[Long-term exposure to high altitude affects spatial working memory in migrants-evidence from time and frequency domain analysis].

Long-term exposure to high altitude affects spatial working memory. Previous studies have focused on the analysis of electroencephalogram (EEG) components in time domain rather than in frequency domain. To explore the influence of long-term high altitude exposure on time dynamic characteristics and neural oscillation process of the spatial working memory, n-back task combined with the technology of event related potential recording was performed on 20 young migrants who grew at low altitude before the age of 18 and moved to high altitude more than three years ago, and 21 young people who had never been to the high altitude. EEG data were recorded, and the time domain and frequency domain analyses were performed. The results showed that the response time was longer and the accuracy rate was lower under the 2-back condition in the high altitude group compared with those in low altitude group. The late positive potential (LPP) amplitude was more negative, P2 amplitude was more positive in the 2-back condition, and the power value of early delta frequency band (1-4 Hz, 160-300 ms) was larger, while the power values of late delta frequency band (1-4 Hz, 450-650 ms) and theta frequency band (4-8 Hz, 450-650 ms) were smaller in the high altitude group compared with those in low altitude group. The results suggested that long-term exposure to high altitude affected the spatial working memory ability of the migrants, which was reflected in the lack of attention resources in the later matching stage, decreased response inhibition ability and information maintenance ability, and thus resulted in impaired spatial working memory.

Comparative studies on ovary and serum hormone levels in silver and blue foxes and their hybrids.

The silver and blue fox appear closely related despite their belonging to different genera, and the male and female fox hybrids are completely sterile in mating inter se or back to either of the parental groups. In the present study, we compared ovarian morphology and serum hormone concentrations among silver foxes, blue foxes, HSBs (silver fox male × blue fox female hybrids) and HBSs (blue fox male × silver fox female hybrids) during the pre-breeding and the breeding period. We found that either the fertile blue and silver foxes or the infertile hybrid foxes showed typical characteristics of ovary, with primordial, primary, secondary, antral and Graafian follicles. The diameters and quantities of different follicle classes in fertile foxes were greater than that in hybrids during the two period, while the thickness of zona pellucida (ZP) represented an opposite trend (P < 0.05). The relative weight of bilateral ovaries in fertile foxes was greater than that in hybrids during the pre-breeding period, while mean serum FSH represented an opposite trend during the breeding period (P < 0.05). The mean serum estradiol in fertile foxes was greater than that in HBS foxes during the pre-breeding period, and greater than hybrids during the breeding period (P < 0.05). These findings indicated that in the infertile hybrid foxes, lower estradiol levels produced by lesser and smaller antral follicles, thicker ZP during the two period, higher FSH levels during the breeding period, could be the basis of interpretations in cases of female fox hybrid infertility.

Altered resting-state network connectivity patterns for predicting attentional function in deaf individuals: An EEG study.

Multiple aspects of brain development are influenced by early sensory loss such as deafness. Despite growing evidence of changes in attentional functions for prelingual profoundly deaf, the brain mechanisms underlying these attentional changes remain unclear. This study investigated the relationships between differential attention and the resting-state brain network difference in deaf individuals from the perspective of brain network connectivity. We recruited 36 deaf individuals and 34 healthy controls (HC). We recorded each participant's resting-state electroencephalogram (EEG) and the event-related potential (ERP) data from the Attention Network Test (ANT). The coherence (COH) method and graph theory were used to build brain networks and analyze network connectivity. First, the ERPs of analysis in task states were investigated. Then, we correlated the topological properties of the network functional connectivity with the ERPs. The results revealed a significant correlation between frontal-occipital connection in the resting state and the amplitude of alert N1 amplitude in the alpha band. Specifically, clustering coefficients and global and local efficiency correlate negatively with alert N1 amplitude, whereas the characteristic path length positively correlates with alert N1 amplitude. In addition, deaf individuals exhibited weaker frontal-occipital connections compared to the HC group. In executive control, the deaf group had longer reaction times and larger P3 amplitudes. However, the orienting function did not significantly differ from the HC group. Finally, the alert N1 amplitude in the ANT task for deaf individuals was predicted using a multiple linear regression model based on resting-state EEG network properties. Our results suggest that deafness affects the performance of alerting and executive control while orienting functions develop similarly to hearing individuals. Furthermore, weakened frontal-occipital connections in the deaf brain are a fundamental cause of altered alerting functions in the deaf. These results reveal important effects of brain networks on attentional function from the perspective of brain connections and provide potential physiological biomarkers to predicting attention.

Oxygen Metabolism-induced Stress Response Underlies Heart-brain Interaction Governing Human Consciousness-breaking and Attention.

