Klaus Willmes | RWTH Aachen University (original) (raw)

Papers by Klaus Willmes

Clinical Neurophysiology, May 1, 2022

Journal of cognitive psychology, Feb 17, 2017

Quarterly Journal of Experimental Psychology, Mar 7, 2023

A growing body of research suggests that basic numerical abilities such as number magnitude and n... more A growing body of research suggests that basic numerical abilities such as number magnitude and number parity processing are influenced by cognitive control. So far, however, evidence for number processing being influenced by cognitive control came primarily from observed adaptations to stimulus set characteristics (e.g., ratio or order of specific stimulus types) and switches between a numerical and non-numerical task. Complementing this previous research, the present study employed a task switching paradigm exclusively involving numerical tasks (i.e., magnitude comparisons and parity judgements) to examine how cognitive control processes influence number processing. Participants were presented with a single-digit number and had to either judge its parity or compare its magnitude with a standard of 5, depending on a preceding cue. Based on previous results, we expected the numerical distance effect and the spatial–numerical association of response codes (SNARC) effect to be modulated in switch trials requiring the exertion of cognitive control. Partly in line with our expectations, the numerical distance effect was reduced in switch trials. However, no modulation of the SNARC effect was observed. The results pattern suggests that number processing is influenced by cognitive control, depending on task requirements and the type of numerical information (i.e., numerical magnitude vs spatial association of numbers) that is processed. To reconcile the present and previous results, we propose an information prioritisation account, suggesting that cognitive control primarily influences the processing of the information type that requires the most explicit processing.

Psychology Press eBooks, 1997

K. Willmes, G. Deloche, Methodological Issues in Neuropsychological Assessment and Rehabilitation... more K. Willmes, G. Deloche, Methodological Issues in Neuropsychological Assessment and Rehabilitation. C. Bergego, P. Azouvi, G. Deloche, C. Samuel, A. Louis-Dreyfus, R. Kaschel, K. Willmes, Rehabilitation of Unilateral Neglect: A Controlled Multiple-Baseline-Across-Subjects Trial Using Computerised Training Procedures. E. Capitani, Normative Data and Neurospychological Assessment. Common Problems in Clinical Practice and Research. S. Carlomagno, P. van Eeckhout, V. Blasi, P. Bellin, Y. Samson, G. Deloche, The Impact of Functional Neuroimaging Methods on the Development of a Theory for Cognitive Remediation. R. Castro -Caldas, A. Reis, M. Guerreiro, Neuropsychological Aspects of Illiteracy. R. De Bleser, J. Cholewa, N. Stadie, S. Tabatabaie, Lemo, an Expert System for Single Case Assessment of Word Processing Impairments in Aphasic Patients. S. Della Sala, R.H. Logie, Impairments of Methodology and Theory in Cognitive Neuropsychology: A Case for Rehabilitation? G. Dellatolas, P. Tubert-Bitter, F. Curt, M. de Agostini, Evolution of Degree and Direction of Hand Preference in Children: Methodological and Theoretical Issues. S. Franklin, Designing Single Case Treatment Studies for Aphasic Patients. H. Guyard, V. Masson, R. Quiniou, E. Siou, Expert Knowledge for Aculculia Assessmnet and Rehabilitation. M.J. Watson, S. Horn, B.A. Wilson, A. Shiel, L. McLellan, The Application of a Paired Comparisons Technique to Identify Sequence of Recovery After Severe Head Injury. Contents Listing, Volume 7. Cumulative Author Index. Cumulative Subject Index.

Journal of stroke and cerebrovascular diseases, Oct 1, 2018

Journal of Neurology, 1994

Sprache-stimme-gehor, Jun 16, 2015

Nuklearmedizin-nuclear Medicine, 1995

Zusammenfassung51 Patienten mit zerebraler Mikroangiopathie wurden mittels Kernspintomographie, 1... more Zusammenfassung51 Patienten mit zerebraler Mikroangiopathie wurden mittels Kernspintomographie, 18FDG-PET und 99mTc-HMPAO-SPECT untersucht. Die genaue Zuordnung funktioneller zu den morphologischen Befunden wurde durch ein spezielles Kopf-halterungssystem für PET, SPECT- und KST-Untersuchungen hergestellt. Patienten mit weniger als vier lakunären Infarkten (LI) und ohne bis geringfügigen Deep White Matter Lesions (DWML) im KST wiesen keine signifikant veränderten Werte für rMRGIu und rCBF in grauer oder weißer Substanz auf im Vergleich zu Patienten mit vier oder mehr LI und ausgedehnten DWML. Eine semiquantitative Einteilung der Atrophie (A: keine bis geringfügige; B: mäßige bis schwere) erbrachte für B) im Vergleich zu A) signifikant erniedrigte rCBF- und rMRGIu-Werte in grauer und weißer Substanz. Somit sind bei Patienten mit ZMA nur die Hirnatrophie, jedoch nicht die charakteristischen LI und DWML mit einer meßbaren Erniedrigung von rCBF und rMRGIu korreliert.

