The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Motomi Toichi - One of the best experts on this subject based on the ideXlab platform.
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right Hemispheric Dominance and interHemispheric cooperation in gaze triggered reflexive shift of attention
Psychiatry and Clinical Neurosciences, 2012Co-Authors: Takashi Okada, Wataru Sato, Motomi Toichi, Yasutaka Kubota, Toshiya MuraiAbstract:Aims: The neural substrate for the processing of gaze remains unknown. The aim of the present study was to clarify which hemisphere dominantly processes and whether bilateral hemispheres cooperate with each other in gaze-triggered reflexive shift of attention. Methods: Twenty-eight normal subjects were tested. The non-predictive gaze cues were presented either in unilateral or bilateral visual fields. The subjects localized the target as soon as possible. Results: Reaction times (RT) were shorter when gaze-cues were congruent toward than away from targets, whichever visual field they were presented in. RT were shorter in left than right visual field presentations. RT in mono-directional bilateral presentations were shorter than both of those in left and right presentations. When bi-directional bilateral cues were presented, RT were faster when valid cues were presented in the left than right visual fields. Conclusion: The right hemisphere appears to be dominant, and there is interHemispheric cooperation in gaze-triggered reflexive shift of attention.
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right Hemispheric Dominance in gaze triggered reflexive shift of attention in humans
Brain and Cognition, 2006Co-Authors: Takashi Okada, Wataru Sato, Motomi ToichiAbstract:Recent findings suggest a right Hemispheric Dominance in gaze-triggered shifts of attention. The aim of this study was to clarify the dominant hemisphere in the gaze processing that mediates attentional shift. A target localization task, with preceding non-predicative gaze cues presented to each visual field, was undertaken by 44 healthy subjects, measuring reaction time (RT). A face identification task was also given to determine Hemispheric Dominance in face processing for each subject. RT differences between valid and invalid cues were larger when presented in the left rather than the right visual field. This held true regardless of individual Hemispheric Dominance in face processing. Together, these results indicate right Hemispheric Dominance in gaze-triggered reflexive shifts of attention in normal healthy subjects.
Udo Reulbach - One of the best experts on this subject based on the ideXlab platform.
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non right handedness and free serum testosterone levels in detoxified patients with alcohol dependence
Alcohol and Alcoholism, 2010Co-Authors: Wolfgang Sperling, Christian Maihöfner, Stefan Bleich, Rose Galvin, Teresa Biermann, Johannes Kornhuber, Udo ReulbachAbstract:Aims : The influence of testosterone on the extent of Hemispheric Dominance has been discussed not just during the first two trimesters of pregnancy but also later in life. An increase in free serum testosterone levels has been found during and after the detoxification phase of patients with alcohol dependence. Methods : In 250 participants (125 men and 125 women) with alcohol dependence immediately after the direct withdrawal phase (Day 21) and in 250 healthy age- and gender-matched participants, free testosterone in the serum was determined and handedness was assessed as a peripheral marker of central Hemispheric Dominance. Results : Patients with alcohol dependence were 2.7-fold (odds ratio, OR: 2.66; 95% confidence interval, CI: 1.62–4.38) and men 4.1-fold (OR: 4.12; 95% CI: 2.44–6.98) more likely to be non-right-handed (NRH). In addition to male gender, non-right-handedness and alcohol dependence contributed statistically significantly to higher serum testosterone levels. Testosterone values of patients with alcohol dependence differed significantly between the four different Lesch subtypes; in particular, participants with alcohol dependence classified according to Lesch subtype IV were found to have significantly higher serum testosterone levels ( F = 20.5; P < 0.001) when compared to participants classified according to Lesch subtypes I–III. Conclusions : An alteration of Hemispheric Dominance and thus an exogenously modifiable neuronal plasticity may be demonstrated directly on a population at risk.
