Abstract: In the present multi-modal study we aimed to investigate the role of visual exploration in relation to the neuronal activity and performance during visuospatial processing. To this end, event related functional magnetic resonance imaging er-fMRI was combined with simultaneous eye tracking recording and transcranial magnetic stimulation (TMS). Two groups of twenty healthy subjects each performed an angle discrimination task with different levels of difficulty during er-fMRI. The number of fixations as a measure of visual exploration effort was chosen to predict blood oxygen level-dependent (BOLD) signal changes using the general linear model (GLM). Without TMS, a positive linear relationship between the visual exploration effort and the BOLD signal was found in a bilateral fronto-parietal cortical network, indicating that these regions reflect the increased number of fixations and the higher brain activity due to higher task demands. Furthermore, the relationship found between the number of fixations and the performance demonstrates the relevance of visual exploration for visuospatial task solving. In the TMS group, offline theta bursts TMS (TBS) was applied over the right posterior parietal cortex (PPC) before the fMRI experiment started. Compared to controls, TBS led to a reduced correlation between visual exploration and BOLD signal change in regions of the fronto-parietal network of the right hemisphere, indicating a disruption of the network. In contrast, an increased correlation was found in regions of the left hemisphere, suggesting an intent to compensate functionality of the disturbed areas. TBS led to fewer fixations and faster response time while keeping accuracy at the same level, indicating that subjects explored more than actually needed.
Abstract: Background: Visual hallucinations (VH) are a common experience and can be distressing and disabling, particularly for people suffering from psychotic illness. However, not everyone with visual hallucinations reports the experience to be distressing. Models of VH propose that appraisals of VH as a threat to wellbeing and the use of safety seeking behaviours help maintain the distress. Aims: This study investigated whether people with distressing VH report threat appraisals and use safety behaviours. Method: The study utilized a single group descriptive design, in which 15 participants with psychosis and VH were asked questions in order to assess the content, distress, appraisals, and behaviours associated with visual hallucinations. Results: People who found visual hallucinations distressing (n = 13) held negative appraisals about those hallucinations and specifically saw them as a threat to their physical or psychological wellbeing. They also engaged in safety seeking behaviours that were logically related to the appraisal and served to maintain the distress. Conclusions: People with distressing VH regard them as a threat to their wellbeing and use safety seeking behaviours as a result of this perceived threat. These key processes are potential targets for treatments that will alleviate the distress associated with VH.
Abstract: Memory Clinics provide evidence based diagnosis and treatment of dementia. Whenever a diagnosis of dementia is made, it is important to inform the patients about the possible impact of dementia on driving. Patients and their next of kin require competent advice whenever this difficult question is addressed and the mobility desire and the risks related to driving need to be carefully weight up. The time of diagnosis does not necessarily equate to the time when a person with dementia becomes an unsafe driver. The cause and severity of dementia, comorbidities and the current medication need to be carefully taken into account for this decision. On behalf of the association of the Swiss Memory Clinics, a group of experts has developed recommendations to assess fitness to drive in cognitively impaired older adults.
Abstract: INTRODUCTION: Gestures are important for nonverbal communication and were shown to be impaired in schizophrenia. Two categories of gestures can be differentiated: pantomime on verbal command and imitation of seen gestures. There is evidence that the neural basis of these domains may be distinct, pantomime being critically dependent on prefrontal cortex function. The aim of the study was to investigate gestural deficits in schizophrenia and their association with frontal lobe function and motor performance. METHODS: In 30 schizophrenia patients, gesture performance was assessed by the comprehensive Test of Upper Limb Apraxia (TULIA) using previously determined cut-off scores. The ratings of videotaped gesture performance were blinded. In addition, a battery of rating scales on frontal lobe function, parkinsonism, dyskinesia, catatonia and instrumental measures of gross and fine motor performance were assessed. RESULTS: Pantomime deficits were found in 40% and imitation deficits in 23% of the patients. Patients with gestural deficits had poorer frontal cortex function, more catatonic symptoms, and more severe psychopathology. Furthermore, trends indicated an association with a more chronic course of the illness. Pantomime was linked to frontal lobe function whereas imitation was associated with catatonic symptoms and gross motor performance. CONCLUSIONS: Pantomime is frequently impaired in chronic schizophrenia and may critically depend on motor planning, reflecting a further example of brain disconnectivity in schizophrenia.
