Publications by authors named "Klemens Gutbrod"

45 Publications

Alcohol consumption and neurocognitive deficits in people with well-treated HIV in Switzerland.

PLoS One 2021 2;16(3):e0246579. Epub 2021 Mar 2.

Infectious Diseases Service, Lausanne University Hospital, Lausanne, Switzerland.

Background: Hazardous alcohol consumption and HIV infection increase the risk of neurocognitive impairment (NCI). We examined the association between alcohol consumption and specific neurocognitive domain function in people with HIV (PWH) taking modern antiretroviral therapy.

Methods: The Neurocognitive Assessment in the Metabolic and Aging Cohort (NAMACO) study is a prospective, longitudinal, multicentre and multilingual (French, German and Italian) study of patients aged ≥45 years old enrolled in the Swiss HIV Cohort Study (SHCS). Baseline data from 981 study participants were examined. Five neurocognitive domains were evaluated: motor skills, speed of information processing, attention/working memory, executive function and verbal episodic memory. NCI was examined as binary (presence/absence) and continuous (mean z-score) outcomes against Alcohol Use Disorders Identification Test for Consumption (AUDIT-C) scores using logistic and linear regression models, respectively.

Results: Most participants (96.2%) had undetectable viral loads and 64% were aged >50 years old. Hazardous alcohol consumption was observed in 49.4% of participants and binge drinking in 4.2%. While alcohol consumption frequency and quantity were not associated with NCI, the practice of binge drinking was significantly associated with impaired motor skills and overall neurocognitive function in both binary (odds ratio, OR ≥2.0, P <0.05) and continuous (mean z-score difference -0.2 to -0.4, P ≤0.01) outcomes. A significant U-shaped distribution of AUDIT-C score was also observed for motor skills and overall neurocognitive function.

Conclusions: In this cohort of PWH with well-controlled HIV infection, NCI was associated with the practice of binge drinking rather than alcohol consumption frequency or quantity. Longitudinal analysis of alcohol consumption and NCI in this population is currently underway.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246579PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7924787PMC
March 2021

The association between depressive symptoms and neurocognitive impairment in people with well-treated HIV in Switzerland.

Int J STD AIDS 2021 Feb 25:956462420987434. Epub 2021 Feb 25.

Infectious Diseases Service, 30635Lausanne University Hospital, Lausanne, Switzerland.

Background: Depression may contribute to neurocognitive impairment (NCI) in people with HIV (PWH). Attributing NCI to depression rather than to HIV is complicated as depression may be both a causal factor and an effect of NCI. This study aimed to determine the association between depressive symptoms and NCI among PWH with well-controlled infection.

Methods: The Neurocognitive Assessment in the Metabolic and Ageing Cohort study is an ongoing, prospective, longitudinal study of PWH aged ≥45 years old nested within the Swiss HIV Cohort Study. Neurocognitive Assessment in the Metabolic and Ageing Cohort study participants underwent neurocognitive assessment and grading of depressive symptoms using the Centre for Epidemiological Studies Depression Scale. Neurocognitive impairment categories were defined using Frascati criteria. Participants with NCI related to neurological or psychiatric confounders other than depression were excluded. The cross-sectional association between the Centre for Epidemiological Studies Depression score and neurocognitive impairment was examined taking Centre for Epidemiological Studies Depression score as a continuous variable and then as a binary variable using two score thresholds, 16 and 27.

Results: Excluding 79 participants with confounding factors, 902 participants were studied: 81% were men; 96% had plasma viral loads <50 copies/ml; 35% had neurocognitive impairment; 28% had Centre for Epidemiological Studies Depression scores ≥16. Higher Centre for Epidemiological Studies Depression scores were associated with female sex ( = 0.0003), non-Caucasian origin ( = 0.011) and current/past intravenous drug use ( = 0.002). Whilst neurocognitive impairment was associated with higher Centre for Epidemiological Studies Depression scores, the Centre for Epidemiological Studies Depression score was a poor predictor of having neurocognitive impairment (area under the ROC curve 0.604). Applying a Centre for Epidemiological Studies Depression score threshold of 16 predicted the presence of neurocognitive impairment with a sensitivity of 38.3% (specificity 77.2%), increasing the threshold to 27 lowered sensitivity to 15.4% (specificity 93.6%).

Conclusion: In this large cohort of PWH in Switzerland, we did not observe a Centre for Epidemiological Studies Depression score threshold that was sensitive in predicting neurocognitive impairment. As neurocognitive impairment was however associated with higher Centre for Epidemiological Studies Depression scores, the data support the screening for and treatment of depression among PWH diagnosed with neurocognitive impairment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/0956462420987434DOI Listing
February 2021

Effects of intensive care unit ambient sounds on healthcare professionals: results of an online survey and noise exposure in an experimental setting.

Intensive Care Med Exp 2020 Jul 23;8(1):34. Epub 2020 Jul 23.

Department of Intensive Care Medicine, University Hospital Bern (Inselspital), University of Bern, CH-3010, Bern, Switzerland.

Background: Noise levels on intensive care units (ICUs) are typically elevated. While many studies reported negative effects of ICU ambient sounds on patients, only few investigated noise as a factor to influence well-being or performance in healthcare professionals.

Methods: An online survey in the German-speaking part of Switzerland was conducted to assess how ICU soundscapes are subjectively perceived by healthcare professionals. The questionnaire was answered by 348 participants. Additionally, effects of noise on working memory performance were evaluated in an experimental noise exposure setting. Twenty-six healthcare professionals and 27 healthy controls performed a 2-back object-location task while being exposed to either ICU or pink noise.

Results: Survey results demonstrate that a majority of participants was aware of heightened noise levels. Participants reported that mostly well-being, performance, and attention could be reduced, along with subjective annoyance and fatigue by ICU ambient sounds. Although no significant effects of noise exposure on working memory performance was observed, self-assessments revealed significantly higher stress levels, increased annoyance and distraction ratings as well as decreased confidence in performance after ICU-noise exposure.

