Purpose: Individuals with presbycusis often show deficits on cognitive function, however, the exact neurophysiological mechanisms are not well understood. This study explored the alterations in ...intra- and inter-network functional connectivity (FC) of multiple networks in presbycusis patients, and further correlated FC with cognitive assessment scores to assess their ability to predict cognitive impairment. Methods: Resting-state functional magnetic resonance imaging (rs-fMRI) was performed in 40 presbycusis patients and 40 matched controls, and 12 resting state networks (RSNs) were identified by independent component analysis (ICA) approach. Two-sample t-test was carried out to detect the intra-network FC differences, and function network connectivity (FNC) was calculated to compare the inter-network FC differences. Pearson or Spearman correlation analysis was subsequently used to explore the correlation between altered FC and cognitive assessment scores. Results: Our study demonstrated that patients with presbycusis showed significantly decreased FC in subcortical limbic network (scLN), default mode network (DMN), executive control network (ECN) and attention network (AN) compared with the control group. Moreover, the connectivity for scLN-AUN (auditory network) and VN (visual network)-DMN were found significantly increased while AN-DMN was found significantly decreased in presbycusis patients. Ultimately, this study revealed the intra- and inter-network alterations associated with some cognitive assessment scores. Conclusion: This study observed intra- and inter-network FC alterations in presbycusis patients, and investigated that presbycusis can lead to abnormal connectivity of RSNs and plasticity compensation mechanism, which may be the basis of cognitive impairment, suggesting that FNC can be used to predict potential cognitive impairment in their early stage.
Few researchers investigated the topological properties and relationships with cognitive deficits in sudden sensorineural hearing loss (SNHL) with tinnitus. To explore the topological characteristics ...of the brain connectome following SNHL from the global level and nodal level, we recruited 36 bilateral SNHL patients with tinnitus and 37 well-matched healthy controls. Every subject underwent pure tone audiometry tests, neuropsychological assessments, and MRI scanning. AAL atlas was employed to divide a brain into 90 cortical and subcortical regions of interest, then investigated the global and nodal properties of "small world" network in SNHL and control groups using a graph-theory analysis. The global characteristics include small worldness, cluster coefficient, characteristic path length, local efficiency, and global efficiency. Node properties include degree centrality, betweenness centrality, nodal efficiency, and nodal clustering coefficient. Interregional connectivity analysis was also computed among 90 nodes. We found that the SNHL group had significantly higher hearing thresholds and cognitive impairments, as well as disrupted internal connections among 90 nodes. SNHL group displayed lower AUC of cluster coefficient and path length lambda, but increased global efficiency. The opercular and triangular parts of the inferior frontal gyrus, rectus gyrus, parahippocampal gyrus, precuneus, and amygdala showed abnormal local features. Some of these connectome alterations were correlated with cognitive ability and the duration of SNHL. This study may prove potential imaging biomarkers and treatment targets for future studies.
In this article, we propose a system that can fuse inertial measurement unit (IMU), light detection and ranging (LiDAR), and intermittent global positioning system (GPS) measurements to achieve high ...precision localization and mapping in large-scale environment. The iterated error-state Kalman filter is used to fuse IMU and LiDAR measurements to estimate relative motion information quickly. Based on the factor graph, LiDAR, GPS measurements, and loop closure are transformed into constraints for joint optimization to construct global map. A real-time GPS outlier detection method based on the IMU preintegration theory and residual chi-square test is designed. In addition, the use of robust kernel is supported to implicitly reduce the impact of undetected GPS outliers on the system. A LiDAR-based loop-closure detector is designed, which can search for a pair of point clouds with similar geometric information. Importantly, the performance of the proposed method is compared with state-of-the-art methods through a series of experiments. The experimental results show that the method is robust and accurate to complete the task of localization and mapping in large-scale environment.
Presbycusis, associated with a diminished quality of life characterized by bilateral sensorineural hearing loss at high frequencies, has become an increasingly critical public health problem. This ...study aimed to identify directed functional connectivity (FC) of the hippocampus in patients with presbycusis and to explore the causes if the directed functional connections of the hippocampus were disrupted. Presbycusis patients (
n
= 32) and age-, sex-, and education-matched healthy controls (
n
= 40) were included in this study. The seed regions of bilateral hippocampus were selected to identify directed FC in patients with presbycusis using Granger causality analysis (GCA) approach. Correlation analyses were conducted to detect the associations of disrupted directed FC of hippocampus with clinical measures of presbycusis. Compared to healthy controls, decreased directed FC between inferior parietal lobule, insula, right supplementary motor area, middle temporal gyrus and hippocampus were detected in presbycusis patients. Furthermore, a negative correlation between TMB score and the decline of directed FC from left inferior parietal lobule to left hippocampus (r = −0.423,
p
= 0.025) and from right inferior parietal lobule to right hippocampus (r = −0.516,
p
= 0.005) were also observed. The decreased directed functional connections of the hippocampus were detected in patients with presbycusis, which was associated with specific cognitive performance. This study mainly emphasizes the crucial role of hippocampus in presbycusis and will enhance our understanding of the neuropathological mechanisms of presbycusis.
