The relationship between self-determined motivation, emotional involvement, cognitive involvement and leisure-time physical activity among college students.

Objective: Grounded in self-determination theory and the stimulus-organism-response framework, this study examines factors that affect college students' leisure-time physical activity by considering the basic psychological needs satisfaction (i.e., autonomy, competence, and relatedness), self-determined motivation, emotional and cognitive involvement. Methods: The sample included 526 students (47.8 % male; 57.2 % female) from four universities in central China. A structural equation model was used to analyze associations among variables. Results: The satisfaction of all three basic psychological needs had a significant positive impact on emotional involvement. Additionally, autonomy and competence need satisfaction had a significant positive impact on self-determined motivation and cognitive involvement. However, contrary to our expectation, there was no significant effect of relatedness need satisfaction on self-determined motivation and cognitive involvement. Furthermore, emotional involvement was found to have a significant effect on leisure-time physical activity intention for male students. Interestingly, the relationship between cognitive involvement and leisure-time physical activity intention is significant, but this effect was observed only among female students. Conclusion: Pedagogical strategies and tactics better satisfied students' psychological needs, promote physical education classes emotional and cognitive involvement, therefore, achieve autonomous active lifestyle behaviors in leisure time.

Cerebellum and hippocampus abnormalities in patients with insomnia comorbid depression: a study on cerebral blood perfusion and functional connectivity.

Chronic insomnia disorder and major depressive disorder are highly-occurred mental diseases with extensive social harm. The comorbidity of these two diseases is commonly seen in clinical practice, but the mechanism remains unclear. To observe the characteristics of cerebral blood perfusion and functional connectivity in patients, so as to explore the potential pathogenesis and biological imaging markers, thereby improving the understanding of their comorbidity mechanism. 44 patients with chronic insomnia disorder comorbid major depressive disorder and 43 healthy controls were recruited in this study. The severity of insomnia and depression were assessed by questionnaire. The cerebral blood perfusion and functional connectivity values of participants were obtained to, analyze their correlation with questionnaire scores. The cerebral blood flow in cerebellum, vermis, right hippocampus, left parahippocampal gyrus of patients were reduced, which was negatively related to the severity of insomnia or depression. The connectivities of left cerebellum-right putamen and right hippocampus-left inferior frontal gyrus were increased, showing positive correlations with the severity of insomnia and depression. Decreased connectivities of left cerebellum-left fusiform gyrus, left cerebellum-left occipital lobe, right hippocampus-right paracentral lobule, right hippocampus-right precentral gyrus were partially associated with insomnia or depression. The connectivity of right hippocampus-left inferior frontal gyrus may mediate between insomnia and depression. Insomnia and depression can cause changes in cerebral blood flow and brain function. Changes in the cerebellar and hippocampal regions are the result of insomnia and depression. They reflect abnormalities in sleep and emotion regulation. That may be involved in the pathogenesis of comorbidity.

Transient hearing abnormalities precede social deficits in a mouse model of autism.

Hearing abnormalities are important symptoms of autism spectrum disorders (ASDs), a neurological and developmental disorder. However, the characteristics of hearing abnormalities associated with ASD during development have not been fully investigated. We found that in Shank3B knockout mice (a high-confidence mouse model of ASD), transient hearing abnormalities can be found in auditory brainstem response, auditory cortical activity, as well as acoustic startle response. More importantly, all hearing abnormalities at 4 weeks were most prominent and preceded the onset of social deficits at 6 weeks. These hearing abnormalities gradually recovered with age. In addition, analysis of ABR data at 4 weeks using Support Vector Machine (SVM) can faithfully predict the genotype of mice with an accuracy of 85.71%. These findings not only revealed hearing changes in Shank3B knockout autistic-like mice during development, but also suggested that hearing abnormalities could potentially be used as an early and effective indicator of ASD risk.

Cerebral neurovascular alterations in stable chronic obstructive pulmonary disease: a preliminary fMRI study.

