Papers by Ysbrand Van Der Werf
In spite of the acknowledged role that the thalamus plays in declarative memory, details about th... more In spite of the acknowledged role that the thalamus plays in declarative memory, details about the precise memory processes it is involved in and which are the structures of the thalamus that contribute to these processes remain unknown. An overview is presented of human clinical and animal experimental findings showing the involvement of the thalamus, at the level of white
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From a review of the literature on the consequences of thalamic infarctions, it may be concluded ... more From a review of the literature on the consequences of thalamic infarctions, it may be concluded that memory problems taking the form of an amnesic syndrome are dependent upon the integrity of the mammillo-thalamic tract (MTT). Memory problems incompatible with an amnesic syndrome however, appear to result from thalamic infarctions involving other areas of the thalamus but which leave MTT
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American Journal of Epidemiology, 2009
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Human Brain Mapping, 2015
Recent studies have shown that response inhibition is impaired in patients with obsessive-compuls... more Recent studies have shown that response inhibition is impaired in patients with obsessive-compulsive disorder and their unaffected siblings, suggesting that these deficits may be considered a cognitive endophenotype of obsessive-compulsive disorder. Structural and functional neural correlates of altered response inhibition have been identified in patients and siblings. This study aims to examine the functional integrity of the response inhibition network in patients with obsessive-compulsive disorder and their unaffected siblings. Forty-one unmedicated patients with obsessive-compulsive disorder, 17 of their unaffected siblings and 37 healthy controls performed a stop signal task during functional magnetic resonance imaging. Psycho-physiological interaction analysis was used to examine functional connectivity between the following regions of interest: the bilateral inferior frontal gyri, presupplementary motor area, subthalamic nuclei, inferior parietal lobes, anterior cingulate cortex, and amygdala. We then used dynamic causal modeling to investigate the directionality of the networks involved. Patients, and to a lesser extent also their unaffected siblings, show altered connectivity between the inferior frontal gyrus and the amygdala during response inhibition. The follow-up dynamic causal modeling suggests a bottom-up influence of the amygdala on the inferior frontal gyrus in healthy controls, whereas processing occurs top-down in patients with obsessive-compulsive, and in both directions in siblings. Our findings suggest that amygdala activation in obsessive-compulsive disorder interferes differently with the task-related recruitment of the inhibition network, underscoring the role of limbic disturbances in cognitive dysfunctions in obsessive-compulsive disorder. Hum Brain Mapp, 2015. © 2015 Wiley Periodicals, Inc.
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Cerebral cortex (New York, N.Y. : 1991), 2015
The hippocampus and cerebellum play a role in the process of temporal memory formation. The inter... more The hippocampus and cerebellum play a role in the process of temporal memory formation. The interaction between these brain regions during the prediction of motor executions nevertheless remains unclear. Using fMRI, we show here that the hippocampus and cerebellum are co-activated during a timing-dependent task that requires accurate prediction timing of finger movements following preceding visual cues, but not during 2 control tasks: a reaction task requiring identical coordination of individual and combined fingers without predicting the motor timing, or an imagery task. In addition, functional connectivity analyses reveal that the hippocampus showed increased functional connectivity with the bilateral hemispheres of the cerebellum. These results suggest that hippocampal-cerebellar interplay occurs during spatio-temporal prediction of movements on the basis of visuomotor integration.
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Neurology, Jan 26, 2014
To examine brain activation patterns during verbal fluency performance in patients with progressi... more To examine brain activation patterns during verbal fluency performance in patients with progressive muscular atrophy (PMA) and amyotrophic lateral sclerosis (ALS). fMRI was used to examine the blood oxygen level-dependent response during letter and category fluency performance in 18 patients with PMA, 21 patients with ALS, and 17 healthy control subjects, matched for age and education. fMRI results are reported at p<0.05, family-wise error (FWE)-corrected for multiple comparisons. We analyzed effects of performance, age-related white matter changes (ARWMC), and regional brain volumes; all participants underwent neuropsychological investigation. Disease duration of patients with PMA (mean 26.0 months, SD 13.6) and ALS (22.2 months, SD 11.4) was comparable. Patients with PMA and ALS had mild to moderate disease severity and showed impaired letter fluency compared with controls. Between-group analysis showed a main effect of group in the left inferior frontal gyrus (IFG, Brodmann ar...
