Distinct neuronal entrainment to beat and meter: Revealed by simultaneous EEG-fMRI.

Rhythm perception refers to the mental interpretation of rhythm by a listener. Musical rhythm perception typically involves two steps: beat extraction and metrical structure assignment (meter perception). The entrainment theories propose that different neuronal oscillations entrain to different levels of metrical structure in the rhythm (e.g., beat and meter) and thereby form a representation of the rhythm in the mind. Thus, neuronal populations that entrain to beat and meter should theoretically be different. However, although entrainment theories have been supported by many studies, the neuronal populations that entrain to beat and meter remain largely unknown. In this study, we used a paradigm to induce neuronal entrainment to beat and meter and obtained images of the neuronal populations with an electroencephalogram functional magnetic resonance imaging (EEG-fMRI) fusion method. We observed that some neuronal populations, including the bilateral putamen, bilateral caudate, left thalamus, and supplementary motor area (SMA), entrain to both beat and meter. We also observed that the bilateral putamen entrains more to meter and the SMA entrains more to beat. Our results suggest that the bilateral putamen plays an important role in meter perception.

The spatiotemporal pattern of pure tone processing: A single-trial EEG-fMRI study.

Although considerable research has been published on pure tone processing, its spatiotemporal pattern is not well understood. Specifically, the link between neural activity in the auditory pathway measured by functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) markers of pure tone processing in the P1, N1, P2, and N4 components is not well established. In this study, we used single-trial EEG-fMRI as a multi-modal fusion approach to integrate concurrently acquired EEG and fMRI data, in order to understand the spatial and temporal aspects of the pure tone processing pathway. Data were recorded from 33 subjects who were presented with stochastically alternating pure tone sequences with two different frequencies: 200 and 6400 Hz. Brain network correlated with trial-to-trial variability of the task-discriminating EEG amplitude was identified. We found that neural responses responding to pure tone perception are spatially along the auditory pathway and temporally divided into three stages: (1) the early stage (P1), wherein activation occurs in the midbrain, which constitutes a part of the low level auditory pathway; (2) the middle stage (N1, P2), wherein correlates were found in areas associated with the posterodorsal auditory pathway, including the primary auditory cortex and the motor cortex; (3) the late stage (N4), wherein correlation was found in the motor cortex. This indicates that trial-by-trial variation in neural activity in the P1, N1, P2, and N4 components reflects the sequential engagement of low- and high-level parts of the auditory pathway for pure tone processing. Our results demonstrate that during simple pure tone listening tasks, regions associated with the auditory pathway transiently correlate with trial-to-trial variability of the EEG amplitude, and they do so on a millisecond timescale with a distinct temporal ordering.

Functional connectivity corresponding to the tonotopic differentiation of the human auditory cortex.

Recent research has demonstrated that resting-state functional connectivity (RS-FC) within the human auditory cortex (HAC) is frequency-selective, but whether RS-FC between the HAC and other brain areas is differentiated by frequency remains unclear. Three types of data were collected in this study, including resting-state functional magnetic resonance imaging (fMRI) data, task-based fMRI data using six pure tone stimuli (200, 400, 800, 1,600, 3,200, and 6,400 Hz), and structural imaging data. We first used task-based fMRI to identify frequency-selective cortical regions in the HAC. Six regions of interest (ROIs) were defined based on the responses of 50 participants to the six pure tone stimuli. Then, these ROIs were used as seeds to determine RS-FC between the HAC and other brain regions. The results showed that there was RS-FC between the HAC and brain regions that included the superior temporal gyrus, dorsolateral prefrontal cortex (DL-PFC), parietal cortex, occipital lobe, and subcortical structures. Importantly, significant differences in FC were observed among most of the brain regions that showed RS-FC with the HAC. Specifically, there was stronger RS-FC between (1) low-frequency (200 and 400 Hz) regions and brain regions including the premotor cortex, somatosensory/-association cortex, and DL-PFC; (2) intermediate-frequency (800 and 1,600 Hz) regions and brain regions including the anterior/posterior superior temporal sulcus, supramarginal gyrus, and inferior frontal cortex; (3) intermediate/low-frequency regions and vision-related regions; (4) high-frequency (3,200 and 6,400 Hz) regions and the anterior cingulate cortex or left DL-PFC. These findings demonstrate that RS-FC between the HAC and other brain areas is frequency selective.