Infant Behavior & Development, Feb 1, 2020

Preterm infants are at risk of experiencing difficulties in their feeding development. For a poss... more Preterm infants are at risk of experiencing difficulties in their feeding development. For a possible early identification of these, we examined the association between sucking patterns, assisted spoon feeding, and chewing skills in 40 healthy preterm infants, and the role of experience in the acquisition of these skills in a prospective longitudinal study. Sucking patterns were evaluated at 34, 37, and 44 weeks postmenstrual age (PMA), assisted spoon feeding was evaluated at 6, 9, and 12 months PMA, and chewing was evaluated at 9, 12, and 24 months PMA. Sucking patterns were rated using the Neonatal Oral Motor Assessment Scale, assisted spoon feeding was rated using the Observation List Spoon Feeding, and chewing was evaluated using the Mastication Observation and Evaluation Instrument. All infants showed progression in their oral motor skills during the study period, but not all demonstrated a stable progression of skills. Quality of sucking patterns was not associated with skill level achievement of assisted spoon feeding or with chewing. Length of experience in sucking was significantly associated with duration of supplemental tube feeding but not with the quality of the sucking pattern. Length of chewing experience was significantly associated with chewing abilities at 9 and 12 months PMA. No clinical characteristics were sufficiently predictive of oral motor skill development. Results show that sucking patterns are not predictive of subsequent feeding development in healthy preterm infants. The food consistency offered and the length of feeding experience influenced the acquisition and quality of oral motor skills differently.

Brain Structure & Function, May 22, 2019

Functional imaging data suggest different regions for semantic, syntactic, and phonological proce... more Functional imaging data suggest different regions for semantic, syntactic, and phonological processing in an anterior-toposterior direction along the inferior frontal gyrus. Language mapping by use of neuro-navigated transcranial magnetic stimulation (TMS) is frequently applied in clinical research to identify language-related cortical regions. Recently, we proposed a high spatial resolution approach for more detailed language mapping of cortical sub-areas such as Broca's region. Here, we employed a phonological picture-word interference paradigm in healthy subjects to reveal functional specialization in Broca's region for phonological processing. The behavioral phonological priming effect is characterized by accelerated naming responses to target pictures accompanied by phonologically related auditory distractor words. We hypothesized that the inhibitory effects of TMS on language processing would reduce phonological priming only at stimulation sites involved in phonological processing. In active as compared to sham TMS, we found reduced phonological facilitation specifically at sites overlapping with the probabilistic cytoarchitectonic area 44. Our findings complemented functional imaging data by revealing structure-function relationship in Broca's region. The introduction of a reaction time based interference paradigm into TMS language mapping increases the objectivity of the method and allows to explore functional specificity with high temporal resolution. Findings may help to interpret results in clinical applications.

Proceedings of SPIE, May 20, 1999

ABSTRACT Functional Magnetic Resonance Imaging (fMRI) data of the brain includes activated parenc... more ABSTRACT Functional Magnetic Resonance Imaging (fMRI) data of the brain includes activated parenchymal voxels, corresponding to the paradigm performed, non-activated parenchymal voxels and background voxels. Statistical tests, e.g. using the general linear model approach of SPM or the Kolmogorov-Smirnov (KS) non-parametric statistic, are common 'supervised' techniques to look for activation in functional brain MRI. Selection of voxel type by comparing the voxel time course with a model of the expected hemodynamic response function (HRF) from the task paradigm has proven to be difficult due to individual and spatial variance of the measured HRF. For the functional differentiation of brain voxels we introduce a method separating brain voxels based on their features in the time domain using a self-organizing map (SOM) neural network technique without modeling the HRF. Since activation measured by fMRI is related to magnetic susceptibility changes in venous blood which represents only 2 - 5% of brain matter, preprocessing is required to remove the majority of non- activated voxels which dominate learning instead of real activation patterns. Using the auto-correlation function one can select voxels which are candidates of being activated. Features of the time course of the selected voxels can be learned with the SOM. In the first step the SOM is trained by the voxels time course, fitting its neurons to the input. After learning, the neurons have adapted to the intrinsic features space of the voxel time courses. Using the trained SOM, voxel time courses are presented again, now labeled by the neuron having the smallest Euclidean distance to the presented voxel time course. The result of the labeling and the learned feature time course vectors are compared visually with the p-value map of the KS statistic. With the SOM map one can visually separate the voxels based on their features in the time domain into different functional task related classes.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

