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Dive into the research topics where Christoph Klein is active.

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Featured researches published by Christoph Klein.


Biological Psychiatry | 2006

Intra-Subject Variability in Attention-Deficit Hyperactivity Disorder

Christoph Klein; Katharina Wendling; Paul Huettner; Hans Ruder; Martin Peper

BACKGROUND This study is based on a comprehensive survey of the neuropsychological attention-deficit hyperactivity disorder (ADHD) literature and presents the first psychometric analyses of different parameters of intra-subject variability (ISV) in patients with ADHD compared to healthy controls, using the Continuous Performance Test, a Go-NoGo task, a Stop Signal Task, as well as N-back tasks. METHODS Data of 57 patients with ADHD and 53 age- and gender-matched controls were available for statistical analysis. Different parameters were used to describe central tendency (arithmetic mean, median), dispersion (standard deviation, coefficient of variation, consecutive variance), and shape (skewness, excess) of reaction time distributions, as well as errors (commissions and omissions). RESULTS Group comparisons revealed by far the strongest effect sizes for measures of dispersion, followed by measures of central tendency, and by commission errors. Statistical control of ISV reduced group differences in the other measures substantially. One (patients) or two (controls) principal components explained up to 67% of the inter-individual differences in intra-individual variability. CONCLUSIONS Results suggest that, across a variety of neuropsychological tests, measures of ISV contribute best to group discrimination, with limited incremental validity of measures of central tendency and errors. Furthermore, increased ISV might be a unitary construct in ADHD.


Psychophysiology | 2001

Development of prosaccade and antisaccade task performance in participants aged 6 to 26 years

Christoph Klein; Fritz Foerster

There are few studies on the development of oculomotor functions during childhood. B. Fischer, M. Biscaldi, and S. Gezeck (1997) reported improvement of antisaccade task performance between ages 6 and 16 years. The present study is a replication and extension of those results. In three age groups (6-7, 10-11, 18-26 years), saccades during pro- and antisaccade tasks with 200-ms gap and overlap and during a fixation task were measured. Adults exhibited faster saccades and less prosaccades during the antisaccade tasks than 10-11-year-old children; these two groups had faster saccades during all tasks and less prosaccades during the anti- and the fixation task than 6-7-year-old subjects. Both children groups made more express saccades than adults. Results suggest different degrees of age-related improvement for different saccadic parameters, the effects being greatest for prosaccade inhibition during the antisaccade task and in line with the assumed protracted development of prefrontal functions.


Psychophysiology | 2012

Perception of effort reflects central motor command during movement execution

Helma M. de Morree; Christoph Klein; Samuele Maria Marcora

It is thought that perception of effort during physical tasks is the conscious awareness of the central motor command sent to the active muscles. The aim of this study was to directly test this hypothesis by experimentally varying perception of effort and measuring movement-related cortical potential (MRCP). Sixteen healthy, recreationally active men made unilateral dynamic elbow flexions to lift a light (20% one repetition maximum, 1RM) and a heavier (35% 1RM) weight with a fatigued arm and a nonfatigued arm while rating of perceived effort (RPE), biceps brachii electromyogram (EMG), and MRCP were recorded. RPE, EMG amplitude, and MRCP amplitude at Cz during weight raising increased with weight and with muscle fatigue. There was a significant correlation between RPE and MRCP amplitude at the vertex during the weight raising epoch. This study provides direct neurophysiological evidence that perception of effort correlates with central motor command during movement execution.


Journal of Cognitive Neuroscience | 2008

Working memory load for faces modulates p300, n170, and n250r

Helen M. Morgan; Christoph Klein; Stephan G. Boehm; Kimron L. Shapiro; David Edmund Johannes Linden

We used event-related potential (ERP) methodology to examine neural activity associated with visual working memory (WM) for faces. There were two main goals. First, to extend previous findings of P300 load modulation to WM for faces. Second, to examine whether N170 and N250r are also influenced by WM load. Between one and four unfamiliar faces were simultaneously presented for memory encoding. After a 1-sec delay, a target face appeared, and participants had to judge whether this face was part of the previous face array. P300 amplitude decreased as WM load increased, and this P300 suppression was observed at both encoding and retrieval. WM load was also found to modulate other ERPs. The amplitude of the N170 elicited by the target face decreased with load, and this N170 decrease leveled off at load 2, reflecting the behavioral WM capacity of around two faces. In addition, the N250r, observed as an ERP difference for target faces that were present in the encoding array relative to target faces that were absent, was also reduced for higher WM loads. These findings extend previous work by showing that P300 modulation by WM load also occurs for faces. Furthermore, we show, for the first time, that WM load affects the N250r and the early visual N170 component. This suggests that higher visual areas play an important role in WM for faces.