Abstract: Kamm CP, Heldner MR, Vanbellingen T, Mattle HP, Müri R, Bohlhalter S. Limb apraxia in multiple sclerosis: prevalence and impact on manual dexterity and activities of daily living. OBJECTIVE: To evaluate the prevalence and impact of limb apraxia on manual dexterity and activities of daily living (ADLs) in patients with multiple sclerosis (MS). DESIGN: Survey. SETTING: University hospital. PARTICIPANTS: Consecutive patients (N=76) with clinically isolated syndrome, relapsing-remitting multiple sclerosis (RRMS), secondary progressive multiple sclerosis (SPMS) or primary progressive multiple sclerosis (PPMS), Expanded Disability Status Scale (EDSS) score from 0 to 6.5, and aged from 18 to 70 years were included. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Apraxia was assessed by the apraxia screen of TULIA (AST). The relationship of apraxia with ADLs and manual dexterity was evaluated using a dexterity questionnaire and the coin rotation task, respectively. RESULTS: Overall, limb apraxia was found in 26.3% of patients (mean AST score ± SD, 7.3±1.3; cutoff <9). Apraxia was significantly correlated with higher EDSS scores, longer disease duration, and higher age with the EDSS being predictive. Furthermore, patients with SPMS and PPMS were more apraxic than patients with RRMS. Finally, limb apraxia was significantly associated with impaired ADLs and manual dexterity. CONCLUSIONS: Limb apraxia is a frequent and clinically significant symptom contributing to disability in MS. It should therefore be evaluated and possibly treated, particularly in patients with MS reporting manual difficulties in everyday life.
Abstract: BACKGROUND: Valid assessment of apraxia in usually non-apraxic Parkinson's disease helps to delineate atypical parkinsonism frequently associated with apraxia. Furthermore, in a subgroup of late Parkinson's disease apraxia, typically the ideomotor subtype, may gradually superimpose onto parkinsonian motor symptoms contributing to defective manual skill. Here we evaluate the utility of a brief, standardized test, the apraxia screen of TULIA (AST). METHODS: Seventy five Parkinson's disease patients were tested with the AST. Parkinsonian motor deficits were measured using Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III and difficulties in activities of daily living (ADL) by modified MDS-UPDRS part II (eating, dressing, personal hygiene, and writing). RESULTS: No association was found between the AST and MDS-UPDRS part III, indicating that AST discriminates well (discriminative validity) between apraxia and parkinsonism. Furthermore, AST was associated with ADL and Hoehn & Yahr stage (convergent validity). CONCLUSIONS: AST is a short and valid test to rule out or detect apraxia in Parkinson's disease.
Abstract: Apraxia in patients with stroke may be overlooked, as clumsiness and deficient gestural communication are often attributed to frequently coexisting sensorimotor deficits and aphasia. Early and reliable detection of apraxia by a bedside test is relevant for functional outcome in patients with stroke. The present study was aimed at constructing a new bedside screening test for apraxia, called the Apraxia Screen of TULIA (AST), based on the comprehensive standardised Test for Upper-Limb Apraxia (TULIA).
Abstract: The traditional view of a predominant inferior parietal representation of gestures has been recently challenged by neuroimaging studies demonstrating that gesture production and discrimination may critically depend on inferior frontal lobe function. The aim of the present work was therefore to investigate the effect of transient disruption of these brain sites by continuous theta burst stimulation (cTBS) on gesture production and recognition.