Conclusion: Subjective assessments indicate that heightened noise levels on ICUs induce annoyance, with heightened stress levels, impaired well-being, and reduced performance being potential consequences. Empirical evidence with objective and physiological measures is warranted.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s40635-020-00321-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7376325PMC
July 2020

Health-Related Quality of Life in Young Adults Following Pediatric Arterial Ischemic Stroke.

Stroke 2020 03 23;51(3):952-957. Epub 2019 Dec 23.

From the Division of Child Neurology, Department of Pediatrics, University Children's Hospital Bern, Bern University Hospital, and University of Bern, Switzerland on behalf of the Swiss Neuropaediatric Stroke Registry (A.R., B.K., K.L., M.R., M.S., S.B.).

Background and Purpose- Pediatric arterial ischemic stroke (AIS) is a rare disease leading to long-lasting neurological sequelae. Little is known about the long-term health-related quality of life (HRQoL) of these patients. The study aims to compare HRQoL in young adults who have had pediatric AIS with a healthy control group. Methods- A cross-sectional study compared self-rated HRQoL, depression, fatigability, and behavior in pediatric stroke survivors to healthy controls. Patients with a confirmed diagnosis of pediatric AIS who were ≥18 years at the time of recruitment and ≥2 years after acute AIS, as well as healthy controls ≥18 years matched for age, sex, and socioeconomic status were included. Primary outcome was HRQoL measured with the Short Form Health Survey. Results- Thirty-three patients (median [interquartile range] aged 22 years [20-26]; 22 males, 67%) and 71 controls (median [interquartile range] aged 23 years [21-25]; 41 males, 58%) were included. Overall, HRQoL, depression, or fatigability did not differ between the patients and the control group. Patients rated themselves lower on the disinhibition scale (=0.049) and tended to rate themselves lower on the executive dysfunction scale (=0.076). Patients with a poor outcome 24 months after AIS showed a clear trend toward impairment of executive functioning (=0.056) and work/productivity in the stroke-specific QoL (=0.05). Conclusions- Self-rated HRQoL, depression, and fatigability in adult pediatric stroke survivors are comparable to healthy adult peers. A poor outcome 24 months after acute stroke might affect work performance and executive functioning in adulthood.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/STROKEAHA.119.027622DOI Listing
March 2020

Search and Match Task: Development of a Taskified Match-3 Puzzle Game to Assess and Practice Visual Search.

JMIR Serious Games 2019 May 9;7(2):e13620. Epub 2019 May 9.

Gerontechnology & Rehabilitation, University of Bern, Bern, Switzerland.

Background: Visual search declines with aging, dementia, and brain injury and is linked to limitations in everyday activities. Recent studies suggest that visual search can be improved with practice using computerized visual search tasks and puzzle video games. For practical use, it is important that visual search ability can be assessed and practiced in a controlled and adaptive way. However, commercial puzzle video games make it hard to control task difficulty, and there are little means to collect performance data.

Objective: The aim of this study was to develop and initially validate the search and match task (SMT) that combines an enjoyable tile-matching match-3 puzzle video game with features of the visual search paradigm (taskified game). The SMT was designed as a single-target visual search task that allows control over task difficulty variables and collection of performance data.

Methods: The SMT is played on a grid-based (width × height) puzzle board, filled with different types of colored polygons. A wide range of difficulty levels was generated by combinations of 3 task variables over a range from 4 to 8 including height and width of the puzzle board (set size) and the numbers of tile types (distractor heterogeneity). For each difficulty level, large numbers of playable trials were pregenerated using Python. Each trial consists of 4 consecutive puzzle boards, where the goal of the task is to find a target tile configuration (search) on the puzzle board and swap 2 adjacent tiles to create a line of 3 identical tiles (match). For each puzzle board, there is exactly 1 possible match (single target search). In a user study with 28 young adults (aged 18 to 31 years), 13 older (aged 64 to 79 years) and 11 oldest (aged 86 to 98 years) adults played the long (young and older adults) or short version (oldest adults) of the difficulty levels of the SMT. Participants rated their perception and the usability of the task and completed neuropsychological tests that measure cognitive domains engaged by the puzzle game.

Results: Results from the user study indicate that the target search time is associated with set size, distractor heterogeneity, and age. Results further indicate that search performance is associated with general cognitive ability, selective and divided attention, visual search, and visuospatial and pattern recognition ability.

Conclusions: Overall, this study shows that an everyday puzzle game-based task can be experimentally controlled, is enjoyable and user-friendly, and permits data collection to assess visual search and cognitive abilities. Further research is needed to evaluate the potential of the SMT game to assess and practice visual search ability in an enjoyable and adaptive way. A PsychoPy version of the SMT is freely available for researchers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2196/13620DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6532342PMC
May 2019

Orthostatic Cognitive Dysfunction in Postural Tachycardia Syndrome After Rapid Water Drinking.

Front Neurosci 2019 9;13:327. Epub 2019 Apr 9.

Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.

Postural tachycardia syndrome (POTS) is a form of autonomic dysregulation and is characterized by an excessive heart rate (HR) increment upon the upright body position while blood pressure is maintained. Patients experience typical symptoms of orthostatic intolerance such as dizziness, nausea and cognitive impairments. The present study assessed position-dependent attentional and cognitive functioning in POTS patients compared to healthy subjects and tested the response of cognitive performance to acute water intake. Data was obtained from eight patients with neuropathic POTS and eight healthy subjects of similar age and gender. All participants completed questionnaires that assessed health-related quality of life and depression and underwent four rounds of neuropsychological testing overall, each before and after the intake of 500 ml still mineral water and both in the supine and in the upright posture. Postural tachycardia syndrome patients showed deficits in working memory (WM) exclusively in the upright position compared to healthy subjects, but no position-dependent impairments in alertness or divided attention. Rapid water ingestion had a beneficial effect on WM in the upright posture, lead to a decrease in HR increment and to an improvement of subjective symptom experience. The results provide support for the occurrence of purely orthostatic cognitive deficits in POTS, especially when increased executive control and cognitive resources are required and document a favorable effect of water intake on cognitive performance. These findings have important implications for the management of cognitive symptoms in POTS as high water intake is an easy and accessible strategy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnins.2019.00327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465605PMC
April 2019

Multimodal Communication in Aphasia: Perception and Production of Co-speech Gestures During Face-to-Face Conversation.

