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ABSTRACT: PURPOSE: Behavioural studies of attention training after brain damage have shown that only training procedures specifically related to the impaired attention function lead to significant improvements in the respective attention domain when using psychometric tests addressing these functions. The main objective of this fMRI study was to investigate specific as well as common neural correlates of alertness and focused attention and to assess the degree of neural overlap for two different tasks of the same attention function. METHODS: To investigate how different attention functions are processed, we tested 32 healthy participants using fMRI. Each participant was randomly assigned to the alertness (n = 16) or the focused attention (n = 16) group, where participants underwent two different attention tasks, one being a diagnostic computerized test procedure and the other being a computer-game like training procedure. RESULTS: The present results show similar activation patterns when assessing the same attention function with two different tasks. Activation overlap for test and training tasks of the same attention function was more clear-cut than the activation overlap for two different attention functions. CONCLUSIONS: Clinically validated diagnostic test paradigms and computer game-like training paradigms for both alertness and focused attention activated common brain systems processing the respective attention function. These findings may help to explain the beneficial effect of specifically designed attentional training procedures and the validity of related psychometric tests in detecting specific changes in performance after training of the same attention functions.
Restorative neurology and neuroscience 02/2013; · 2.51 Impact Factor
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ABSTRACT: The auditory mismatch responses are elicited in absence of directed attention but are thought to reflect attention modulating effects. Little is known however, if the deviants in a stream of standards are specifically directing attention across modalities and how they interact with other attention directing signals such as emotions. We applied the well-established paradigm of left- or right-lateralized deviant syllables within a dichotic listening design. In a simple target detection paradigm with lateralized visual stimuli, we hypothesized that responses to visual stimuli would be speeded after ignored auditory deviants on the same side. Moreover, stimuli with negative valence in the visual domain could be expected to reduce this effect due to attention capture for this emotion, resulting in speeded responses to visual stimuli even when attention was directed to the opposite side by the auditory deviant beforehand. Reaction times of 17 subjects confirmed the speeding of responses after deviant events. However, reduced facilitation was observed for positive targets at the left after incongruent deviants, i.e., at the right ear. In particular, significant interactions of valence and visual field and of valence and spatial congruency emerged. Pre-attentive auditory processing may modulate attention in a spatially selective way. However, negative valence processing in the right hemisphere may override this effect. Resource allocation such as spatial attention is regulated dynamically by multimodal and emotion information processing.
Frontiers in Behavioral Neuroscience 01/2013; 7:6.
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ABSTRACT: Hemodynamic mismatch responses can be elicited by deviant stimuli in a sequence of standard stimuli even during cognitive demanding tasks. Emotional context is known to modulate lateralized processing. Right-hemispheric negative emotion processing may bias attention to the right and enhance processing of right-ear stimuli. The present study examined the influence of induced mood on lateralized pre-attentive auditory processing of dichotic stimuli using functional magnetic resonance imaging (fMRI). Faces expressing emotions (sad/happy/neutral) were presented in a blocked design while a dichotic oddball sequence with consonant-vowel (CV) syllables in an event-related design was simultaneously administered. Twenty healthy participants were instructed to feel the emotion perceived on the images and to ignore the syllables. Deviant sounds reliably activated bilateral auditory cortices and confirmed attention effects by modulation of visual activity. Sad mood induction activated visual, limbic and right prefrontal areas. A lateralization effect of emotion-attention interaction was reflected in a stronger response to right-ear deviants in the right auditory cortex during sad mood. This imbalance of resources may be a neurophysiological correlate of laterality in sad mood and depression. Conceivably, the compensatory right-hemispheric enhancement of resources elicits increased ipsilateral processing.