Purpose: Cognitive impairment (CI) is very common in patients with chronic obstructive pulmonary disease (COPD). Cerebral structural and functional abnormalities have been reported in cognitively impaired patients with COPD, and the neurovascular coupling changes are rarely investigated. To address this issue, arterial spin labeling (ASL) and resting-state blood oxygenation level dependent (BOLD) fMRI techniques were used to determine whether any neurovascular changes in COPD patients. Methods: Forty-five stable COPD patients and forty gender- and age-matched healthy controls were recruited. Furthermore, resting-state BOLD fMRI and ASL were acquired to calculate degree centrality (DC) and cerebral blood flow (CBF) respectively. The CBF-DC coupling and CBF/DC ratio were compared between the two groups. Results: COPD patients showed abnormal CBF, DC and CBF/DC ratio in several regions. Moreover, lower CBF/DC ratio in the left lingual gyrus negatively correlated with naming scores, lower CBF/DC ratio in medial frontal cortex/temporal gyrus positively correlated with the Montreal Cognitive Assessment (MoCA), visuospatial/executive and delayed recall scores. Conclusion: These findings may provide new potential insights into neuropathogenesis of cognition decline in stable COPD patients.

Mindfulness-Based Interventions for the Recovery of Mental Fatigue: A Systematic Review.

Background: There is evidence that mindfulness-based interventions (MBI) can help one to recover from mental fatigue (MF). Although the strength model of self-control explains the processes underlying MF and the model of mindfulness and de-automatization explains how mindfulness training promotes adaptive self-regulation leading to the recovery of MF, a systematic overview detailing the effects of MBI on the recovery of MF is still lacking. Thus, this systematic review aims to discuss the influences of MBI on the recovery of MF. Methods: We used five databases, namely, PubMed, Web of Science, EBSCOhost, Scopus, and China National Knowledge Infrastructure (CNKI) for articles published up to 24 September 2021, using a combination of keywords related to MBI and MF. Results: Eight articles fulfilled all the eligibility criteria and were included in this review. The MBI directly attenuated MF and positively affected the recovery of psychology (attention, aggression and mind-wandering) and sports performance (handgrip, plank exercise and basketball free throw) under MF. However, the interaction did not reach statistical significance for the plank exercise. Therefore, the experience and duration of mindfulness are necessary factors for the success of MBI. Conclusions: mindfulness appears to be most related to a reduction in MF. Future research should focus on improving the methodological rigor of MBI to confirm these results and on identifying facets of mindfulness that are most effective for attenuating MF.

A temperature-regulated circuit for feeding behavior.

Both rodents and primates have evolved to orchestrate food intake to maintain thermal homeostasis in coping with ambient temperature challenges. However, the mechanisms underlying temperature-coordinated feeding behavior are rarely reported. Here we find that a non-canonical feeding center, the anteroventral and periventricular portions of medial preoptic area (apMPOA) respond to altered dietary states in mice. Two neighboring but distinct neuronal populations in apMPOA mediate feeding behavior by receiving anatomical inputs from external and dorsal subnuclei of lateral parabrachial nucleus. While both populations are glutamatergic, the arcuate nucleus-projecting neurons in apMPOA can sense low temperature and promote food intake. The other type, the paraventricular hypothalamic nucleus (PVH)-projecting neurons in apMPOA are primarily sensitive to high temperature and suppress food intake. Caspase ablation or chemogenetic inhibition of the apMPOA→PVH pathway can eliminate the temperature dependence of feeding. Further projection-specific RNA sequencing and fluorescence in situ hybridization identify that the two neuronal populations are molecularly marked by galanin receptor and apelin receptor. These findings reveal unrecognized cell populations and circuits of apMPOA that orchestrates feeding behavior against thermal challenges.

Mental Fatigue and Basketball Performance: A Systematic Review.

