Syntactic and semantic contributions of pitch accents during sentence comprehension

Syntactic, semantic, and prosodic cues all establish expectations that guide sentence comprehension. In the prosodic domain, pitch accents can assign contrastive focus and resolve a syntactically ambiguous phrase. However, can prosodic focus marking (by pitch accenting) influence the interpretation of a sentence in the presence of syntactic and semantic cues? Our auditory experiment revolved around the sentence (in German) “Yesterday the policeman arrested the thief, not the murderer”. A pitch accent on either POLICEMAN or THIEF placed one of those arguments in contrastive focus with the ellipsis structure ("the murderer”). The two contrasted arguments could contain violations: in the syntax condition, the grammatical case of the article in the ellipsis structure mismatched the focused constituent in the main clause (nominative vs. accusative). In the semantic condition, the thematic roles of the contrasted words were incongruent (typical agent vs. patient roles of “arrest”). Visual comprehension questions probed the agent/patient role of the arguments in the sentence (subject or object), followed by a button-press response. Reaction times showed that if the pitch accent marked syntactic information that mismatched the syntactic information in the ellipsis structure, responses were delayed. The direction of the semantic effect depended on the focused noun. The response patterns showed that participants were led by the syntactic information to make their syntactic judgements, despite a conflicting expectation established by prosody. The experiment shows that pitch accents establish a syntactic expectation during sentence comprehension. However, these expectations are overwritten by incoming syntactic information to yield an interpretation of the sentence

Determination of the lowest energy structure of Ag8_8 from first-principles calculations

The ground-state electronic and structural properties, and the electronic excitations of the lowest energy isomers of the Ag$_8$ cluster are calculated using density functional theory (DFT) and time-dependent DFT (TDDFT) in real time and real space scheme, respectively. The optical spectra provided by TDDFT predict that the D$_{2d}$ dodecahedron isomer is the structural minimum of Ag$_8$ cluster. Indeed, it is borne out by the experimental findings.Comment: 4 pages, 2 figures. Accepted in Physical Review A as a brief repor

Differential contributions of inferior frontal gyrus subregions to sentence processing guided by intonation

Auditory sentence comprehension involves processing content (semantics), grammar (syntax), and intonation (prosody). The left inferior frontal gyrus (IFG) is involved in sentence comprehension guided by these different cues, with neuroimaging studies preferentially locating syntactic and semantic processing in separate IFG subregions. However, this regional specialisation has not been confirmed with a neurostimulation method. Consequently, the causal role of such a specialisation remains unclear. This study probed the role of the posterior IFG (pIFG) for syntactic processing and the anterior IFG (aIFG) for semantic processing with repetitive transcranial magnetic stimulation (rTMS) in a task that required the interpretation of the sentence's prosodic realisation. Healthy participants performed a sentence completion task with syntactic and semantic decisions, while receiving 10 Hz rTMS over either left aIFG, pIFG, or vertex (control). Initial behavioural analyses showed an inhibitory effect on accuracy without task-specificity. However, electric field simulations revealed differential effects for both subregions. In the aIFG, stronger stimulation led to slower semantic processing, with no effect of pIFG stimulation. In contrast, we found a facilitatory effect on syntactic processing in both aIFG and pIFG, where higher stimulation strength was related to faster responses. Our results provide first evidence for the functional relevance of left aIFG in semantic processing guided by intonation. The stimulation effect on syntactic responses emphasises the importance of the IFG for syntax processing, without supporting the hypothesis of a pIFG-specific involvement. Together, the results support the notion of functionally specialised IFG subregions for diverse but fundamental cues for language processing