PLoS ONE 01/2012; 7(2):e31936. · 4.09 Impact Factor
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ABSTRACT: Functional cerebral asymmetries (FCAs) in women have been shown to vary with changing levels of sex hormones during the menstrual cycle. Previous studies have suggested that interhemispheric interaction forms a key component in generating FCAs and it has been shown behaviorally and by functional imaging that interhemispheric interaction changes during the menstrual cycle, at least for a left hemisphere dominant task. We used functional MRI and an analysis of functional connectivity to examine whether changes in right hemisphere advantage for a figure comparison task as found in behavioral studies, are based on comparable mechanisms like those identified for the verbal task. Women were examined three times during the menstrual cycle, during the menstrual, follicular and luteal phases. The behavioral data confirmed the right hemisphere advantage for the figure comparison task as well as changes of the right hemisphere advantage during the menstrual cycle. Imaging data showed cycle phase-related changes in lateralized brain activation within the task-dominant hemisphere and changes in connectivity between nonhomotopic areas of both hemispheres, suggesting that changes in functional brain organization in women during the menstrual cycle are not only restricted to hormone-related changes of interhemispheric inhibition between homotopic areas, as has been proposed earlier, but might additionally apply to changes of neuronal processes within the hemispheres which seem to be modulated by heterotopic functional connectivity between hemispheres.
Human Brain Mapping 10/2011; 32(10):1544-56. · 5.88 Impact Factor
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ABSTRACT: Previous brain imaging studies identified the neural networks underlying free choice of self-initiated actions. In contrast, the neural mechanisms underlying free choice of external objects remain to be elucidated. In this event-related functional magnetic resonance imaging study, participants had to choose one out of two different single-colored target squares presented at two of three possible locations. In 50% of the trials the choice was either free or specified, which was indicated by a preceding cue. In order to disentangle processes associated with object choice from those related to motor responses, object-response mapping was orthogonally varied. Processes related to the freedom of choice were isolated by means of an adaptive algorithm: based on the subjects individual choices in the free trials, specified trials were continuously generated in a way that matched the free trials in all aspects but the freedom to choose the object. Comparing free and specified trials revealed enhanced neural activity of a bilateral symmetrical network including the dorsolateral prefrontal, medial frontal, and medial parietal cortex. This network overlaps with that shown previously to be associated with free motor selection. It includes the pre-supplementary motor area (pre-SMA), suggesting that this area is rather associated with a supramodal function of initiating choice than with a specific motor function. Neural activity specifically associated with the freedom to choose an object was found bilaterally in the lateral superior parietal cortex. A psychophysiological interaction (PPI) analysis showed increased functional connectivity of this area with bilateral areas of the extrastriate visual cortex. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Human Brain Mapping 09/2011; 33(11):2686-93. · 5.88 Impact Factor
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ABSTRACT: Valid expectations are known to improve target detection, but the preparatory attentional mechanisms underlying this perceptual facilitation remain an open issue. Using functional magnetic resonance imaging, we show here that expecting auditory, tactile, or visual targets, in the absence of stimulation, selectively increased baseline activity in corresponding sensory cortices and decreased activity in irrelevant ones. Regardless of sensory modality, expectancy activated bilateral premotor and posterior parietal areas, supplementary motor area as well as right anterior insula and right middle frontal gyrus. The bilateral putamen was sensitive to the modality specificity of expectations during the unexpected omission of targets. Thus, across modalities, detection improvement arising from selectively directing attention to a sensory modality appears mediated through transient changes in pretarget activity. This flexible advance modulation of baseline activity in sensory cortices resolves ambiguities among previous studies unable to discriminate modality-specific preparatory activity from attentional modulation of stimulus processing. Our results agree with predictive-coding models, which suggest that these expectancy-related changes reflect top-down biases--presumably originating from the observed supramodal frontoparietal network--that modulate signal-detection sensitivity by differentially modifying background activity (i.e., noise level) in different input channels. The putamen appears to code omission-related Bayesian "surprise" that depends on the specificity of predictions.