Mental fatigue (MF) is a psycho-biological state that impairs sports-related performances. Recently, it has been proved that MF can affect basketball performance. However, a systematic overview detailing the influences of MF on basketball performance is still lacking. This study aims to investigate the effects of MF on the physical, technical, tactical, and cognitive performance of basketball. We used the databases of PubMed, Web of Science, SPORTDiscus, Scopes, and CKNI for articles published up to 31 May 2021. The articles included in this study were projected to test whether MF influences basketball athlete performance. Only experimental design studies were selected, and the control condition was without MF. Finally, seven articles fit the inclusion criteria. The results imply that MF impairs the technical aspects of basketball (free throws, three-point shots, and total turnover) and the players' cognitive [take-the-first (TTF) heuristics and decision-making] performance, which results in athletes not using their techniques skillfully and being unable to make practical decisions during critical points in the game. In addition to that, the influences of MF on physical and tactical performance have not been studied. Further studies should look into comprehensive research on the influences of MF on basketball performance, especially on a player's physical and tactical performance. Systematic Review Registration: [https://inplasy.com/] [INPLASY2021100017].

Disrupted Anti-correlation Between the Default and Dorsal Attention Networks During Hyperthermia Exposure: An fMRI Study.

Environmental hyperthermia is a common risk factor for occupational safety in many situations due to decreased vigilance performances. Previously, we have reported that decreased resting-state functional connectivity within the default mode network (DMN) and decreased activations in dorsal attention network (DAN) such as dorsolateral prefrontal cortex (DLPFC) were correlated with selective attention deficits during hyperthermia. However, whether the inherent functionally organized anti-correlation between the DMN and DAN would contribute to the behavioral deficits remains unclear. In this study, we collected the resting-state fMRI data of 25 participants during two simulated thermal conditions: normothermic condition (25°C for 1 h) and hyperthermic condition (50°C for 1 h). Using group independent component analysis (ICA), we investigated the functional connectivity within the DMN and DAN, as well as the anti-correlations between both networks. Paired comparisons revealed that decreased intranetwork functional connectivity in the medial prefrontal cortex (mPFC)/anterior cingulate cortex (ACC) in the DMN contributed to executive control performance during hyperthermia using multivariate linear regression analysis. Paired comparison on the DAN showed that increased one in the posterior part of the middle and inferior temporal gyrus nearby the temporal-parietal junction area contributed to preserved alerting performance. Lastly but most importantly, we found that decreased correlation between mPFC in the DMN and intraparietal sulcus (IPS) area in the DAN contributed to the executive control deficit, suggesting a weaker intrinsic anti-correlation between DMN and DAN during hyperthermia. These findings indicated that a functional reorganized architecture of DMN and DAN might provide a potential neural basis of the selective deficits for different cognitive-demand attention tasks in high-temperature environments.

Resting-state brain activity predicts selective attention deficits during hyperthermia exposure.

Purpose: Environmental hyperthermia exerts detrimental effect on attention performance that might increase the probability of accidents for high risk occupation. Previously, we reported aberrant activations and selective attention deficits under task performing during hyperthermia. However, whether resting-state baseline during hyperthermia would contribute to the reported selective attention deficits remains unclear.Materials and methods: Here, we investigated the resting-state activity within two attention subsystems named dorsal attention network (DAN) and ventral attention network (VAN) using the conjoint analysis of functional connectivity (FC) and regional cerebral blood flow (CBF). Blood oxygenation level dependent (BOLD) and 3 D arterial spin labeling data were obtained from 25 healthy male participants under two simulated thermal conditions: normothermic (25 °C for 1 h) and hyperthermic condition (50 °C for 1 h).Results: Paired comparisons on the FC and CBF showed decreased activity in the bilateral frontal eye field (FEF) and intraparietal sulcus (IPS) in the DAN but increased activity in the ventral frontal cortex (VFC) in the VAN. The CBF-FC correlation analysis further confirmed decreased CBF-FC coupling in the bilateral FEF in the DAN and increased coupling in the VFC in the VAN. Additionally, the left IPS and FEF in the DAN showed altered CBF per unit functional connectivity in the CBF/FC ratio analysis. Multiple regression analysis revealed that the selectively altered performances were predicted by alterations of the multiple metrics within the DAN and VAN.Conclusions: These findings suggested that altered resting-state brain activity within the attention networks might provide potential neural basis of the selective deficits for different cognitive-demand attention tasks under hyperthermia.

Atypical Response Properties of the Auditory Cortex of Awake MECP2-Overexpressing Mice.