A distinction between two instruments measuring dispositional mindfulness and the correlations between those measurements and the neuroanatomical structure.

The most widely used measurements of mindfulness are the Mindful Attention Awareness Scale (MAAS) and the Five Facet Mindfulness Questionnaire (FFMQ). However, controversies exist regarding the application of these scales. Additionally, the neural mechanisms of dispositional mindfulness havebecome a topic of interest. In the current study, we used surface-based methodology to identify the brain regions underlying individual differences in dispositional mindfulness in a large non-clinical sampleand compared the two instruments for measuring the dispositional mindfulness. The results indicated that theMAAS scores were significantly associated with increased greymatter volumes in the right precuneus and the significant association between the precuneus and depression symptomatology was mediated by MAAS scores. Regarding the FFMQ, the Describing, Nonjudging, and Nonreactivity facets were selectively associated with the cortical volume, thickness and surface area of multiple prefrontal regions as well as the inferior parietal lobule. Importantly, Describing mediated the association between the dorsolateral PFC volume and the cognitive reappraisal strategies of emotion regulation. These resultssuggested that the MAASwere mainly associated with self-awareness, while the FFMQ facets were selectively involved in emotion regulation, attention control and self-awareness. Therefore, this study characterized the differences in inter-individual variability between the two typical measurements of dispositional mindfulnessand the correlations between those measurements and imaging analyses.

Neural basis of scientific innovation induced by heuristic prototype.

A number of major inventions in history have been based on bionic imitation. Heuristics, by applying biological systems to the creation of artificial devices and machines, might be one of the most critical processes in scientific innovation. In particular, prototype heuristics propositions that innovation may engage automatic activation of a prototype such as a biological system to form novel associations between a prototype's function and problem-solving. We speculated that the cortical dissociation between the automatic activation and forming novel associations in innovation is critical point to heuristic creativity. In the present study, novel and old scientific innovations (NSI and OSI) were selected as experimental materials in using learning-testing paradigm to explore the neural basis of scientific innovation induced by heuristic prototype. College students were required to resolve NSI problems (to which they did not know the answers) and OSI problems (to which they knew the answers). From two fMRI experiments, our results showed that the subjects could resolve NSI when provided with heuristic prototypes. In Experiment 1, it was found that the lingual gyrus (LG; BA18) might be related to prototype heuristics in college students resolving NSI after learning a relative prototype. In Experiment 2, the LG (BA18) and precuneus (BA31) were significantly activated for NSI compared to OSI when college students learned all prototypes one day before the test. In addition, the mean beta-values of these brain regions of NSI were all correlated with the behavior accuracy of NSI. As our hypothesis indicated, the findings suggested that the LG might be involved in forming novel associations using heuristic information, while the precuneus might be involved in the automatic activation of heuristic prototype during scientific innovation.

The electrophysiological effect of working memory load on involuntary attention in an auditory-visual distraction paradigm: an ERP study.

Event-related brain potentials (ERPs) were used to examine the electrophysiological effect of working memory (WM) load on involuntary attention caused by a task-irrelevant sound in an auditory-visual distraction paradigm. The different WM loads were manipulated by requiring subjects to remember the order of either three digits (low-load condition) or seven digits (high-load condition), and the irrelevant auditory stimuli consisted of repetitive standard sounds (80%) and environmental novel sounds (20%). We found that the difference waves (novel-minus-standard) showed significant MMN and Novelty-P3 components in the two WM load conditions. The amplitude of MMN increased with increasing the WM load, which indicated a more engaged change detection process under high-load condition. Then, the amplitude of Novelty-P3 was attenuated under high-load condition, which indicated a much reduced involuntary orienting of attention to novel sounds when increasing the WM load. These results indicated the top-down control of involuntary attention might be mainly active at the early change detection stage and the control of the later involuntary orienting of attention might be passive.