115 resultados para Functional-cognitive approach
Resumo:
Training can change the functional and structural organization of the brain, and animal models demonstrate that the hippocampus formation is particularly susceptible to training-related neuroplasticity. In humans, however, direct evidence for functional plasticity of the adult hippocampus induced by training is still missing. Here, we used musicians' brains as a model to test for plastic capabilities of the adult human hippocampus. By using functional magnetic resonance imaging optimized for the investigation of auditory processing, we examined brain responses induced by temporal novelty in otherwise isochronous sound patterns in musicians and musical laypersons, since the hippocampus has been suggested previously to be crucially involved in various forms of novelty detection. In the first cross-sectional experiment, we identified enhanced neural responses to temporal novelty in the anterior left hippocampus of professional musicians, pointing to expertise-related differences in hippocampal processing. In the second experiment, we evaluated neural responses to acoustic temporal novelty in a longitudinal approach to disentangle training-related changes from predispositional factors. For this purpose, we examined an independent sample of music academy students before and after two semesters of intensive aural skills training. After this training period, hippocampal responses to temporal novelty in sounds were enhanced in musical students, and statistical interaction analysis of brain activity changes over time suggests training rather than predisposition effects. Thus, our results provide direct evidence for functional changes of the adult hippocampus in humans related to musical training.
Resumo:
We have developed a haptic-based approach for retraining of interjoint coordination following stroke called time-independent functional training (TIFT) and implemented this mode in the ARMin III robotic exoskeleton. The ARMin III robot was developed by Drs. Robert Riener and Tobias Nef at the Swiss Federal Institute of Technology Zurich (Eidgenossische Technische Hochschule Zurich, or ETH Zurich), in Zurich, Switzerland. In the TIFT mode, the robot maintains arm movements within the proper kinematic trajectory via haptic walls at each joint. These arm movements focus training of interjoint coordination with highly intuitive real-time feedback of performance; arm movements advance within the trajectory only if their movement coordination is correct. In initial testing, 37 nondisabled subjects received a single session of learning of a complex pattern. Subjects were randomized to TIFT or visual demonstration or moved along with the robot as it moved though the pattern (time-dependent [TD] training). We examined visual demonstration to separate the effects of action observation on motor learning from the effects of the two haptic guidance methods. During these training trials, TIFT subjects reduced error and interaction forces between the robot and arm, while TD subject performance did not change. All groups showed significant learning of the trajectory during unassisted recall trials, but we observed no difference in learning between groups, possibly because this learning task is dominated by vision. Further testing in stroke populations is warranted.
Resumo:
Currently, a variety of linear and nonlinear measures is in use to investigate spatiotemporal interrelation patterns of multivariate time series. Whereas the former are by definition insensitive to nonlinear effects, the latter detect both nonlinear and linear interrelation. In the present contribution we employ a uniform surrogate-based approach, which is capable of disentangling interrelations that significantly exceed random effects and interrelations that significantly exceed linear correlation. The bivariate version of the proposed framework is explored using a simple model allowing for separate tuning of coupling and nonlinearity of interrelation. To demonstrate applicability of the approach to multivariate real-world time series we investigate resting state functional magnetic resonance imaging (rsfMRI) data of two healthy subjects as well as intracranial electroencephalograms (iEEG) of two epilepsy patients with focal onset seizures. The main findings are that for our rsfMRI data interrelations can be described by linear cross-correlation. Rejection of the null hypothesis of linear iEEG interrelation occurs predominantly for epileptogenic tissue as well as during epileptic seizures.
Resumo:
Functional abdominal pain is an inhomogeneous group of disorders concerning aetiology and clinical presentation. Support for classification is provided by the ROME-Foundation with its criteria catalogue, ROME-III being the most recent one. However, basic approach consists of exclusion of somatic or psychiatric as well as psychosomatic disorders that are sharply defined and readily diagnosable. This article outlines a pragmatic gastroenterological approach by exemplary means of dyspepsia and irritable bowel syndrome. Dyspepsia includes a broad complex of mainly epigastric located symptoms, whereas irritable bowel syndrome is symptomatic with altered bowel habits and mid-abdominal pain in the majority. Gastreoenterologic therapy modalities are mainly based on empirical and symptomatic grounds, more than on precisely explaining pathophysioligic understanding.
