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The phase of low-frequency, rhythmic cortical activity is essential for organizing brain processes because it provides a recurrent temporal frame for information coding. However, the low-frequency cortical phase exhibits great flexibility in response to external influences. Given that brain rhythms have been found to track respiratory inputs, we hypothesized that slow breathing, commonly associated with mental regulation, could reorganize the relationship between these two rhythmic systems through the adjustment of the cortical phase to such a slow train of inputs. Based on simultaneous magnetoencephalography and respiratory measurements, we report that while participants performed paced breathing, slow relative to normal breathing modulated cortical phase activity in the alpha range across widespread brain areas. Such modulation effects were specifically locked to the middle of the inspiration stage and exhibited a well-structured pattern. At the single-subject level, the phase angles underlying the effects became more likely to be diametrically opposed across breaths, indicating unique and consistent phase adjustment to slow inspiratory inputs. Neither cardiac fluctuations nor breathing-unrelated task effects could account for the findings. We suggest that slow-paced inspiration could organize the cortical phase in a regularized phase pattern, revealing a rhythmic but dynamic neural network integrated with different neurophysiological systems through volitional control. NEW & NOTEWORTHY Breathing is more complicated than a simple gas exchange, as it is integrated with numerous cognitive and emotional functions. Controlled slow breathing has often been used to regulate mental processes. This magnetoencephalography study demonstrates that slow-paced relative to normal-paced inspiration could organize the timing of alpha rhythmic activities across breathing cycles in a structured manner over widespread brain areas. Our results reveal how a volitionally controlled change in respiratory behavior could systematically modulate cortical activity.

Learning non-native phonetic categories in adulthood is an exceptionally challenging task, characterized by large interindividual differences in learning speed and outcomes. The neurobiological mechanisms underlying the interindividual differences in the learning efficacy are not fully understood. Here we examine the extent to which training-induced neural representations of non-native Mandarin tone categories in English listeners (n = 53) are increasingly similar to those of the native listeners (n = 33) who acquired these categories early in infancy. We assess the extent to which the neural similarities in representational structure between non-native learners and native listeners are robust neuromarkers of interindividual differences in learning success. Using intersubject neural representational similarity (IS-NRS) analysis and predictive modeling on two functional magnetic resonance imaging datasets, we examined the neural representational mechanisms underlying speech category learning success. Learners’ neural representations that were significantly similar to the native listeners emerged in brain regions mediating speech perception following training; the extent of the emerging neural similarities with native listeners significantly predicted the learning speed and outcome in learners. The predictive power of IS-NRS outperformed models with other neural representational measures. Furthermore, neural representations underlying successful learning were multidimensional but cost-efficient in nature. The degree of the emergent native-similar neural representations was closely related to the robustness of neural sensitivity to feedback in the frontostriatal network. These findings provide important insights into the experience-dependent representational neuroplasticity underlying successful speech learning in adulthood and could be leveraged in designing individualized feedback-based training paradigms that maximize learning efficacy.

In contrast to the classic view that facial expressions convey specific emotional states, recent theories have postulated that perception is a highly contextualised phenomenon. The present study utilised sequential effects as a probe to examine how the preceding context informs current facial expression perception, while participants performed a binary categorisation task on a sequence of expressions morphed from fearful to disgusted prototypes. We found that preceding stimuli/responses played differential roles in expression-based sequential effects. When preceding responses were analytically controlled for, the participants were biased to categorise the current targets as being either away from or close to the category of preceding expressions, yielding stimulus-related contrast or assimilation effects, depending on whether the stimulus similarity between the preceding and current expressions was small or large. When the stimulus similarity between successive expressions was analytically controlled for, preceding responses slanted current categorisation judgments toward response-related assimilative consequences. Distinct from stimulus-related contrast, both stimulus-related and response-related assimilations were robust since they could persist for expressions presented up to two trials back and when the perceptual quality of the stimuli was poor. We suggest that the criterion-shift account is generally compatible with the overall findings, revealing how facial expression perception is temporally contextualised.

An important issue facing the empirical study of consciousness concerns how the contents of incoming stimuli gain access to conscious processing. According to classic theories, facial stimuli are processed in a hierarchical manner. However, it remains unclear how the brain determines which level of stimulus content is consciously accessible when facing an incoming facial stimulus. Accordingly, with a magnetoencephalography technique, this study aims to investigate the temporal dynamics of the neural mechanism mediating which level of stimulus content is consciously accessible. Participants were instructed to view masked target faces at threshold so that, according to behavioral responses, their perceptual awareness alternated from consciously accessing facial identity in some trials to being able to consciously access facial configuration features but not facial identity in other trials. Conscious access at these two levels of facial contents were associated with a series of differential neural events. Before target presentation, different patterns of phase angle adjustment were observed between the two types of conscious access. This effect was followed by stronger phase clustering for awareness of facial identity immediately during stimulus presentation. After target onset, conscious access to facial identity, as opposed to facial configural features, was able to elicit more robust late positivity. In conclusion, we suggest that the stages of neural events, ranging from prestimulus to stimulus-related activities, may operate in combination to determine which level of stimulus contents is consciously accessed. Conscious access may thus be better construed as comprising various forms that depend on the level of stimulus contents accessed. NEW & NOTEWORTHY The present study investigates how the brain determines which level of stimulus contents is consciously accessible when facing an incoming facial stimulus. Using magnetoencephalography, we show that prestimulus activities together with stimulus-related activities may operate in combination to determine conscious face detection or identification. This finding is distinct from the previous notion that conscious face detection precedes identification and provides novel insights into the temporal dynamics of different levels of conscious face perception.