Cerebral Cortex 04/2011; 21(12):2850-62. · 6.54 Impact Factor
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ABSTRACT: Although attention functions are often impaired after stroke, traumatic brain injury or inflammatory diseases, little is known about the time course and the long-term efficacy of training-induced improvement. The present single case study evaluates the time course and longitudinal stability of attention improvement after alertness training by repeatedly testing the subject between individual training sessions as well as one and seven months after the end of the training. The outpatient (M.P.) trained developed severe alertness deficits following brainstem encephalitis in 2003 without signs of cortical damage, and since then had not achieved full recovery. In 2008, M.P. participated in 15 treatment sessions on 15 separate working days over a period of three weeks. In each session a 45-minute alertness training task was administered, using the CogniPlus ALERT computer training program. Attention performance was assessed by neuropsychological tests four years, one year, and immediately before the therapy after every third training session and three times after the termination of therapy. Furthermore, a self-report questionnaire measured subjective experience of attention in everyday life situations. In order to compare the performance between training sessions, a procedure specialised for psychometric single-case diagnosis was used to analyse the data. Surprisingly, even after three consecutive training sessions, M.P. showed immense improvement in alertness. Furthermore, after two weeks she felt more energetic and more able to concentrate. Six months after the end of the training the improvement remained stable. The unexpectedly fast time course of recovery induced by the training, as well as the stable long-term effects, probably depend on intact cortical structures. In M.P. it appeared that top-down control of the alertness network on impaired brainstem arousal structures had been re-activated by the training procedure and had remained stable across a long time period.
Neuropsychological Rehabilitation 04/2011; 21(2):164-82. · 1.72 Impact Factor
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ABSTRACT: Sustained responsiveness to external stimulation is fundamental to many time-critical interactions with the outside world. We used functional magnetic resonance imaging during speeded stimulus detection to identify convergent and divergent neural correlates of maintaining the readiness to respond to auditory, tactile, and visual stimuli. In addition, using a multimodal condition, we investigated the effect of making stimulus modality unpredictable. Relative to sensorimotor control tasks, all three unimodal detection tasks elicited stronger activity in the right temporo-parietal junction, inferior frontal cortex, anterior insula, dorsal premotor cortex, and anterior cingulate cortex as well as bilateral mid-cingulum, midbrain, brainstem, and medial cerebellum. The multimodal detection condition additionally activated left dorsal premotor cortex and bilateral precuneus. Modality-specific modulations were confined to respective sensory areas: we found activity increases in relevant, and decreases in irrelevant sensory cortices. Our findings corroborate the modality independence of a predominantly right-lateralized core network for maintaining an alert (i.e., highly responsive) state and extend previous results to the somatosensory modality. Monitoring multiple sensory channels appears to induce additional processing, possibly related to stimulus-driven shifts of intermodal attention. The results further suggest that directing attention to a given sensory modality selectively enhances and suppresses sensory processing-even in simple detection tasks, which do not require inter- or intra-modal selection.
Human Brain Mapping 03/2011; 33(2):398-418. · 5.88 Impact Factor
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ABSTRACT: Cognitive deficits are a substantial burden in clinical depression. The present study considered dysfunction in the right-hemispheric attention network in depression, examining alertness and visuospatial attention.
Three computerized visuospatial attention tests and an alertness test were administered to 16 depressive patients and 16 matched healthy controls.
Although no significant group effect was observed, alertness predicted reduced visuospatial performance in the left hemifield. Furthermore, sad mood showed a trend towards predicting left visual field omissions.
Decreased alertness may lead to lower left hemifield visuospatial attention; this mechanism may be responsible for a spatial bias to the right side in depression, even though treatment of depression and anxiety may reduce this cognitive deficit.
BMC Psychiatry 01/2011; 11:78. · 2.55 Impact Factor
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ABSTRACT: Purpose: In an fMRI study the functional networks involved in auditory selective attention for sounds and words were investigated. Methods: 24 healthy volunteers (12 male, 12 female) had to respond to a category of targets (animal sounds vs. musical instruments, spoken names of instruments vs. animals; 6 targets, 12 nontargets) presented via headphones. Results: Under both the sound and word condition besides left superior and middle temporal lobe activation there was bilateral activity in the superior frontal (including the anterior cingulate cortex ACC), middle and inferior frontal and inferior parietal lobes. Under both conditions we also found cerebellar activity. In general there was a high overlap of the related attention networks for both conditions. Conclusions: The activation patterns revealed a high overlap across stimulus conditions with only slight modulation caused by the quality of the auditory material. For rehabilitation of attention deficits after brain damage this implicates that a single training procedure might address a common network for selective attention deficits under different stimulus conditions.