It has been recently shown that if an input-affine nonlinear MIMO system is uniformly invertible and its normal form has a special structure, it is possible to design feedback laws that solve ...relevant design problems via dynamic output feedback, such as asymptotic stabilization and/or robust almost feedback linearization. The purpose of this note is to shed some light into the issue of existence of normal forms having such special structure and, in particular, to show that this is actually a consequence of a stronger property of invertibility, introduced by Hirschorn in the late 1970s.
The central nervous mechanism of acute tinnitus is different from that of chronic tinnitus, which may be related to the difference of cerebral blood flow (CBF) perfusion in certain regions. To verify ...this conjecture, we used arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) in this study to compare the CBF alterations of patients with acute and chronic tinnitus.
The current study included patients with chronic tinnitus (
= 35), acute tinnitus (
= 30), and healthy controls (
= 40) who were age-, sex-, and education-matched. All participants underwent MRI scanning and then ASL images were obtained to measure CBF of the entire brain and analyze the differences between groups as well as the correlations with tinnitus characteristics.
The chronic tinnitus group showed increased z-CBF in the right superior temporal gyrus (STG) and superior frontal gyrus (SFG) when compared with the acute tinnitus patients. Further connectivity analysis found enhanced CBF connectivity between the right STG and fusiform gyrus (FG), the right SFG and left middle occipital gyrus (MOG), as well as the right parahippocampal gyrus (PHG). Moreover, in the chronic tinnitus group, the tinnitus handicap questionnaire (THQ) score was positively correlated with the normalized z-CBF of right STG (
= 0.440,
= 0.013).
Our results confirmed that the CBF changes in some brain regions were different between acute and chronic tinnitus patients, which was correlated with certain tinnitus characteristics. This is of great value to further research on chronicity of tinnitus, and ASL has a promising application in the measurement of CBF.
Age-related hearing loss (ARHL), associated with the function of speech perception decreases characterized by bilateral sensorineural hearing loss at high frequencies, has become an increasingly ...critical public health problem. This study aimed to investigate the topological features of the brain functional network and structural dysfunction of the central nervous system in ARHL using graph theory.
Forty-six patients with ARHL and forty-five age, sex, and education-matched healthy controls were recruited to undergo a resting-state functional magnetic resonance imaging (fMRI) scan in this study. Graph theory was applied to analyze the topological properties of the functional connectomes by studying the local and global organization of neural networks.
Compared with healthy controls, the patient group showed increased local efficiency (E
) and clustering coefficient (C
) of the small-world network. Besides, the degree centrality (Dc) and nodal efficiency (Ne) values of the left inferior occipital gyrus (IOG) in the patient group showed a decrease in contrast with the healthy control group. In addition, the intra-modular interaction of the occipital lobe module and the inter-modular interaction of the parietal occipital module decreased in the patient group, which was positively correlated with Dc and Ne. The intra-modular interaction of the occipital lobe module decreased in the patient group, which was negatively correlated with the E
.
Based on fMRI and graph theory, we indicate the aberrant small-world network topology in ARHL and dysfunctional interaction of the occipital lobe and parietal lobe, emphasizing the importance of dysfunctional left IOG. These results suggest that early diagnosis and treatment of patients with ARHL is necessary, which can avoid the transformation of brain topology and decreased brain function.
This article provides a detailed comparative analysis of five orientational, two degrees of freedom (DOF) mechanisms whose envisioned application is the wrist of the iCub humanoid robot. Firstly, the ...current iCub mk.2 wrist implementation is presented, and the desired design objectives are proposed. Prominent architectures from literature such as the spherical five-bar linkage and spherical six-bar linkage, the OmniWrist-III and the Quaternion joint mechanisms are modeled and analyzed for the said application. Finally, a detailed comparison of their workspace features is presented. The Quaternion joint mechanism emerges as a promising candidate from this study.
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