Participants performed a priming task during which emotional faces served as prime stimuli and emotional words served as targets. Prime-target pairs were congruent or incongruent and two levels of prime visibility were obtained by varying the duration of the masked primes. To probe a neural signature of the impact of the masked primes, lateralized readiness potentials (LRPs) were recorded over motor cortex. During the high-visibility condition, responses to word targets were faster when the prime-target pairs were congruent than when they were incongruent, providing evidence of priming effects. In line with the behavioral results, the electrophysiological data showed that high-visibility face primes resulted in LRP differences between congruent and incongruent trials, suggesting that prime stimuli initiated motor preparation. Contrary to the above pattern, no evidence for reaction time or LRP differences was observed during the low-visibility condition, revealing that the depth of facial expression processing is dependent upon stimulus visibility.

Objective Occult clinical presentations usually hinder the early detection and management of patients with bone metastases from thyroid carcinoma. We retrospectively investigated the clinical outcomes of such patients from 1993 to 2004 and analyzed the prognostic parameters. Design The basic demographic data and manifestations of 44 patients who had thyroid carcinoma with bone metastases were reviewed. We studied the gender, age, locations of metastases, histological types, treatment methods, hypercalcemic episodes and results of treatments. We used Kaplan-Meier survival analysis and log-rank tests to access the statistical significance. Main Outcome The incidence of bone metastasis from thyroid carcinomas in this series was 5.0%. Twenty patients (45.4%) had follicular, 16 (36.3%) had papillary, 3 (6.8%) had anaplastic, 3 (6.8%) had medullary, and 2 (4.5%) had Hurthel cell carcinomas. Twelve patients had hypercalcemic episodes, ranging from 2.6 to 2.9 mmolL−1 (mean ± SD: 2.68 ± 0.15 mmolL−1). Survival time after bone metastases ranged from 2 months to 8 years (mean ± SD: 5.3 ± 1.3 years). The 5-year survival rate was 79.4% and the 10-year survival rate was 52.9%. Regarding the histological cancer type, patients with papillary and follicular cancers survived significantly longer than those with anaplastic and medullary cancers (p < 0.05). In addition, the patients presenting with hypercalcemia had the worst survival (p < 0.05). Conclusions Thyroid carcinoma can present with bone metastases in its early stage. We found that both tumor type and hypercalcemia were significant prognostic factors for survival time.

Existing models of facial identity perception often assume that information conveyed by facial stimuli provides the sole basis for identity judgments, largely ignoring the involvement of contextual effects. Capitalizing on sequential effects, the present study investigates whether facial identity is judged relative to a context shaped by stimuli presented in previous trials. When categorizing a sequence of facial identities, our results demonstrated that participants' categorization of current faces varied according to the local sequential context provided by the immediately preceding faces and, to some extent, by the preceding stimuli presented two trials prior to the current trial. Moreover, this variation depended on the relative distance between the preceding and current faces. Notably, the nature of these identity-based sequential effects was qualitatively different between male and female participants. Female participants tended to respond to the current faces with the same category label as on the preceding faces. However, male participants responded with the same label only when the relative distance was small, but responded with a different label when the relative distance was increasingly large. The present study demonstrates that relative information between the preceding and current faces may be used as evidence to inform a judgment. However, this process is multifaceted rather than unitary and depends in part on participant gender.

While the role of attention in determining the neural fate of unattended emotional items has been investigated in the past, it remains unclear whether bottom-up and top-down factors have differential effects in shaping responses evoked by such stimuli. To study the effects of bottom-up and top-down factors on the processing of neutral and fearful faces, we employed functional magnetic resonance imaging (fMRI) while participants performed attentional tasks that manipulated these factors. To probe the impact of top-down mechanisms on the processing of face distractors, target letters either had to be found among several distinct nontarget letters (attentional load condition) or among identical nontarget letters (baseline condition). To probe the impact of bottom-up factors, we decreased the salience of the targets by reducing their size and contrast relative to baseline (salience condition). Our findings revealed that bottom-up and top-down manipulations produced dissociable effects on amygdala and fusiform gyrus responses to fearful-face distractors when task difficulty was equated. When the attentional load of the main task was high, weaker responses were evoked by fearful-face distractors relative to baseline during the early trials. By contrast, decreasing target salience resulted in increased responses relative to baseline. The present findings suggest that responses evoked by unattended fearful faces are modulated by several factors, including attention and stimulus salience.