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cognitive and behavioural aspects non right handedness and free serum testosterone levels in detoxified patients with alcohol dependence
2010Co-Authors: Wolfgang Sperling, Christian Maihöfner, Stefan Bleich, Rose Galvin, Teresa Biermann, Johannes Kornhuber, Udo ReulbachAbstract:Aims: The influence of testosterone on the extent of Hemispheric Dominance has been discussed not just during the first two trimesters of pregnancy but also later in life. An increase in free serum testosterone levels has been found during and after the detoxification phase of patients with alcohol dependence. Methods: In 250 participants (125 men and 125 women) with alcohol de- pendence immediately after the direct withdrawal phase (Day 21) and in 250 healthy age- and gender-matched participants, free testosterone in the serum was determined and handedness was assessed as a peripheral marker of central Hemispheric Dominance. Results: Patients with alcohol dependence were 2.7-fold (odds ratio, OR: 2.66; 95% confidence interval, CI: 1.62-4.38) and men 4.1-fold (OR: 4.12; 95% CI: 2.44-6.98) more likely to be non-right-handed (NRH). In addition to male gender, non-right-handedness and alcohol dependence contributed statistically significantly to higher serum testosterone levels. Testosterone values of patients with alcohol dependence differed significantly between the four different Lesch subtypes; in particular, participants with alcohol dependence classified according to Lesch subtype IV were found to have significantly higher serum testosterone levels (F = 20.5; P < 0.001) when compared to participants classified according to Lesch subtypes I-III. Conclusions: An alteration of Hemispheric Dominance and thus an exogenously modifiable neuronal plasticity may be demonstrated directly on a population at risk.
Stefan Knecht - One of the best experts on this subject based on the ideXlab platform.
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Dominance for language and spatial processing limited capacity of a single hemisphere
Neuroreport, 2005Co-Authors: Andreas Jansen, Agnes Floel, Ricarda A L Menke, Martin Kanowski, Stefan KnechtAbstract:Using functional magnetic resonance imaging during word generation and spatial judgement (Landmark task), we investigated how Hemispheric specializations for language and spatial processing interact in healthy individuals. We found individuals with atypical, right-Hemispheric Dominance for language
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atypical Hemispheric Dominance for attention functional mri topography
Journal of Cerebral Blood Flow and Metabolism, 2005Co-Authors: Andreas Jansen, Agnes Floel, Martin Kanowski, Michael Deppe, Carsten Konrad, Jens Sommer, Stefan KnechtAbstract:The right hemisphere is predominantly involved in tasks associated with spatial attention. However, left Hemispheric Dominance for spatial attention can be found in healthy individuals, and both spatial attention and language can be lateralized to the same hemisphere. Little is known about the underlying regional distribution of neural activation in these 'atypical' individuals. Previously a large number of healthy subjects were screened for Hemispheric Dominance of visuospatial attention and language, using functional Doppler ultrasonography. From this group, subjects were chosen who were 'atypical' for Hemispheric Dominance of visuospatial attention and language, and their pattern of brain activation was studied with functional magnetic resonance imaging during a task probing spatial attention. Right-handed subjects with the 'typical' pattern of brain organization served as control subjects. It was found that subjects with an inverted lateralization of language and spatial attention (language right, attention left) recruited left-Hemispheric areas in the attention task, homotopic to those recruited by control subjects in the right hemisphere. Subjects with lateralization of both language and attention to the right hemisphere activated an attentional network in the right hemisphere that was comparable to control subjects. The present findings suggest that not the Hemispheric side, but the intraHemispheric pattern of activation is the distinct feature for the neural processes underlying language and attention.
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determining the Hemispheric Dominance of spatial attention a comparison between ftcd and fmri
Human Brain Mapping, 2004Co-Authors: Andreas Jansen, Agnes Floel, Martin Kanowski, Michael Deppe, Jutta Van Randenborgh, Bianca Drager, Stefan KnechtAbstract:Human brain mapping allows the systematic assessment of interindividual differences in functional brain anatomy. Functional transcranial Doppler sonography (fTCD) is an imaging tool that allows for fast and mobile assessment of Hemispheric lateralization of task-related brain activation. It is ideal to screen large cohorts of subjects. The goal of the present study was to investigate whether fTCD and functional magnetic resonance imaging (fMRI) determine Hemispheric lateralization of brain activation related to visuospatial attention concordantly. Used together, fMRI and fTCD may then open up a wide range of potential applica- tions in neuroscience. Fifteen subjects were examined both with fTCD and fMRI while they judged accuracy of line bisections (Landmark task). For fTCD, the maximal mean difference in stimulus-related relative cerebral blood flow velocity changes in the left and right middle cerebral arteries was assessed as the lateralization index LIfTCD. For fMRI, two approaches were used to determine Hemispheric Dominance. First, we measured brain activity as the extent of the activated region, i.e., the number of activated voxels above a statistical threshold. Second, we calculated the magnitude of the fMRI signal change between the activation and the control task within a region of interest. Results of fTCD and fMRI were concordant in every single case. Therefore, scanning large cohorts with fTCD for Hemispheric Dominance during Landmark task will provide results consistent with fMRI. FMRI can then be used for in depth assessment of the specific patterns of activation. Hum Brain Mapp 23:168 -180, 2004. © 2004 Wiley-Liss, Inc.