Resumo:
Standardized recovery criteria go beyond symptom remission and put special emphasis on personal and social functioning in residence, work, and leisure. Against this background, evidence-based integrated approaches combining cognitive remediation with social skills therapy show promise for improving functional recovery of schizophrenia patients. Over the past 30 years, research groups in 12 countries have evaluated integrated psychological therapy (IPT) in 36 independent studies. IPT is a group therapy program for schizophrenia patients. It combines neurocognitive and social cognitive interventions with social skills and problem-solving approaches. The aim of the present study was to update and integrate the growing amount of research data on the effectiveness of IPT. We quantitatively reviewed the results of these 36 studies, including 1601 schizophrenia patients, by means of a meta-analytic procedure. Patients undergoing IPT showed significantly greater improvement in all outcome variables (neurocognition, social cognition, psychosocial functioning, and negative symptoms) than those in the control groups (placebo-attention conditions and standard care). IPT patients maintained their mean positive effects during an average follow-up period of 8.1 months. They showed better effects on distal outcome measures when all 5 subprograms were integrated. This analysis summarizes the broad empirical evidence indicating that IPT is an effective rehabilitation approach for schizophrenia patients and is robust across a wide range of sample characteristics as well as treatment conditions. Moreover, the cognitive and social subprograms of IPT may work in a synergistic manner, thereby enhancing the transfer of therapy effects over time and improving functional recovery.
Resumo:
Cognitive impairments are currently regarded as important determinants of functional domains and are promising treatment goals in schizophrenia. Nevertheless, the exact nature of the interdependent relationship between neurocognition and social cognition as well as the relative contribution of each of these factors to adequate functioning remains unclear. The purpose of this article is to systematically review the findings and methodology of studies that have investigated social cognition as a mediator variable between neurocognitive performance and functional outcome in schizophrenia. Moreover, we carried out a study to evaluate this mediation hypothesis by the means of structural equation modeling in a large sample of 148 schizophrenia patients. The review comprised 15 studies. All but one study provided evidence for the mediating role of social cognition both in cross-sectional and in longitudinal designs. Other variables like motivation and social competence additionally mediated the relationship between social cognition and functional outcome. The mean effect size of the indirect effect was 0.20. However, social cognitive domains were differentially effective mediators. On average, 25% of the variance in functional outcome could be explained in the mediation model. The results of our own statistical analysis are in line with these conclusions: Social cognition mediated a significant indirect relationship between neurocognition and functional outcome. These results suggest that research should focus on differential mediation pathways. Future studies should also consider the interaction with other prognostic factors, additional mediators, and moderators in order to increase the predictive power and to target those factors relevant for optimizing therapy effects.
Resumo:
Purpose of review: We aimed to review literature on the efficacy and tolerability of psychosocial and psychopharmacological interventions in youth with early-onset schizophrenia spectrum disorders (EOS). A rationale for pragmatic psychopharmacology in EOS, including dosing, switching and adverse effect monitoring and management, is provided. Recent findings: Three randomized controlled trials (RCTs) over the last 8 years demonstrated benefits of psychosocial interventions (i.e. psychoeducation, cognitive remediation, cognitive behavioural therapy) for EOS without clear advantages of one psychosocial treatment over another. Six large, placebo-controlled, short-term RCTs over the last 4 years demonstrated that aripiprazole, olanzapine, paliperidone, quetiapine and risperidone, but not ziprasidone, were superior to placebo. Except for clozapine's superiority in treatment-refractory EOS, efficacy appeared similar across studied first-generation and second-generation antipsychotics, but tolerability varied greatly across individual agents. Summary: Antipsychotics are efficacious in the treatment of EOS. Given the lack of efficacy differences between antipsychotics (except for clozapine for treatment-refractory EOS), we propose that tolerability considerations need to guide choice of antipsychotics. Further and longer-term efficacy and effectiveness studies are urgently needed that should also explore pharmacologic and nonpharmacologic augmentation strategies.
Resumo:
Deep brain stimulation (DBS) for Parkinson's disease often alleviates the motor symptoms, but causes cognitive and emotional side effects in a substantial number of cases. Identification of the motor part of the subthalamic nucleus (STN) as part of the presurgical workup could minimize these adverse effects. In this study, we assessed the STN's connectivity to motor, associative, and limbic brain areas, based on structural and functional connectivity analysis of volunteer data. For the structural connectivity, we used streamline counts derived from HARDI fiber tracking. The resulting tracks supported the existence of the so-called "hyperdirect" pathway in humans. Furthermore, we determined the connectivity of each STN voxel with the motor cortical areas. Functional connectivity was calculated based on functional MRI, as the correlation of the signal within a given brain voxel with the signal in the STN. Also, the signal per STN voxel was explained in terms of the correlation with motor or limbic brain seed ROI areas. Both right and left STN ROIs appeared to be structurally and functionally connected to brain areas that are part of the motor, associative, and limbic circuit. Furthermore, this study enabled us to assess the level of segregation of the STN motor part, which is relevant for the planning of STN DBS procedures.
