Balancing the 2 Hemispheres in Simple Calculation: Evidence From Direct Cortical Electrostimulation

Published: 24 September 2016How do the parietal lobes contribute to simple calculation? Clinical and neuroimaging methods, which are based mainly on correlational evidence, have provided contrasting results so far. Here we used direct cortical electrostimulation during brain surgery to causally infer the role of the left and right parietal lobes in simple calculation. Stimulation provoked errors for addition and multiplication in different parietal areas on both hemispheres. Crucially, an innovative qualitative error analysis unveiled the functional contrast of the 2 parietal lobes. Right or left stimulation led to different types of substitution errors in multiplication, unveiling the function of the more active hemisphere. While inhibition of the left hemisphere led mainly to approximation errors, right hemisphere inhibition enhanced retrieval within a stored repertory. These results highlight the respective roles of each hemisphere in the network: rote retrieval of possible solutions by the left parietal areas and approximation to the correct solution by the right hemisphere. The bilateral orchestration between these functions guarantees precise calculation.This work was supported by the Italian Ministry of Health (grant RF-2009-1530973); by the University of Padua (Grant Progetto d’Ateneo CPDA131328 and Progetto strategico NEURAT) to C.S., and by the Spanish Ministry of Science and Innovation (grant PSI2014-53351) to E.S. and by financial assistance as a Severo Ochoa Center of Excellence SEV-2015-0490 to the BCBL (E.S.)

Inmersión en el mundo de la nano-ciencia a través de una experiencia de indagación guiada con alumnos de Educación Secundaria

En este trabajo se presenta un proyecto de inmersión en el mundo de la ciencia a escala nanométrica. Este proyecto se desarrolló con alumnos de 4º de ESO, a los que se les presentó un fenómeno sobre el qu e tenían que indagar. Dicho fenómeno consistió en la aplicación de un aerosol sobre muestras textiles observando como este aerosol evitaba que los textiles se ensuciaran. El objetivo principal de la experiencia ha sido analizar las destrezas que los alumno s han desarrollado en el proceso para dar explicación al fenómeno observado. Se ha prestado especial atención al tipo de preguntas que éstos formularon a lo largo de la actividad. A partir de las preguntas, se han analizado las destrezas y su nivel de dese mpeño en esta experiencia de indagación en grupo colaborativo. Se puede concluir que los niveles de desempeño relacionados con la planificación y la observación son bajos. Por otro lado, parte del alumnado ha conseguido dar explicación al fenómeno plantean do las preguntas adecuadas. This paper presents a project of immersion in the world of science to scale Nano. This project was developed with the students of 4 degrees CSE. These were presented with an unknown phenomenon on which to enquire. This phenomenon consisted in the application of an aerosol on textile samples observing how this spray prevented the textiles from getting dirty. The main goal has been to analyse the skills developed by the students in the process of explanation to the observed phenomenon. Special attention to the kinds of questions they made throughout the process has been paid. From these questions, the skills and their level of performance has been studied in this experience of research in cooperative group. It can be concluded that the performance levels related to planning and observation are low. On the other hand, some students were able to give explanation to the phenomenon by posing the right questions

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

Electrophysiological Evidence for Spatiotemporal Flexibility in the Ventrolateral Attention Network

Successful completion of many everyday tasks depends on interactions between voluntary attention, which acts to maintain current goals, and reflexive attention, which enables responding to unexpected events by interrupting the current focus of attention. Past studies, which have mostly examined each attentional mechanism in isolation, indicate that volitional and reflexive orienting depend on two functionally specialized cortical networks in the human brain. Here we investigated how the interplay between these two cortical networks affects sensory processing and the resulting overt behavior. By combining measurements of human performance and electrocortical recordings with a novel analytical technique for estimating spatiotemporal activity in the human cortex, we found that the subregions that comprise the reflexive ventrolateral attention network dissociate both spatially and temporally as a function of the nature of the sensory information and current task demands. Moreover, we found that together with the magnitude of the early sensory gain, the spatiotemporal neural dynamics accounted for the high amount of the variance in the behavioral data. Collectively these data support the conclusion that the ventrolateral attention network is recruited flexibly to support complex behaviors

Behavioural and neurophysiological evidence of semantic interaction between iconic gestures and words

We report two experiments that provide converging behavioural and neurophysiological evidence on the relationship between the meaning of iconic gestures and words. Experiment 1 exploited a semantic priming paradigm and revealed interference between gestures and words when they were not related in meaning, but no facilitation when they were. This result was confirmed in Experiment 2, where ERPs were recorded during silent word reading with the same paradigm. The analysis showed a negative deflection peaking near 400 ms (N400) and, in the left hemisphere, greater negative values for verbs than for nouns. Differently from the classical distribution obtained with verbal stimuli, we found an N400 that spread more over central-anterior areas of the scalp, suggesting that the meaning systems of gesture and language do not overlap completely. These results are consistent with the view that the meaning systems for gesture and speech are tightly integrated

The integration between the word and gesture meaning systems: evidence from RTs and ERPs.

Aim of the present study was to assess the relationships between the gesture and language meaning systems with a priming paradigm at both the behavioral and the neurophysiological levels. Fifteen participants watched forty video-clips of different types of iconic gestures followed by words (nouns or verbs), which could be related or unrelated in meaning. Behavioral results showed an interference effect between the meaning of iconic gestures and that of unrelated words. ERPs analyses showed a greater P200 component for nouns than for verbs, which was modulated by the relation with the preceding gesture, and a clear N400 with greater negative values for verbs than for nouns. Although there was evidence for a deep integration between word and gesture in the P200 time window; the lack of interaction between the meaning relation and the grammatical class in the N400 time window suggests that the meaning systems of word and gesture diffe

Electophysiological evidence of cross-modal priming between the meaning system of gesture and language

Behavioral results showed an interference effect between the meaning of iconic gestures and that of unrelated words. ERPs analyses showed a greater P200 component for nouns than for verbs, which was modulated by the relation with the preceding gesture, and a clear N400 with greater negative values for verbs than for nouns