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is Hemispheric language Dominance relevant in musical hallucinations two case reports
European Archives of Psychiatry and Clinical Neuroscience, 2002Co-Authors: Stefan Evers, Tanja Ellger, E B Ringelstein, Stefan KnechtAbstract:It has been suggested that musical hallucinations are often due to a focal brain lesion predominantly of right Hemispheric pathologies. We report about two patients with musical hallucinations associated with a brain tumor of the right hemisphere. Although both patients were right-handed, one of them had a right Hemispheric Dominance for language as proven by the Wada test. The musical ability as measured by the Seashore test was not impaired. We conclude that the language Dominance of the hemisphere is not primarily relevant for the development of musical hallucinations.
Andrew C. Papanicolaou - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Hemispheric Dominance for receptive language in pediatric patients under sedation using magnetoencephalography.
Frontiers in Human Neuroscience, 2014Co-Authors: Roozbeh Rezaie, Shalini Narayana, Katherine Schiller, Liliya Birg, James W. Wheless, Frederick A. Boop, Andrew C. PapanicolaouAbstract:Non-invasive assessment of Hemispheric Dominance for receptive language using Magnetoencephalography (MEG) is now a well-established procedure used across several epilepsy centers in the context of pre-surgical evaluation of children and adults while awake, alert and attentive. However, the utility of MEG for the same purpose, in cases of sedated patients, is contested. Establishment of the efficiency of MEG is especially important in the case of children who, for a number of reasons, must be assessed under sedation. Here we explored the efficacy of MEG language mapping under sedation through retrospective review of 95 consecutive pediatric patients, who underwent our receptive language test as part of routine clinical evaluation. Localization of receptive language cortex and subsequent determination of laterality was successfully completed in 78% (n=36) and 55% (n=27) of non-sedated and sedated patients, respectively. Moreover, the proportion of patients deemed left hemisphere dominant for receptive language did not differ between non-sedated and sedated patients, exceeding 90% in both groups. Considering the challenges associated with assessing brain function in pediatric patients, the success of passive MEG in the context of the cases reviewed in this study support the utility of this method in pre-surgical receptive language mapping.
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optimizing estimation of Hemispheric Dominance for language using magnetic source imaging
Brain Research, 2011Co-Authors: Antony D Passaro, Roozbeh Rezaie, Dana C Moser, Nadeeka Dias, Andrew C. PapanicolaouAbstract:The efficacy of magnetoencephalography (MEG) as an alternative to invasive methods for investigating the cortical representation of language has been explored in several studies. Recently, studies comparing MEG to the gold standard Wada procedure have found inconsistent and often less-than accurate estimates of laterality across various MEG studies. Here we attempted to address this issue among normal right-handed adults (N=12) by supplementing a well-established MEG protocol involving word recognition and the single dipole method with a sentence comprehension task and a beamformer approach localizing neural oscillations. Beamformer analysis of word recognition and sentence comprehension tasks revealed a desynchronization in the 10-18Hz range, localized to the temporo-parietal cortices. Inspection of individual profiles of localized desynchronization (10-18Hz) revealed left Hemispheric Dominance in 91.7% and 83.3% of individuals during the word recognition and sentence comprehension tasks, respectively. In contrast, single dipole analysis yielded lower estimates, such that activity in temporal language regions was left-lateralized in 66.7% and 58.3% of individuals during word recognition and sentence comprehension, respectively. The results obtained from the word recognition task and localization of oscillatory activity using a beamformer appear to be in line with general estimates of left Hemispheric Dominance for language in normal right-handed individuals. Furthermore, the current findings support the growing notion that changes in neural oscillations underlie critical components of linguistic processing.