Abstract: Visual symptoms are common in PD and PD dementia and include difficulty reading, double vision, illusions, feelings of presence and passage, and complex visual hallucinations. Despite the established prognostic implications of complex visual hallucinations, the interaction between cognitive decline, visual impairment, and other visual symptoms remains poorly understood. Our aim was to characterize the spectrum of visual symptomatology in PD and examine clinical predictors for their occurrence. Sixty-four subjects with PD, 26 with PD dementia, and 32 age-matched controls were assessed for visual symptoms, cognitive impairment, and ocular pathology. Complex visual hallucinations were common in PD (17%) and PD dementia (89%). Dementia subjects reported illusions (65%) and presence (62%) more frequently than PD or control subjects, but the frequency of passage hallucinations in PD and PD dementia groups was equivalent (48% versus 69%, respectively; P = 0.102). Visual acuity and contrast sensitivity was impaired in parkinsonian subjects, with disease severity and age emerging as the key predictors. Regression analysis identified a variety of factors independently predictive of complex visual hallucinations (e.g., dementia, visual acuity, and depression), illusions (e.g., excessive daytime somnolence and disease severity), and presence (e.g., rapid eye movement sleep behavior disorder and excessive daytime somnolence). Our results demonstrate that different "hallucinatory" experiences in PD do not necessarily share common disease predictors and may, therefore, be driven by different pathophysiological mechanisms. If confirmed, such a finding will have important implications for future studies of visual symptoms and cognitive decline in PD and PD dementia.
Abstract: Psychotropic medication is commonly used in nursing homes, to treat behavioural and psychological symptoms of dementia (BPSD) for example. Treatment with antipsychotics may improve BPSD in some residents but can be associated with serious side effects, such as higher mortality, faster disease progression and cerebrovascular events. In the current study, psychotropic medication use was analysed in a representative sample of nursing home residents in the German-speaking part of Switzerland, at entry and during follow-up.
Abstract: Acquired cataract and cognitive impairment are both common age-related problems, and ophthalmologists are increasingly likely to encounter patients who have both. Patients with dementia types who display early visuoperceptual impairment may present first to ophthalmology services. When these patients have coexisting cataract, it may be difficult to distinguish visual complaints due to cataract from those due to dementia. The interaction between visual impairment due to cataract and neurodegenerative disorders affecting the central visual pathways, is not fully understood. Visual impairment due to cataract may stress impaired attentional mechanisms and cataract extraction may improve cognitive performance in some patients with early cognitive impairment; however, the benefits of cataract surgery in established dementia are less clear. In this study, the literature on this subject was reviewed and the implications for practice were considered.
Abstract: A controversial concept suggests that impaired finger dexterity in Parkinson's disease may be related to limb kinetic apraxia that is not explained by elemental motor deficits such as bradykinesia. To explore the nature of dexterous difficulties, the aim of the present study was to assess the relationship of finger dexterity with ideomotor praxis function and parkinsonian symptoms. Twenty-five patients with Parkinson's disease participated in the study. Their left and right arms were tested independently. Testing was done in an OFF and ON state as defined by a modified version of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Finger dexterity was assessed by a coin rotation (CR) task and ideomotor praxis using a novel test of upper limb apraxia (TULIA), in which the patients were requested to imitate and pantomime 48 meaningless, as well as communicative and tool-related gestures. Coin rotation significantly correlated with TULIA irrespective of the motor state and arm involved, but not with the MDS-UPDRS. This association was significantly influenced by Hoehn and Yahr stage. The strong association of finger dexterity with praxis function but not the parkinsonian symptoms indicates that impaired finger dexterity in Parkinson's disease may be indeed apraxic in nature, yet, predominantly in advanced stages of the disease when cortical pathology is expected to develop. The findings are discussed within a cognitive-motor model of praxis function.
Abstract: To test the prediction by the Perception and Attention Deficit (PAD) model of complex visual hallucinations that cognitive impairment, specifically in visual attention, is a key risk factor for complex hallucinations in eye disease.