Restorative neurology and neuroscience 01/2011; 29(2):73-83. · 2.51 Impact Factor
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ABSTRACT: Clinical observations and neuroimaging data revealed a right-hemisphere fronto-parietal-thalamic-brainstem network for intrinsic alertness, and additional left fronto-parietal activity during phasic alertness. The primary objective of this fMRI study was to map the functional neuroanatomy of intrinsic alertness as precisely as possible in healthy participants, using a novel assessment paradigm already employed in clinical settings. Both the paradigm and the experimental design were optimized to specifically assess intrinsic alertness, while at the same time controlling for sensory-motor processing. The present results suggest that the processing of intrinsic alertness is accompanied by increased activity within the brainstem, thalamus, anterior cingulate gyrus, right insula, and right parietal cortex. Additionally, we found increased activation in the left hemisphere around the middle frontal gyrus (BA 9), the insula, the supplementary motor area, and the cerebellum. Our results further suggest that rather minute aspects of the experimental design may induce aspects of phasic alertness, which in turn might lead to additional brain activation in left-frontal areas not normally involved in intrinsic alertness. Accordingly, left BA 9 activation may be related to co-activation of the phasic alertness network due to the switch between rest and task conditions functioning as an external warning cue triggering the phasic alertness network. Furthermore, activation of the intrinsic alertness network during fixation blocks due to enhanced expectancy shortly before the switch to the task block might, when subtracted from the task block, lead to diminished activation in the typical right hemisphere intrinsic alertness network. Thus, we cautiously suggest that--as a methodological artifact--left frontal activations might show up due to phasic alertness involvement and intrinsic alertness activations might be weakened due to contrasting with fixation blocks, when assessing the functional neuroanatomy of intrinsic alertness with a block design in fMRI studies.
PLoS ONE 01/2011; 6(9):e25453. · 4.09 Impact Factor
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ABSTRACT: While the ecological validity of virtual reality (VR) applications is usually assessed by behavioral data or interrogation, an alternative approach on a neuronal level is offered by brain imaging methods. Because it is yet unclear if 3D space in virtual environments is processed analogically to the real world, we conducted a study investigating virtual spatial processing in the brain using functional magnetic resonance imaging (fMRI). Results show differences in VR spatial brain processing as compared to known brain activations in reality. Identifying differences and commonalities of brain processing in VR reveals limitations and holds important implications for VR therapy and training tools. When VR therapy aims at the rehabilitation of brain function and activity, differences in brain processing have to be taken into account for designing effective VR training tools. Furthermore, for an evaluation of possible restoration effects caused by VR training, it is necessary to integrate information about the brain activation networks elicited by the training. The present study provides an example for demonstrating the benefit of fMRI as an evaluation tool for the mental processes involved in virtual environments.
Cyberpsychology, Behavior, and Social Networking 04/2010; 13(2):211-5.
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ABSTRACT: The efficiency of cognition is modulated by energetic factors like effort, fatigue or circadian variation, which affect even the most basic cognitive operations. For instance, speeded detection in simple reaction-time (SRT) tasks usually slows down over time. The literature suggests that either mindlessness due to routinization or mental fatigue due to attentional resource depletion might underlie this decrement. We tested these assumptions in three 25-min visual SRT tasks using easy-to-detect high-intensity and hard-to-detect low-intensity stimuli presented in both blocked and mixed fashion. Mindlessness theory predicts that less monotonous stimulation (i.e. the mixed presentation) would mitigate the time-related decrement for high- and low-intensity stimuli alike, whereas resource-depletion theory predicts opposite effects of mixed presentation on high- versus low-intensity stimuli. Indeed, stimulus intensity and presentation mode cross-interacted significantly, indicating that the performance decline was steeper for high-intensity stimuli but less steep for low-intensity stimuli during mixed compared to blocked presentation, respectively. These results strongly suggest that the time-related efficiency decrement during prolonged SRT performance is related to accumulating mental fatigue. A conjecture is put forward that explains both resource depletion and mindlessness from the perspective of self-regulation. Our study underscores the need to incorporate energetic factors into models of cognition to facilitate their translation into real-world applications.
