Decreased Event-Related Desynchronization of Mental Rotation Tasks in Young Tibetan Immigrants

Impaired Neurological Activity in the Mental Rotation Ability of Tibetan Indigenous Residents After Chronic Exposure to High Altitude

Mental rotation is a core indicator of spatial ability, and a threshold for cognitive impairment may exist at approximately 4,000 m above sea level, but the specific thresholds for the severity of hypoxia in Tibetan indigenous populations in mental rotation ability remain largely unknown. To determine whether a threshold for mental rotation impairment exists in indigenous residents, we related a mental rotation task to inter-individual differences in a range of behavioral performance and neuropsychological characteristics across 51 indigenous Tibetan highlanders and 34 matched controls at three different altitudes (sea level, 2,900 m, and 4,200 m). Analyses of reaction time showed delayed behavioral responses in the 4,200 m altitude group. Further analyses of rotation-related negativity (RRN) revealed that the RRN was significantly more negative and the differences disappeared gradually for different angles among individuals exposed to an altitude of 4,200 m. Moreover, a time-frequency analysis showed significantly enhanced alpha- and beta-band power values for the 4,200 m altitude participants after stimulus presentation. The impairment in mental rotation ability is related to hypoxia and can be attributed to the absence of sufficient cognitive resources, which demonstrates the existence of a threshold for the effects of high altitude on the brain's mental rotation ability. Taken together, our findings have important implications for exploring the altitude threshold for the influence of high-altitude exposure on brain function, as well as for guiding the development of innovative strategies to optimize the response of the organism against chronic hypoxia-induced under extreme environments.

Reliability of MUSE 2 and Tobii Pro Nano at capturing mobile application users' real-time cognitive workload changes

Introduction

Despite the importance of cognitive workload in examining the usability of smartphone applications and the popularity of smartphone usage globally, cognitive workload as one attribute of usability tends to be overlooked in Human-Computer Interaction (HCI) studies. Moreover, limited studies that have examined the cognitive workload aspect often measured some summative workloads using subjective measures (e.g., questionnaires). A significant limitation of subjective measures is that they can only assess the overall, subject-perceived cognitive workload after the procedures/tasks have been completed. Such measurements do not reflect the real-time workload fluctuation during the procedures. The reliability of some devices on a smartphone setting has not been thoroughly evaluated.

Methods

This study used mixed methods to empirically study the reliability of an eye-tracking device (i.e., Tobii Pro Nano) and a low-cost electroencephalogram (EEG) device (i.e., MUSE 2) for detecting real-time cognitive workload changes during N-back tasks.

Results

Results suggest that the EEG measurements collected by MUSE 2 are not very useful as indicators of cognitive workload changes in our setting, eye movement measurements collected by Tobii Pro Nano with mobile testing accessory are useful for monitoring cognitive workload fluctuations and tracking down interface design issues in a smartphone setting, and more specifically, the maximum pupil diameter is the preeminent indicator of cognitive workload surges.

Discussion

In conclusion, the pupil diameter measure combined with other subjective ratings would provide a comprehensive user experience assessment of mobile applications. They can also be used to verify the successfulness of a user interface design solution in improving user experience.

The human brain in a high altitude natural environment: A review

With the advancement of in vivo magnetic resonance imaging (MRI) technique, more detailed information about the human brain at high altitude (HA) has been revealed. The present review aimed to draw a conclusion regarding changes in the human brain in both unacclimatized and acclimatized states in a natural HA environment. Using multiple advanced analysis methods that based on MRI as well as electroencephalography, the modulations of brain gray and white matter morphology and the electrophysiological mechanisms underlying processing of cognitive activity have been explored in certain extent. The visual, motor and insular cortices are brain regions seen to be consistently affected in both HA immigrants and natives. Current findings regarding cortical electrophysiological and blood dynamic signals may be related to cardiovascular and respiratory regulations, and may clarify the mechanisms underlying some behaviors at HA. In general, in the past 10 years, researches on the brain at HA have gone beyond cognitive tests. Due to the sample size is not large enough, the current findings in HA brain are not very reliable, and thus much more researches are needed. Moreover, the histological and genetic bases of brain structures at HA are also needed to be elucidated.

Resting-State Neuronal Activity and Functional Connectivity Changes in the Visual Cortex after High Altitude Exposure: A Longitudinal Study

Damage to the visual cortex structures after high altitude exposure has been well clarified. However, changes in the neuronal activity and functional connectivity (FC) of the visual cortex after hypoxia/reoxygenation remain unclear. Twenty-three sea-level college students, who took part in 30 days of teaching at high altitude (4300 m), underwent routine blood tests, visual behavior tests, and magnetic resonance imaging scans before they went to high altitude (Test 1), 7 days after they returned to sea level (Test 2), as well as 3 months (Test 3) after they returned to sea level. In this study, we investigated the hematological parameters, behavioral data, and spontaneous brain activity. There were significant differences among the tests in hematological parameters and spontaneous brain activity. The hematocrit, hemoglobin concentration, and red blood cell count were significantly increased in Test 2 as compared with Tests 1 and 3. As compared with Test 1, Test 3 increased amplitudes of low-frequency fluctuations (ALFF) in the right calcarine gyrus; Tests 2 and 3 increased ALFF in the right supplementary motor cortex, increased regional homogeneity (ReHo) in the left lingual gyrus, increased the voxel-mirrored homotopic connectivity (VMHC) value in the motor cortex, and decreased FC between the left lingual gyrus and left postcentral gyrus. The color accuracy in the visual task was positively correlated with ALFF and ReHo in Test 2. Hypoxia/reoxygenation increased functional connection between the neurons within the visual cortex and the motor cortex but decreased connection between the visual cortex and motor cortex.