Neuropsychologia
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Randomized Controlled Trial
The effects of high frequency rTMS on negative attentional bias are influenced by baseline state anxiety.
High frequency (HF) repetitive Transcranial Magnetic Stimulation (rTMS) of the right dorsolateral prefrontal cortex (DLPFC) has been shown to induce an attentional bias towards threatening information in healthy adults, associated with decreased activation in the right DLPFC and increased activation in the right amygdala. Additionally, it has been shown that healthy individuals with higher state anxiety portray similar negative attentional biases and cortico-subcortical activation patterns to those induced by HF-rTMS of the right DLPFC. Therefore, the aim of this study is to investigate whether inter-individual differences in state anxiety levels prior to the administration of HF-rTMS of the right DLPFC might be related to the degree to which rTMS induces such a negative attentional bias in healthy volunteers. ⋯ More specifically, we found that healthy individuals who scored higher on self-reports of state anxiety acquired more attentional bias towards negative information after HF-rTMS. Therefore, the effects of a single placebo-controlled rTMS session of the right DLPFC is consistent with the effects of a disrupted prefrontal-amygdala circuitry. The effects on attentional bias are largest in those participants reporting higher state anxiety scores, possibly because underlying amygdala activation is highest.
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Research has firmly established a link between recognition memory and the functional integrity of the medial temporal lobes (MTL). Dual-process models of MTL organization maintain that there is a division of labour within the MTL, with the hippocampus (HC) supporting recollective processes and perirhinal cortex (PRc) supporting familiarity assessment. An older neuropsychological literature suggested a different type of division of labour within the MTL, with left-sided structures playing a critical role in memory for verbal materials and right-sided structures being differentially involved in memory for material that cannot easily be verbalized. ⋯ We found that NB exhibited a deficit in overall recognition of aurally presented pronounceable non-words that reflected a specific impairment of familiarity assessment with preservation of recollective processes. Examination of recognition memory for visually presented abstract pictures and faces did not reveal any impairment, neither at the level of overall recognition nor, more specifically, at the level of familiarity assessment. These findings suggest that the neural mechanisms that support familiarity assessment in the temporal lobe operate in a manner that is tied to the specific stimulus class being assessed.
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Evidence from event-related potential (ERP) analyses of English spoken words suggests that the time course of English word recognition in monosyllables is cumulative. Different types of phonological competitors (i.e., rhymes and cohorts) modulate the temporal grain of ERP components differentially (Desroches, Newman, & Joanisse, 2009). The time course of Chinese monosyllabic spoken word recognition could be different from that of English due to the differences in syllable structure between the two languages (e.g., lexical tones). ⋯ In contrast to the English findings, our findings showed that the three partial mismatches (onset, rime, and tone mismatches) equally modulated the amplitudes and time courses of the N400 (a negative component that peaks about 400ms after the spoken word), whereas, the syllable mismatched words elicited an earlier and stronger N400 than the three partial mismatched words. The results shed light on the important role of syllable-level awareness in Chinese spoken word recognition and also imply that the recognition of Chinese monosyllabic words might rely more on global similarity of the whole syllable structure or syllable-based holistic processing rather than phonemic segment-based processing. We interpret the differences in spoken word processing between Chinese and English listeners as being due to morphosyllabic structural differences between the two languages.