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Progress in brain research, 2011
Total sleep deprivation in healthy subjects has a profound effect on the performance on tasks mea... more Total sleep deprivation in healthy subjects has a profound effect on the performance on tasks measuring sustained attention or vigilance. We here report how a selective disruption of deep sleep only, that is, selective slow-wave activity (SWA) reduction, affects the performance of healthy well-sleeping subjects on several tasks: a "simple" and a "complex" vigilance task, a declarative learning task, and an implicit learning task despite unchanged duration of sleep. We used automated electroencephalogram (EEG) dependent acoustic feedback aimed at selective interference with-and reduction of-SWA. In a within-subject repeated measures crossover design, performance on the tasks was assessed in 13 elderly adults without sleep complaints after either SWA-reduction or after normal sleep. The number of vigilance lapses increased as a result of SWA reduction, irrespective of the type of vigilance task. Recognition on the declarative memory task was also affected by SWA re...
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Journal of neural transmission. Supplementum, 2007
Transcranial magnetic stimulation is a tool in the neurosciences to study motor functions and ner... more Transcranial magnetic stimulation is a tool in the neurosciences to study motor functions and nervous disorders, amongst others. Single pulses of TMS applied over the primary motor cortex lead to a so-called cortical silent period in the recording from the corresponding muscle, i.e. a period of approximately 100ms with no muscle activity. We here show that in Parkinson's disease (PD), this cortical silent period in some cases is interrupted by short bursts of EMG activity. We describe in detail these interruptions in two patients with PD. These interruptions may number up to 3 per cortical silent period and show a consistent frequency across trials and hemispheres within a given patient; the two patients described here do differ, however, in the time-delay of the interruptions and hence the induced frequency. For one patient, the frequency of the interruptions proved to be around 13 Hz, the other patient showed a frequency of around 17 Hz. The results corroborate earlier finding...
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Progress in Brain Research, 2010
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Frontiers in Human Neuroscience, 2014
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Cognitive Brain Research, 2001
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Slow Brain Oscillations of Sleep, Resting State and Vigilance, 2011
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Parkinsonism & Related Disorders, 2014
Anxiety disorders are highly prevalent in patients with Parkinson&amp;amp;amp;amp;amp;amp;amp... more Anxiety disorders are highly prevalent in patients with Parkinson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease (PD) and have a major impact on wellbeing. They nevertheless receive limited scientific attention. This study aimed to establish the symptom dimensions of anxiety in PD, and their relationship with depression, autonomic failure and motor symptoms. In this cross-sectional observational study, symptoms of anxiety were measured with the Beck Anxiety Inventory (BAI) in 294 PD patients. Symptom dimensions of anxiety in PD were explored through principal component analysis (PCA) of BAI items. The relationship between anxiety and depressive, autonomic and motor symptoms was assessed through PCA and regression analyses. Clinically relevant symptoms of anxiety were present in 45% of patients. PCA of the BAI resulted in five subscales, corresponding to a single affective and four somatic symptom dimensions (thermoregulation, hypotension, hyperventilation and trembling) of anxiety. Symptoms of anxiety and depression displayed a large overlap. All somatic BAI subscales were significantly influenced by motor and autonomic symptoms, while the affective subscale was not. Anxiety in PD comprises affective and somatic symptom dimensions. The affective subscale of the BAI is not influenced by motor or autonomic symptoms, and may therefore prove useful for future research. Scores on the somatic subscales of the BAI were associated with autonomic failure and motor impairment, demonstrating a strong interplay between motor and non-motor symptoms in PD. These results stress the importance of a holistic approach of anxiety in PD.
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Neurobiology of aging, 2015
Behavioral impairments in response inhibition and initiation are common in Parkinson's diseas... more Behavioral impairments in response inhibition and initiation are common in Parkinson's disease (PD) and are associated with reduced impulse control. No prior study, however, has investigated the functional correlates of response inhibition in de novo PD. Twenty-one de novo PD patients and 37 matched healthy controls performed a stop-signal task during functional magnetic resonance imaging. The results showed that PD patients, compared with healthy controls, were slower on response initiation but not inhibition. Task-related activation of the response inhibition network, including the inferior frontal gyrus, was reduced in PD patients, and the activity in the inferior frontal gyrus correlated negatively with motor symptom severity. These findings show that de novo PD patients exhibit functional deficits in the response inhibition network, which are partly related to disease pathology and already evident before commencing dopamine replacement therapy. This study provides insights ...
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SLEEP, 2000
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Parkinsonism & Related Disorders, 2006
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Neuropsychologia, 2000
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Neuropsychologia, 2003
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NeuroImage, 2011
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Nature Neuroscience, 2009
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Papers by Ysbrand Van Der Werf