Biomedical subjects

D Yves von Cramon

Publications and source records attributed to D Yves von Cramon.

At least 19 recordsLinked to original sources

PubMed2007

The role of the posterior superior temporal sulcus in the processing of unmarked transitivity.

Is it living or not? The ability to differentiate between animate and inanimate entities is of considerable value in everyday life, since it allows for the dissociation of individuals that may willfully cause an action from objects that cannot. The present fMRI study aimed to shed light on the neural correlates of animacy at a relational-interpretive level, i.e. on the role of animacy in the establishment of relations between entities that are more or less likely to cause an event and differ in their potential to act volitionally. To this end, we investigated the processing of visually presented transitive German sentences (nominative-accusative structures) in which the factors animacy and argument order were manipulated. The relations between the arguments differed in that the animate subject either acted on an inanimate object (a very natural construction in terms of transitivity) or on an animate object (resulting in a sentence deviating from an unmarked transitive structure). Participants performed an acceptability judgment task. Violations of unmarked transitivity yielded a significant activation increase within the posterior left superior temporal sulcus (pSTS), thus suggesting a specific role of this cortical region in the relational use of animacy information. This result indicates that the influence of animacy as a relational feature differs from the impact of this parameter on the word level and is in line with other neuroimaging studies showing an engagement of the pSTS when a matching between syntax and semantics is required. A comparison between object- and subject-initial conditions further revealed a robust effect of argument order in the pars opercularis of the left inferior frontal gyrus (a subregion of Broca's area), thereby replicating previous findings demonstrating a sensitivity of this region to fine-grained language-specific linearization rules.

Adult↗

PubMed2007

Role of the corpus callosum in speech comprehension: interfacing syntax and prosody.

The role of the corpus callosum (CC) in the interhemispheric interaction of prosodic and syntactic information during speech comprehension was investigated in patients with lesions in the CC, and in healthy controls. The event-related brain potential experiment examined the effect of prosodic phrase structure on the processing of a verb whose argument structure matched or did not match the prior prosody-induced syntactic structure. While controls showed an N400-like effect for prosodically mismatching verb argument structures, thus indicating a stable interplay between prosody and syntax, patients with lesions in the posterior third of the CC did not show this effect. Because these patients displayed a prosody-independent semantic N400 effect, the present data indicate that the posterior third of the CC is the crucial neuroanatomical structure for the interhemispheric interplay of suprasegmental prosodic information and syntactic information.

Adult↗

PubMed2006

Neural correlates of error awareness.

Error processing results in a number of consequences on multiple levels. The posterior frontomedian cortex (pFMC) is involved in performance monitoring and signalling the need for adjustments, which can be observed as post-error speed-accuracy shifts at the behavioural level. Furthermore autonomic reactions to an error have been reported. The role of conscious error awareness for this processing cascade has received little attention of researchers so far. We examined the neural correlates of conscious error perception in a functional magnetic resonance imaging (fMRI) study. An antisaccade task known to yield sufficient numbers of aware and unaware errors was used. Results from a metaanalysis were used to guide a region of interest (ROI) analysis of the fMRI data. Consistent with previous reports, error-related activity in the rostral cingulate zone (RCZ), the pre-supplementary motor area (pre-SMA) and the insular cortex bilaterally was found. Whereas the RCZ activity did not differentiate between aware and unaware errors, activity in the left anterior inferior insular cortex was stronger for aware as compared to unaware errors. This could be due to increased awareness of the autonomic reaction to an error, or the increased autonomic reaction itself. Furthermore, post-error adjustments were only observed after aware errors and a correlation between post-error slowing and the hemodynamic activity in the RCZ was revealed. The data suggest that the RCZ activity alone is insufficient to drive error awareness. Its signal appears to be useful for post-error speed-accuracy adjustments only when the error is consciously perceived.

Adult↗

PubMed2006

Neural networks in frontotemporal dementia--a meta-analysis.