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magnetocephalography a noninvasive alternative to the wada procedure
Journal of Neurosurgery, 2004Co-Authors: Andrew C. Papanicolaou, James W. Wheless, Panagiotis G Simos, Eduardo M Castillo, Joshua I Breier, Shirin Sarkari, Ekaterina Pataraia, Rebecca L Billingsley, Scott Buchanan, Vijayalakshmi MaggioAbstract:Object. In this study the authors evaluated the sensitivity and selectivity of a noninvasive language mapping procedure based on magnetoencephalography (MEG), for determining Hemispheric Dominance for language functions. Methods. Magnetic activation profiles of the brain were obtained from 100 surgical candidates (age range 8‐56 years) with medically intractable seizure disorder by using a whole-head MEG system within the context of a word recognition task. The degree of language-specific activity was indexed according to the number of consecutive sources (modeled as single, moving current dipoles) in perisylvian brain areas. Only activity sources that were observed with a high degree of spatial and temporal overlap in two split-half data sets were used to compute the MEG laterality index. Independently, all patients underwent Wada testing for the determination of Hemispheric Dominance for language. Independent clinical judgments based on MEG and Wada data showed a high degree of concordance (87%). Magnetoencephalography laterality judgments had an overall sensitivity of 98%, but a lower selectivity of 83%, which was due to the fact that MEG detected more activity in the nondominant hemisphere than was predicted based on the Wada test. A number of objective criteria were derived based on this large patient series to ensure data quality and bolster the clinical usefulness of MEG for language mapping. Conclusions. Although the availability of MEG is still limited across epilepsy surgery centers, this study method may be substituted for the Wada procedure in assessing Hemispheric Dominance for language in select cases.
Wolfgang Sperling - One of the best experts on this subject based on the ideXlab platform.
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non right handedness and free serum testosterone levels in detoxified patients with alcohol dependence
Alcohol and Alcoholism, 2010Co-Authors: Wolfgang Sperling, Christian Maihöfner, Stefan Bleich, Rose Galvin, Teresa Biermann, Johannes Kornhuber, Udo ReulbachAbstract:Aims : The influence of testosterone on the extent of Hemispheric Dominance has been discussed not just during the first two trimesters of pregnancy but also later in life. An increase in free serum testosterone levels has been found during and after the detoxification phase of patients with alcohol dependence. Methods : In 250 participants (125 men and 125 women) with alcohol dependence immediately after the direct withdrawal phase (Day 21) and in 250 healthy age- and gender-matched participants, free testosterone in the serum was determined and handedness was assessed as a peripheral marker of central Hemispheric Dominance. Results : Patients with alcohol dependence were 2.7-fold (odds ratio, OR: 2.66; 95% confidence interval, CI: 1.62–4.38) and men 4.1-fold (OR: 4.12; 95% CI: 2.44–6.98) more likely to be non-right-handed (NRH). In addition to male gender, non-right-handedness and alcohol dependence contributed statistically significantly to higher serum testosterone levels. Testosterone values of patients with alcohol dependence differed significantly between the four different Lesch subtypes; in particular, participants with alcohol dependence classified according to Lesch subtype IV were found to have significantly higher serum testosterone levels ( F = 20.5; P < 0.001) when compared to participants classified according to Lesch subtypes I–III. Conclusions : An alteration of Hemispheric Dominance and thus an exogenously modifiable neuronal plasticity may be demonstrated directly on a population at risk.
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cognitive and behavioural aspects non right handedness and free serum testosterone levels in detoxified patients with alcohol dependence
2010Co-Authors: Wolfgang Sperling, Christian Maihöfner, Stefan Bleich, Rose Galvin, Teresa Biermann, Johannes Kornhuber, Udo ReulbachAbstract:Aims: The influence of testosterone on the extent of Hemispheric Dominance has been discussed not just during the first two trimesters of pregnancy but also later in life. An increase in free serum testosterone levels has been found during and after the detoxification phase of patients with alcohol dependence. Methods: In 250 participants (125 men and 125 women) with alcohol de- pendence immediately after the direct withdrawal phase (Day 21) and in 250 healthy age- and gender-matched participants, free testosterone in the serum was determined and handedness was assessed as a peripheral marker of central Hemispheric Dominance. Results: Patients with alcohol dependence were 2.7-fold (odds ratio, OR: 2.66; 95% confidence interval, CI: 1.62-4.38) and men 4.1-fold (OR: 4.12; 95% CI: 2.44-6.98) more likely to be non-right-handed (NRH). In addition to male gender, non-right-handedness and alcohol dependence contributed statistically significantly to higher serum testosterone levels. Testosterone values of patients with alcohol dependence differed significantly between the four different Lesch subtypes; in particular, participants with alcohol dependence classified according to Lesch subtype IV were found to have significantly higher serum testosterone levels (F = 20.5; P < 0.001) when compared to participants classified according to Lesch subtypes I-III. Conclusions: An alteration of Hemispheric Dominance and thus an exogenously modifiable neuronal plasticity may be demonstrated directly on a population at risk.
