Limb-kinetic apraxia affects activities of daily living in Parkinson's disease: a multi-center study.

BACKGROUND AND PURPOSE: Impaired dexterity (fine hand movements) is often present in Parkinson's disease (PD), even at early to moderate disease stages. It has a detrimental impact on activities of daily living (ADL) such as buttoning, contributing to reduced quality of life. Limb-kinetic apraxia, a loss of the ability to make precise, independent but coordinated finger and hand movements, may contribute to impaired dexterity even more than bradykinesia per se. However, the impact of limb-kinetic apraxia on ADL remains controversial. Our aim was to identify the strongest predictor of buttoning and unbuttoning in PD. It was hypothesized that coin rotation (a surrogate of limb-kinetic apraxia) represents the most important determinant. METHODS: Sixty-four right-handed, early to moderate PD patients were recruited from three movement disorder centers (Hoehn andYahr stages 1-3). Buttoning, unbuttoning and coin rotation (right and left hand) represented the target tasks. Motor impairment was assessed according to the Unified Parkinson's Disease Rating Scale. RESULTS: Multiple linear regression analysis showed that coin rotation with the right hand was the only significant predictor of buttoning (P < 0.001) and unbuttoning (P = 0.002). Notably, measures of bradykinesia or overall motor impairment did not represent significant predictors. CONCLUSIONS: Constituting the novel key finding, limb-kinetic apraxia seems to be particularly relevant for ADL requiring dexterity skills in PD, even at early to moderate disease stages. Our results prompt research into the pathophysiological background and therapeutic options to treat limb-kinetic apraxia. The simple coin rotation test provides valuable information about ADL-related dexterity skills.

Fractal image perception provides novel insights into hierarchical cognition.

Hierarchical structures play a central role in many aspects of human cognition, prominently including both language and music. In this study we addressed hierarchy in the visual domain, using a novel paradigm based on fractal images. Fractals are self-similar patterns generated by repeating the same simple rule at multiple hierarchical levels. Our hypothesis was that the brain uses different resources for processing hierarchies depending on whether it applies a "fractal" or a "non-fractal" cognitive strategy. We analyzed the neural circuits activated by these complex hierarchical patterns in an event-related fMRI study of 40 healthy subjects. Brain activation was compared across three different tasks: a similarity task, and two hierarchical tasks in which subjects were asked to recognize the repetition of a rule operating transformations either within an existing hierarchical level, or generating new hierarchical levels. Similar hierarchical images were generated by both rules and target images were identical. We found that when processing visual hierarchies, engagement in both hierarchical tasks activated the visual dorsal stream (occipito-parietal cortex, intraparietal sulcus and dorsolateral prefrontal cortex). In addition, the level-generating task specifically activated circuits related to the integration of spatial and categorical information, and with the integration of items in contexts (posterior cingulate cortex, retrosplenial cortex, and medial, ventral and anterior regions of temporal cortex). These findings provide interesting new clues about the cognitive mechanisms involved in the generation of new hierarchical levels as required for fractals.

Differential functional benefits of ultra highfield MR systems within the language network.

Several investigations have shown limitations of fMRI reliability with the current standard field strengths. Improvement is expected from ultra highfield systems but studies on possible benefits for cognitive networks are lacking. Here we provide an initial investigation on a prominent and clinically highly-relevant cognitive function: language processing in individual brains. 26 patients evaluated for presurgical language localization were investigated with a standardized overt language fMRI paradigm on both 3T and 7T MR scanners. During data acquisition and analysis we made particular efforts to minimize effects not related to static magnetic field strength differences. Six measures relevant for functional activation showed a large dissociation between essential language network nodes: although in Wernicke's area 5/6 measures indicated a benefit of ultra highfield, in Broca's area no comparison was significant. The most important reason for this discrepancy was identified as being an increase in susceptibility-related artifacts in inferior frontal brain areas at ultra high field. We conclude that functional UHF benefits are evident, however these depend crucially on the brain region investigated and the ability to control local artifacts.

Model-free fMRI group analysis using FENICA.

