Changes of the Brain Causal Connectivity Networks in Patients With Long-Term Bilateral Hearing Loss.

It remains poorly understood how brain causal connectivity networks change following hearing loss and their effects on cognition. In the current study, we investigated this issue. Twelve patients with long-term bilateral sensorineural hearing loss [mean age, 55.7 ± 2.0; range, 39-63 years; threshold of hearing level (HL): left ear, 49.0 ± 4.1 dB HL, range, 31.25-76.25 dB HL; right ear, 55.1 ± 7.1 dB HL, range, 35-115 dB HL; the duration of hearing loss, 16.67 ± 4.5, range, 3-55 years] and 12 matched normally hearing controls (mean age, 52.3 ± 1.8; range, 42-63 years; threshold of hearing level: left ear, 17.6 ± 1.3 dB HL, range, 11.25-26.25 dB HL; right ear, 19.7 ± 1.3 dB HL, range, 8.75-26.25 dB HL) participated in this experiment. We constructed and analyzed the causal connectivity networks based on functional magnetic resonance imaging data of these participants. Two-sample t-tests revealed significant changes of causal connections and nodal degrees in the right secondary visual cortex, associative visual cortex, right dorsolateral prefrontal cortex, left subgenual cortex, and the left cingulate cortex, as well as the shortest causal connectivity paths from the right secondary visual cortex to Broca's area in hearing loss patients. Neuropsychological tests indicated that hearing loss patients presented significant cognitive decline. Pearson's correlation analysis indicated that changes of nodal degrees and the shortest causal connectivity paths were significantly related with poor cognitive performances. We also found a cross-modal reorganization between associative visual cortex and auditory cortex in patients with hearing loss. Additionally, we noted that visual and auditory signals had different effects on neural activities of Broca's area, respectively. These results suggest that changes in brain causal connectivity network are an important neuroimaging mark of cognitive decline. Our findings provide some implications for rehabilitation of hearing loss patients.

Alterations of Prefrontal-Posterior Information Processing Patterns in Autism Spectrum Disorders.

Autism spectrum disorder (ASD) is a heterogeneous disorder characterized by different levels of repetitive and stereotypic behavior as well as deficits in social interaction and communication. In this current study, we explored the changes in cerebral neural activities in ASD. The purpose of this study is to investigate whether there exists a dysfunction of interactive information processing between the prefrontal cortex and posterior brain regions in ASD. We investigated the atypical connectivity and information flow between the prefrontal cortex and posterior brain regions in ASD utilizing the entropy connectivity (a kind of directional connectivity) method. Eighty-nine patients with ASD and 94 typical developing (TD) teenagers participated in this study. Two-sample t-tests revealed weakened interactive entropy connectivity between the prefrontal cortex and posterior brain regions. This result indicates that there exists interactive prefrontal-posterior underconnectivity in ASD, and this disorder might lead to less prior knowledge being used and updated. Our proposals highlighted that aforementioned atypical change might accelerate the deoptimization of brain networks in ASD.

[Grounding technique for the safety and noise rejection of medical imaging equipments].

Grounding technique is very important to ensure the human safety, imaging devices' safety and the devices' reliable running. This paper expatriates the principles of the grounding safety, interference rejection earth, and the grounding modes and the mode selection for each imaging devices and equipments, and related grounding requirements.