The representation of the verb's argument structure as disclosed by fMRI

<p>Abstract</p> <p>Background</p> <p>In the composition of an event the verb's argument structure defines the number of participants and their relationships. Previous studies indicated distinct brain responses depending on how many obligatory arguments a verb takes. The present functional magnetic resonance imaging (fMRI) study served to verify the neural structures involved in the processing of German verbs with one (e.g. "snore") or three (e.g. "gives") argument structure. Within a silent reading design, verbs were presented either in isolation or with a minimal syntactic context ("snore" vs. "Peter snores").</p> <p>Results</p> <p>Reading of isolated one-argument verbs ("snore") produced stronger BOLD responses than three-argument verbs ("gives") in the inferior temporal fusiform gyrus (BA 37) of the left hemisphere, validating previous magnetoencephalographic findings. When presented in context one-argument verbs ("Peter snores") induced more pronounced activity in the inferior frontal gyrus (IFG) of the left hemisphere than three-argument verbs ("Peter gives").</p> <p>Conclusion</p> <p>In line with previous studies our results corroborate the left temporal lobe as site of representation and the IFG as site of processing of verbs' argument structure.</p

Representation of the verb's argument-structure in the human brain

<p>Abstract</p> <p>Background</p> <p>A verb's argument structure defines the number and relationships of participants needed for a complete event. One-argument (intransitive) verbs require only a subject to make a complete sentence, while two- and three-argument verbs (transitives and ditransitives) normally take direct and indirect objects. Cortical responses to verbs embedded into sentences (correct or with syntactic violations) indicate the processing of the verb's argument structure in the human brain. The two experiments of the present study examined whether and how this processing is reflected in distinct spatio-temporal cortical response patterns to isolated verbs and/or verbs presented in minimal context.</p> <p>Results</p> <p>The magnetoencephalogram was recorded while 22 native German-speaking adults saw 130 German verbs, presented one at a time for 150 ms each in experiment 1. Verb-evoked electromagnetic responses at 250 – 300 ms after stimulus onset, analyzed in source space, were higher in the left middle temporal gyrus for verbs that take only one argument, relative to two- and three-argument verbs. In experiment 2, the same verbs (presented in different order) were preceded by a proper name specifying the subject of the verb. This produced additional activation between 350 and 450 ms in or near the left inferior frontal gyrus, activity being larger and peaking earlier for one-argument verbs that required no further arguments to form a complete sentence.</p> <p>Conclusion</p> <p>Localization of sources of activity suggests that the activation in temporal and frontal regions varies with the degree by which representations of an event as a part of the verbs' semantics are completed during parsing.</p

Brain regions essential for improved lexical access in an aged aphasic patient: a case report

BACKGROUND: The relationship between functional recovery after brain injury and concomitant neuroplastic changes is emphasized in recent research. In the present study we aimed to delineate brain regions essential for language performance in aphasia using functional magnetic resonance imaging and acquisition in a temporal sparse sampling procedure, which allows monitoring of overt verbal responses during scanning. CASE PRESENTATION: An 80-year old patient with chronic aphasia (2 years post-onset) was investigated before and after intensive language training using an overt picture naming task. Differential brain activation in the right inferior frontal gyrus for correct word retrieval and errors was found. Improved language performance following therapy was mirrored by increased fronto-thalamic activation while stability in more general measures of attention/concentration and working memory was assured. Three healthy age-matched control subjects did not show behavioral changes or increased activation when tested repeatedly within the same 2-week time interval. CONCLUSION: The results bear significance in that the changes in brain activation reported can unequivocally be attributed to the short-term training program and a language domain-specific plasticity process. Moreover, it further challenges the claim of a limited recovery potential in chronic aphasia, even at very old age. Delineation of brain regions essential for performance on a single case basis might have major implications for treatment using transcranial magnetic stimulation

