Altered functional connectivity of primary olfactory cortex-hippocampus-frontal cortex in subjective cognitive decline during odor stimulation.

Subjective cognitive decline (SCD) is a high-risk population in the preclinical stage of Alzheimer's disease (AD), and olfactory dysfunction is a risk factor for dementia progression. The present study aimed to explore the patterns of functional connectivity (FC) changes in the olfactory neural circuits during olfactory stimulation in SCD subjects. A total of 56 SCD subjects and 56 normal controls (NCs) were included. All subjects were assessed with a cognitive scale, an olfactory behavior test, and olfactory task-based functional magnetic resonance imaging scanning. The FC differences in olfactory neural circuits between the two groups were analyzed by the generalized psychophysiological interaction. Additionally, we calculated and compared the activation of brain regions within the olfactory neural circuits during odor stimulation, the volumetric differences in brain regions showing FC differences between groups, and the correlations between neuroimaging indicators and olfactory behavioral and cognitive scale scores. During odor stimulation, the FC between the bilateral primary olfactory cortex (bPOC) and the right hippocampus in the SCD group was significantly reduced; while the FC between the right hippocampus and the right frontal cortex was significantly increased in the SCD group. The bPOC of all subjects showed significant activation, but no significant difference in activation between groups was found. No significant differences were observed in the volume of the brain regions within the olfactory neural circuits or in olfactory behavior between groups. The volume of the bPOC and right frontal cortex was significantly positively correlated with olfactory identification, and the volume of the right frontal cortex and right hippocampus was significantly correlated with cognitive functions. Furthermore, a significant correlation between the activation of bPOC and the olfactory threshold was found in the whole cohort. These results suggested that while the structure of the olfactory neural circuits and olfactory behavior in SCD subjects remained stable, there were significant changes observed in the FC of the olfactory neural circuits (specifically, the POC-hippocampus-frontal cortex neural circuits) during odor stimulation. These findings highlight the potential of FC alterations as sensitive imaging markers for identifying high-risk individuals in the early stage of AD.

The role of leadership level in college students' facial emotion recognition: evidence from event-related potential analysis.

While the role of emotion in leadership practice is well-acknowledged, there is still a lack of clarity regarding the behavioral distinctions between individuals with varying levels of leadership and the underlying neurocognitive mechanisms at play. This study utilizes facial emotion recognition in conjunction with electroencephalograms to explore the temporal dynamics of facial emotion recognition processes among college students with high and low levels of leadership. The results showed no significant differences in the amplitude of P1 during the early stage of facial emotion recognition between the two groups. In the middle stage of facial emotion recognition, the main effect of group was significant on the N170 component, with higher N170 amplitude evoked in high-leadership students than low-leadership students. In the late stage of facial emotion recognition, low-leadership students evoked greater LPP amplitude in the temporal-parietal lobe when recognizing happy facial emotions compared to high-leadership students. In addition, time-frequency results revealed a difference in the alpha frequency band, with high-leadership students exhibiting lower alpha power than low-leadership students. The results suggest differences in the brain temporal courses of facial emotion recognition between students with different leadership levels, which are mainly manifested in the middle stage of structural encoding and the late stage of delicate emotional processing during facial emotion recognition.

Working memory impairment in children orphaned by parental HIV/AIDS: An event-related potentials study.

A large body of literature has established that children orphaned by HIV/AIDS ('AIDS orphans') face numerous challenges, such as parental death, poverty, disrupted school attendance and stigma. All of these early life adversities can have long-lasting effects on brain function, especially the executive functions. Working memory, as one of the most studied aspects of executive functions, is also reported to be impaired in children with early adversity. However, limited data are available regarding how early life adverse events affect the neural dynamic associated with working memory processing in AIDS orphans. This study applied the electroencephalogram (EEG) technique to investigate the working memory process in 81 AIDS orphans and 62 non-orphan controls with n-back tasks. Results from EEG analysis and time-frequency analysis showed that AIDS orphans displayed smaller N2 and larger P2, P3 activation as well as enhanced theta and attenuated alpha band oscillations compared to the controls. The present findings indicated a deficit in working memory process in AIDS orphans and suggested that this deficit might be due to the impairments in attention allocation, detection and classification of stimuli and updating process in working memory.

Total synthesis and stereochemical assignment of rakicidin F.

Total synthesis of rakicidin F was accomplished in 20 linear steps (0.68% overall yield), which enabled the configural determination of its six stereogenic centers as 2R, 15R, 16R, 17S, 19S, and 21S. The macrolactonization of the rakicidin linear precursor was investigated and the unsuccessful results might be attributed to the steric hindrance near C16-OH.

The Role of Leadership Level in College Students' Decision-Making: Evidence From Event-Related Potential Analysis.

Although risk decision-making plays an important role in leadership practice, the distinction in behavior between humans with differing levels of leadership, as well as the underlying neurocognitive mechanisms involved, remain unclear. In this study, the Ultimatum Game (UG) was utilized in concert with electroencephalograms (EEG) to investigate the temporal course of cognitive and emotional processes involved in economic decision-making between high and low leadership level college students. Behavioral results from this study found that the acceptance rates in an economic transaction, when the partner was a computer under unfair/sub unfair condition, were significantly higher than in transactions with real human partners for the low leadership group, while there was no significant difference in acceptance rates for the high leadership group. Results from Event-Related Potentials (ERP) analysis further indicated that there was a larger P3 amplitude in the low leadership group than in the high leadership group. We concluded that the difference between high and low leadership groups was at least partly due to their different emotional management abilities.