Biomedical subjects

Dazhi Yin

Publications and source records attributed to Dazhi Yin.

3 recordsLinked to original sources

PubMed2026

Context-dependent functional diversity of dorsomedial posterior parietal neurons revealed by single-unit fMRI mapping during naturalistic viewing.

The dorsomedial posterior parietal cortex (dmPPC) plays an important role in episodic processing by integrating sensory, cognitive, and motor information across distributed brain systems. However, how individual dmPPC neurons participate in large-scale functional organization during naturalistic experience remains poorly understood. To address this question, we combined single-unit electrophysiology and awake fMRI in five rhesus macaques of both sexes viewing identical naturalistic video stimuli. Using single-unit fMRI mapping, we generated whole-brain neuron-BOLD functional maps by correlating individual neuronal activity with voxel-wise fMRI signals across the brain. We found that neuron-BOLD functional maps exhibited strong context-dependent organization, with neurons recorded during the same video context showing substantially greater similarity than neurons recorded during different video conditions. Compared with neuronal spiking activity or critical fMRI frames alone, neuron-BOLD functional maps more robustly captured contextual structure. Despite this shared large-scale organization, a substantial subset of neighboring neurons recorded simultaneously from the same electrode displayed markedly distinct whole-brain association patterns, revealing substantial local functional heterogeneity within the dmPPC. This local heterogeneity was not readily explained by waveform-based putative cell class or by opposing neuronal firing dynamics. In addition, distributed cortical and medial temporal regions exhibited highly context-dependent neuron-BOLD association patterns during naturalistic viewing. Together, these findings demonstrate that dmPPC neurons participate in dynamic and heterogeneous large-scale functional organization during naturalistic episodic processing. More broadly, this study establishes single-unit fMRI mapping as a framework for linking single-neuron activity to distributed whole-brain dynamics across contextual conditions.Significance Statement Using single-unit fMRI mapping, this study examined how individual dorsomedial posterior parietal cortex (dmPPC) neurons relate to large-scale brain activity during naturalistic video viewing in macaque monkeys. We found that neuron-BOLD functional maps exhibit strong context-dependent organization and capture contextual structure more robustly than neuronal spiking activity or fMRI frames alone. Despite this shared organization, a substantial subset of neighboring dmPPC neurons displayed markedly distinct whole-brain association patterns, revealing local functional heterogeneity that was not readily explained by waveform-based putative cell class or opposing firing dynamics. These findings provide insight into how local neuronal populations participate in distributed brain-wide functional organization during naturalistic episodic processing.

Journal Article↗

PubMed2026

Brain-wide spontaneous neural avalanches: Definition, functional dynamics and cognitive relevance.

Although spontaneous activity is ubiquitous across multiple spatiotemporal scales, its functional organization and cognitive relevance remain poorly understood. Following the classic neuronal avalanche framework, a spontaneous avalanche is defined as consecutively active frames separated by inactive time bins. Hence, multiple distinct avalanches may be considered as one avalanche, thereby ignoring their spatial and temporal distinguishability. Furthermore, group-level power-law fitting of such neural avalanches is often performed to evaluate brain criticality (referring to a system perched between order and disorder) due to the limited recording length of macroscale neuroimaging (such as functional magnetic resonance imaging), and the functional representation of brain-wide neural avalanches is largely unexplored. To address these issues, we proposed large-scale neural avalanches as a single, spatially consecutive cascade pattern and further investigated their functional dynamics, network propagation, and association with task-evoked activity. Compared with the conventional inactive-bin definition, our current approach is more favorable to power-law fitting of avalanche size and duration distributions at the individual level. We also demonstrated that participants whose brain activities were close to the critical point tend to have higher cognitive abilities. Notably, the ratio of neural avalanches that evolved from primary sensory to association networks negatively correlated with cognitive abilities. Moreover, the geometric distance between low-dimensional representations of task-evoked activity and spontaneous avalanches was associated with behavioral performance. This study not only provides a promising avenue for measuring avalanche criticality based on human whole-brain neuroimaging, but also suggests that spontaneous neural avalanches and their low-dimensional representations contribute to human cognitive abilities.

Humans↗

PubMed2025

Exploring the transmission of cognitive task information through optimal brain pathways.

Understanding the large-scale information processing that underlies complex human cognition is the central goal of cognitive neuroscience. While emerging activity flow models demonstrate that cognitive task information is transferred by interregional functional or structural connectivity, graph-theory-based models typically assume that neural communication occurs via the shortest path of brain networks. However, whether the shortest path is the optimal route for empirical cognitive information transmission remains unclear. Based on a large-scale activity flow mapping framework, we found that the performance of activity flow prediction with the shortest path was significantly lower than that with the direct path. The shortest path routing was superior to other network communication strategies, including search information, path ensembles, and navigation. Intriguingly, the shortest path outperformed the direct path in activity flow prediction when the physical distance constraint and asymmetric routing contribution were simultaneously considered. This study not only challenges the shortest path assumption through empirical network models but also suggests that cognitive task information routing is constrained by the spatial and functional embedding of the brain network.

Humans↗