Impaired performance on the Wisconsin Card Sorting Test under left- when compared to right-sided deep brain stimulation of the subthalamic nucleus in patients with Parkinson's disease.

Over the past decade, deep brain stimulation (DBS) has become an effective treatment option for managing severe Parkinson's disease (PD). However, evidence is accumulating that DBS of target sites like the subthalamic nucleus (STN) can result in unintended cognitive effects that lie beyond motor control. The aim of the present study was to evaluate whether changes in executive task performance after chronic DBS might be predominantly associated with the stimulation of only one hemisphere.

Altered tonic and phasic cortisol secretion following unilateral stroke.

Evidence is accumulating that cerebral laterality appears to be an important feature in the regulation of the stress response with the right hemisphere being closely linked to stress-regulatory systems, including the hypothalamic-pituitary-adrenal (HPA) axis. Although some animal and human data support this hypothesis, studies on brain damaged patients yet failed to substantiate laterality effects on cortisol secretion. The aim of this study was to examine whether unilateral stroke differentially affects tonic and phasic response characteristics of the HPA axis, and to evaluate the impact of intrahemispheric lesion location.

Effects of anterior cingulate fissurization on cognitive control during stroop interference.

The midcingulate cortex, as part of the more anteriorly located cingulate regions, is thought to play a major role in cognitive processes like conflict monitoring or response selection. Regarding midcingulate fissurization, the occurrence of a second or paracingulate sulcus is more common in the left than in the right hemisphere and has been shown to be associated with an advantageous performance on tests of executive functions. However, the cognitive mechanisms underlying such behavioral differences are completely unknown.

Hemispheric and gender related differences in the midcingulum bundle: a DTI study.

The midcingulate cortex and therefore the underlying midcingulum bundle (MCB) as well play a major role in attention. Although a specific structure's function does strongly depend on its neuroanatomical characteristics, research assessing the morphological variability of the midcingulate region is rather sparse. The present study examined the micro- and macrostructure of the MCB in both hemispheres by means of diffusion-tensor imaging.

Corticospinal tract asymmetries at the level of the internal capsule: is there an association with handedness?

The functional integrity of the corticospinal tract (CST) is of crucial importance for fine and independent finger movement. Therefore, it has been frequently speculated that interhemispheric asymmetries in this tract might be associated with handedness. The objective of the present study was to examine this proposed relationship, by studying the effects of handedness on macro- and microstructural properties of the CST.

Morphologic asymmetry of the human anterior cingulate cortex.

The anterior cingulate cortex (ACC) is thought to play a major role in executive processes. Studies assessing neuroanatomical attributes of this region report a high degree of morphological variability. Recent theories consider the fissurization of the cortex to be a product of gross mechanical processes related to cortical growth and local cytoarchitectural characteristics.

Interhemispheric transfer time and structural properties of the corpus callosum.

The present study examined how interhemispheric transfer time (IHTT) is affected by interindividual differences in corpus callosum (CC) architecture. For this purpose the CC of 42 healthy male subjects was assessed by applying a combination of morphological and diffusion-tensor magnetic resonance imaging to characterize the CC on macro- (midsagittal area) and microstructural level (mean diffusion, fractional anisotropy). Following the so-called Poffenberger paradigm, IHTT was determined with both reaction time measures and event-related potentials recorded in response to stimuli briefly presented to either left or right visual hemifield.

The role of the corpus callosum in dichotic listening: a combined morphological and diffusion tensor imaging study.

The objective of the present study was to examine the role of the corpus callosum (CC) in dichotic listening. For this purpose, 40 right-handed healthy male participants were assessed with morphological and diffusion tensor imaging, which yielded macrostructural (midsagittal area) and microstructural (mean diffusion, fractional anisotropy) measures of the total CC and predefined subregions. Applying the standard consonant-vowel Bergen Dichotic Listening Test (including 3 different attentional instructions), the authors found dichotic listening performance to be substantially related to the integrity of the CC at both macro- and microstructural levels.

The association of macro- and microstructure of the corpus callosum and language lateralisation.

The present study aimed to examine how differences in functional lateralisation of language are related to interindividual variations in interhemispheric connectivity. Utilising an fMRI silent word-generation paradigm, 89 left- and right-handed subjects were subdivided into four lateralisation subgroups. Applying morphological and diffusion-tensor MRI, midsagittal cross-sectional area as well as quantitative measures of molecular diffusion (anisotropy, mean diffusion) of the corpus callosum were determined to assess interhemispheric connectivity.

Handedness, dichotic-listening ear advantage, and gender effects on planum temporale asymmetry--a volumetric investigation using structural magnetic resonance imaging.

Previous research has often examined whether the asymmetrical structure of the planum temporale (PT) represents an anatomical correlate of lateralized language-processing functions, gathering diverging empirical evidence by comparing PT asymmetry in subjects with differing handedness, gender, or speech lateralization. Apart from other methodological problems, direct comparisons between studies are hampered by insufficient assessment and consideration of all three potential determinants of structural cerebral asymmetry. Based on volumetric assessment of structural Magnetic Resonance Imaging (MRI) scans of 104 healthy subjects, the present study replicated earlier observations of an overall leftward PT asymmetry, which was found to prevail irrespective of handedness, gender, or dichotic-listening ear advantage.

Effects of handedness and gender on macro- and microstructure of the corpus callosum and its subregions: a combined high-resolution and diffusion-tensor MRI study.

The corpus callosum (CC) represents the major commissural tract connecting the two cerebral hemispheres and is supposed to play crucial integrative role in functional hemispheric specialization. The present study examined whether interindividual variations in macro- and microstructure of the human CC are associated with handedness and gender. Therefore, a combined diffusion-tensor (DTI) and high-resolution morphological MRI study was performed on 34 right- and 33 left-handed subjects of both sexes.

The influence of handedness and gender on the microstructure of the human corpus callosum: a diffusion-tensor magnetic resonance imaging study.

The aim of the present study was to examine whether handedness and gender are associated with microstructural differences in human corpus callosum (CC). For this purpose, diffusion-tensor magnetic resonance imaging (DTI) was performed on 34 right- and 33 left-handed subjects of both sexes. Four quantitative variables (Mean Diffusion, Relative Anisotropy, parallel and orthogonal diffusion) were computed within the CC.