OBJECTIVE: Frontotemporal dementia is the most common form of frontotemporal lobar degeneration. It is characterized by deep alterations in behavior and personality. We conducted a systematic and quantitative meta-analysis to examine its neural correlates and place the disease in a framework of cognitive neuropsychiatry. METHODS: MedLine and Current Contents search engines were used to identify imaging studies investigating frontotemporal dementia between 1980 and 2005. Nine studies were identified reporting either atrophy or decreases in glucose utilization. Finally, the analysis involved 132 patients and 166 controls. A quantitative meta-analysis was performed. Maxima of the studies resulted in activation likelihood estimates. RESULTS: The meta-analysis revealed a particularly frontomedian network impaired in frontotemporal dementia. Additionally, right anterior insula, and medial thalamus were identified. CONCLUSIONS: Our study specifies frontotemporal dementia as the frontomedian variant of frontotemporal lobar degeneration. The disease affects neural networks enabling self-monitoring, theory of mind capabilities, processing/evaluation of internal mental states, perception of pain and emotions, and sustaining personality and self. Our study contributes to placing frontotemporal dementia in cognitive neuropsychiatry.

Aged↗

PubMed2006

Lesion-site affects grammatical gender assignment in German: perception and production data.

Two experiments investigated phonological, derivational-morphological and semantic aspects of grammatical gender assignment in a perception and a production task in German aphasic patients and age-matched controls. The agreement of a gender indicating adjective (feminine, masculine or neuter) and a noun was evaluated during perception in Experiment 1 (grammaticality judgment). In Experiment 2 the same participants had to produce the matching definite article to a noun. In the perception task patients with left frontal lesions (LF) made more errors during phonological gender assignment as compared to derivational-morphological and semantic gender assignment, while patients with lesions of the posterior superior temporal gyrus (pSTG) made more errors in derivational-morphological gender assignment as compared to phonological and semantic gender assignment. In the production task no differences between patient groups were found. These data support previous evidence that left frontal brain areas are critically involved in phonological processing. The pSTG on the other hand may be critically engaged in the integration of phonological and lexical information essential for phonological and derivational-morphological gender assignment.

Adult↗

PubMed2006

Neurovascular coupling is impaired in cerebral microangiopathy--An event-related Stroop study.

Small-vessel disease or cerebral microangiopathy is a common finding in elderly people leading finally to subcortical ischemic vascular dementia. Because cerebral microangiopathy impairs vascular reactivity and affects mainly the frontal lobes, we hypothesized that brain activation decreases during an event-related color-word matching Stroop task. 12 patients suffering from cerebral microangiopathy were compared with 12 age-matched controls. As an imaging method we applied functional near-infrared spectroscopy, because it is particularly sensitive to the microvasculature. The Stroop task led to activations in the lateral prefrontal cortex. Generally, the amplitude of the hemodynamic response was reduced in patients in tight correlation with behavioral slowing during the Stroop task and with neuropsychological deficits, namely attentional and executive dysfunction. Interestingly, patients showed an early deoxygenation of blood right after stimulation onset, and a delay of the hemodynamic response. Whereas the amplitude of the hemodynamic response is reduced in the frontal lobes also with normal aging, data suggest that impairments of neurovascular coupling are specific for cerebral microangiopathy. In summary, our findings indicate frontal dysfunction and impairments of neurovascular coupling in cerebral microangiopathy.

Aged↗

PubMed2006

Linguistic prominence and Broca's area: the influence of animacy as a linearization principle.

Previous neuroimaging findings suggest a sensitivity of the pars opercularis of the left inferior frontal gyrus (i.e. a core subregion of Broca's area) to a number of linguistic dependencies governing the linear sequencing of information in a sentence (e.g. subjects should precede objects; the participant role hierarchy should be respected). The present study used event-related fMRI to examine the hitherto untested hypothesis that the violation of a linearization principle that is purely semantic in nature (animate arguments should precede inanimate arguments) would also lead to increased pars opercularis activation. To this end, we manipulated the features animacy and argument order in German sentences and found a significant increase of activation in the pars opercularis for a violation of the animacy principle even when the other factors mentioned above were controlled for. This result therefore calls for a "supra-syntactic" account of pars opercularis function in the real-time understanding of sentences.

Adult↗

PubMed2006

The parcellation of cortical areas using replicator dynamics in fMRI.