Resumo:
Based on the exponential aging of the population and the increasing life expectancy in industrialized western countries, prostate cancer (PCa) in elderly men is becoming a disease of increasing significance. Consensus exists that men over the age of 75 years should not be screened for PCa; however, higher age as a single parameter should not exclude men from being diagnosed with prostate cancer and treated accordingly. It is well-known that overdiagnosis and overtreatment are frequent in this age group. Competing mortality risks of men older than 75 years may supersede the risk of dying from PCa several fold. Both the treating physician and the patient himself should therefore balance the possible risks and benefits of diagnosing and treating prostate cancer concerning the impact on quality of life. This is of special importance when taking into account that the complication rates of curative treatment modalities are higher in older patients than in younger men and that hormonal treatment might have negative effects especially in older men.Age, existing comorbidities, cognitive and physical status in combination with specific tumor parameters are useful tools for an individualized treatment.Therapy should be considered for healthy, active men aged 75 years or older who present with high-risk PCa and/or with a PSA doubling time <12 months. Elderly men who are unfit or have low to intermediate risk PCa will most likely not benefit from treatment.
Resumo:
The deterioration of performance over time is characteristic for sustained attention tasks. This so-called "performance decrement" is measured by the increase of reaction time (RT) over time. Some behavioural and neurobiological mechanisms of this phenomenon are not yet fully understood. Behaviourally, we examined the increase of RT over time and the inter-individual differences of this performance decrement. On the neurophysiological level, we investigated the task-relevant brain areas where neural activity was modulated by RT and searched for brain areas involved in good performance (i.e. participants with no or moderate performance decrement) as compared to poor performance (i.e. participants with a steep performance decrement). For this purpose, 20 healthy, young subjects performed a carefully designed task for simple sustained attention, namely a low-demanding version of the Rapid Visual Information Processing task. We employed a rapid event-related functional magnetic resonance imaging (fMRI) design. The behavioural results showed a significant increase of RT over time in the whole group, and also revealed that some participants were not as prone to the performance decrement as others. The latter was statistically significant comparing good versus poor performers. Moreover, high BOLD-responses were linked to longer RTs in a task-relevant bilateral fronto-cingulate-insular-parietal network. Among these regions, good performance was associated with significantly higher RT-BOLD correlations in the pre-supplementary motor area (pre-SMA). We concluded that the task-relevant bilateral fronto-cingulate-insular-parietal network was a cognitive control network responsible for goal-directed attention. The pre-SMA in particular might be associated with the performance decrement insofar that good performers could sustain activity in this brain region in order to monitor performance declines and adjust behavioural output.
A clinical approach to arterial ischemic childhood stroke: increasing knowledge over the last decade
Resumo:
Childhood stroke is increasingly being recognized as an important burden not only for affected children and families, but also for socioeconomic reasons. A primary problem is delayed diagnosis, due to the many mimics of childhood stroke, and the variety of manifesting symptoms. The most important is hemiparesis (with/without dysphasia or facial palsy), but ataxia, seizures, and many more are also possible. Suspicion of stroke has to be ascertained by neuroimaging, gold standard being (diffusion weighted) magnetic resonance. Risk factors are multiple, but their presence might help to increase the suspicion of stroke. The most important factors are infectious/parainfectious etiologies, frequently possibly manifesting by transient focal cerebral arteriopathy (FCA). Cardiological underlying problems are the second most important. Arteriopathies can be detected in about half of the children, besides FCA and dissection and MoyaMoya disease are the most important. Hereditary coagulopathies increase the risk of stroke. There is still a controversy on best treatment in children: platelet antiaggregation and heparinization are used about equally. Thrombolysis is being discussed increasingly. Severity of symptoms at manifestation and on follow-up are not less significant in children than in young adults. About two-third of the children have significant residual neurological problems and a majority cognitive and behavior problems.
