Research On Low-frequency Characteristics And Aging Of Brain Attention Network

Attention is a behavior and cognitive process that selectively focuses on specific subjective or objective information.It plays an essential role in sensing and processing external physical stimuli of the brain.It is also a necessary condition for individuals to adapt to society and be considered as a pivotal issue in the field of cognitive science.Dysfunctional attention may cause a series of mental diseases,such as attentiondeficit/hyperactivity disorder,schizophrenia.Previous studies have found that the attentional cognitive function of the brain is closely related to blood oxygen leveldependent(BOLD)signals,and a significant change of such function has occurred in the aging process of human beings,which may be associated with the dysregulation of the dorsal and the ventral attention network,two parts of the attention network.Although many theories have been used to explain the change of the attentional function along with aging processing,the brain mechanisms of such change is still poorly understood.Additionally,the existing research regarding the attention are mainly focused on the highband BOLD signals related changes,and relatively little anchored in low-band BOLD signals.In the first part of this study,we performed coherence analysis on 407 healthy subjects.The frequency-specific of the attention network was revealed by using the statistical analysis and between-group comparisons concerning the between and within functional connectivity of the DAN and VAN networks.The results showed that the attention network has three specific frequencies which different from physiological frequencies such as breathing and heartbeat,revealing the spontaneous neural activity of the coherence.Subsequent analysis of variance examined the main effects of frequency and age of the attention network and the interaction effect of frequency and age,revealing that aging may lead to weakened DAN connection and affect the attention-oriented function of the elderly,which is consistent with previous findings.More importantly,we also discovered the compensatory mechanisms of the attention system.Specifically,when a certain aspect of the attention system is affected by the aging,the attention system will call or strengthen other neural resources of the brain to complete the attention Cognitive task,which is consistent with the previous compensation hypothesis.In addition,we found a significant dedifferentiation trend on the time scale.These results provide new insights into deep understanding of the attention system of the brain,and also provide new avenues for the treatment of attention dysfunction that caused by aging.In the second part of the study,we use the frequency division method proposed in the first part,and combined with the graph theory method to analyze the topological properties of the attention network.Then,we divided the participants into different groups according to the age and frequency band.Area under the curve of the global efficiency,the local efficiency,the shortest path,the clustering coefficient and the small-world was performed based on variance.The results showed that with the increasing frequency band,the global efficiency increases,while the local efficiency,clustering coefficient,shortest path,and small world decreases.These findings indicated that the integration and segregation of attention networks are dynamically changing on different time scales.Furthermore,we also found that the overall activity of attention networks at the network level has a frequency advantage effect.We did not find any significant differences between elderly and young adults regarding the global efficiency by examining the aging effect of the attention network.However,in the low frequency(0.046-0.129Hz)band,the clustering coefficient and local efficiency decreased with aging.These findings provide new evidence for the dedifferentiation hypothesis and served as a new theoretical basis for revealing the aging effect on the attention network.In summary,this article explores the low-frequency characteristics and aging of the attention networks from the functional connectivity to the macro-network prospective,which provided new evidence for the compensation hypothesis and dedifferentiation hypothesis of the attention cognition,and provides a new basis for revealing the cognitive neural mechanisms of the aging effect on the brain attention system.