Resolution of diaschisis contributes to early recovery from post-stroke aphasia

Diaschisis is a phenomenon observed in stroke that is defined as neuronal dysfunction in regions spared by the infarction but connected to the lesion site. We combined lesion network mapping and task-based functional MRI in 71 patients with post-stroke aphasia to investigate, whether diaschisis and its resolution contribute to early loss and recovery of language functions. Language activation acquired in the acute, subacute and chronic phase was analyzed in compartments with high and low normative resting-state functional connectivity to the lesion site on an individual basis. Regions with high compared to regions with low lesion connectivity showed a steeper increase in language reactivation from the acute to the subacute phase. This finding is compatible with the assumption of resolution of diaschisis. Additionally, language performance in the subacute phase and improvement from the subacute to the chronic phase significantly correlated with the diaschisis effect and its resolution, respectively, suggesting a behavioral relevance of this effect. We therefore assume that undamaged but functionally connected regions become dysfunctional due to missing input from the lesion contributing to the aphasic deficit. Since these regions are structurally intact, dysfunction resolves over time contributing to the rapid early behavioral improvement observed in aphasic stroke patients. Our results demonstrate that diaschisis and its resolution might be a relevant mechanism of early loss and recovery of language function in acute stroke patients

The role of the angular gyrus in semantic cognition: A synthesis of five functional neuroimaging studies

Semantic knowledge is central to human cognition. The angular gyrus (AG) is widely considered a key brain region for semantic cognition. However, the role of the AG in semantic processing is controversial. Key controversies concern response polarity (activation vs. deactivation) and its relation to task difficulty, lateralization (left vs. right AG), and functional-anatomical subdivision (PGa vs. PGp subregions). Here, we combined the fMRI data of five studies on semantic processing (n = 172) and analyzed the response profiles from the same anatomical regions-of-interest for left and right PGa and PGp. We found that the AG was consistently deactivated during non-semantic conditions, whereas response polarity during semantic conditions was inconsistent. However, the AG consistently showed relative response differences between semantic and non-semantic conditions, and between different semantic conditions. A combined analysis across all studies revealed that AG responses could be best explained by separable effects of task difficulty and semantic processing demand. Task difficulty effects were stronger in PGa than PGp, regardless of hemisphere. Semantic effects were stronger in left than right AG, regardless of subregion. These results suggest that the AG is engaged in both domain-general task-difficulty-related processes and domain-specific semantic processes. In semantic processing, we propose that left AG acts as a "multimodal convergence zone" that binds different semantic features associated with the same concept, enabling efficient access to task-relevant features

Acoustical-Mode-Driven Electron-Phonon Coupling in Transition-Metal Diborides

We show that the electron-phonon coupling in the transition-metal diborides NbB2 and TaB2 is dominated by the longitudinal acoustical (LA) mode, in contrast to the optical E_{2g} mode dominated coupling in MgB2. Our ab initio results, described in terms of phonon dispersion, linewidth, and partial electron-phonon coupling along Gamma to A, also show that (i) NbB2 and TaB2 have a relatively weak electron-phonon coupling, (ii) the E_{2g} linewidth is an order of magnitude larger in MgB2 than in NbB2 or TaB2, (iii) the E_{2g} frequency in NbB2 and TaB2 is considerably higher than in MgB2, and (iv) the LA frequency at A for TaB2 is almost half of that of MgB2 or NbB2.Comment: 4 pages, 4 figures, and 1 tabl

fMRI evidence of ‘mirror’ responses to geometric shapes

Mirror neurons may be a genetic adaptation for social interaction [1]. Alternatively, the associative hypothesis [2], [3] proposes that the development of mirror neurons is driven by sensorimotor learning, and that, given suitable experience, mirror neurons will respond to any stimulus. This hypothesis was tested using fMRI adaptation to index populations of cells with mirror properties. After sensorimotor training, where geometric shapes were paired with hand actions, BOLD response was measured while human participants experienced runs of events in which shape observation alternated with action execution or observation. Adaptation from shapes to action execution, and critically, observation, occurred in ventral premotor cortex (PMv) and inferior parietal lobule (IPL). Adaptation from shapes to execution indicates that neuronal populations responding to the shapes had motor properties, while adaptation to observation demonstrates that these populations had mirror properties. These results indicate that sensorimotor training induced populations of cells with mirror properties in PMv and IPL to respond to the observation of arbitrary shapes. They suggest that the mirror system has not been shaped by evolution to respond in a mirror fashion to biological actions; instead, its development is mediated by stimulus-general processes of learning within a system adapted for visuomotor control