Sprachverstehen im Kontext: Bildgebende Studien zu Kohärenzbildung und Pragmatik

Communicative compentence requires the interpretation of ut- terances in light of background knowledge, comprehension goal and context information .In addition to aphasic language disor- ders so-called non-aphasic communication deficits have been described .These deficits manifest themselves whenever non-li- teral meanings are relevant or when the global context or structure needs to be derived .In neuropsychological research the focus has been on the frontal lobes and the right hemisphere. Recent neuroimaging studies have accumulated evidence for both of these brain regions to be involved during most aspects of complex language comprehension .In particular the anterior temporal lobes and the fronto-medial cortex play a specific role for the integration and interpretation of verbal information .Cli- nical diagnosis of brain damaged patients should therefore inclu- de an assessment of contextual language processing in addition to the evaluation of aphasic language deficits

Dynamic patterns make the premotor cortex interested in objects: Influence of stimulus and task revealed by fMRI

Research in monkey and man indicates that the ventrolateral premotor cortex (PMv) underlies not only the preparation of manual movements, but also the perceptual representation of pragmatic object properties. However, visual stimuli without any pragmatic meaning were recently found to elicit selective PMv responses if they were subjected to a perceivable pattern of change. We used functional magnetic resonance imaging (fMRI) to investigate if perceptual representations in the PMv might apply not only to pragmatic, but also to dynamic stimulus properties. To this end, a sequential figure matching task that required the processing of dynamic features was contrasted with a non-figure control task (Experiment 1) and an individual figure matching task (Experiment 2). In order to control for potential influences of stimulus properties that might be associated with pragmatic attributes, different types of abstract visual stimuli were employed. The experiments yielded two major findings: if their dynamic properties are attended, then abstract 2D visual figures are sufficient to trigger activation within premotor areas involved in hand-object interaction. Moreover, these premotor activations are independent from stimulus properties that might relate to pragmatic features. The results imply that the PMv is engaged in the processing of stimuli that are usually or actually embedded within either a pragmatic or a dynamic context

A blueprint for target motion: fMRI reveals perceived sequential complexity to modulate premotor cortex

The execution of movements that are guided by an increasingly complex target motion is known to draw on premotor cortices. Whole-brain functional magnetic resonance imaging was used to investigate whether, in the absence of any movement, attending to and predicting increasingly complex target motion also rely on premotor cortices. Complexity was varied as a function of number of sequential elements and amount of dynamic sequential trend in a pulsing target motion. As a result, serial prediction caused activations in premotor and parietal cortices, particularly within the right hemisphere. Parametric analyses revealed that the right ventrolateral premotor cortex and the right anterior intraparietal sulcus were the only areas that, in addition, covaried positively with both behavioral and physical measures of sequential complexity. Further areas that covaried positively with increasing task difficulty reflected influences of both number and trend manipulation. In particular, increasing element number drew on dorsal premotor and corresponding posterior intraparietal regions, whereas increasing trend drew on the visual motion area and area V4. The present findings demonstrate that premotor involvement directly reflects perceptual complexity in attended and predicted target motion. It is suggested that when we try to predict how a target will move, the motor system generates a “blueprint” of the observed motion that allows potential sensorimotor integration. In the absence of any motor requirement, this blueprint appears to be not a by-product of motor planning, but rather the basis for target motion prediction

The functional neuroanatomy of human working memory revisited. Evidence from 3-T fMRI studies using classical domain-specific interference tasks

In the present event-related functional magnetic resonance imaging study, the neural implementation of human working memory was reinvestigated using a factorial design with verbal and visuospatial item-recognition tasks each performed under single-task conditions, under articulatory suppression, and under visuospatial suppression. This approach allowed to differentiate between brain systems subserving domain-specific working memory processes and possible neural correlates of more "central" executive or storage functions. The results of this study indicate (1) a domain-specific functional-neuroanatomical organization of verbal and visuospatial working memory, (2) a dual architecture of verbal working memory in contrast to a unitary macroscopic architecture of visuospatial working memory, (3) possible neural correlates for a domain-unspecific "episodic buffer" in contrast to a failure to find brain areas attributable to a "central executive," and (4) competition for neuronal processing resources as the causal principle for the occurrence of domain-specific interference in working memory

Processing linguistic complexity and grammaticality in the left frontal cortex

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Amplitude differences of evoked alpha and gamma oscillations in two different age groups