Methyl-CpG binding protein 2 (MECP2) is a gene associated with DNA methylation and has been found to be important for maintaining brain function. In humans, overexpression of MECP2 can cause a severe developmental disorder known as MECP2 duplication syndrome. However, it is still unclear whether MECP2 overexpression also causes auditory abnormalities, which are common in people with autism. MECP2-TG is a mouse model of MECP2 duplication syndrome and has been widely used for research on social difficulty and other autism-like disorders. In this study, we used a combination of multiple electrophysiological techniques to document the response properties of the auditory cortex of awake MECP2-TG mice. Our results showed that while the auditory brainstem responses are similar, cortical activity patterns including local field potentials (LFPs), multiunit activity (MUA), and single-neuron responses differ between MECP2-TG and wild-type (WT) mice. At the single-neuron level, the spike waveform of fast-spiking (FS) neurons from MECP2-TG mice is different from that of WT mice, as reflected by reduced peak/trough ratios in the transgenic mice. Both regular-spiking (RS) and FS neurons exhibited atypical response properties in MECP2-TG mice compared with WT mice, such as prolonged latency and an elevated intensity threshold; furthermore, regarding the response strength to different stimuli, MECP2-TG mice exhibited stronger responses to noise than to pure tone, while this pattern was not observed in WT mice. Our findings suggest that MECP2 overexpression can cause the auditory cortex to have atypical response properties, an implication that could be helpful for further understanding the nature of auditory deficits in autism.

Anterior Auditory Field Is Needed for Sound Categorization in Fear Conditioning Task of Adult Rat.

Both primary auditory cortex (A1) and anterior auditory field (AAF) are core regions of auditory cortex of many mammalians. While the function of A1 has been well documented, the role of AAF in sound related behavioral remain largely unclear. Here in adult rats, sound cued fear conditioning paradigm, surgical ablation, and chemogenetic manipulations were used to examine the role of AAF in fear related sound context recognition. Precise surgical ablation of AAF cannot block sound cued freezing behavior but the fear conditioning became non-selective to acoustic cue. Reversible inhibition of AAF using chemogenetic activation at either training or testing phase can both lead to strong yet non-selective sound cued freezing behavior. These simple yet clear results suggested that in sound cued fear conditioning, sound cue and detailed content in the cue (e.g., frequency) are processed through distinct neural circuits and AAF is a critical part in the cortex dependent pathway. In addition, AAF is needed and playing a gating role for precise recognition of sound content in fear conditioning task through inhibiting fear to harmless cues.

Thalamocortical neural responses during hyperthermia: a resting-state functional MRI study.

The neural responses during hyperthermia, once thought of as simple physiological processes (e.g. thermal sensation and regulation), have now been recognised involving more cognitive processes, which would be of high importance to the management of those occupations during heavy heat exposure. Previous studies have demonstrated altered activity in localised subcortical clusters for thermal sensation and regulation, as well as cortical-cortical activity for behavioural tasks during hyperthermia. However, the involvement of cortical-subcortical activity during hyperthermia has not been investigated. In this study, we performed exploratory analyses comparing thalamocortical functional connectivity during whole body hyperthermic condition for an hour at 50 °C and normothermic condition at 25 °C. We found weakened functional connectivity of cortical fronto-polar/anterior cingulate cortex and prefrontal areas with the corresponding thalamic nuclei during hyperthermic versus normothermic comparisons. On the contrary, the motor/premotor, somatosensory and temporal cortical subdivisions showed increased connectivity with thalamic nuclei during hyperthermia. Thalamocortical connectivity changes in the prefrontal were identified to be correlated with the behavioural reaction time during psychomotor vigilance test after controlling for physiological variables. These distinct thalamocortical pathway alterations might reflect physiologically thermal sensation and regulation, as well as psychologically neural behaviour changes underlying cortical-subcortical activity during hyperthermia.

Regional and long-range neural synchronization abnormality during passive hyperthermia.