In this paper, we show that replicator dynamics can be used as an exploratory analysis tool to detect subregions of cortical areas on the basis of the similarity between fMRI time series. As similarity measure, we propose to use canonical correlation, a multivariate extension to the typically employed Pearson's correlation coefficient. We applied the replicator process to data obtained from two different experimental paradigms in the search for subregions within the left lateral frontal cortex (LFC). In both cases, the replicator process resulted in a parcellation that corresponds to a recently suggested subdivision of the LFC in anterior-posterior direction. Most notably, these results were very consistent when compared across different measurements of a single subject and across a group of subjects.

Brain Mapping↗

PubMed2006

Hemispheric asymmetry for auditory processing in the human auditory brain stem, thalamus, and cortex.

We report evidence for a context- and not stimulus-dependent functional asymmetry in the left and right human auditory midbrain, thalamus, and cortex in response to monaural sounds. Neural activity elicited by left- and right-ear stimulation was measured simultaneously in the cochlear nuclei, inferior colliculi (ICs), medial geniculate bodies (MGBs), and auditory cortices (ACs) in 2 functional magnetic resonance imaging experiments. In experiment 1, pulsed noise was presented monaurally to either ear, or binaurally, simulating a moving sound source. In experiment 2, only monaural sounds were presented. The results show a modulation of the neural responses to monaural sounds by the presence of binaural sounds at a time scale of tens of seconds: In the absence of binaural stimulation, the left and right ICs, MGBs, and ACs responded stronger to stimulation of the contralateral ear. When blocks of binaural stimuli were interspersed in the sound sequence, the contralateral preference vanished in those structures in the right hemisphere. The resulting hemispheric asymmetry was similar to the asymmetry demonstrated for spatial sound processing. Taken together, the data demonstrate that functional asymmetries in auditory processing are modulated by context. The observed long time constant suggests that this effect results from a "top-down" mechanism.

Acoustic Stimulation↗

PubMed2006

The neural implementation of multi-attribute decision making: a parametric fMRI study with human subjects.

Decision making is not a unitary entity but involves rather a series of interdependent processes. Decisions entail a choice between two or more alternatives. Within the complex series of decisional processes, at least two levels can be differentiated: a first level of information integration (process level) and a second level of information interpretation (control level), leading to a subsequent motor response or cognitive process. The aim of this study was to investigate the neural network of these decisional processes. In a single trial fMRI study, we implemented a simple decision-making task, where subjects had to decide between two alternatives represented on five attributes. The similarity between the two alternatives was varied systematically in order to achieve a parametric variation of decisional effort. For easy trials, the two alternatives differed significantly in several attributes, whereas for difficult trials, the two alternatives differed only in small details. The results show a distributed neural network related to decisional effort. By means of time course analysis different subprocesses within this network could be differentiated: regions subserving the integration of the presented information (premotor areas and superior parietal lobe) and regions subserving the interpretation of this information (frontolateral and frontomedial cortex, anterior insula, and caudate) as well as a region in the inferior frontal junction updating task rules.

Adult↗

PubMed2006

How does error correction differ from error signaling? An event-related potential study.

It has been a question of debate whether immediate error corrections in speeded forced-choice reaction time tasks require an error detection signal from the performance monitoring system or whether they reflect delayed correct responses that are executed after the premature error like in a horserace. In contrast, signaling the error by pressing a response button that is unrelated to the primary task is based on error detection. The present study investigates the similarities and differences between immediate error corrections and signaling responses by means of behavioral and event-related potential data. In a within-subject design, participants performed two sessions of the flanker task. In one session, errors had to be corrected by immediately pressing the correct response, in the other session, errors had to be signaled by pressing an error signaling button. Compared to the signaling session, in the correction session, more errors and error corrections were made, reaction times were shorter, and the amplitude of the error-related negativity (ERN) was reduced. Whereas the error significance did not seem to differ across session, participants have most likely reduced the motor threshold in the correction session to enable efficient immediate corrections. This interpretation is supported by the lateralized readiness potentials and is consistent with the response conflict monitoring hypothesis of the ERN. The present study demonstrates that differences in error corrections may be attributable to differences in motor threshold. We conclude that the error signaling procedure is a more direct and reliable way to behaviorally test the functional integrity of the performance monitoring system than the instruction to correct errors. The consequences for studies in patients and with pharmacological challenges are discussed.