Front Hum Neurosci 2018 14;12:200. Epub 2018 Jun 14.

Perception and Eye Movement Laboratory, Department of Neurology and Clinical Research, University of Bern Inselspital, Bern, Switzerland.

The role of nonverbal communication in patients with post-stroke language impairment (aphasia) is not yet fully understood. This study investigated how aphasic patients perceive and produce co-speech gestures during face-to-face interaction, and whether distinct brain lesions would predict the frequency of spontaneous co-speech gesturing. For this purpose, we recorded samples of conversations in patients with aphasia and healthy participants. Gesture perception was assessed by means of a head-mounted eye-tracking system, and the produced co-speech gestures were coded according to a linguistic classification system. The main results are that meaning-laden gestures (e.g., iconic gestures representing object shapes) are more likely to attract visual attention than meaningless hand movements, and that patients with aphasia are more likely to fixate co-speech gestures overall than healthy participants. This implies that patients with aphasia may benefit from the multimodal information provided by co-speech gestures. On the level of co-speech gesture production, we found that patients with damage to the anterior part of the arcuate fasciculus showed a higher frequency of meaning-laden gestures. This area lies in close vicinity to the premotor cortex and is considered to be important for speech production. This may suggest that the use of meaning-laden gestures depends on the integrity of patients' speech production abilities.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnhum.2018.00200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6010555PMC
June 2018

Measuring the Impact of Delayed Cerebral Ischemia on Neuropsychological Outcome After Aneurysmal Subarachnoid Hemorrhage-Protocol of a Swiss Nationwide Observational Study (MoCA-DCI Study).

Neurosurgery 2019 05;84(5):1124-1132

Department of Neurosurgery, University Hospital Zurich, Clinical Neuroscience Center, University of Zurich, Switzerland.

Background: The exact relationship between delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) and neuropsychological impairment remains unknown, as previous studies lacked a baseline examination after aneurysm occlusion but before the DCI-period. Neuropsychological evaluation of acutely ill patients is often applied in a busy intensive care unit (ICU), where distraction represents a bias to the obtained results.

Objective: To evaluate the relationship between DCI and neuropsychological outcome after aSAH by comparing the Montreal Cognitive Assessment (MoCA) results in aSAH patients with and without DCI at 3 mo with a baseline examination before the DCI-period (part 1). To determine the reliability of the MoCA, when applied in an ICU setting (part 2).

Methods: Prospective, multicenter, and observational study performed at all Swiss neurovascular centers. For part 1, n = 240 consecutive aSAH patients and for part 2, n = 50 patients with acute brain injury are recruited.

Expected Outcomes: Part 1: Effect size of the relationship between DCI and neuropsychological outcome (MoCA). Part 2: Reliability measures for the MoCA.

Discussion: The institutional review boards approved this study on July 4, 2017 under case number BASEC 2017-00103. After completion, the results will be offered to an international scientific journal for peer-reviewed publication. This study determines the exact impact of DCI on the neuropsychological outcome after aSAH, unbiased by confounding factors such as early brain injury or patient-specific characteristics. The study provides unique insights in the neuropsychological state of patients in the early period after aSAH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/neuros/nyy155DOI Listing
May 2019

Amnesic patients have residual prospective memory capacities.

Clin Neuropsychol 2019 04 13;33(3):606-621. Epub 2018 Feb 13.

b Department of Neurology , University of Bern , Bern , Switzerland.

Objective: To investigate, in two separate studies, whether amnesic patients with a severe memory impairment can learn to perform a habitual prospective memory task when they receive immediate feedback on prospective memory failures (Study 1) and whether amnesic patients are able to benefit from previous habitual prospective memory performance after a 24-h retention interval.

Method: A prospective memory task was embedded in a lexical decision task (Study 1) and in a perceptual discrimination task (Study 2). Performance was compared across test halves. Participants received immediate performance feedback on prospective memory failures that served as a reminder for the prospective memory task. A retest was performed after 24 h in Study 2, but without immediate feedback in the first test half.

Results: In Study 1, amnesic patients performed at a lower level than the control group, but they improved significantly across the experiment. In Study 2, the results of the first session replicated this pattern. The results of the second session showed a performance breakdown in amnesic patients. However, one single reminder was enough to boost performance again on the level of the second part of day one.

Conclusions: This indicates that amnesic patients have residual prospective memory capacities and that providing immediate feedback is a promising strategy to draw on these capacities.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/13854046.2018.1438516DOI Listing
April 2019

Behavioral Changes in Patients with Multiple Sclerosis.

Front Neurol 2017 28;8:437. Epub 2017 Aug 28.

Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.

Background: Behavioral changes are common in patients with multiple sclerosis (MS), however not as readily recognized as cognitive impairments.

Objective: The aim of this study was to analyze behavioral changes and its relation to disease characteristics, disability, and cognitive impairments in patients with MS.

Method: This is a single-center cross-sectional study. A detailed neuropsychological examination, including the Frontal Systems Behavior Scale (FrSBe), the Beck depression inventory (BDI), and the Wuerzburg Fatigue Inventory for Multiple Sclerosis (WEIMuS) test, was performed. FrSBe results were correlated with disease characteristics, disability, and cognitive assessments.

Results: 66 patients were enrolled (mean age: 43.4 years; disease duration: 9.3 years; Expanded Disability Status Scale: 3.0). Up to one third of patients showed behavioral changes in at least one domain or the total score of the FrSBe. Patients were mildly affected with regard to cognitive functioning. Consistent correlation was found between behavioral changes and fatigue (WEIMuS) and depressive symptoms (BDI), but not with disease characteristics, disability, or cognitive functions. There was an increase of behavioral changes on all FrSBe scales in the current status compared to the retrospectively rated status before disease onset. Self- and family ratings with regard to current behavioral changes were similar.