Psychophysiologische Korrelate der Sprachverarbeitung im menschlichen Gehirn

Cells that fire together, wire together. Donald Hebb introduced this learning principle in 1949 (Hebb, 1949). He named ensembles of neurons connected by this principle Cell Assemblies . Using the psychophysiological method of magnetoencephalography (MEG), the present work scrutinised linguistic aspects of single words on the background of Hebb s principle. Features under investigation were the orthographic word length, the familiarity of a word, its meaning, some of its syntactic features and its phonetic transcription. With the help of topography and timing of the word evoked brain responses it can be speculated about a time-line of word-processing: First, from 60ms after stimulus-onset on visual features of words are analyzed. Signatures of semantic processes can be measured from 80ms on whereas word frequency gains influence on the brain response from 120ms. Finally, syntactic processes become evident from 140ms. The reported processing cascade indicates that the brain can work on words very early after stimulus onset. Based on these findings, architectural implications and applications on other linguistic aspects are proposed in the (intentionally highly speculative) introduction. As experimental paradigms we used a active memory task, a passive reading task and a Mismatch Negativity (MMN, or, more precisely, its magnetic equivalent MMNm). Data analysis methods used in this work comprised the analysis of averaged raw data, its Minimum Norm Estimate (MNE) and the wavelet convolution of the continuous MNE. Statistical analysis was performed either on the global field power (GFP) or on regions of interest (ROI) of channels (raw data) or assumed dipoles (MNE)

Neuromagnetic brain responses to words from semantic sub- and supercategories

BackgroundWe explored spatio-temporal patterns of cortical activity evoked by written words from super-ordinate and sub-ordinate semantic categories and hoped to find a differential cortical and/or temporal distribution of the brain response depending on the level of the categories. Twenty-three subjects saw 360 words belonging to six sub-ordinate categories (mammals, birds, fish, fruit, flowers, trees) within two super-ordinate categories (fauna, flora). Visually evoked magnetic fields were determined from whole-head (148-sensor) magnetoencephalography and analyzed in the source space (Minimum Norm Estimate).ResultsActivity (MNE amplitudes) 100–150 ms after stimulus onset in the left occipito-temporal area distinguished super-ordinate categories, while later activity (300–550 ms) in the left temporal area distinguished the six sub-ordinate categories.ConclusionOur results document temporally and spatially distinct processing and representation of words according to their categorical information. If further studies can rule out possible confounds then our results may help constructing a theory about the internal structure of entries in the mental lexicon and its access

Short communication : neuromagnetic evidence for early semantic access in word recognition

Magnetic brain responses recorded in the human magnetoencephalogram (MEG) distinguished between words with different semantics but carefully matched for frequency and length. Multiple recordings from a single subject showed that 100 ms following stimulus onset, significantly stronger neuromagnetic responses were elicited by words with strong multimodal semantic associations than by other word material. At this early processing step, there was a highly significant correlation (0.80) between the magnitude of brain responses to individual words recorded over parieto-occipital areas and their semantic association strengths. Subsequent to this early difference related to word meaning, additional differences in MEG responses emerged for words from different grammatical categories. Together, these results suggest that word meaning can be reflected by early neuromagnetic brain responses and before the grammatical information about the word is encoded

Spatial Semantic Features: ‘Convergent ’ vs. ‘Divergent ’ Verbs

In this study, we investigate two classes of spatial semantic features for verbs, using a priming paradigm. The verb classification is based on a distinction between the movement directions ‘convergent ’ (reducing the distance) and ‘divergent ’ (enlarging the distance between two objects). These directionality features were also applied to abstract conceptual domains like social contact or functional relation. The results confirm the concrete / abstract distinction for verbs and show that ‘convergent’ and ‘divergent ’ are able to produce priming effects within, and possibly across, conceptual domains. Convergent and divergent did not behave symmetrically leading us to the conclusion that they may be two different features rather than values of a ‘direction ’ feature

A: Topographical distribution of cortical activation (left-hemispheric view) in the source space (MNE in nAm) for verbs presented in minimal context

Anatomical projection as in Figure 1. In contrast to experiment 1, the early activation (250–300 ms, left) in the temporal region is weaker, whereas later activation (350–450 ms, right) in the more frontal region is stronger. B: Time course of activation for verbs presented together with a noun averaged across subjects separately for the three verb categories (with one, two, and three arguments). C: Group mean and standard error of the latencies (ordinate: in msec) for name-verb pairs with verbs including either one, two, or three arguments (abscissa).<p><b>Copyright information:</b></p><p>Taken from "Representation of the verb's argument-structure in the human brain"</p><p>http://www.biomedcentral.com/1471-2202/9/69</p><p>BMC Neuroscience 2008;9():69-69.</p><p>Published online 21 Jul 2008</p><p>PMCID:PMC2490697.</p><p></p