Experimental Brain Research | 2000

Optomotor and neuropsychological performance in old age

Christoph Klein; Burkhart Fischer; Klaus Hartnegg; W. H. Heiss; Markus Roth

While a delayed initiation of visually guided saccades with increasing age has been documented in a number of studies, little research has been done on the control of antisaccades. The present study investigates aging effects on the control of visually guided saccades (prosaccades) and antisaccades as well as a selection of neuropsychological functions by the cross-sectional comparison of 14, 22, and 16 participants aged 20–35 years, 59–73 years, and 74–88 years, respectively. The geriatric and neurological status of the elder participants (including evidence from computed tomography, electroencephalography, and neurological soft signs) was assessed. In four task blocks of 200 trials each, pro- and antisaccades were elicited under the 200-ms-gap and overlap conditions. Left- and right-sided stimuli were presented in random order at 4°, and the order of the task blocks was varied within each age group. In addition, the Wisconsin card-sorting test (WCST) and working memory, go-nogo discrimination, alertness, and stimulus-response incompatibility tests were administered. Participants aged 59–73 years exhibited widespread reductions of optomotor and neuropsychological performance, with greatest effect sizes of age differences in the optomotor parameters and the WCST measures. A further decay after the age of 73 years was discernible in those optomotor functions reflecting saccade disinhibition (in particular, directional errors during the antisaccade task and premature responses) and the performance in some neuropsychological tests. In line with previously published reports, variance in optomotor performance could be explained by two factors, accounting for a total of 76% of the age variance. Our results suggest that the investigation of saccade control may be a highly sensitive tool for neurodevelopmental aging research.


Biological Psychiatry | 2000

Impaired modulation of the saccadic contingent negative variation preceding antisaccades in schizophrenia.

Christoph Klein; Theda Heinks; Burghard Andresen; Patrick Berg; Steffen Moritz

BACKGROUND The contingent negative variation (CNV) is considered to reflect prefrontal functioning and can be observed before manual and ocular motor responses. Schizophrenic patients exhibit reduced CNV amplitudes in tasks requiring manual motor responses. A number of studies has also found normal prosaccades, but delayed antisaccades and an augmented rate of erroneous prosaccades during the antisaccade task in schizophrenia. In this study we examined the CNV during pro- and antisaccade tasks in schizophrenic patients and healthy control subjects. METHODS Data of 17 medicated schizophrenics (ICD-10, F20) and 18 control subjects, matched with patients for age, gender, and education were analyzed. Horizontal pro- and antisaccades were elicited in four blocks, each consisting of 80 trials. Electroencephalogram was recorded from 32 channels with a DC amplifier. RESULTS Patients exhibited delayed correct responses and more erroneous prosaccades during the antisaccade task than control subjects, but normal prosaccadic reaction times. In control subjects, the vertex-predominant saccadic CNV was generally larger than in patients, and larger during the anti- than during the prosaccade task. This task-related amplitude augmentation was absent in patients. Analyses of additional components suggested specificity of impaired event-related potential modulation to the saccadic CNV. CONCLUSIONS In accordance with the presumed prefrontal dysfunction, our results suggest deficient preparation and execution of antisaccades in schizophrenia.


Biological Psychology | 2010

On the functional significance of Novelty-P3: facilitation by unexpected novel sounds.

Iria SanMiguel; Helen M. Morgan; Christoph Klein; David Edmund Johannes Linden; Carles Escera

The unexpected occurrence of a change in the auditory context has been shown to result in distraction due to a momentary attention shift. These unexpected sounds elicit the Novelty-P3 (NP3) response which has been proposed as an electrophysiological index of distractibility, and used as such in the evaluation of several clinical populations. However, unexpected sounds also result in facilitation under certain conditions. Here, we investigate the electrophysiological concomitants of novel sounds in a task in which these sounds facilitate visual task performance. Novel sounds elicited NP3 and resulted in an enhancement of the visual P300 response to subsequent visual targets. This result clearly argues against the use of NP3 as an index of distractibility and asks for a reformulation of the functional significance of this response. We suggest that the NP3 is a complex signal that comprises alerting, orienting and executive control processes triggered by the unexpected stimulus.


Journal of Abnormal Psychology | 2014

Specificity of affective instability in patients with borderline personality disorder compared to posttraumatic stress disorder, bulimia nervosa, and healthy controls.