Abstract: In the past decade, several arm rehabilitation robots have been developed to assist neurological patients during therapy. Early devices were limited in their number of degrees of freedom and range of motion, whereas newer robots such as the ARMin robot can support the entire arm. Often, these devices are combined with virtual environments to integrate motivating game-like scenarios. Several studies have shown a positive effect of game-playing on therapy outcome by increasing motivation. In addition, we assume that practicing highly functional movements can further enhance therapy outcome by facilitating the transfer of motor abilities acquired in therapy to daily life. Therefore, we present a rehabilitation system that enables the training of activities of daily living (ADL) with the support of an assistive robot. Important ADL tasks have been identified and implemented in a virtual environment. A patient-cooperative control strategy with adaptable freedom in timing and space was developed to assist the patient during the task. The technical feasibility and usability of the system was evaluated with seven healthy subjects and three chronic stroke patients.
Abstract: Acquired cataract and cognitive impairment are both common age-related problems, and ophthalmologists are increasingly likely to encounter patients who have both. Patients with dementia types who display early visuoperceptual impairment may present first to ophthalmology services. When these patients have coexisting cataract, it may be difficult to distinguish visual complaints due to cataract from those due to dementia. The interaction between visual impairment due to cataract and neurodegenerative disorders affecting the central visual pathways, is not fully understood. Visual impairment due to cataract may stress impaired attentional mechanisms and cataract extraction may improve cognitive performance in some patients with early cognitive impairment; however, the benefits of cataract surgery in established dementia are less clear. In this study, the literature on this subject was reviewed and the implications for practice were considered.
Abstract: In Switzerland, approximately 350,000 people aged 70 years or older own a valid driving license. By law, these drivers are medically assessed every other year, most commonly by their general practitioner, to exclude that a medical condition is interfering with their driving skills. A prerequisite for driving is the integration of high-level cognitive functions with perception and motor function. Ageing, per se, does not necessarily impair driving or increase the crash risk. However, medical conditions, such as cognitive impairment and dementia, become more prevalent with advancing age and may contribute to poor driving and an increased crash risk. The extent to which driving skills are impaired depends on the cause of dementia, disease severity, other co-morbidities and individual compensation strategies. Dementia often remains undiagnosed and therefore general practitioners (GPs) can find themselves in the difficult situation to disclose a suspicion about cognitive impairment and queries about medical fitness to drive, at the same time. In addition, the literature suggests that cognitive screening tests, most commonly used by GPs, have a limited role in judging whether an older person remains fit to drive. Further specialist assessment, for example in a memory clinic or on the road testing (ORT), may be helpful when the diagnosis or its implication for driving remain unclear. Here, we review the literature about cognition and driving, for GPs who advise older drivers who wish to continue driving.
Abstract: Visuoperceptual deficits in dementia are common and can reduce quality of life. Testing of visuoperceptual function is often confounded by impairments in other cognitive domains and motor dysfunction. We aimed to develop, pilot, and test a novel visuocognitive prototype test battery which addressed these issues, suitable for both clinical and functional imaging use.
Abstract: Visual symptoms are common in Parkinson's disease with studies consistently demonstrating reductions in visual acuity, contrast sensitivity, colour and motion perception as well as alterations in electroretinogram latencies and amplitudes. Optical coherence tomography can examine retinal structure non-invasively and retinal thinning has been suggested as a potential biomarker for neurodegeneration in Parkinson's disease. Our aim was to examine the retinal thickness of a cohort of Parkinson's disease subjects (and age-matched controls) to establish the practical utility of optical coherence tomography in a representative older Parkinson's disease group.
Abstract: 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.
Abstract: A new overground body-weight support system called ZeroG has been developed that allows patients with severe gait impairments to practice gait and balance activities in a safe, controlled manner. The unloading system is capable of providing up to 300 lb of static support and 150 lb of dynamic (or constant force) support using a custom-series elastic actuator. The unloading system is mounted to a driven trolley, which rides along an overhead rail. We evaluated the performance of ZeroG's unloading system, as well as the trolley tracking system, using benchtop and human-subject testing. Average root-mean-square and peak errors in unloading were 2.2 and 7.2 percent, respectively, over the range of forces tested while trolley tracking errors were less than 3 degrees, indicating the system was able to maintain its position above the subject. We believe training with ZeroG will allow patients to practice activities that are critical to achieving functional independence at home and in the community.