International Journal of Speech-Language Pathology, Apr 30, 2020

Neurotoxicology, Dec 1, 2017

HighlightsA significant effect of PCBs on word fluency and sensorimotor processing is described.L... more HighlightsA significant effect of PCBs on word fluency and sensorimotor processing is described.Lower chlorinated PCBs (LPCBS) have a negative impact on word generation.LPCBs are associated with a time‐on‐task effect in word fluency.Higher chlorinated PCBs and dioxin‐like PCBs show adverse effects on motor function.PCB‐induced neurotoxic effects on dopamine and norepinephrine are suggested. &NA; In the context of a health surveillance program for former PCB‐exposed workers of a transformer and capacitor recycling company in Germany, their family members, employees of surrounding companies and area residents a broad range of cognitive functions covering attention, executive processing, reasoning, memory and motor performance was examined. The study aimed at identifying potential adverse effects of PCB load on cognitive functions. Detailed analysis of PCB burden of the participants revealed rather high correlations of lower and higher chlorinated as well as dioxin‐like PCBs. Nearly one half of the participants exhibited increased burden in all three PCB classes whereas only 33 out of 237 participants did not show any increased PCB burden. Thus, data analysis followed a two‐fold strategy: (1) Based on studies providing data on PCB exposure of the German general population the PCB burden of every participant was classified as normal (percentile rank PR <95) or increased (PR ≥95). Increased burden with respect to lower (LPCBs) and higher chlorinated (HPCBs) as well as dioxin‐like (dlPCBs) PCBs was assumed if a participant showed at least one congener surpassing the PR95 criterion for the respective congener class and (2) Overall plasma PCB level per congener class was used as measure of PCB load. In a multivariate approach using structural equation modelling and multiple regression analysis we found a significant impact of PCBs on word fluency and sensorimotor processing irrespective of the measure of PCB burden (PR95 criterion or overall plasma level). However, no effect of PCB burden on memory, attention, and cognitive flexibility could be demonstrated. Particularly, an increase of LPCBs was associated with an overall reduction of verbal fluency of letter and semantic word generation as well as word production based on a single or two alternating criteria. In addition, participants with increased burden of LPCBs exhibited a time‐on‐task effect in terms of a stronger decline of performance with increasing duration of the verbal fluency task. Moreover, we found adverse effects of HPCBs on Aiming and of dlPCBs on Line Tracking. Results are discussed in terms of (1) a decrease of cerebral dopamine (DA) with non‐coplanar PCBs resulting in an impact on fronto‐striatal cerebral structures subserving verbal fluency and motor processing, (2) a PCB‐induced reduction of norepinephrine leading to the time‐on‐task effect with verbal fluency, and (3) adverse effects of PCBs on dopaminergic receptors in the cerebellum resulting in impaired fine motor function.

NeuroImage: Clinical, 2019

Previous lesion studies suggest that semantic and phonological fluency are differentially subserv... more Previous lesion studies suggest that semantic and phonological fluency are differentially subserved by distinct brain regions in the left temporal and the left frontal cortex, respectively. However, as of yet, this often implied double dissociation has not been explicitly investigated due to mainly two reasons: (i) the lack of sufficiently large samples of brain-lesioned patients that underwent assessment of the two fluency variants and (ii) the lack of tools to assess interactions in factorial analyses of non-normally distributed behavioral data. In addition, previous studies did not control for task resource artifacts potentially introduced by the generally higher task difficulty of phonological compared to semantic fluency. We addressed these issues by task-difficulty adjusted assessment of semantic and phonological fluency in 85 chronic patients with ischemic stroke of the left middle cerebral artery. For classical region-based lesion-behavior mapping patients were grouped with respect to their primary lesion location. Building on the extension of the non-parametric Brunner-Munzel rank-order test to multi-factorial designs, ANOVA-type analyses revealed a significant two-way interaction for cue type (semantic vs. phonological) by lesion location (left temporal vs. left frontal vs. other as stroke control group). Subsequent contrast analyses further confirmed the proposed double dissociation by demonstrating that (i) compared to stroke controls, left temporal lesions led to significant impairments in semantic but not in phonological fluency, whereas left frontal lesions led to significant impairments in phonological but not in semantic fluency, and that (ii) patients with frontal lesions showed significantly poorer performance in phonological than in semantic fluency, whereas patients with temporal lesions showed significantly poorer performance in semantic than in phonological fluency. The anatomical specificity of these findings was further assessed in voxel-based lesion-behavior mapping analyses using the multi-factorial extension of the Brunner-Munzel test. Voxel-wise ANOVA-type analyses identified circumscribed parts of left inferior frontal gyrus and left superior and middle temporal gyrus that significantly double-dissociated with respect to their differential contribution to phonological and semantic fluency, respectively. Furthermore, a main effect of lesion with significant impairments in both fluency types was found in left inferior frontal regions adjacent to but not overlapping with those showing the differential effect for phonological fluency. The present study hence not only provides first explicit evidence for the anatomical double dissociation in verbal fluency at the group level but also clearly underlines that its formulation constitutes an oversimplification as parts of left frontal cortex appear to contribute to both semantic and phonological fluency.

Aphasiology, Nov 11, 2021