Philip Santangelo; Iris Reinhard; Lutz Mussgay; Regina Steil; Günther Sawitzki; Christoph Klein; Timothy J. Trull; Martin Bohus; Ulrich Ebner-Priemer

Affective instability is a core feature of borderline personality disorder (BPD). The use of advanced assessment methodologies and appropriate statistical analyses has led to consistent findings that indicate a heightened instability in patients with BPD compared with healthy controls. However, few studies have investigated the specificity of affective instability among patients with BPD with regard to relevant clinical control groups. In this study, 43 patients with BPD, 28 patients with posttraumatic stress disorder (PTSD), 20 patients with bulimia nervosa (BN), and 28 healthy controls carried e-diaries for 24 hours and were prompted to rate their momentary affective states approximately every 15 minutes while awake. To quantify instability, we used 3 state-of-the-art indices: multilevel models for squared successive differences (SSDs), multilevel models for probability of acute changes (PACs), and aggregated point-by-point changes (APPCs). Patients with BPD displayed heightened affective instability for emotional valence and distress compared with healthy controls, regardless of the specific instability indices. These results directly replicate earlier studies. However, affective instability did not seem to be specific to patients with BPD. With regard to SSDs, PACs, and APPCs, patients with PTSD or BN showed a similar heightened instability of affect (emotional valence and distress) to that of patients with BPD. Our results give raise to the discussion if affective instability is a transdiagnostic or a disorder-specific mechanism. Current evidence cannot answer this question, but investigating psychopathological mechanisms in everyday life across disorders is a promising approach to enhance validity and specificity of mental health diagnoses.


Journal of Neurophysiology | 2012

Mapping brain activation and information during category-specific visual working memory

David Edmund Johannes Linden; Nikolaas N. Oosterhof; Christoph Klein; Paul E. Downing

How is working memory for different visual categories supported in the brain? Do the same principles of cortical specialization that govern the initial processing and encoding of visual stimuli also apply to their short-term maintenance? We investigated these questions with a delayed discrimination paradigm for faces, bodies, flowers, and scenes and applied both univariate and multivariate analyses to functional magnetic resonance imaging (fMRI) data. Activity during encoding followed the well-known specialization in posterior areas. During the delay interval, activity shifted to frontal and parietal regions but was not specialized for category. Conversely, activity in visual areas returned to baseline during that interval but showed some evidence of category specialization on multivariate pattern analysis (MVPA). We conclude that principles of cortical activation differ between encoding and maintenance of visual material. Whereas perceptual processes rely on specialized regions in occipitotemporal cortex, maintenance involves the activation of a frontoparietal network that seems to require little specialization at the category level. We also confirm previous findings that MVPA can extract information from fMRI signals in the absence of suprathreshold activation and that such signals from visual areas can reflect the material stored in memory.


Journal of Applied Physiology | 2014

Cortical substrates of the effects of caffeine and time-on-task on perception of effort

Helma M. de Morree; Christoph Klein; Samuele Maria Marcora

Caffeine intake results in a decrease in perception of effort, but the cortical substrates of this perceptual effect of caffeine are unknown. The aim of this randomized counterbalanced double-blind crossover study was to investigate the effect of caffeine on the motor-related cortical potential (MRCP) and its relationship with rating of perceived effort (RPE). We also investigated whether MRCP is associated with the increase in RPE occurring over time during submaximal exercise. Twelve healthy female volunteers performed 100 intermittent isometric knee extensions at 61 ± 5% of their maximal torque 1.5 h after either caffeine (6 mg/kg) or placebo ingestion, while RPE, vastus lateralis electromyogram (EMG), and MRCP were recorded. RPE and MRCP amplitude at the vertex during the first contraction epoch (0-1 s) were significantly lower after caffeine ingestion compared with placebo (P < 0.05) and were significantly higher during the second half of the submaximal intermittent isometric knee-extension protocol compared with the first half (P < 0.05). No significant effects of caffeine and time-on-task were found for EMG amplitude and submaximal force output variables. The covariation between MRCP and RPE across both caffeine and time-on-task (r10 = -0.335, P < 0.05) provides evidence in favor of the theory that perception of effort arises from neurocognitive processing of corollary discharges from premotor and motor areas of the cortex. Caffeine seems to reduce perception of effort through a reduction in the activity of cortical premotor and motor areas necessary to produce a submaximal force, and time-on-task has the opposite effect.

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Bernd Feige

University of Freiburg

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Stephan Bender

Goethe University Frankfurt

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