Exploratory analysis of functional MRI data allows activation to be detected even if the time course differs from that which is expected. Independent Component Analysis (ICA) has emerged as a powerful approach, but current extensions to the analysis of group studies suffer from a number of drawbacks: they can be computationally demanding, results are dominated by technical and motion artefacts, and some methods require that time courses be the same for all subjects or that templates be defined to identify common components. We have developed a group ICA (gICA) method which is based on single-subject ICA decompositions and the assumption that the spatial distribution of signal changes in components which reflect activation is similar between subjects. This approach, which we have called Fully Exploratory Network Independent Component Analysis (FENICA), identifies group activation in two stages. ICA is performed on the single-subject level, then consistent components are identified via spatial correlation. Group activation maps are generated in a second-level GLM analysis. FENICA is applied to data from three studies employing a wide range of stimulus and presentation designs. These are an event-related motor task, a block-design cognition task and an event-related chemosensory experiment. In all cases, the group maps identified by FENICA as being the most consistent over subjects correspond to task activation. There is good agreement between FENICA results and regions identified in prior GLM-based studies. In the chemosensory task, additional regions are identified by FENICA and temporal concatenation ICA that we show is related to the stimulus, but exhibit a delayed response. FENICA is a fully exploratory method that allows activation to be identified without assumptions about temporal evolution, and isolates activation from other sources of signal fluctuation in fMRI. It has the advantage over other gICA methods that it is computationally undemanding, spotlights components relating to activation rather than artefacts, allows the use of familiar statistical thresholding through deployment of a higher level GLM analysis and can be applied to studies where the paradigm is different for all subjects.

[Functional magnetic resonance imaging with ultra-high fields]. / Funktionelle Magnetresonanztomographie bei ultrahohen Feldern.

Functional magnetic resonance imaging (fMRI) is currently the primary method for non-invasive functional localization in the brain. With the emergence of MR systems with field strengths of 4 Tesla and above, neuronal activation may be studied with unprecedented accuracy. In this article we present different approaches to use the improved sensitivity and specificity for expanding current fMRT resolution limits in space and time based on several 7 Tesla studies. In addition to the challenges that arise with ultra-high magnetic fields possible solutions will be discussed.

Olfactory training induces changes in regional functional connectivity in patients with long-term smell loss.

Recently, olfactory training has been introduced as a promising treatment for patients with olfactory dysfunction. However, less is known about the neuronal basis and the influence on functional networks of this training. Thus, we aimed to investigate the neuroplasticity of chemosensory perception through an olfactory training program in patients with smell loss. The experimental setup included functional MRI (fMRI) experiments with three different types of chemosensory stimuli. Ten anosmic patients (7f, 3m) and 14 healthy controls (7f, 7m) underwent the same testing sessions. After a 12-week olfactory training period, seven patients (4f, 3m) were invited for follow-up testing using the same fMRI protocol. Functional networks were identified using independent component analysis and were further examined in detail using functional connectivity analysis. We found that anosmic patients and healthy controls initially use the same three networks to process chemosensory input: the olfactory; the somatosensory; and the integrative network. Those networks did not differ between the two groups in their spatial extent, but in their functional connectivity. After the olfactory training, the sensitivity to detect odors significantly increased in the anosmic group, which was also manifested in modifications of functional connections in all three investigated networks. The results of this study indicate that an olfactory training program can reorganize functional networks, although, initially, no differences in the spatial distribution of neural activation were observed.

A systematic investigation of the invariance of resting-state network patterns: is resting-state fMRI ready for pre-surgical planning?

OBJECTIVES: Measurements of resting-state networks (RSNs) have been used to investigate a wide range of diseases, such as dementia or epilepsy. This raises the question whether this method could also serve as a pre-surgical planning tool. Generating reliable functional connectivity patterns is of crucial importance, particularly for pre-surgical planning, as these patterns may directly affect the outcome. METHODS: This study investigated the reproducibility of four commonly used resting-state conditions: fixation of a black crosshair on a white screen; fixation of the center of a black screen; eyes-closed and fixation of the words "Entspann dich!" (Engl., "relax"). Ten healthy, right-handed male subjects (mean age, 25 years; SD 2) participated in the experiment. The spatial overlap for different RSNs across the four conditions was calculated. RESULTS: The spatial overlap across all four conditions was calculated for each seed region on a single subject and at the group level. Activation maps at the single-subject and group levels were highly stable, especially for the reading network (RNW). The lowest consistency measures were found for the visual network (VIN). At the single-subject level spatial overlap values ranged from 0.31 (VIN) to 0.45 (RNW). CONCLUSION: These findings suggest that RSN measurements are a reliable tool to assess language-related networks in clinical settings. Generally, resting-state conditions showed comparable activation patterns, therefore no specific conditions appears to be preferable.

The benefits of skull stripping in the normalization of clinical fMRI data.

