Aprendizaje de palabras nuevas concretas y abstractas

El significado de una palabra nueva puede adquirirse extrayéndolo de un contexto lingüístico, tanto durante la lectura como durante una conversación. Aún no sabemos cómo nuestro cerebro lleva a cabo este proceso de extracción y posterior aprendizaje del significado de nuevas palabras. En esta investigación hemos simulado el aprendizaje de palabras nuevas concretas y abstractas a partir de información contextual verbal, con el fin de caracterizar las regiones cerebrales implicadas durante el curso de este proceso

Imaging bilinguals: When the neurosciences meet the languange sciences

The starting point of our investigation was the longstanding notion that bilingual individuals need effective mechanisms to prevent interference from one language while processing material in the other (e.g. Penfield and Roberts, 1959). To demonstrate how the prevention of interference is implemented in the brain we employed event-related brain potentials (ERPs; see Munte, Urbach, ¨ Duzel and Kutas, 2000, for an introductory review) ¨ and functional magnetic resonance imaging (fMRI) techniques, thus pursuing a combined temporal and spatial imaging approach. In contrast to previous investigations using neuroimaging techniques in bilinguals, which had been mainly concerned with the localization of the primary and secondary languages (e.g. Perani, Paulesu, Galles, Dupoux, Dehaene, Bettinardi, Cappa, Fazio and Mehler, 1998; Chee, Caplan, Soon, Sriram, Tan, Thiel and Weekes, 1999), our study addressed the dynamic aspects of bilingual language processing.

Functional connectivity of reward processing in the brain

Controversial results have been reported concerning the neural mechanisms involved in the processing of rewards and punishments. On the one hand, there is evidence suggesting that monetary gains and losses activate a similar fronto-subcortical network. On the other hand, results of recent studies imply that reward and punishment may engage distinct neural mechanisms. Using functional magnetic resonance imaging (fMRI) we investigated both regional and interregional functional connectivity patterns while participants performed a gambling task featuring unexpectedly high monetary gains and losses. Classical univariate statistical analysis showed that monetary gains and losses activated a similar fronto-striatallimbic network, in which main activation peaks were observed bilaterally in the ventral striatum. Functional connectivity analysis showed similar responses for gain and loss conditions in the insular cortex, the amygdala, and the hippocampus that correlated with the activity observed in the seed region ventral striatum, with the connectivity to the amygdala appearing more pronounced after losses. Larger functional connectivity was found to the medial orbitofrontal cortex for negative outcomes. The fact that different functional patterns were obtained with both analyses suggests that the brain activations observed in the classical univariate approach identifi es the involvement of different functional networks in the current task. These results stress the importance of studying functional connectivity in addition to standard fMRI analysis in reward-related studies.

Reward networks in the brain as captured by connectivity measures

An assortment of human behaviors is thought to be driven by rewards including reinforcement learning, novelty processing, learning, decision making, economic choice, incentive motivation, and addiction. In each case the ventral tegmental area/ventral striatum (nucleus accumbens) (VTAVS) system has been implicated as a key structure by functional imaging studies, mostly on the basis of standard, univariate analyses. Here we propose that standard functional magnetic resonance imaging analysis needs to be complemented by methods that take into account the differential connectivity of the VTAVS system in the different behavioral contexts in order to describe reward based processes more appropriately. We fi rst consider the wider network for reward processing as it emerged from animal experimentation. Subsequently, an example for a method to assess functional connectivity is given. Finally, we illustrate the usefulness of such analyses by examples regarding reward valuation, reward expectation and the role of reward in addiction.

TCDI vs TCD for stroke risk prevention in children with sickle cell anemia: a cross-sectional study

Children with sickle cell anemia (SCA) are at increased risk of stroke. Elevated blood-flow velocities in the middle cerebral artery detected by Transcranial Doppler (TCD) are a good predictor of stroke risk in these children. Velocities obtained by TCD are measured by using a specific parameter, the time-averaged mean of the maximum velocity (TAMM). Children with TAMM velocities ≥200 cm/sec are at high risk of stroke, and transfusions as primary prevention might be done. Transcranial Doppler-imaging (TCDI) is now widely available and it allows the visualization of intracranial vessels.Few studies have compared the TAMM in TCD and TCDI, and no studies have established a cutoff point for TAMM in TCDI equivalent to the STOP criteria of “normal”, “conditional” and “abnormal”, which could predict a high risk of stroke in children with SCAObjectives: To compare the TAMM velocity obtained by TCDI with the TAMM velocity obtained with TCD in the middle cerebral artery, and to determine a cutoff point for TAMM in TCDI that could predict a high risk of stroke in children with SCAMethods: This study is a cross-sectional study of a diagnostic test. 78 children with sickle cell anemia between 2 to 16 years will be evaluated with both TCD and TCDI in order to determinate the TAMM with the two devices. Velocities obtained with both Doppler techniques will be compared using an intraclass correlation coefficient

Studying Memory Encoding to Promote Reliable Engagement of the Medial Temporal Lobe at the Single-subject Level

The medial temporal lobe (MTL)-comprising hippocampus and the surrounding neocortical regions-is a targeted brain area sensitive to several neurological diseases. Although functional magnetic resonance imaging (fMRI) has been widely used to assess brain functional abnormalities, detecting MTL activation has been technically challenging. The aim of our study was to provide an fMRI paradigm that reliably activates MTL regions at the individual level, thus providing a useful tool for future research in clinical memory-related studies. Twenty young healthy adults underwent an event-related fMRI study consisting of three encoding conditions: word-pairs, face-name associations and complex visual scenes. A region-of-interest analysis at the individual level comparing novel and repeated stimuli independently for each task was performed. The results of this analysis yielded activations in the hippocampal and parahippocampal regions in most of the participants. Specifically, 95% and 100% of participants showed significant activations in the left hippocampus during the face-name encoding and in the right parahippocampus, respectively, during scene encoding. Additionally, a whole brain analysis, also comparing novel versus repeated stimuli at the group level, showed mainly left frontal activation during the word task. In this group analysis, the face-name association engaged the HP and fusiform gyri bilaterally, along with the left inferior frontal gyrus, and the complex visual scenes activated mainly the parahippocampus and hippocampus bilaterally. In sum, our task design represents a rapid and reliable manner to study and explore MTL activity at the individual level, thus providing a useful tool for future research in clinical memory-related fMRI studies.