Conclusion: Behavioral changes are common in otherwise mildly affected MS patients with up to one third being affected. In this patient cohort, behavioral changes occur largely independent of disease characteristics, physical disability, and cognitive functioning but correlate with both fatigue and depressive symptoms. Therefore, they should be tested specifically.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fneur.2017.00437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5581390PMC
August 2017

The Presence of Human Immunodeficiency Virus-Associated Neurocognitive Disorders Is Associated With a Lower Adherence to Combined Antiretroviral Treatment.

Open Forum Infect Dis 2017 6;4(2):ofx070. Epub 2017 Apr 6.

Community Pharmacy, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Switzerland.

Background: Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) are defined according to their diagnostic degrees as follows: asymptomatic neurocognitive impairment, mild neurocognitive disorder, and HIV-associated dementia. Because high adherence to combined antiretroviral therapy (cART) is required to maintain viral suppression among HIV-infected patients, it is important to investigate the impact of HAND on medication adherence. Our study hypothesis was that patients with HAND had a lower medication adherence than patients who did not have HAND.

Methods: This was an observational, exploratory, 2-center pilot study of patients who had a state-of-the-art neurocognitive assessment performed between January 2011 and June 2015 while also being followed at their respective adherence clinics. Adherence was measured with electronic monitors. Patients' sociodemographic characteristics, HIV viral load, and CD4 counts were retrieved from the Swiss HIV Cohort Study database. At each time , adherence was computed as the proportion of patients taking medication as prescribed at that time.

Results: We included 59 patients, with a median (Q1, Q3) age of 53 years (47-58) and 39 (66%) were male participants. Twenty-two patients (35%) had no neurocognitive deficits, 16 (27%) patients had HAND, and 21 (35%) patients had non-HAND (mostly depression). Implementation over 3 years showed a significant decline (50%) in medication adherence among patients diagnosed with HAND in comparison with patients who had a normal neuropsychological status or a non-HIV-related cognitive deficit (implementation stayed 90% during follow-up).

Conclusions: Our findings support the hypothesis that HAND is associated with reduced cART adherence.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/ofid/ofx070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5450901PMC
April 2017

Pure optic ataxia and visual hemiagnosia - extending the dual visual hypothesis.

J Neuropsychol 2018 Jun 4;12(2):271-290. Epub 2017 Mar 4.

Department of Neurology, Inselspital, University Hospital Bern, Switzerland.

Goodale and Milner's two visual system hypothesis is an influential model for the understanding of the primate visual system. Lesions of either the ventral (occipito-temporal) or the dorsal (occipito-parietal) stream produce distinct and dissociated syndromes in humans: visual agnosia is typical for ventral damage, whereas optic ataxia (OA) for dorsal damage. We studied the case of a 59-year-old left-handed woman with a circumscribed lesion around the left posterior occipital sulcus, extending to the underlying white matter. Initially, she presented with a central visual field OA, which regressed to an OA to the right visual hemifield during the 3 months observation period. In addition, tachistoscopic experiments showed visual hemiagnosia to the right visual hemifield. In line with the findings of the neuropsychological experiments, the analysis of the structural MR data by means of a trackwise hodologic probabilistic approach revealed damage to the left superior longitudinal fasciculus and to the left inferior longitudinal fasciculus, indicating an impairment of both the dorsal and the ventral stream. The combination of OA and visual hemiagnosia in the same patient has never been previously described. The present case study thus provides further insights for the understanding of visual processing.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jnp.12119DOI Listing
June 2018

Neurorehabilitation kognitiver Störungen.

Ther Umsch 2017;74(9):503-509

1 Universitäre Neurorehabilitation, Universitätsklinik für Neurologie, Inselspital, Bern.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1024/0040-5930/a000948DOI Listing
July 2018

The influence of reading direction on hemianopic reading disorders.

J Clin Exp Neuropsychol 2016 12 28;38(10):1077-83. Epub 2016 Jun 28.

a Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research , Inselspital, Bern University Hospital, and University of Bern , Bern , Switzerland.

Unlabelled: Hemianopic reading impairment is a consequence of a visual field defect to either the right or the left side and is characterized by an increased reading time and reduced reading performance. Depending on the side of the visual field defect, reading will be affected differently: Patients suffering from a visual field defect to the right side have noticeable difficulties in reading fluently with slowing. Patients suffering from a visual field defect to the left usually struggle to find the beginning of a line and read more fluently. It was suggested in the literature that changing the reading direction from horizontal to vertical may be a training strategy to reduce reading problems in patients with hemianopia. The aim of the study was to investigate the influence of reading direction on reading speed in patients with left- or right-sided visual field defects and in healthy controls.

Method: In 13 patients with hemianopia and in 13 age-matched controls, reading speed was calculated for texts in standard as well as in clockwise rotated orientation of 90, 180, and 270°.

Results: In both groups, text rotation reduced reading speed compared to standard reading. Patients with left-sided hemianopia had the greatest reduction after text rotation. Patients with right-sided hemianopia had the smallest speed reduction in 90° vertically rotated texts.

Conclusions: Text rotation has different effects in left- or right-sided hemianopia patients. For patients with left-sided heminanopia, rotation of the text may not be a helpful training strategy, for right-sided hemianopia vertical rotation of the text of 90° may be a beneficial training strategy to reduce reading deficits.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/13803395.2016.1189884DOI Listing
December 2016

Eye Gaze Behavior at Turn Transition: How Aphasic Patients Process Speakers' Turns during Video Observation.

J Cogn Neurosci 2016 Oct 31;28(10):1613-24. Epub 2016 May 31.

University Hospital Inselspital Bern.