Abstract: To analyze oculomotor recovery in a patient with ischemic lesions restricted to the left frontal eye field (FEF) and the left parietal eye field (PEF).
Abstract: Neglect is defined as the failure to attend and to orient to the contralesional side of space. A horizontal bias towards the right visual field is a classical finding in patients who suffered from a right-hemispheric stroke. The vertical dimension of spatial attention orienting has only sparsely been investigated so far. The aim of this study was to investigate the specificity of this vertical bias by means of a search task, which taps a more pronounced top-down attentional component. Eye movements and behavioural search performance were measured in thirteen patients with left-sided neglect after right hemispheric stroke and in thirteen age-matched controls. Concerning behavioural performance, patients found significantly less targets than healthy controls in both the upper and lower left quadrant. However, when targets were located in the lower left quadrant, patients needed more visual fixations (and therefore longer search time) to find them, suggesting a time-dependent vertical bias.
Abstract: Hemispatial neglect - defined as the failure to attend, explore, and act upon the contralesional side of space - is a frequent and disabling neurological syndrome. Interhemispheric rivalry is considered as a major pathophysiological mechanism underlying hemispatial neglect. According to this account, the contralesional, intact hemisphere undergoes a pathological hyperactivity due to a deficient transcallosal inhibition from the damaged hemisphere. This model offers a framework for possible therapeutic interventions with repetitive transcranial magnetic stimulation (rTMS), i.e. a reduction of the pathological hyperactivity with a rTMS protocol that has lasting inhibitory effects. In the present work, we will first review evidence for the interhemispheric rivalry account coming from animals and humans. We will then describe studies showing the possibility to perturb and to restore interhemispheric balance in healthy subjects as a proof of concept for therapeutic rTMS application. Finally, we will consider studies applying rTMS as a therapeutic approach in hemispatial neglect. We conclude that rTMS is a promising approach to reduce the interhemispheric imbalance in neglect patients and to ameliorate symptoms. Newly developed protocols such as Theta Burst Stimulation (TBS) - with short stimulation times and long offline effects - seem to be particularly convenient. However, future studies should assess stimulation effects not only in clinical testing, but also on disability, considering combination with traditional therapies as well.
Abstract: Synaesthesia is a condition in which the input of one sensory modality triggers extraordinary additional experiences. On an explicit level, subjects affected by this condition normally report unidirectional experiences. In grapheme-colour synaesthesia for example, the letter A printed in black may trigger a red colour experience but not vice versa. However on an implicit level, at least for some types of synaesthesia, bidirectional activation is possible. In this study we tested whether bidirectional implicit activation is mediated by the same brain areas as explicit synaesthetic experiences. Specifically, we demonstrated suppression of implicit bidirectional activation with the application of transcranial magnetic stimulation over parieto-occipital brain areas. Our findings indicate that parieto-occipital regions are not only involved in explicit but also implicit synaesthetic binding.
Abstract: Cerebral achromatopsia is a rare disorder of colour vision caused by bilateral damage to the occipito-temporal cortex. Patients with cerebral achromatopsia are commonly said to suffer due to their disturbed colour sense. Here, we report the case of a patient with cerebral achromatopsia who was initially unaware of his deficit, although three experiments with eye movement recordings demonstrated his severe inability to use colour information in everyday tasks. During two months, the evolution of his colour vision deficit was followed with repeated standardized colour vision tests and eye movement recordings. While his performance continuously improved, he became more and more aware of the deficit. Only after colour vision had almost normalized, his subjective colour sensation was inconspicuous again. The simultaneous occurrence of achromatopsia and the corresponding anosognosia and their parallel recovery suggest that both deficits were due to dysfunction of the same brain region. Consequently, the subjective experience of colour loss in achromatopsia may depend on the residual function of the damaged colour centre.
Abstract: We wished to investigate the prevalence of delirium in patients upon admission to nursing homes and whether or not the previous place of residence predicts delirium.