Passive hyperthermia would impair wide-domain cognitive performances (e.g. attention, working memory), which may involve abnormal regional and long-range neural activity. Combining the regional homogeneity (ReHo) and seed-based functional connectivity analysis, this study investigated the regional and long-range neural synchronization abnormality during passive hyperthermia. We acquired the resting-state blood oxygenation level dependent (BOLD) data from twenty-three healthy male participants in two simulated thermal conditions: normothermic condition (NC) with temperature at 25°C for 1 h and hyperthermic condition (HC) with temperature at 50°C for 1 h. After scanning, participants were asked to perform an attention network test (ANT). Relative to NC participants, the participants in HC group exhibited decreased regional neural synchronization in the frontal-occipital cortex, specifically in the left opercular part of inferior frontal gyrus/insula, bilateral middle occipital gyrus, and posterior cingulate cortex/precuneus, but increased one in the left dorsal superior/middle frontal gyrus. Using these significantly differed ReHo clusters as seeds, we further performed functional connectivity analysis and found aberrant long-range neural synchronization in the orbital medial frontal cortex, temporal-parietal junction areas. Further neurobehavioral correlation analysis showed significant positive correlation between the regional ReHo alteration in left dorsolateral superior/middle frontal gyrus and executive control effect. Additionally, the functional connectivity of the orbital medial frontal cortex with the seeds "left superior/middle frontal gyrus" and "posterior cingulate cortex/precuneus" were negatively correlated with the increase of rectal temperature. In current study, the participants showed hyperthermia-induced brain activity disruptions, appearing as altered local ReHo and long-range functional connectivity, which might help understand the relationship between neuronal and circuit activities and physiological thermal sensation and regulation as well as behavioral changes.

The effects of head-cooling on brain function during passive hyperthermia: an fMRI study.

PURPOSE: To investigate the effect of head-cooling on resting-state spontaneous brain activity during passive hyperthermia. METHODS: An environmental heat exposure was simulated on 16 healthy men under a normal control condition (NC) at 25 °C and two hot conditions at 50 °C with hyperthermia with head-cooling condition (HHC) and without hyperthermia condition (HOT) keeping the head cool, respectively. Resting-state functional MRI (fMRI) data were acquired under each condition and the values of amplitude low frequency fluctuations (ALFF) and z functional connectivity (zFC) were computed to examine regional activity and functional integration, respectively. Pearson's correlation analysis between the ALFF value and subjective sensations scores were performed. RESULTS: Brain regions with significant ALFF differences among the three conditions were found primarily in the right medial prefrontal cortex/anterior cingulate cortex (MPFC/ACC), bilateral posterior cingulate cortex/precuneus (PCC/PCu), and right fusiform gyrus. Compared to the NC or HOT condition, the HHC condition exhibited significantly increased ALFF in the bilateral PCC/PCu and decreased ALFF in the right fusiform gyrus. However, ALFF of the right MPFC/ACC showed no significant difference between the NC and HHC conditions. Positive FC between the right MPFC/ACC and bilateral PCC/PCu was significantly increased in HHC condition with respect to HOT condition. Negative FC between the right fusiform gyrus and the right MPFC/ACC, bilateral PCC/PCu was observed with a decreasing trend from the HHC condition to the HOT condition. Moreover, head-cooling also improved thermal comfort during passive hyperthermia. CONCLUSIONS: Head-cooling could substantially reduce the negative effect of hyperthermia on human brain activity as well as thermal sensation.

Resting-state BOLD oscillation frequency predicts vigilance task performance at both normal and high environmental temperatures.

