Search results for "Laterality"
showing 10 items of 307 documents
Inhibition processes are dissociable and lateralized in human prefrontal cortex
2016
The prefrontal cortex (PFC) is known to make fundamental contributions to executive functions. However, the precise nature of these contributions is incompletely understood. We focused on a specific executive function, inhibition, the ability to suppress a pre-potent response. Functional imaging and animal studies have studied inhibition. However, there are only few lesion studies, typically reporting discrepant findings. For the first time, we conducted cognitive and neuroimaging investigations on patients with focal unilateral PFC lesions across two widely used inhibitory tasks requiring a verbal response: The Hayling Part 2 and Stroop Colour-Word Tests. We systematically explored the rel…
Prismatic adaptation effects on spatial representation of time in neglect patients
2011
Abstract Processing of temporal information may require the use of spatial attention to represent time along a mental time line. We used prismatic adaptation (PA) to explore the contribution of spatial attention to the spatial representation of time in right brain damaged patients with and without neglect of left space and in age-matched healthy controls. Right brain damaged patients presented time underestimation deficits, that were significantly greater in patients with neglect than in patients without neglect. PA inducing leftward attentional deviation reduced time underestimation deficit in patients with neglect. The results support the hypothesis that a right hemispheric network has a …
N1 and P2 components of auditory event-related potentials in children with and without reading disabilities.
2007
Abstract Objective The effects of within stimulus presentation rate and rise time on basic auditory processing were investigated in children with reading disabilities and typically reading children. Methods Children with reading disabilities (RD; N =19) and control children ( N =20) were studied using event-related potentials (ERPs). Paired stimuli were used with two different within-pair-intervals (WPI; 10 and 255ms) and two different rise times (10 and 130ms). Each stimulus was presented with equal probability and long between-pair inter-stimulus intervals (1–5s). The study focused on N1 and P2 components. Results The P2 responses to the first tone in the pair showed differences between c…
Training labels for hippocampal segmentation based on the EADC-ADNI harmonized hippocampal protocol
2015
Abstract Background The European Alzheimer's Disease Consortium and Alzheimer's Disease Neuroimaging Initiative (ADNI) Harmonized Protocol (HarP) is a Delphi definition of manual hippocampal segmentation from magnetic resonance imaging (MRI) that can be used as the standard of truth to train new tracers, and to validate automated segmentation algorithms. Training requires large and representative data sets of segmented hippocampi. This work aims to produce a set of HarP labels for the proper training and certification of tracers and algorithms. Methods Sixty-eight 1.5 T and 67 3 T volumetric structural ADNI scans from different subjects, balanced by age, medial temporal atrophy, and scanner…
Influence of spatial information on responses of tonically active neurons in the monkey striatum.
2006
Influence of spatial information on responses of tonically active neurons in the monkey striatum. J Neurophysiol 95: 2975–2986, 2006. First published February 8, 2006; doi:10.1152/jn.01113.2005. Previous studies have demonstrated that tonically active neurons (TANs) in the primate striatum play an important role in the detection of rewarding events. However, the influence of the spatial features of stimuli or actions required to obtain reward remains unclear. Here, we examined the activity of TANs in the striatum of monkeys trained to make spatially directed movements elicited by visual stimuli presented ipsilaterally or contralaterally to the moving arm. Among 181 neurons responding to the…
Space representation in children with dyslexia and children without dyslexia: Contribution of line bisection and circle centering tasks
2013
International audience; Line bisection tasks (different space locations and different line lengths) and circle centering tasks (visuo-proprioceptive and proprioceptive explorations, with left or right starting positions) were used to investigate space representation in children with dyslexia and children without dyslexia. In line bisection, children with dyslexia showed a significant rightward bias for central and right-sided locations and a leftward bias for left-sided location. Furthermore, the spatial context processing was asymmetrically more efficient in the left space. In children without dyslexia, no significant bias was observed in central lines but the spatial context processing wa…
Identity–expression interaction in face perception: Sex, visual field, and psychophysical factors
2012
International audience; We investigated the psychophysical factors underlying the identity-emotion interaction in face perception. Visual field and sex were also taken into account. Participants had to judge whether a probe face, presented in either the left or the right visual field, and a central target face belonging to same person while emotional expression varied (Experiment 1) or to judge whether probe and target faces expressed the same emotion while identity was manipulated (Experiment 2). For accuracy we replicated the mutual facilitation effect between identity and emotion; no sex or hemispheric differences were found. Processing speed measurements, however, showed a lesser degree…
Early emergence of deviant frontal fMRI activity for phonological processes in poor beginning readers.
2010
Phonological awareness refers to the ability to perceive and manipulate the sound structure of language and is especially important when children learn to read. Poor phonological awareness is considered the major cause for the emergence of reading difficulties. In this functional magnetic resonance imaging (fMRI) study, we examined the brain correlates of phonological processing in young beginning readers (aged 8.3+/-0.4 y, 2nd grade) with poor (25th percentile) or normal, age-appropriate reading skills (40th percentile) using a covert reading and mental letter substitution task. Letter substitution in words and nonwords induced pronounced activity in a left frontal language network related…
Newborn event-related potentials predict poorer pre-reading skills in children at risk for dyslexia.
2009
Earlier results from the Jyväskylä Longitudinal Study of Dyslexia showed that newborn event-related potentials (ERPs) of children with and without familial risk for dyslexia were associated with receptive language and verbal memory skills between 2.5 and 5 years of age. We further examined whether these ERPs (responses to synthetic consonant-vowel syllables /ba/, /da/, /ga/; presented equiprobably with 3,910—7,285 ms interstimulus intervals) predict later pre-reading skills measured before the onset of school (6.5 years of age). In line with our earlier results, the at-risk children ( N = 11) with atypical speech processing in the right hemisphere (a slower shift in polarity from positivit…
Functional reorganization of the attentional networks in low-grade glioma patients: a longitudinal study.
2015
International audience; Right brain damage often provokes deficits of visuospatial attention. Although the spatial attention networks have been widely investigated in stroke patients as well as in the healthy brain, little is known about the impact of slow growing lesions in the right hemisphere. We here present a longitudinal study of 20 patients who have been undergoing awake brain surgery with per-operative line bisection testing. Our aim was to investigate the impact of tumour presence and of tumour resection on the functional (re)organization of the attention networks. We assessed patients' performance on lateralized target detection, visual exploration and line bisection before surger…