The human turn-taking system regulates the smooth and precise exchange of speaking turns during face-to-face interaction. Recent studies investigated the processing of ongoing turns during conversation by measuring the eye movements of noninvolved observers. The findings suggest that humans shift their gaze in anticipation to the next speaker before the start of the next turn. Moreover, there is evidence that the ability to timely detect turn transitions mainly relies on the lexico-syntactic content provided by the conversation. Consequently, patients with aphasia, who often experience deficits in both semantic and syntactic processing, might encounter difficulties to detect and timely shift their gaze at turn transitions. To test this assumption, we presented video vignettes of natural conversations to aphasic patients and healthy controls, while their eye movements were measured. The frequency and latency of event-related gaze shifts, with respect to the end of the current turn in the videos, were compared between the two groups. Our results suggest that, compared with healthy controls, aphasic patients have a reduced probability to shift their gaze at turn transitions but do not show significantly increased gaze shift latencies. In healthy controls, but not in aphasic patients, the probability to shift the gaze at turn transition was increased when the video content of the current turn had a higher lexico-syntactic complexity. Furthermore, the results from voxel-based lesion symptom mapping indicate that the association between lexico-syntactic complexity and gaze shift latency in aphasic patients is predicted by brain lesions located in the posterior branch of the left arcuate fasciculus. Higher lexico-syntactic processing demands seem to lead to a reduced gaze shift probability in aphasic patients. This finding may represent missed opportunities for patients to place their contributions during everyday conversation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1162/jocn_a_00983DOI Listing
October 2016

Comprehension of Co-Speech Gestures in Aphasic Patients: An Eye Movement Study.

PLoS One 2016 6;11(1):e0146583. Epub 2016 Jan 6.

Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, and University of Bern, Bern, Switzerland.

Background: Co-speech gestures are omnipresent and a crucial element of human interaction by facilitating language comprehension. However, it is unclear whether gestures also support language comprehension in aphasic patients. Using visual exploration behavior analysis, the present study aimed to investigate the influence of congruence between speech and co-speech gestures on comprehension in terms of accuracy in a decision task.

Method: Twenty aphasic patients and 30 healthy controls watched videos in which speech was either combined with meaningless (baseline condition), congruent, or incongruent gestures. Comprehension was assessed with a decision task, while remote eye-tracking allowed analysis of visual exploration.

Results: In aphasic patients, the incongruent condition resulted in a significant decrease of accuracy, while the congruent condition led to a significant increase in accuracy compared to baseline accuracy. In the control group, the incongruent condition resulted in a decrease in accuracy, while the congruent condition did not significantly increase the accuracy. Visual exploration analysis showed that patients fixated significantly less on the face and tended to fixate more on the gesturing hands compared to controls.

Conclusion: Co-speech gestures play an important role for aphasic patients as they modulate comprehension. Incongruent gestures evoke significant interference and deteriorate patients' comprehension. In contrast, congruent gestures enhance comprehension in aphasic patients, which might be valuable for clinical and therapeutic purposes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0146583PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703302PMC
July 2016

Cue Recognition and Integration - Eye Tracking Evidence of Processing Differences in Sentence Comprehension in Aphasia.

PLoS One 2015 12;10(11):e0142853. Epub 2015 Nov 12.

Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, and University of Bern, Bern, Switzerland.

Purpose: We aimed at further elucidating whether aphasic patients' difficulties in understanding non-canonical sentence structures, such as Passive or Object-Verb-Subject sentences, can be attributed to impaired morphosyntactic cue recognition, and to problems in integrating competing interpretations.

Methods: A sentence-picture matching task with canonical and non-canonical spoken sentences was performed using concurrent eye tracking. Accuracy, reaction time, and eye tracking data (fixations) of 50 healthy subjects and 12 aphasic patients were analysed.

Results: Patients showed increased error rates and reaction times, as well as delayed fixation preferences for target pictures in non-canonical sentences. Patients' fixation patterns differed from healthy controls and revealed deficits in recognizing and immediately integrating morphosyntactic cues.

Conclusion: Our study corroborates the notion that difficulties in understanding syntactically complex sentences are attributable to a processing deficit encompassing delayed and therefore impaired recognition and integration of cues, as well as increased competition between interpretations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0142853PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4642964PMC
July 2016

Call for uniform neuropsychological assessment after aneurysmal subarachnoid hemorrhage: Swiss recommendations.

Acta Neurochir (Wien) 2015 Sep 16;157(9):1449-58. Epub 2015 Jul 16.

Division of Neuropaediatrics, Development, and Rehabilitation, Department of Paediatrics, Inselspital Bern, Bern, Switzerland.

Background: In a high proportion of patients with favorable outcome after aneurysmal subarachnoid hemorrhage (aSAH), neuropsychological deficits, depression, anxiety, and fatigue are responsible for the inability to return to their regular premorbid life and pursue their professional careers. These problems often remain unrecognized, as no recommendations concerning a standardized comprehensive assessment have yet found entry into clinical routines.

Methods: To establish a nationwide standard concerning a comprehensive assessment after aSAH, representatives of all neuropsychological and neurosurgical departments of those eight Swiss centers treating acute aSAH have agreed on a common protocol. In addition, a battery of questionnaires and neuropsychological tests was selected, optimally suited to the deficits found most prevalent in aSAH patients that was available in different languages and standardized.

Results: We propose a baseline inpatient neuropsychological screening using the Montreal Cognitive Assessment (MoCA) between days 14 and 28 after aSAH. In an outpatient setting at 3 and 12 months after bleeding, we recommend a neuropsychological examination, testing all relevant domains including attention, speed of information processing, executive functions, verbal and visual learning/memory, language, visuo-perceptual abilities, and premorbid intelligence. In addition, a detailed assessment capturing anxiety, depression, fatigue, symptoms of frontal lobe affection, and quality of life should be performed.

Conclusions: This standardized neuropsychological assessment will lead to a more comprehensive assessment of the patient, facilitate the detection and subsequent treatment of previously unrecognized but relevant impairments, and help to determine the incidence, characteristics, modifiable risk factors, and the clinical course of these impairments after aSAH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00701-015-2480-yDOI Listing
September 2015

Neglect and Motion Stimuli--Insights from a Touchscreen-Based Cancellation Task.

PLoS One 2015 9;10(7):e0132025. Epub 2015 Jul 9.

Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland; Gerontechnology & Rehabilitation Group, University of Bern, Bern, Switzerland; Center of Neurology and Neurorehabilitation, Luzerner Kantonsspital, Luzern, Switzerland.