Neuroscientists have emphasized visceral influences on consciousness and attention, but the potential neurophysiological pathways remain under exploration. Here, we found two neurophysiological pathways of heart-brain interaction based on the relationship between oxygen-transport by red blood cells (RBCs) and consciousness/attention. To this end, we collected a dataset based on the routine physical examination, the breaking continuous flash suppression (b-CFS) paradigm, and an attention network test (ANT) in 140 immigrants under the hypoxic Tibetan environment. We combined electroencephalography and multilevel mediation analysis to investigate the relationship between RBC properties and consciousness/attention. The results showed that RBC function, via two independent neurophysiological pathways, not only triggered interoceptive re-representations in the insula and awareness connected to orienting attention but also induced an immune response corresponding to consciousness and executive control. Importantly, consciousness played a fundamental role in executive function which might be associated with the level of perceived stress. These results indicated the important role of oxygen-transport in heart-brain interactions, in which the related stress response affected consciousness and executive control. The findings provide new insights into the neurophysiological schema of heart-brain interactions.

Changes in Hippocampus and Amygdala Volume with Hypoxic Stress Related to Cardiorespiratory Fitness under a High-Altitude Environment.

The morphology of the hippocampus and amygdala can be significantly affected by a long-term hypoxia-induced inflammatory response. Cardiorespiratory fitness (CRF) has a significant effect on the neuroplasticity of the hippocampus and amygdala by countering inflammation. However, the role of CRF is still largely unclear at high altitudes. Here, we investigated brain limbic volumes in participants who had experienced long-term hypoxia exposure in Tibet (3680 m), utilizing high-resolution structural images to allow the segmentation of the hippocampus and amygdala into their constituent substructures. We recruited a total of 48 participants (48 males; aged = 20.92 ± 1.03 years) to undergo a structural 3T MRI, and the levels of maximal oxygen uptake (VO2max) were measured using a cardiorespiratory function test. Inflammatory biomarkers were also collected. The participants were divided into two groups according to the levels of median VO2max, and the analysis showed that the morphological indexes of subfields of the hippocampus and amygdala of the lower CRF group were decreased when compared with the higher CRF group. Furthermore, the multiple linear regression analysis showed that there was a higher association with inflammatory factors in the lower CRF group than that in the higher CRF group. This study suggested a significant association of CRF with hippocampus and amygdala volume, which may be related to hypoxic stress in high-altitude environments. A better CRF reduced physiological stress and a decrease in the inflammatory response was observed, which may be related to the increased oxygen transport capacity of the body.

Identification of key genes associated with spermatogenesis arrest in fox hybrids using weighted gene co-expression network analysis.

The silver fox and the blue fox represent different genera, but produce viable offspring. Although these hybrids show obvious heterosis, they are completely sterile due to spermatogenic arrest at the early stages of spermatogenesis, especially mitosis and meiosis I; the hybrids produce few spermatogonia and primary spermatocytes, and no secondary spermatocytes. Although the mechanisms of spermatogenic arrest have been well investigated, transcriptomic differences between hybrid and the pure-species testes have not clarified. In the present study, we used RNA sequencing (RNA-Seq) to generate testicular transcriptomic profiles for silver foxes, blue foxes, and reciprocal hybrids during the pre-breeding period and the breeding season. In total, 1,344,022 transcripts (≥200 bp) were generated; 1,057,724 genes were obtained; and 33,423 genes were shown to have fragments per kilobase of transcript per million mapped reads (FPKM) > 0.3. To identify the hub genes associated with spermatogenesis arrest, weighted gene co-expression network analysis (WGCNA) was used. Nine modules were explored. Genes in only a single module were consistently downregulated in the hybrids as compared to the pure species; these genes were significantly associated with fox hybrid male infertility. Six of the genes in this module (CATSPERD, DMRTC2, RNF17, NME5, SPEF2, SPINK2) also play key roles in mitosis and meiosis during spermatogenesis. Therefore, these six genes might be associated with fox hybrid male infertility.

Development and validation of a brief diabetic foot ulceration risk checklist among diabetic patients: a multicenter longitudinal study in China.

The study aims to develop and assess and validate a brief diabetic foot ulceration risk checklist among diabetic patients through a longitudinal study. Patients who had diabetes mellitus and had no foot ulceration and severe systematic disorders were recruited from eleven tertiary hospitals in nine provinces or municipalities of China. Internal consistency reliability, construct validity, concurrent validity, item property, and measurement invariance of the tool were assessed. The predictive capability of the tool was validated by the follow-up data using the receiver operating characteristic curve. At baseline, 477 valid cases were collected. Twelve items were remained after initial selection. Cronbach's alpha was 0.56. Confirmatory factor analysis showed that the model had acceptable goodness-of-fit yet local dependency between two items. Item response theory showed that most items had acceptable discrimination and difficulty parameters. Differential item functioning showed that tool had measurement invariance. 278 were followed up one year after the baseline. Follow-up showed that one-year incidence of ulceration among the patients was 3.6%, and the area under the receiver operating characteristic curve was 0.77 (95% confidence interval: 0.61-0.93). The cut-off point of the tool was 4, when sensitivity and specificity were 0.62 and 0.75 respectively. The checklist has good psychometric properties according to mixed evidences from classical and modern test theory, and has good predictive capability.