Psychological Research 02/2010; 74(5):499-512. · 2.47 Impact Factor
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ABSTRACT: Performance decrements attributed to mental fatigue have been found to be especially pronounced in tasks that involve the voluntary control of attention. Here we explored whether mental fatigue from prolonged time on task (TOT) also impairs temporal preparation for speeded action in a simple reaction-time task. Temporal preparation is enabled by a warning signal presented before the imperative stimulus and usually results in shorter reaction time (RT). When the delay between warning and imperative stimuli - the foreperiod (FP) - varies between trials, responses are faster with longer FPs. This pattern has been proposed to arise from either voluntary attentional processes (temporal orienting) or automatic trial-to-trial learning (trace conditioning). The former account suggests a selective RT increase on long-FP trials with fatigue; the latter account suggests no such change. Over a work period of 51 min, we found the typical increase in overall RT but no selective RT increase after long FPs. This additivity indicates that TOT-induced mental fatigue generally reduces cognitive efficiency but leaves temporal preparation under time uncertainty unaffected. We consider this result more consistent with the trace-conditioning account of temporal preparation.
Acta psychologica 10/2009; 133(1):64-72. · 2.19 Impact Factor
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ABSTRACT: According to the hypothesis of progesterone-mediated interhemispheric decoupling (Hausmann and Güntürkün, 2000), functional cerebral asymmetries (FCAs), which are stable in men and change during the menstrual cycle in women, are generated by interhemispheric inhibition of the dominant on the nondominant hemisphere. The change of lateralization during the menstrual cycle in women might indicate that sex hormones play an important role in modulating FCAs. We used functional magnetic resonance imaging to examine the role of estradiol in determining cyclic changes of interhemispheric inhibition. Women performed a word-matching task, while they were scanned twice during the cycle, once during the menstrual and once during the follicular phase. By use of a connectivity analysis we found that the inhibitory influence of left-hemispheric language areas on homotopic areas of the right hemisphere is strongest during the menses, resulting in a pronounced lateralization. During the follicular phase, due to rising estradiol levels, inhibition and thus functional cerebral asymmetries are reduced. These results reveal a powerful neuromodulatory action of estradiol on the dynamics of functional brain organization in the female brain. They may further contribute to the ongoing discussion of sex differences in brain function in that they help explain the dynamic part of functional brain organization in which the female differs from the male brain.
Journal of Neuroscience 01/2009; 28(50):13401-10. · 7.11 Impact Factor
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ABSTRACT: We prospectively investigated by means of neuropsychological tests and functional magnetic resonance imaging (fMRI) the behavioural and neural effects of a 3-week optokinetic stimulation (OKS) training in 7 patients with chronic visuospatial neglect resulting from right-hemisphere lesions. Behaviourally, OKS caused both a short- and a long-term (4 weeks) improvement of performance in a neglect test battery (compared to a 3-week baseline period). This amelioration of neglect symptoms was associated with increases of neural activity during an fMRI spatial attention task bilaterally in the middle frontal gyrus and the precuneus. Additional left hemisphere increases in neural activity were observed in the cingulate gyrus, angular gyrus, middle temporal gyrus and occipital cortex. This pattern of activation represents a combination of areas normally involved in spatial attention plus a compensatory recruitment of left hemisphere areas. These results were then compared with data from our previous study (Thimm et al., 2006) which employed an alertness training (AIXTENT) with an otherwise identical treatment study design. After the OKS training there was more activation bilaterally in the precuneus than after the AIXTENT training. In contrast, after AIXTENT training there was more activation bilaterally in frontal cortex. Taken together, the results show that amelioration of neglect can be induced by both OKS and alertness training. The data furthermore suggest that the differential activations of frontal or parietal areas may reflect the specific impact of the two types of training either on an anterior system for the control of attention intensity (AIXTENT) or on the posterior system of spatial attention (OKS).