Background And Purpose: In stroke patients, neglect diagnostic is often performed by means of paper-pencil cancellation tasks. These tasks entail static stimuli, and provide no information concerning possible changes in the severity of neglect symptoms when patients are confronted with motion. We therefore aimed to directly contrast the cancellation behaviour of neglect patients under static and dynamic conditions. Since visual field deficits often occur in neglect patients, we analysed whether the integrity of the optic radiation would influence cancellation behaviour.

Methods: Twenty-five patients with left spatial neglect after right-hemispheric stroke were tested with a touchscreen cancellation task, once when the evenly distributed targets were stationary, and once when the identic targets moved with constant speed on a random path. The integrity of the right optic radiation was analysed by means of a hodologic probabilistic approach.

Results: Motion influenced the cancellation behaviour of neglect patients, and the direction of this influence (i.e., an increase or decrease of neglect severity) was modulated by the integrity of the right optic radiation. In patients with an intact optic radiation, the severity of neglect significantly decreased in the dynamic condition. Conversely, in patients with damage to the optic radiation, the severity of neglect significantly increased in the dynamic condition.

Conclusion: Motion may influence neglect in stroke patients. The integrity of the optic radiation may be a predictor of whether motion increases or decreases the severity of neglect symptoms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0132025PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4497636PMC
April 2016

Induction of Fear by Intraoperative Stimulation During Awake Craniotomy: Case Presentation and Systematic Review of the Literature.

World Neurosurg 2015 Aug 8;84(2):470-4. Epub 2015 Apr 8.

Department of Neurosurgery, University Hospital Bern, 3010 Bern, Switzerland.

Purpose: A case is presented and a systematic review of the literature is provided to update our current knowledge of induction of fear by cortical stimulation.

Methods: We present a case of refractory epilepsy associated with a lesion where fear could be induced by intraoperative electrical stimulation of the posterior inner part of the superior temporal gyrus. We performed a systematic review of the literature using PubMed with the key words "epilepsy AND emotion", "cortical stimulation AND emotion," and "human brain stimulation AND behavior".

Results: Intraoperative cortical stimulation of the inner part of the posterior superior temporal gyrus reliably induced fear and progressive screaming behavior. Stimulation through subdural grid electrodes did not induce this phenomenon. A systematic review of the literature identified fear induction by stimulation of different widespread cortical areas including the temporal pole, the insula, and the anterior cingulate cortex. The posterior part of the superior temporal gyrus has so far not been associated with fear induction after electrical stimulation.

Conclusion: Although our observation suggests that this area of the brain could be part of a network involved in the elicitation of fear, dysfunction of this network induced by epilepsy could also explain the observed phenomenon. Electrophysiologic and imaging studies must be conducted to improve our understanding of the cortical networks forming the neuroanatomical substrate of higher brain functions and experiences such as fear.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.wneu.2015.03.056DOI Listing
August 2015

Different visual exploration of tool-related gestures in left hemisphere brain damaged patients is associated with poor gestural imitation.

Neuropsychologia 2015 May 2;71:158-64. Epub 2015 Apr 2.

Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, Switzerland; Division of Cognitive and Restorative Neurology, Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland; Gerontechnology and Rehabilitation Group, University of Bern, Bern, Switzerland; Center for Cognition, Learning and Memory, University of Bern, Bern, Switzerland. Electronic address:

According to the direct matching hypothesis, perceived movements automatically activate existing motor components through matching of the perceived gesture and its execution. The aim of the present study was to test the direct matching hypothesis by assessing whether visual exploration behavior correlate with deficits in gestural imitation in left hemisphere damaged (LHD) patients. Eighteen LHD patients and twenty healthy control subjects took part in the study. Gesture imitation performance was measured by the test for upper limb apraxia (TULIA). Visual exploration behavior was measured by an infrared eye-tracking system. Short videos including forty gestures (20 meaningless and 20 communicative gestures) were presented. Cumulative fixation duration was measured in different regions of interest (ROIs), namely the face, the gesturing hand, the body, and the surrounding environment. Compared to healthy subjects, patients fixated significantly less the ROIs comprising the face and the gesturing hand during the exploration of emblematic and tool-related gestures. Moreover, visual exploration of tool-related gestures significantly correlated with tool-related imitation as measured by TULIA in LHD patients. Patients and controls did not differ in the visual exploration of meaningless gestures, and no significant relationships were found between visual exploration behavior and the imitation of emblematic and meaningless gestures in TULIA. The present study thus suggests that altered visual exploration may lead to disturbed imitation of tool related gestures, however not of emblematic and meaningless gestures. Consequently, our findings partially support the direct matching hypothesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neuropsychologia.2015.04.001DOI Listing
May 2015

The neuropsychological assessment of cognitive deficits considering measures of performance variability.

Arch Clin Neuropsychol 2015 May 15;30(3):217-27. Epub 2015 Mar 15.

Department of Neurology, Division of Cognitive and Restorative Neurology, Inselspital, Bern University Hospital, and University of Bern, Bern CH-3010, Switzerland.

Neuropsychologists often face interpretational difficulties when assessing cognitive deficits, particularly in cases of unclear cerebral etiology. How can we be sure whether a single test score below the population average is indicative of a pathological brain condition or normal? In the past few years, the topic of intra-individual performance variability has gained great interest. On the basis of a large normative sample, two measures of performance variability and their importance for neuropsychological interpretation will be presented in this paper: the number of low scores and the level of dispersion. We conclude that low scores are common in healthy individuals. On the other hand, the level of dispersion is relatively small. Here, base rate information about abnormally low scores and abnormally high dispersion across cognitive abilities are provided to improve the awareness of normal variability and to serve clinicians as additional interpretive measures in the diagnostic process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/arclin/acv008DOI Listing
May 2015

Perception of co-speech gestures in aphasic patients: a visual exploration study during the observation of dyadic conversations.

Cortex 2015 Mar 4;64:157-68. Epub 2014 Nov 4.

Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, and University of Bern, Switzerland; Division of Cognitive and Restorative Neurology, Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland; Gerontechnology and Rehabilitation Group, University of Bern, Bern, Switzerland; Center for Cognition, Learning and Memory, University of Bern, Bern, Switzerland. Electronic address:

Background: Co-speech gestures are part of nonverbal communication during conversations. They either support the verbal message or provide the interlocutor with additional information. Furthermore, they prompt as nonverbal cues the cooperative process of turn taking. In the present study, we investigated the influence of co-speech gestures on the perception of dyadic dialogue in aphasic patients. In particular, we analysed the impact of co-speech gestures on gaze direction (towards speaker or listener) and fixation of body parts. We hypothesized that aphasic patients, who are restricted in verbal comprehension, adapt their visual exploration strategies.

Methods: Sixteen aphasic patients and 23 healthy control subjects participated in the study. Visual exploration behaviour was measured by means of a contact-free infrared eye-tracker while subjects were watching videos depicting spontaneous dialogues between two individuals. Cumulative fixation duration and mean fixation duration were calculated for the factors co-speech gesture (present and absent), gaze direction (to the speaker or to the listener), and region of interest (ROI), including hands, face, and body.

Results: Both aphasic patients and healthy controls mainly fixated the speaker's face. We found a significant co-speech gesture × ROI interaction, indicating that the presence of a co-speech gesture encouraged subjects to look at the speaker. Further, there was a significant gaze direction × ROI × group interaction revealing that aphasic patients showed reduced cumulative fixation duration on the speaker's face compared to healthy controls.

Conclusion: Co-speech gestures guide the observer's attention towards the speaker, the source of semantic input. It is discussed whether an underlying semantic processing deficit or a deficit to integrate audio-visual information may cause aphasic patients to explore less the speaker's face.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cortex.2014.10.013DOI Listing
March 2015

Bottom-up Visual Integration in the Medial Parietal Lobe.

Cereb Cortex 2016 Mar 19;26(3):943-949. Epub 2014 Oct 19.

Department of Neurology.

Largely based on findings from functional neuroimaging studies, the medial parietal lobe is known to contribute to internally directed cognitive processes such as visual imagery or episodic memory. Here, we present 2 patients with behavioral impairments that extend this view. Both had chronic unilateral lesions of nearly the entire medial parietal lobe, but in opposite hemispheres. Routine neuropsychological examination conducted >4 years after the onset of brain damage showed little deficits of minor severity. In contrast, both patients reported persistent unusual visual impairment. A comprehensive series of tachistoscopic experiments with lateralized stimulus presentation and comparison with healthy participants revealed partial visual hemiagnosia for stimuli presented to their contralesional hemifield, applying inferential single-case statistics to evaluate deficits and dissociations. Double dissociations were found in 4 experiments during which participants had to integrate more than one visual element, either through comparison or formation of a global gestalt. Against the background of recent neuroimaging findings, we conclude that of all medial parietal structures, the precuneus is the most likely candidate for a crucial involvement in such bottom-up visual integration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/cercor/bhu256DOI Listing
March 2016

Unconscious relational encoding depends on hippocampus.

Brain 2014 Dec 1;137(Pt 12):3355-70. Epub 2014 Oct 1.

1 Division of Experimental Psychology and Neuropsychology, Department of Psychology, University of Bern, Bern, Switzerland 2 Centre for Cognition, Learning and Memory, University of Bern, Bern, Switzerland

Textbooks divide between human memory systems based on consciousness. Hippocampus is thought to support only conscious encoding, while neocortex supports both conscious and unconscious encoding. We tested whether processing modes, not consciousness, divide between memory systems in three neuroimaging experiments with 11 amnesic patients (mean age=45.55 years, standard deviation=8.74, range=23-60) and 11 matched healthy control subjects. Examined processing modes were single item versus relational encoding with only relational encoding hypothesized to depend on hippocampus. Participants encoded and later retrieved either single words or new relations between words. Consciousness of encoding was excluded by subliminal (invisible) word presentation. Amnesic patients and controls performed equally well on the single item task activating prefrontal cortex. But only the controls succeeded on the relational task activating the hippocampus, while amnesic patients failed as a group. Hence, unconscious relational encoding, but not unconscious single item encoding, depended on hippocampus. Yet, three patients performed normally on unconscious relational encoding in spite of amnesia capitalizing on spared hippocampal tissue and connections to language cortex. This pattern of results suggests that processing modes divide between memory systems, while consciousness divides between levels of function within a memory system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/brain/awu270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4240286PMC
December 2014

Impairments in an early stage of the decision-making process in patients with ventromedial prefrontal damage: preliminary results.

Neurocase 2015 1;21(4):509-19. Epub 2014 Aug 1.

a Neurological Rehabilitation Centre, Reha Rheinfelden , Rheinfelden Switzerland.

Lesions of the ventromedial prefrontal cortex can result in a deficient decision-making behavior. So far, most experimental results in the neuropsychological decision-making research have been obtained with gambling tasks. Due to their high complexity, it is difficult to evaluate the underlying processes of the decision-making deficits. The aim of this study was to assess if patients with ventromedial prefrontal damage compared to patients with dorsolateral prefrontal damage and controls show a deficit in an early stage of the decision-making process. Nine patients with ventromedial prefrontal damage, three with dorsolateral prefrontal damage, and eleven healthy controls were tested with a newly developed decision task in which they had to search actively for the information they needed for their decisions. Our results show that patients with ventromedial prefrontal damage compared to the brain-lesioned dorsolateral prefrontal control group and healthy controls searched less for information with regard to risk defusing operators or consequences of their decisions indicating impairment already in the early stage of the decision-making process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/13554794.2014.944545DOI Listing
January 2016

Spinal cerebrospinal fluid leak as the cause of chronic subdural hematomas in nongeriatric patients.

J Neurosurg 2014 Dec 18;121(6):1380-7. Epub 2014 Jul 18.

Departments of Neurosurgery.

Object: The etiology of chronic subdural hematoma (CSDH) in nongeriatric patients (≤ 60 years old) often remains unclear. The primary objective of this study was to identify spinal CSF leaks in young patients, after formulating the hypothesis that spinal CSF leaks are causally related to CSDH.