The aim of this study was to investigate whether the amplitude of gamma-band activity is influenced by the factor age. We examined alpha- and gamma-band EEG activity and event-related potentials (ERPs) of 12 subjects. Six subjects constituted the younger (mean age=36.6 years) and another six the older age group (mean age=47.6 years). Subjects performed a visual discrimination task which required a response to Kanizsa squares (targets) among Kanizsa-triangles and non-Kanizsa figures. The ERPs of the younger group revealed a significantly larger N170 amplitude. The amplitudes of evoked alpha- and gamma-band activity were also found to be significantly higher in the younger group. We discuss the implications of these findings and possible reasons for a change of the oscillatory activity in the older age group

Reality = Relevance? Insights from Spontaneous Modulations of the Brain's Default Network when Telling Apart Reality from Fiction

BACKGROUND: Although human beings regularly experience fictional worlds through activities such as reading novels and watching movies, little is known about what mechanisms underlie our implicit knowledge of the distinction between reality and fiction. The first neuroimaging study to address this issue revealed that the mere exposure to contexts involving real entities compared to fictional characters led to engagement of regions in the anterior medial prefrontal and posterior cingulate cortices (amPFC, PCC). As these core regions of the brain's default network are involved during self-referential processing and autobiographical memory retrieval, it was hypothesized that real entities may be conceptually coded as being more personally relevant to us than fictional characters. METHODOLOGY/PRINCIPAL FINDINGS: In the present functional magnetic resonance imaging (fMRI) study, we directly test the hypothesis that entity-associated personal relevance is the critical factor underlying the differential engagement of these brain regions by comparing the brain's response when processing contexts involving family or friends (high relevance), famous people (medium relevance), or fictional characters (low relevance). In line with predictions, a gradient pattern of activation was observed such that higher entity-associated personal relevance was associated with stronger activation in the amPFC and the PCC. CONCLUSIONS/SIGNIFICANCE: The results of the study have several important implications. Firstly, they provide informed grounds for characterizing the dynamics of reality-fiction distinction. Secondly, they provide further insights into the functions of the amPFC and the PCC. Thirdly, in view of the current debate related to the functional relevance and specificity of brain's default network, they reveal a novel approach by which the functions of this network can be further explored

Premotor cortex in observing erroneous action: An fMRI study

The lateral premotor cortex (PMC) is involved during action observation in monkeys and humans, reflecting a matching process between observed actions and their corresponding motor schemata. In the present study, functional magnetic resonance imaging (fMRI) was used to investigate if paying attention to the two observable action components, objects and movements, modulates premotor activation during the observation of actions. Participants were asked to classify presented movies as showing correct actions, erroneous actions, or senseless movements. Erroneous actions were incorrect either with regard to employed objects, or to performed movements. The experiment yielded two major results: (1) The ventrolateral premotor cortex (vPMC) and the anterior part of the intraparietal sulcus (aIPS) are strongly activated during the observation of actions in humans. Premotor activation was dominantly located within Brodmann Area (BA) 6, and sometimes extended into BA 44. (2) The presentation of object errors and movements errors allowed to disentangle brain activations corresponding to the analysis of movements and objects in observed actions. Left premotor areas were more involved in the analysis of objects, whereas right premotor areas were dominant in the analysis of movements. It is suggested that the analysis of categorical information, like objects, and that of coordinate information, like movements, are pronounced in different hemispheres

Gender and age effects in structural brain asymmetry as measured by MRI texture analysis

Effects of gender and age on structural brain asymmetry were studied by 3D texture analysis in 380 adults. Asymmetry is detected by comparing the complex 3D gray-scale image patterns in the left and right cerebral hemispheres as revealed by anatomical T1-weighted MRI datasets. The Talairach and Tournoux parcellation system was applied to study the asymmetry on five levels: the whole cerebrum, nine coronal sections, 12 axial sections, boxes resulting from both coronal and axial subdivisions, and by a sliding spherical window of 9 mm diameter. The analysis revealed that the brain asymmetry increases in the anterior-posterior direction starting from the central region onward. Male brains were found to be more asymmetric than female. This gender-related effect is noticeable in all brain areas but is most significant in the superior temporal gyrus, Heschl's gyrus, the adjacent white matter regions in the temporal stem and the knee of the optic radiation, the thalamus, and the posterior cingulate. The brain asymmetry increases significantly with age in the inferior frontal gyrus, anterior insula, anterior cingulate, parahippocampal gyrus, retrosplenial cortex, coronal radiata, and knee region of the internal capsule. Asymmetry decreases with age in the optic radiation, precentral gyrus, and angular gyrus. The texture-based method reported here is based on extended multisort cooccurrence matrices that employ intensity, gradient, and anisotropy features in a uniform way. It is sensitive, simple to reproduce, robust, and unbiased in the sense that segmentation of brain compartments and spatial transformations are not necessary. Thus, it should be considered as another tool for digital morphometry in neuroscience