Adult↗

PubMed2006

Processing linguistic complexity and grammaticality in the left frontal cortex.

We used event-related functional magnetic resonance imaging to directly compare the hemodynamic responses associated with varying degrees of linguistic complexity with those engendered by the processing of ungrammatical utterances. We demonstrate a dissociation within the left inferior frontal cortex between the deep frontal operculum, which responds to syntactic violations, and a core region of Broca's area, that is, the inferior portion of the left pars opercularis in Brodmann area 44, the activation of which is modulated as a function of the complexity of well-formed sentences. The data demonstrate that different brain regions in the prefrontal cortex support distinct mechanisms in the mapping from a linguistic form onto meaning, thereby separating ungrammaticality from linguistic complexity.

Adult↗

PubMed2006

Cognitive sequelae of diffuse axonal injury.

BACKGROUND: The results of recent studies on cognitive disability after traumatic brain injury-associated diffuse axonal injury (DAI) are inconsistent. In these studies, the diagnosis of DAI relied on cranial computed tomography. OBJECTIVE: To further clarify the extent and severity of a possibly DAI-associated cognitive impairment by the use of magnetic resonance imaging (MRI) and detailed neuropsychological testing. DESIGN AND PARTICIPANTS: From a databank of 299 patients with traumatic brain injury, 18 patients (age range, 17-50 years; median initial Glasgow Coma Scale score, 5) who showed an MRI lesion pattern compatible with pure DAI were identified. All of the patients had undergone MRI on a 3-T system. Pure DAI was defined by the findings of traumatic microbleeds on T2*-weighted gradient-echo images in the absence of otherwise traumatic or nontraumatic MRI abnormalities. MAIN OUTCOME MEASURES: Neuropsychological performance in the categories of attention and psychomotor speed, executive functions, spans, learning and memory, and intelligence 4 to 55 months (median, 9 months) after traumatic brain injury. RESULTS: All of the patients showed impairments of 1 or more cognitive subfunctions, and no cognitive domain was fundamentally spared. Memory and executive dysfunctions were most frequent, the former reaching a moderate to severe degree in half of the patients. In comparison, deficits of attention, executive functions, and short-term memory were mostly mild. Correlations between the amount of traumatic microbleeds and specific or global cognitive performance were absent. CONCLUSIONS: An MRI lesion pattern compatible with isolated DAI is associated with persistent cognitive impairment. The traumatic microbleed load is no sufficient parameter for the assessment of DAI severity or functional outcome.

Adolescent↗

PubMed2006

The anatomical segregation of the frontal cortex: what does it mean for function?

The frontal cortex consists of numerous areas, each with a special architecture (cyto-, myelo-, receptorarchitecture, etc.), connectivity and function. Quantitative tools of the analysis may assist in defining these cortical areas, and their position in a hierarchy of cortical regions and subregions. They enable a reliable definition of areal borders, and the consideration of intersubject variability. In our particular case, fMRI studies investigating certain aspects of cognitive control indicated to a rather circumscribed area in the posterior frontolateral cortex--the so-called IFJ area--which seems to correspond anatomically to a previously uncharted cortical area dorsally to area 44 as detected in histological sections of post mortem brains.

Animals↗

PubMed2006

The clinical spectrum of blunt cerebrovascular injury.

BACKGROUND: Incidence, prevalence, and clinical impact of blunt cerebrovascular injury (BCVI) are unknown. There are no standardized recommendations for screening. REVIEW SUMMARY: A databank of 306 patients with a history of trauma was searched for all subjects with a proven or suspected concomitant BCVI. All patients had undergone MRI for the evaluation of traumatic and vascular cerebral lesions. The diagnosis of BCVI relies on angiographic and/or ultrasound findings. By way of illustration, the case histories of the patients are reported. Eleven subjects (3.6%) were identified. In 8 patients (2.6%), the diagnosis of BCVI can be regarded as proven; in 3 patients (0.98%), a diagnosis of BCVI is probable. The patients could be sorted into the following categories: (i) patients with BCVI and early strokes, (ii) patients with BCVI and late strokes, (iii) patients with early strokes and no detectable BCVI/vessel abnormality, (iv) patients with occult BCVI. Evidence of cerebral ischemia/stroke was present in 9 patients (82%, or 2.9% of all patients). In all patients with stroke, it was the major or sole cause of disability. CONCLUSIONS: BCVI and BCVI-related strokes are not rare. The time window for the development of ischemic complications is highly variable and may be longer than is currently assumed. Even if clinically silent, a diagnosis of BCVI has medicolegal implications and may influence therapy and prognosis in later life. Because of the association of BCVI and motor vehicle accidents, screening is suggested in these patients, and ultrasound could be a practical tool. Although there is substantial suspicion for BCVI in individual trauma patients suffering from stroke, the diagnosis cannot always been proven.