Methods: All consecutive patients 60 years of age or younger who underwent operations for CSDH between September 2009 and April 2011 at Bern University Hospital were included in this prospective cohort study. The patient workup included an extended search for a spinal CSF leak using a systematic algorithm: MRI of the spinal axis with or without intrathecal contrast application, myelography/fluoroscopy, and postmyelography CT. Spinal pathologies were classified according to direct proof of CSF outflow from the intrathecal to the extrathecal space, presence of extrathecal fluid accumulation, presence of spinal meningeal cysts, or no pathological findings. The primary outcome was proof of a CSF leak.

Results: Twenty-seven patients, with a mean age of 49.6 ± 9.2 years, underwent operations for CSDH. Hematomas were unilateral in 20 patients and bilateral in 7 patients. In 7 (25.9%) of 27 patients, spinal CSF leakage was proven, in 9 patients (33.3%) spinal meningeal cysts in the cervicothoracic region were found, and 3 patients (11.1%) had spinal cysts in the sacral region. The remaining 8 patients (29.6%) showed no pathological findings.

Conclusions: The direct proof of spinal CSF leakage in 25.9% of patients suggests that spinal CSF leaks may be a frequent cause of nongeriatric CSDH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2014.6.JNS14550DOI Listing
December 2014

In your eyes only: deficits in executive functioning after frontal TMS reflect in eye movements.

Front Behav Neurosci 2014 27;8. Epub 2014 Jan 27.

Perception and Eye Movement Laboratory, Department of Neurology and Clinical Research, University Hospital Bern Inselspital Bern, Switzerland ; Center for Cognition, Learning, and Memory, University of Bern Bern, Switzerland.

This study investigated the roles of the right and left dorsolateral prefrontal (rDLPFC, lDLPFC) and the medial frontal cortex (MFC) in executive functioning using a theta burst transcranial magnetic stimulation (TMS) approach. Healthy subjects solved two visual search tasks: a number search task with low cognitive demands, and a number and letter search task with high cognitive demands. To observe how subjects solved the tasks, we assessed their behavior with and without TMS using eye movements when subjects were confronted with specific executive demands. To observe executive functions, we were particularly interested in TMS-induced changes in visual exploration strategies found to be associated with good or bad performance in a control condition without TMS stimulation. TMS left processing time unchanged in both tasks. Inhibition of the rDLPFC resulted in a decrease in anticipatory fixations in the number search task, i.e., a decrease in a good strategy in this low demand task. This was paired with a decrease in stimulus fixations. Together, these results point to a role of the rDLPFC in planning and response selection. Inhibition of the lDLPFC and the MFC resulted in an increase in anticipatory fixations in the number and letter search task, i.e., an increase in the application of a good strategy in this task. We interpret these results as a compensatory strategy to account for TMS-induced deficits in attentional switching when faced with high switching demands. After inhibition of the lDLPFC, an increase in regressive fixations was found in the number and letter search task. In the context of high working memory demands, this strategy appears to support TMS-induced working memory deficits. Combining an experimental TMS approach with the recording of eye movements proved sensitive to discrete decrements of executive functions and allows pinpointing the functional organization of the frontal lobes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnbeh.2014.00007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3902210PMC
January 2014

Implicit task sequence learning in patients with Parkinson's disease, frontal lesions and amnesia: the critical role of fronto–striatal loops.

Neuropsychologia 2013 Dec;51(14):3014-24

The purpose of this study was to investigate the role of the fronto–striatal system for implicit task sequence learning. We tested performance of patients with compromised functioning of the fronto–striatal loops, that is, patients with Parkinson's disease and patients with lesions in the ventromedial or dorsolateral prefrontal cortex. We also tested amnesic patients with lesions either to the basal forebrain/orbitofrontal cortex or to thalamic/medio-temporal regions. We used a task sequence learning paradigm involving the presentation of a sequence of categorical binary-choice decision tasks. After several blocks of training, the sequence, hidden in the order of tasks, was replaced by a pseudo-random sequence. Learning (i.e., sensitivity to the ordering) was assessed by measuring whether this change disrupted performance. Although all the patients were able to perform the decision tasks quite easily, those with lesions to the fronto–striatal loops (i.e., patients with Parkinson's disease, with lesions in the ventromedial or dorsolateral prefrontal cortex and those amnesic patients with lesions to the basal forebrain/orbitofrontal cortex) did not show any evidence of implicit task sequence learning. In contrast, those amnesic patients with lesions to thalamic/medio-temporal regions showed intact sequence learning. Together, these results indicate that the integrity of the fronto–striatal system is a prerequisite for implicit task sequence learning.
View Article and Find Full Text PDF

Download full-text PDF

Source
December 2013

Novel CACNA1A mutation(s) associated with slow saccade velocities.

J Neurol 2013 Dec 18;260(12):3010-4. Epub 2013 Sep 18.

Perception and Eye Movement Laboratory, Departments of Clinical Research and Neurology, Inselspital, Bern University Hospital, and University of Bern, Freiburgstrasse 10, 3010, Bern, Switzerland,

Mutations in the voltage-gated Cav2.1 P/Q-type calcium channel (CACNA1A) can cause a wide spectrum of phenotypes, including the episodic ataxia type 2. Beside the growing number of descriptions of novel CACNA1A mutations with episodic ataxia type 2 phenotype; there are only rare reports on interictal oculomotor signs other than nystagmus. We describe a novel CACNA1A mutation and an unclassified CACNA1A in-frame variant in a Swiss family presenting as the episodic ataxia type 2 phenotype associated with reduced saccade velocity. In this case series interictal clinical examination showed only minimal neurological findings as mild limb ataxia and nystagmus, but most interestingly saccade analysis of all three affected individuals demonstrated reduced mean saccade velocity. Genetic testing of CACNA1A revealed a de novo frame-shift mutation (c.2691dupC/p.Thyr898Leufs 170) in the index patient in addition to an unclassified in-frame variant (c.6657_6659dupCCA/p.His2220dup) segregating in all three affected individuals. The de novo frame-shift CACNA1A mutation and the unclassified in-frame CACNA1A variant were associated with the episodic ataxia type 2 phenotype and reduced mean saccade velocity, which suggests involvement of brainstem or neural pathways connecting brainstem and the cerebellum in this disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00415-013-7099-4DOI Listing
December 2013