Resumo:
OBJECTIVE: To describe the advantages and surgical technique of a trochanteric flip osteotomy in combination with a Kocher-Langenbeck approach for the treatment of selected acetabular fractures. DESIGN: Consecutive series, teaching hospital. METHODS: Through mobilization of the vastus lateralis muscle, a slice of the greater trochanter with the attached gluteus medius muscle can be flipped anteriorly. The gluteus minimus muscle can then be easily mobilized, giving free access to the posterosuperior and superior acetabular wall area. Damage to the abductor muscles by vigorous retraction can be avoided, potentially resulting in less ectopic ossification. Ten consecutive cases of acetabular fractures treated with this approach are reported. In eight cases, an anatomic reduction was achieved; in the remaining two cases with severe comminution, the reduction was within one to three millimeters. The trochanteric fragment was fixed with two 3.5-millimeter cortical screws. RESULTS: All osteotomies healed in anatomic position within six to eight weeks postoperatively. Abductor strength was symmetric in eight patients and mildly reduced in two patients. Heterotopic ossification was limited to Brooker classes 1 and 2 without functional impairment at an average follow-up of twenty months. No femoral head necrosis was observed. CONCLUSION: This technique allows better visualization, more accurate reduction, and easier fixation of cranial acetabular fragments. Cranial migration of the greater trochanter after fixation with two screws is unlikely to occur because of the distal pull of the vastus lateralis muscle, balancing the cranial pull of the gluteus medius muscle.
Resumo:
This article provides a selective overview of the functional neuroimaging literature with an emphasis on emotional activation processes. Emotions are fast and flexible response systems that provide basic tendencies for adaptive action. From the range of involved component functions, we first discuss selected automatic mechanisms that control basic adaptational changes. Second, we illustrate how neuroimaging work has contributed to the mapping of the network components associated with basic emotion families (fear, anger, disgust, happiness), and secondary dimensional concepts that organise the meaning space for subjective experience and verbal labels (emotional valence, activity/intensity, approach/withdrawal, etc.). Third, results and methodological difficulties are discussed in view of own neuroimaging experiments that investigated the component functions involved in emotional learning. The amygdala, prefrontal cortex, and striatum form a network of reciprocal connections that show topographically distinct patterns of activity as a correlate of up and down regulation processes during an emotional episode. Emotional modulations of other brain systems have attracted recent research interests. Emotional neuroimaging calls for more representative designs that highlight the modulatory influences of regulation strategies and socio-cultural factors responsible for inhibitory control and extinction. We conclude by emphasising the relevance of the temporal process dynamics of emotional activations that may provide improved prediction of individual differences in emotionality.
Resumo:
Searching for the neural correlates of visuospatial processing using functional magnetic resonance imaging (fMRI) is usually done in an event-related framework of cognitive subtraction, applying a paradigm comprising visuospatial cognitive components and a corresponding control task. Besides methodological caveats of the cognitive subtraction approach, the standard general linear model with fixed hemodynamic response predictors bears the risk of being underspecified. It does not take into account the variability of the blood oxygen level-dependent signal response due to variable task demand and performance on the level of each single trial. This underspecification may result in reduced sensitivity regarding the identification of task-related brain regions. In a rapid event-related fMRI study, we used an extended general linear model including single-trial reaction-time-dependent hemodynamic response predictors for the analysis of an angle discrimination task. In addition to the already known regions in superior and inferior parietal lobule, mapping the reaction-time-dependent hemodynamic response predictor revealed a more specific network including task demand-dependent regions not being detectable using the cognitive subtraction method, such as bilateral caudate nucleus and insula, right inferior frontal gyrus and left precentral gyrus.
Resumo:
During development of the vertebrate vascular system essential signals are transduced via protein-tyrosine phosphorylation. Null-mutations of receptor-tyrosine kinase (RTK) genes expressed in endothelial cells (ECs) display early lethal vascular phenotypes. We aimed to identify endothelial protein-tyrosine phosphatases (PTPs), which should have similar importance in EC-biology. A murine receptor-type PTP was identified by a degenerated PCR cloning approach from endothelial cells (VE-PTP). By in situ hybridization this phosphatase was found to be specifically expressed in vascular ECs throughout mouse development. In experiments using GST-fusion proteins, as well as in transient transfections, trapping mutants of VE-PTP co-precipitated with the Angiopoietin receptor Tie-2, but not with the Vascular Endothelial Growth Factor receptor 2 (VEGFR-2/Flk-1). In addition, VE-PTP dephosphorylates Tie-2 but not VEGFR-2. We conclude that VE-PTP is a Tie-2 specific phosphatase expressed in ECs, and VE-PTP phosphatase activity serves to specifically modulate Angiopoietin/Tie-2 function. Based on its potential role as a regulator of blood vessel morphogenesis and maintainance, VE-PTP is a candidate gene for inherited vascular malformations similar to the Tie-2 gene.