Adolescent↗

PubMed2006

Decision-making and the frontal lobes.

PURPOSE OF REVIEW: This article reviews the most significant advances concerning the neural correlates of decision-making with emphasis on those imaging studies investigating the neural implementation of evaluative judgment processes. This is done against the background of current concepts from the field of judgment and decision-making. RECENT FINDINGS: Actual neuroscientific findings suggest that subject to the extent of how deeply a decision-maker has to explore his/her value system in order to reach a decision, distinguishable orbital and medial prefrontal areas will be engaged. Decisions low in costs mapping the values onto the decision problem mainly rely on orbital and ventromedial prefrontal cortex, whereas decisions high in costs particularly draw on anterior-medial and dorsomedial prefrontal areas. This suggestion is related to the anatomic properties of the respective areas. SUMMARY: Combining neuroimaging data with concepts from research in judgment and decision-making may facilitate advances in our understanding of the contrast between normative theories and descriptive theories of decision-making. Incorporating findings from research on decision-making behavior in patients with specific prefrontal lesions may have much to offer for an understanding of both the areas' functions and cognitive theories on decision-making.

Decision Making↗

PubMed2006

Correlation of cognitive status, MRI- and SPECT-imaging in CADASIL patients.

Although there is evidence for correlations between disability and magnetic resonance imaging (MRI) total lesion volume in autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), the significance of structural MRI abnormalities for cognitive dysfunction remains controversial. We performed detailed neuropsychological testing, high resolution MRI, and Tc-99m-ethyl cysteinate-dimer SPECT in three CADASIL patients. MR-images were rated independently by two investigators for the presence of white matter lesions, lacunar infarcts, microbleeds, and ventricular enlargement. Cortical atrophy was quantified by the use of automatic morphometric assessment of the cortical thickness. In addition, laboratory and patients' history data were collected in order to assess the individual vascular risk factor profile. The differences in cognitive performance between the three patients are neither explained by structural-, or functional neuroimaging, nor by the patient-specific vascular risk factor profiles. The neuroradiologically least affected patient met criteria for dementia, whereas the most severely affected patient was in the best clinical and cognitive state. Conventional structural and functional neuroimaging is important for the diagnosis of CADASIL, but it is no sufficient surrogate marker for the associated cognitive decline. Detailed neuropsychological assessment seems to be more useful, particularly with respect to the implementation of reliable outcome parameters in possible therapeutic trials.

Adult↗

PubMed2006

Voluntary selection of task sets revealed by functional magnetic resonance imaging.

In everyday life, we have to selectively adapt our behavior to different situations and tasks. In cognitive psychology, such adaptive behavior can be investigated with the task-switching paradigm. However, in contrast to everyday life, in experiments participants are unequivocally told which task to perform. The present functional magnetic resonance imaging (fMRI) study was set out to investigate processes that are relevant when participants can decide by their own which task to perform. The number of tasks to choose from was varied between a forced condition (no choice) and two voluntary selection conditions (two or three choices). We expected to find prolonged reaction times as well as higher activations within the midcingulate cortex for the choice conditions compared to the no-choice condition. The fMRI results revealed a significant activation difference for the choice conditions versus the no-choice condition. For the choice contrast, activation was found in the rostral cingulate zone (RCZ) as well as the superior parietal lobule and the posterior part of the intraparietal sulcus. These activations revealed no selection-specific difference between three and two choices. Finally, a post hoc analysis showed that the activation in the RCZ is not associated with higher task-dependent response conflict when participants can select a task set. Taken together, these findings indicate that distinct brain areas are involved in the voluntary selection of abstract task set information.

Adult↗