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Fumitaka Homae

Publications and source records attributed to Fumitaka Homae.

3 recordsLinked to original sources

Sentence processing is uniquely human.

In this article, we will focus on three fundamental issues concerning language processing in the human brain, and update recent advances made by functional neuroimaging and magnetic stimulation studies of language. First, we will provide the first experimental evidence that the neural basis of sentence comprehension is indeed specialized. Specifically, our recent functional magnetic resonance imaging (fMRI) study has clarified that the human left prefrontal cortex (PFC) is more specialized in the syntactic processes of sentence comprehension than other domain-general processes such as short-term memory. Second, the distinction between explicit and implicit syntactic processes will be clarified, based on our fMRI studies that elucidate syntactic specialization in the left PFC. Third, we will advance a hypothesis stating that distinct subregions of the left PFC are recruited for the syntactic integration of lexico-semantic information. The current direction of research in the neuroscience of language is beginning to reveal the uniqueness of the human mind.

Animals↗

Selective enhancement of functional connectivity in the left prefrontal cortex during sentence processing.

We present the results of correlation analyses for identifying temporally correlated activations between multiple regions of interest. We focused on functional connectivity for two regions in the prefrontal cortex: the left inferior frontal gyrus (L. F3t/F3O) and the left precentral sulcus (L. PrCS). Temporal correlations of functional magnetic resonance imaging signals were separately examined during a sentence comprehension task and a lexical decision task, thereby averaging data throughout all voxels within a region of interest used as a reference region. We found that the reciprocal connectivity between L. F3t/F3O and L. PrCS was significantly enhanced during sentence processing, but not during lexico-semantic processing, which was confirmed under both auditory and visual conditions. Furthermore, significantly correlated regions were mostly concentrated in the left prefrontal cortex during the sentence task. These results demonstrate that the functional connectivity within the left prefrontal cortex is selectively enhanced for processing sentences, which may subserve the use of syntactic information for integrating lexico-semantic information.

Adult↗

From perception to sentence comprehension: the convergence of auditory and visual information of language in the left inferior frontal cortex.

We used functional magnetic resonance imaging (fMRI) to characterize cortical activation associated with sentence processing, thereby elucidating where in the brain auditory and visual inputs of words converge during sentence comprehension. Within one scanning session, subjects performed three types of tasks with different linguistic components from perception to sentence comprehension: nonword (N(AV); auditory and visual), phrase (P; either auditory or visual), and sentence (S; either auditory or visual) tasks. In a comparison of the P and N(AV) tasks, the angular and supramarginal gyri showed bilateral activation, whereas the inferior and middle frontal gyri showed left-lateralized activation. A comparison of the S and P tasks, together with a conjunction analysis, revealed a ventral region of the left inferior frontal gyrus (F3t/F3O), which was sentence-processing selective and modality-independent. These results unequivocally demonstrated that the left F3t/F3O is involved in the selection and integration of semantic information that are separable from lexico-semantic processing.

Adult↗