli were presented to 20 subjects following the rapid stream stimulation procedure and without repetition of any test stimulus. As previously, the RP showed its maximal amplitude at the PO7 electrode. It showed sensitivity to all levels of lexical processing, its response being maximal for semantically correct stimuli, and its topographical distribution was similar for all types of stimulus. Direct statistical comparisons with the data of a previous study where repetition effects could not be disregarded were performed, confirming the similarity between the results obtained in both experiments. The neural generators of the RP were placed again, as in previous studies, within the lingual gyrus. Although repetition effects have been reported to affect other semantic-related components such as the N400, they do not seem to affect either the topography or the waveform of the RP.

Prevalencia, consecuencias y antecedentes de miedo, ansiedad y fobia dental / Prevalence, consequences and antecedents of dental fear, anxiety and phobia

En este trabajo de revisión se recogen las definiciones sobre los conceptos de miedo, ansiedad y fobia dental. Se recoge la prevalencia y la incidencia de estos trastornos en distintas poblaciones. Se indican las principales consecuencias en el cuidado y salud bucodental y los problemas dentales más importantes que padecen los pacientes que presentan niveles más altos de miedo, ansiedad y fobia dental. Se revisan tanto en niños como en adultos, los antecedentes de estos trastornos, el modo de adquisición y las variables que influyen en su mantenimiento. Se indican los elementos y componentes del tratamiento dental que más miedo y ansiedad producen en los pacientes

Prevalencia, consecuencias y antecedentes de miedo, ansiedad y fobia dental / Prevalence, consequences and antecedents of dental fear, anxiety and phobia

En este trabajo de revisión se recogen las definiciones sobre los conceptos de miedo, ansiedad y fobia dental. Se recoge la prevalencia y la incidencia de estos trastornos en distintas poblaciones. Se indican las principales consecuencias en el cuidado y salud bucodental y los problemas dentales más importantes que padecen los pacientes que presentan niveles más altos de miedo, ansiedad y fobia dental. Se revisan tanto en niños como en adultos, los antecedentes de estos trastornos, el modo de adquisición y las variables que influyen en su mantenimiento. Se indican los elementos y componentes del tratamiento dental que más miedo y ansiedad producen en los pacientes (AU)