Search results for "Functional Laterality"
showing 10 items of 274 documents
The EADC-ADNI Harmonized Protocol for manual hippocampal segmentation on magnetic resonance : Evidence of validity
2014
BackgroundAn international Delphi panel has defined a harmonized protocol (HarP) for the manual segmentation of the hippocampus on MR. The aim of this study is to study the concurrent validity of the HarP toward local protocols, and its major sources of variance.MethodsFourteen tracers segmented 10 Alzheimer's Disease Neuroimaging Initiative (ADNI) cases scanned at 1.5 T and 3T following local protocols, qualified for segmentation based on the HarP through a standard web-platform and resegmented following the HarP. The five most accurate tracers followed the HarP to segment 15 ADNI cases acquired at three time points on both 1.5 T and 3T.ResultsThe agreement among tracers was relatively low…
The bilateral field advantage effect in memory precision.
2018
Previous research has demonstrated that visual working memory performance is better when visual items are allocated in both left and right visual fields than within only one hemifield. This phenomenon is called the bilateral field advantage (BFA). The BFA is thought to be driven by an enhanced probability of storage, rather than by greater precision. In the present experiments, we sought to test whether the BFA can also extend to precision when the parameters of the task are modified. Using a moderate number of to-be-remembered items and 400 ms presentation time, we found better precision in the bilateral condition than in the unilateral condition. The classic BFA was still found in the for…
Hypertonic fluid resuscitation from subarachnoid hemorrhage in rats: A comparison between small volume resuscitation and mannitol
2005
Abstract Objective Death and severe morbidity after subarachnoid hemorrhage (SAH) are mainly caused by global cerebral ischemia through increased intracranial pressure (ICP) and decreased cerebral blood flow (CBF). We have recently demonstrated neuroprotective effects of small volume resuscitation (7.5% saline in combination with 6% dextran 70) in an animal model of SAH, leading to normalization of increased ICP, reduced morphological damage and improved neurological recovery. In the present study, we compared the concept of small volume resuscitation represented by two clinically licenced hypertonic–hyperoncotic saline solutions with the routinely used hyperosmotic agent–mannitol–and inves…
Responsivity to dyslexia training indexed by the N170 amplitude of the brain potential elicited by word reading.
2016
The present study examined training effects in dyslexic children on reading fluency and the amplitude of N170, a negative brain-potential component elicited by letter and symbol strings. A group of 18 children with dyslexia in 3rd grade (9.05 ± 0.46 years old) was tested before and after following a letter-speech sound mapping training. A group of 20 third-grade typical readers (8.78 ± 0.35 years old) performed a single time on the same brain potential task. The training was differentially effective in speeding up reading fluency in the dyslexic children. In some children, training had a beneficial effect on reading fluency (‘improvers’) while a training effect was absent in others (‘non-im…
The role of the prefrontal cortex in familiarity and recollection processes during verbal and non verbal recognition memory: a rTMS study.
2010
Neuroimaging and lesion studies have documented the involvement of the frontal lobes in recognition memory. However, the precise nature of prefrontal contributions to verbal and non-verbal memory and to familiarity and recollection processes remains unclear. The aim of the current rTMS study was to investigate for the first time the role of the DLPFC in encoding and retrieval of non-verbal and verbal memoranda and its contribution to recollection and familiarity processes. Recollection and familiarity processes were studied using the ROC and unequal variance signal detection methodologies. We found that rTMS delivered over left and right DLPFC at encoding resulted in material specific later…
The role of left supplementary motor area in grip force scaling
2013
Skilled tool use and object manipulation critically relies on the ability to scale anticipatorily the grip force (GF) in relation to object dynamics. This predictive behaviour entails that the nervous system is able to store, and then select, the appropriate internal representation of common object dynamics, allowing GF to be applied in parallel with the arm motor commands. Although psychophysical studies have provided strong evidence supporting the existence of internal representations of object dynamics, known as "internal models", their neural correlates are still debated. Because functional neuroimaging studies have repeatedly designated the supplementary motor area (SMA) as a possible …
The middle house or the middle floor: Bisecting horizontal and vertical mental number lines in neglect
2007
Abstract This study explores the processing of mental number lines and physical lines in five patients with left unilateral neglect. Three tasks were used: mental number bisection (‘report the middle number between two numbers’), physical line bisection (‘mark the middle of a line’), and a landmark task (‘is the mark on the line to the left/right or higher/lower than the middle of the line?’). We manipulated the number line orientation purely by task instruction: neglect patients were told that the number-pairs represented either houses on a street (horizontal condition) or floors in a building (vertical condition). We also manipulated physical line orientation for comparison. All five negl…
Metabolic changes in vestibular and visual cortices in acute vestibular neuritis
2004
Five right-handed patients with a right-sided vestibular neuritis were examined twice with fluorodeoxyglucose positron emission tomography while lying supine with eyes closed: once during the acute stage (mean, 6.6 days) and then 3 months later when central vestibular compensation had occurred. Regional cerebral glucose metabolism (rCGM) was significantly increased (p <0.001 uncorrected) during the acute stage in multisensory vestibular cortical and subcortical areas (parietoinsular vestibular cortex in the posterior insula, posterolateral thalamus, anterior cingulate gyrus [Brodmann area 32/24], pontomesencephalic brainstem, hippocampus). Simultaneously, there was a significant rCGM decrea…
Unconditioned stimulus pathways to the amygdala: Effects of lesions of the posterior intralaminar thalamus on foot-shock-induced c-Fos expression in …
2008
The lateral nucleus of the amygdala (LA) is a site of convergence for auditory (conditioned stimulus) and foot-shock (unconditioned stimulus) inputs during fear conditioning. The auditory pathways to LA are well characterized, but less is known about the pathways through which foot shock is transmitted. Anatomical tracing and physiological recording studies suggest that the posterior intralaminar thalamic nucleus, which projects to LA, receives both auditory and somatosensory inputs. In the present study we examined the expression of the immediate-early gene c-fos in the LA in rats in response to foot-shock stimulation. We then determined the effects of posterior intralaminar thalamic lesio…
Contralateral increase in thigmotactic scanning following unilateral barrel-cortex lesion in mice.
2005
Adult C57BL/6 mice received uni- or bilateral cryogenic or sham-lesions over the barrel field and their exploratory behaviour was assessed in an open field between 1 and 7 days post-lesion. Bilateral cortical lesions produced a short-lasting increase in thigmotactic scanning with both sides of the face on the first day of testing. Mice with a unilateral barrel-cortex lesion showed more contralateral wall scanning with a recovery to behavioural symmetry after 5-7 days. Furthermore, the increase in contralateral thigmotaxis was most pronounced in animals with damage to the left barrel field, indicative of a lateralization of the lesion-induced behavioural changes. The cortical lesions did not…