Cortex 12/2008; 45(7):850-62. · 6.08 Impact Factor
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ABSTRACT: Using functional magnetic resonance imaging, we asked participants to perform a visual target detection task with peripheral cues. In the first part of the experiment, cues were not predictive of the side of occurrence of the incoming target. In the second part of the experiment, unbeknownst to the participants, cues became 80% predictive, thus inducing an endogenous orienting of spatial attention. Confirming previous results, in the second part response times (RTs) decreased for validly cued trials and increased for invalid trials. Half of the participants were subsequently able to correctly describe the cue-target relationships ('verbalizers'), thus demonstrating reflective consciousness of endogenous orienting. Also non-verbalizer participants showed a similar RT pattern, indicating the occurrence of endogenous orienting without reflective consciousness. Both groups of participants showed fronto-parietal activity typically observed in spatial attention tasks. Verbalizers, in addition, demonstrated stronger activity in the anterior cingulate cortex (ACC), consistent with the proposed role of this structure in purposeful behaviour and in the monitoring of its consequences. The extensive pattern of connectivity of the ACC is ideally suited to integrate the activity of the large neural assemblies necessary for reflective consciousness to emerge.
Neuropsychologia 02/2008; 46(1):348-61. · 3.64 Impact Factor
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ABSTRACT: In the present study, we were interested in distinguishing the cortical representations of within-modal and cross-modal divided attention tasks by using functional magnetic resonance imaging. Sixteen healthy male subjects aged between 21 and 30 years underwent two within-modal (auditory/auditory, visual/visual) and one cross-modal (auditory/visual) divided attention task, as well as related selective attention control conditions. After subtraction of the corresponding control task the three divided attention tasks, irrespective of sensory modality, revealed significant activation in a predominantly right hemisphere network involving the prefrontal cortex, the inferior parietal cortex, and the claustrum. Under the cross-modal condition, however, the frontal and parietal activation was more extended and more bilateral and there also was stronger right hemisphere activation of the anterior cingulate cortex and the thalamus. In comparison to the within-modal conditions additional bilateral frontal and left inferior parietal activation was found for the cross-modal condition. The supplementary fronto-parietal, anterior cingulate cortex, and thalamus activation in the auditory/visual condition could be argued to reflect an additional demand for coordination of two ongoing cross-modal cognitive processes.
Human Brain Mapping 01/2008; 28(12):1267-75. · 5.88 Impact Factor
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Walter Sturm
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ABSTRACT: Neuropsychological assessment is one of the main fields of activity of clinical neuropsychologists. Goals of this assessment are verification and description of cognitive and affective impairments as the consequence of brain damage. Included are examinations of basal and higher sensory functions, the intellectual profile, memory, attention and sensorimotor functions, executive functions, specific education- and profession-related skills as well as affectivity and emotional functions. Diagnostic assignment encompasses the description of the current status, follow-up examinations, experts' reports, planning of rehabilitation measures but also the uncovering of dysfunctions after brain damage that are morphologically not yet verifiable. Referring to the respective diagnostic question, assessment has to be planned thoroughly including results of prior examinations, exploration and anamnesis, also taking into account factors which might hamper test administration or which otherwise might affect the results. The assessment also includes monitoring of behaviour and the registration of tendencies for aggravation or simulation. Analysis and interpretation of the results both refer to the diagnostic question and to the hypotheses developed at the beginning of the examination. Results and conclusions derived from the examination are documented in reports of diagnostic findings or in experts' reports.
Journal of Neurology 06/2007; 254 Suppl 2:II12-4. · 3.47 Impact Factor
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HCI and Usability for Medicine and Health Care, Third Symposium of the Workgroup Human-Computer Interaction and Usability Engineering of the Austrian Computer Society, USAB 2007, Graz, Austria, November, 22, 2007, Proceedings; 01/2007
