Linking semantic priming effect in functional MRI and event-related potentials

Graduate School of Environmental Studies, Nagoya University, Nagoya, Aichi, 464-8601, Japan.
NeuroImage (Impact Factor: 6.36). 03/2005; 24(3):624-34. DOI: 10.1016/j.neuroimage.2004.09.008
Source: PubMed


The aim of this study is to examine the neural substrates involved in semantic priming using a combined event-related functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) study. Twelve subjects were instructed to judge whether the presented target word was a real word or a nonword. Under the related condition, target words were preceded by a semantically related prime word. On the other hand, under the unrelated condition, prime words did not have semantic relatedness with the target word. The reaction time for reaching a judgment was longer under the unrelated condition than under the related condition, indicating that the recognition of target words is promoted by semantic priming under the related condition. In the fMRI results, we found reduced activity in the dorsal and ventral left inferior frontal gyrus, the anterior cingulate, and left superior temporal cortex for related versus unrelated conditions (i.e., the repetition suppression effect). ERP analysis revealed that the amplitude of the N400 component was reduced under the related condition compared with the unrelated condition (i.e., the N400 priming effect). Correlation analysis between the BOLD repetition suppression effect and the N400 priming effect decomposed by independent component analysis (ICA) across subjects showed significant correlation in the left superior temporal gyrus. This finding is consistent with the recent MEG data suggesting that the source of N400 is judged to be the bilateral superior temporal lobe. We discussed this finding herein in relation to the modulation of access to the phonological representation caused by semantic priming.

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Available from: Tomohisa Okada
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    • "Following the timing of a previous study (Gold et al., 2006) which used short SOA (study 2) and long SOA (study 3) separately to emphasize early and late stages of word recognition, we also employed a short SOA of 150 ms and a long SOA of 600 ms. Following previous studies (Matsumoto et al., 2005; Rissman, Eliassen, & Blumstein, 2003), we used 600 ms as long SOA to ensure that stimuli would be presented within an appropriate time frame for TMS. A schematic is shown in Fig. 1A. "
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    ABSTRACT: Activation of left anterior inferior frontal gyrus (aLIFG) and left middle temporal gyrus (LMTG) has been observed in some functional neuroimaging studies of lexical decision but not others. It is thus unclear whether these two regions are necessary for word recognition. By applying continuous theta-burst transcranial magnetic stimulation (TMS) which temporally suppresses local brain function, we examined whether aLIFG and LMTG play causal roles in word recognition in a visual lexical decision task (LDT). Furthermore, we manipulated stimulus onset asynchrony (SOA) between prime and target to test whether these regions contribute to word recognition differently. In the LDT task, target words were preceded by semantically related primes (Related Condition; RC) or semantically unrelated words (Unrelated Condition; UC), under both short (150 ms) and long (600 ms) SOA conditions. TMS of aLIFG and LMTG significantly affected the word recognition speed compared to TMS of Vertex. Our results provide evidence that both aLIFG and LMTG contribute to word recognition speed. Furthermore, at short SOA, TMS of aLIFG or LMTG prolonged reaction time (RT). In contrast, at long SOA, there was a significant region by SOA by TMS interaction such that TMS of aLIFG prolonged RT, whereas TMS of LMTG speeded RT. These results suggest that aLIFG and LMTG may play different roles in word recognition.
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    • "Supraliminal semantic priming, which also involves controlled semantic mechanisms such as a comparison of the meaning of the prime and the target word (semantic matching) in addition to automatic semantic processing (Neely, 1991), modulated activity also in brain regions other than vOT. The regions varied widely across studies and included the superior and the middle temporal gyri (Copland et al., 2003; Giesbrecht et al., 2004; Gold et al., 2006; Kotz et al., 2002; Matsumoto et al., 2005; Rissman et al., 2003; Wible et al., 2006), as well as the inferior and the middle frontal gyri (Copland et al., 2003; Giesbrecht et al., 2004; Kotz et al., 2002; Matsumoto et al., 2005; Rissman et al., 2003; Wheatley et al., 2005; Wible et al., 2006). It has therefore been suggested that vOT reflects automatic semantic activation whereas other temporal and frontal areas support controlled semantic processing (Ulrich et al., 2013). "
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    ABSTRACT: In classical theories of attention, unconscious automatic processes are thought to be independent of higher-level attentional influences. Here, we propose that unconscious processing depends on attentional enhancement of task-congruent processing pathways implemented by a dynamic modulation of the functional communication between brain regions. Using functional magnetic resonance imaging, we tested our model with a subliminally primed lexical decision task preceded by an induction task preparing either a semantic or a perceptual task set. Subliminal semantic priming was significantly greater after semantic compared to perceptual induction in ventral occipito-temporal (vOT) and inferior frontal cortex, brain areas known to be involved in semantic processing. The functional connectivity pattern of vOT varied depending on the induction task and successfully predicted the magnitude of behavioral and neural priming. Together, these findings support the proposal that dynamic establishment of functional networks by task sets is an important mechanism in the attentional control of unconscious processing. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
    Full-text · Article · Nov 2014 · Human Brain Mapping
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    • "Furthermore, to investigate the relationship between the fMRI and ERP activations, we calculated correlations of the experimental effect in the identified ERP sources with those from selected fMRI clusters, similar to the approach taken by Matsumoto and colleagues [16]. Following their procedure, we calculated the differences between mean activations to unrelated vs. related primes (semantic effect), and additionally, we calculated the unrelated vs. identical difference (identity effect). "
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    ABSTRACT: Numerous studies have reported neurophysiological effects of semantic priming in electroencephalography (EEG) and in functional magnetic resonance imaging (fMRI). Because of differing methodological constraints, the comparability of the observed effects remains unclear. To directly compare EEG and fMRI effects and neural sources of semantic priming, we conducted a semantic word-picture priming experiment while measuring EEG and fMRI simultaneously. The visually presented primes were pseudowords, words unrelated to the target, semantically related words and the identical names of the target. Distributed source analysis of the event-related potentials (ERPs) successfully revealed a large effect of semantic prime-target relatedness (the N400 effect), which was driven by activations in a left-temporal source region. However, no significantly differing activations between priming conditions were found in the fMRI data. Our results support the notion that, for joint interpretations of existing EEG and fMRI studies of semantic priming, we need to fully appreciate the respective methodological limitations. Second, they show that simultaneous EEG-fMRI, including ERP source localization, is a feasible and promising methodological advancement for the investigation of higher-cognitive processes. Third, they substantiate the finding that, compared to fMRI, ERPs are often more sensitive to subtle cognitive effects.
    Full-text · Article · Dec 2013 · PLoS ONE
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