Establishing a reliable correspondence between lesioned brains and a template is challenging using current normalization techniques. The optimum procedure has not been conclusively established, and a critical dichotomy is whether to use input data sets which contain skull signal, or whether skull signal should be removed. Here we provide a first investigation into whether clinical fMRI benefits from skull stripping, based on data from a presurgical language localization task. Brain activation changes related to deskulled/not-deskulled input data are determined in the context of very recently developed (New Segment, Unified Segmentation) and standard normalization approaches. Analysis of structural and functional data demonstrates that skull stripping improves language localization in MNI space - particularly when used in combination with the New Segment normalization technique.

Facial aesthetics and the assignment of personality traits before and after orthognathic surgery.

Processing and interpreting the face is generally very important because one is often required to make rapid decisions in life on the basis of meagre information. Ninety-two volunteers used a computer-assisted test battery to assess 40 profiles of patients (8 skeletal Class II and 8 skeletal Class III patients, each pre- and postoperatively, with 8 skeletal Class I photographs serving as controls). On a 7-point Likert scale the raters were asked to evaluate aesthetics and a few relevant personality traits (e.g. unintelligent, inhibited, aggressive, brutal). The photographs of the two patient groups were rated significantly less attractive and intelligent prior to surgery than the photographs of the control group. In respect of personality traits, the photographs of the skeletal Class III group differed more strongly from normal ones. In respect of aesthetics and intelligence, both patient groups benefited markedly from surgery. For some personality traits, significant interactions were found between the two groups on pre-post comparison. The method underlying the study is useful for evaluating the outcome of orthognathic surgery, but also indicates the strongly generalized and unconscious processes involved in the estimation of people's personality traits, especially when these concern deviations from the socially normal condition.

Fully exploratory network ICA (FENICA) on resting-state fMRI data.

Independent component analysis (ICA) is one of the most valuable explorative methods for analyzing resting-state networks (RSNs) in fMRI, representing a data-driven approach that enables decomposition of high-dimensional data into discrete components. Extensions to a group-level suffer from the drawback of evaluating single-subject resting-state components of interest either using a predefined spatial template or via visual inspection. FENICA introduced in the context of group ICA methods is based solely on spatially consistency across subjects directly reflecting similar networks. Therefore, group data can be processed without further visual inspection of the single-subject components or the definition of a template (Schöpf et al., 2009). In this study FENICA was applied to fMRI resting-state data from 28 healthy subjects resulting in eight group RSNs. These RSNs resemble the spatial patterns of the following previously described networks: (1) visual network, (2) default mode network, (3) sensorimotor network, (4) dorsolateral prefrontal network, (5) temporal prefrontal network, (6) basal ganglia network, (7) auditory processing network, and (8) working memory network. This novel analysis approach for identifying spatially consistent networks across a group of subjects does not require manual or template-based selection of single-subject components and, therefore, offers a truly explorative procedure of assessing RSNs.

Long-term results of unstable pelvic ring fractures in children.

Seventeen patients less than 12 years old sustained unstable pelvic ring fractures and were treated non-operatively. They were followed for 2 to 25 years. The subjective long-term results depended on the presence or absence of low back pain. This correlated strongly with pelvic asymmetry. Five patients complained about chronic back pain, two were functionally impaired by severe pelvic asymmetry. Healing of an unstable pelvic fracture in malposition with asymmetry causes poor results and must be prevented.

[2 years results of conservative therapy of unstable fractures of the pelvic ring in children]. / 2-Jahres-Ergebnisse der konservativen Therapie instabiler Beckenringfrakturen bei Kindern.

Unstable fractures of the pelvic ring in children are usually treated conservatively. The results of this therapy were evaluated retrospectively in 17 children who had been under 13 years old at the time of injury. All but 4 of the children had additional injuries. The pelvic fracture had a rotational instability in 9 patients and was vertically unstable in 8 patients. The follow-up period was 2-25 years. Clinical results were good provided that there was a good radiological result with only minimal asymmetry of the pelvic ring or none at all. Functional leg length differences and scoliotic deformation of the lumbar spine due to traumatic and/or growth-related asymmetry of the pelvis caused chronic low back pain in 5 of 8 patients. Only fracture healing in a near-anatomical position can ensure good clinical results in pelvic fractures in children. Considering the results presented here, operative reduction has to be recommended when reduction cannot be achieved by conservative means. However, there is no proof that open reduction and internal fixation provide better results than conservative therapy in unstable pelvic ring fractures in children.