It remains controversial whether Broca's aphasia is an articulatory deficit, a lexical-access problem, or agrammatism. In spite of recent neuroimaging studies, the causal link between cortical activity and linguistic subcomponents has not been elucidated. Here we report an experiment with event-related transcranial magnetic stimulation (TMS) to clarify the role of Broca's area, more specifically, the left inferior frontal gyrus (F3op/F3t), in syntactic processing. An experimental paradigm contrasted sentences requiring syntactic decisions with those requiring semantic decisions. We found selective priming effects on syntactic decisions when TMS was administered to the left F3op/F3t at a specific timing, but not to the left middle frontal gyrus (F2). Our results provide direct evidence of the involvement of the left F3op/F3t in syntactic processing.

Perceiving the passage of time is an essential ability for humans and animals. Here we used magnetoencephalography and investigated how our internal clock system in the brain converts sensory experiences into their time representations. We focused on neural activities in the high-level visual areas of human subjects when they saw visual patterns and estimated the duration of their presentation. The activities in the visual areas could give us neural indices about when subjects perceived the appearance and disappearance of visual patterns, thus enabling us to measure the stimulus duration "in the brain." Comparing these neural indices of time with subjective durations of stimuli measured psychophysically, we showed that, under some circumstances, these 2 durations can be dissociated in the opposite directions: although the neural index signals a "longer" interval of a stimulus over another one, it is perceived as "shorter" in subjective time scale. Instead, we found that these subjective intervals are closely linked to the strength, not timings, of neural activity evoked by visual patterns. Our results indicate that "nontemporal information" of perceptual neural activity, such as the strength (not latency) of neural responses, can influence the shaping of time representations in our brain.

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We aimed at testing the cortical representation of complex natural sounds within auditory cortex by conducting 2 human magnetoencephalography experiments. To this end, we employed an adaptation paradigm and presented subjects with pairs of complex stimuli, namely, animal vocalizations and spectrally matched noise. In Experiment 1, we presented stimulus pairs of same or different animal vocalizations and same or different noise. Our results suggest a 2-step process of adaptation effects: first, we observed a general itemunspecific reduction of the N1m peak amplitude at 100 ms, followed by an item-specific amplitude reduction of the P2m component at 200 ms after stimulus onset for both animal vocalizations and noise. Multiple dipole source modeling revealed the right lateral Heschl's gyrus and the bilateral superior temporal gyrus as sites of adaptation.In Experiment 2, we tested for cross-adaptation between animal vocalizations and spectrally matched noise sounds, by presenting pairs of an animal vocalization and its corresponding or a different noise sound. We observed cross-adaptation effects for the P2m component within bilateral superior temporal gyrus. Thus, our results suggest selectivity of the evoked magnetic field at 200 ms after stimulus onset in nonprimary auditory cortex for the spectral fine structure of complex sounds rather than their temporal dynamics.

While viewing works of art in galleries, we evaluate them by integrating at least two types of information: their visual properties (e.g., colors, symmetry, and proportion) and contextual information accompanying them (e.g., titles and names of artists). How rapidly the brain integrates visual and contextual information of artworks remains to be investigated. Using electroencephalography (EEG), we investigated neural activity when subjects with no professional experience in art viewed images of sculptures (masterpieces from the Classical and Renaissance periods, characterized by a canonical proportion of the golden ratio) and performed a five-scale rating of how appealing they were. At the beginning of each trial, we manipulated the expectations of the subjects for an upcoming sculpture by presenting information about its authenticity (either "genuine" or "fake"), although all images were actually taken from genuine artworks. The image of the sculpture was then presented, either in its original proportion or after being deformed by a photo-editing software. This 2 × 2 factorial design enabled us to identify whether each component of the EEG response was sensitive to contextual information (genuine or fake), visual information (original or deformed), or both. Results revealed that amplitudes of a positive EEG component emerging at 200-300ms after the presentation of the artworks (mainly distributed over the parietal cortex) were significantly modulated by both visual and contextual factors, indicating a rapid integration of these two types of information in the brain.

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A previous study reported the misbinding illusion in which visual features belonging to overlapping sets of items were erroneously integrated (Wu, Kanai, & Shimojo, 2004, Nature, 429, 262). In this illusion, central and peripheral portions of a transparent motion field combined color and motion in opposite fashions. When observers saw such stimuli, their perceptual color-motion bindings in the periphery were re-arranged in such a way as to accord with the bindings in the central region, resulting in erroneous color-motion pairings (misbinding) in peripheral vision. Here we show that this misbinding illusion is also seen in the binding of color and orientation. When the central field of a stimulus array was composed of objects that had coherent (regular) color-orientation pairings, subjective color-orientation bindings in the peripheral stimuli were automatically altered to match the coherent pairings of the central stimuli. Interestingly, the illusion was induced only when all items in the central field combined color and orientation in an orthogonal fashion (e.g. all red bars were horizontal and all green bars were vertical). If this orthogonality was disrupted (e.g. all red and green bars were horizontal), the central field lost its power to induce the misbinding illusion in the peripheral stimuli. The original misbinding illusion study proposed that the illusion stemmed from a perceptual extrapolation that resolved peripheral ambiguity with clear central vision. However, our present results indicate that visual analyses of the correlational structure between two features (color and orientation) are critical for the illusion to occur, suggesting a rapid integration of multiple featural cues in the human visual system.

Event-related functional magnetic resonance imaging was used to investigate brain processing of the signals ascending from peripheral C and Adelta fibers evoked by phasic laser stimuli on the right hand in humans. The stimulation of both C and Adelta nociceptors activated the bilateral thalamus, bilateral secondary somatosensory cortex, right (ipsilateral) middle insula, and bilateral Brodmann's area (BA) 24/32, with the majority of activity found in the posterior portion of the anterior cingulate cortex (ACC). However, magnitude of activity in the right (ipsilateral) BA32/8/6, including dorsal parts in the anterior portion of the ACC (aACC) and pre-supplementary motor area (pre-SMA), and the bilateral anterior insula was significantly stronger following the stimulation of C nociceptors than Adelta nociceptors. It was concluded that the activation of C nociceptors, related to second pain, evokes different brain processing from that of Adelta nociceptors, related to first pain, probably due to the differences in the emotional and motivational aspects of either pain, which are mainly related to the aACC, pre-SMA, and anterior insula.