Hyperthermia may impair vigilance functions and lead to slower reaction times (RTs) in the psychomotor vigilance task (PVT) and possibly disturbing cerebral hemodynamic rhythms. To test these hypotheses, we acquired the resting-state BOLD and cerebral blood flow (CBF) data, as well as PVTRTs from 15 participants in two simulated environmental thermal conditions (50 °C/25 °C). We adopted a data-driven method, frequency component analysis, to quantify the mean frequency of the BOLD series of each voxel. Across-subject correlation analysis was employed to detect the brain areas whose BOLD oscillation frequency was correlated with the RTs. Significant changes of BOLD frequency and CBF within these areas were compared between hyperthermia and normothermia conditions. Spatial correlations between BOLD frequency and CBF were calculated within different brain areas for each subject under both thermal conditions. Results showed that, under both thermal conditions, the RTs correlated with the BOLD frequency positively in the default mode network (DMN) and negatively in the sensorimotor network (SMN). The increase of BOLD frequency in the thalamus and ventral medial prefrontal cortex was correlated with the increase of RTs in hyperthermia compared with normothermia. Hyperthermia decreased BOLD frequency and CBF in the SMN, while it increased CBF in the thalamus and posterior cingulate. In both thermal conditions, the spatial distribution of CBF negatively correlated with the spatial distribution of BOLD oscillation frequency in most cortical areas, especially in cingulate cortices, precuneus, and primary visual cortex. These results suggest that hyperthermia might deteriorate task performance by interfering with the resting-state CBF, and with BOLD rhythms. The overlapping of the thermoregulatory and vigilance functions in the SMN and DMN might underlie the neural mechanisms of the cognitive-behavioral impairments induced by hyperthermia.

Reduced white matter integrity and its correlation with clinical symptom in first-episode, treatment-naive generalized anxiety disorder.

The purpose of this study was to explore white matter microstructural alterations in the patients with generalized anxiety disorder (GAD) using diffusion tensor imaging (DTI) technique, and to assess neural associations with the symptom severity. Twenty-eight first-episode, treatment-naive GAD patients without co-morbidities and 28 matched healthy controls underwent DTI acquisition and clinical symptom assessments. Tract-based spatial statistics (TBSS) was used to analyze white matter microstructural abnormalities in patients with GAD, as well as their associations with clinical symptom scores in a voxel-wise manner. Compared to controls, patients showed decreased fractional anisotropy (FA) values in 7 clusters of white matter in bilateral uncinate fasciculus, body of corpus callosum, left middle cingulum (cingulate gyrus), bilateral anterior thalamic radiation and corona radiate, right anterior limb of internal capsule, bilateral inferior frontal-occipital fasciculus, bilateral superior and inferior longitudinal fasciculus, and increased mean diffusivity and radial diffusivity in widespread white matter regions. Reduced FA values in right uncinate fasciculus, left cingulum bundle showed significantly negative correlations with clinical symptom severity for Hamilton anxiety Rating Scale scores. Our findings suggest microstructural abnormalities in uncinate fasciculus and cingulum bundle play key roles in the underlying neural basis of GAD.

Aberrant regional neural fluctuations and functional connectivity in generalized anxiety disorder revealed by resting-state functional magnetic resonance imaging.

The purpose of this study was to investigate the neural activity and functional connectivity in generalized anxiety disorder (GAD) during resting state, and how these alterations correlate to patients' symptoms. Twenty-eight GAD patients and 28 matched healthy controls underwent resting-state functional magnetic resonance (fMRI) scans. Amplitude of low-frequency fluctuation (ALFF) and seed-based resting-state functional connectivity (RSFC) were computed to explore regional activity and functional integration, and were compared between the two groups using the voxel-based two-sample t test. Pearson's correlation analyses were performed to examine the neural relationships with demographics and clinical symptoms scores. Compared to controls, GAD patients showed functional abnormalities: higher ALFF in the bilateral dorsomedial prefrontal cortex, bilateral dorsolateral prefrontal cortex and left precuneus/posterior cingulate cortex; lower connectivity in prefrontal gyrus; lower in prefrontal-limbic and cingulate RSFC and higher prefrontal-hippocampus RSFC were correlated with clinical symptoms severity, but these associations were unable to withstand correction for multiple testing. These findings may help facilitate further understanding of the potential neural substrate of GAD.

White Matter Changes in Posttraumatic Stress Disorder Following Mild Traumatic Brain Injury: A Prospective Longitudinal Diffusion Tensor Imaging Study.

BACKGROUND: The ability to predict posttraumatic stress disorder (PTSD) is a critical issue in the management of patients with mild traumatic brain injury (mTBI), as early medical and rehabilitative interventions may reduce the risks of long-term cognitive changes. The aim of the present study was to investigate how diffusion tensor imaging (DTI) metrics changed in the transition from acute to chronic phases in patients with mTBI and whether the alteration relates to the development of PTSD. METHODS: Forty-three patients with mTBI and 22 healthy volunteers were investigated. The patients were divided into two groups: successful recovery (SR, n = 22) and poor recovery (PR, n = 21), based on neurocognitive evaluation at 1 or 6 months after injury. All patients underwent magnetic resonance imaging investigation at acute (within 3 days), subacute (10-20 days), and chronic (1-6 months) phases after injury. Group differences of fractional anisotropy (FA) and mean diffusivity (MD) were analyzed using tract-based spatial statistics (TBSS). The accuracy of DTI metrics for classifying PTSD was estimated using Bayesian discrimination analysis. RESULTS: TBSS showed white matter (WM) abnormalities in various brain regions. In the acute phase, FA values were higher for PR and SR patients than controls (all P < 0.05). In subacute phase, PR patients have higher mean MD than SR and controls (all P < 0.05). In the chronic phase, lower FA and higher MD were observed in PR compared with both SR and control groups (all P < 0.05). PR and SR groups could be discriminated with a sensitivity of 73%, specificity of 78%, and accuracy of 75.56%, in terms of MD value in subacute phase. CONCLUSIONS: Patients with mTBI have multiple abnormalities in various WM regions. DTI metrics change over time and provide a potential indicator at subacute stage for PTSD following mTBI.

Mental fatigue after mild traumatic brain injury: a 3D-ASL perfusion study.

Our purpose was to evaluate mental fatigue associated with mild traumatic brain injury (MTBI) and investigate the underlying neurological mechanisms. We used a 20-min psychomotor vigilance test (PVT) related ASL-fMRI to evaluate mental fatigue in 25 MTBI patients in acute phase, 21 MTBI patients in chronic phase, and 20 healthy subjects. Mental fatigue in patients in acute phase was more severe than in chronic phase patients and healthy controls. The first 5-min-PVT increased CBF of patients in acute phase in "bottom-up" and "top-down" attention areas, and decreased CBF in default mode network (DMN) areas. Twenty-min-PVT results showed that sustained attention of patients was more fragile than in healthy subjects, while sustained attention in the acute phase was less stable than that in the chronic phase. CBF results showed that in patients in the acute phase, the second, third, and last 5-min-PVT decreased CBF in DMN areas, increased CBF of "bottom-up" and "top-down" areas; in the chronic phase, the third and last 5-min-PVT increased CBF of "bottom-up" and "top-down" cortex, while the second 5-min-PVT only increased CBF of the "top-down" cortex. Mental fatigue of MTBI patients persists for more than 12 months, and can be mitigated partly within the first year after injury. The "bottom-up" and "top-down" deficits result in mental fatigue of MTBI patients.

Impact of Elevated Core Body Temperature on Attention Networks.

OBJECTIVE AND BACKGROUND: Cognitive function can be impaired after passive heat exposure and with an elevation in core body temperature (Tcore). This study examined the dynamic correlation among passive heat exposure, Tcore, and cognition. METHODS: We gave the Attention Network Test of alerting, orienting, and executive control to five groups of five young men who were being exposed to a hyperthermic condition (50°C, 40% relative humidity) for 0, 10, 20, 30, or 40 minutes. We used the participants' reaction time, accuracy (correct responses), efficiency (accuracy÷reaction time), and Tcore to estimate optimal curve models for best fit of data. RESULTS: We could not estimate an appropriate curve model for either alerting or orienting with Tcore, change in Tcore, or duration of passive heat exposure. We estimated quadratic models for Tcore and duration (adjusted R=0.752), change in Tcore and duration (0.906), executive control score and duration (0.509), and efficiency of executive control and duration (0.293). We estimated linear models for executive control score and Tcore (0.479), efficiency of executive control and Tcore (0.261), executive control score and change in Tcore (0.279), and efficiency of executive control and change in Tcore (0.262). CONCLUSIONS: Different attentional abilities had different sensitivities to thermal stress. Executive control of attention deteriorated linearly with a rise in Tcore within the normal physiologic range, but deteriorated nonlinearly with longer passive heat exposure.