Dissociable brainstem functional connectivity changes correlate with objective and subjective vigilance decline after total sleep deprivation in healthy male subjects.

The maintenance of vigilance relies on the activation of the cerebral cortex by the arousal system centered on the brainstem. Previous studies have suggested that both objective and subjective vigilance are susceptible to sleep deprivation. This study aims to explore the alterations in brainstem arousal system functional connectivity (FC) and its involvement in these two types of vigilance decline following total sleep deprivation (TSD). Thirty-seven healthy male subjects underwent two counterbalanced resting-state fMRI scans, once in rested wakefulness (RW) and once after 36 h of TSD. The pontine tegmental area and caudal midbrain (PTA-cMidbrain), the core regions of the brainstem arousal system, were chosen as the seeds for FC analysis. The difference in PTA-cMidbrain FC between RW and TSD conditions was then investigated, as well as its associations with objective vigilance measured by psychomotor vigilance task (PVT) and subjective vigilance measured by Stanford Sleepiness Scale. The sleep-deprived subjects showed increased PTA-cMidbrain FC with the thalamus and cerebellum and decreased PTA-cMidbrain FC with the occipital, parietal, and sensorimotor regions. TSD-induced increases in PVT reaction time were negatively correlated with altered PTA-cMidbrain FC in the dorsolateral prefrontal cortex, extrastriate visual cortex, and precuneus. TSD-induced increases in subjective sleepiness were positively correlated with altered PTA-cMidbrain FC in default mode regions including the medial prefrontal cortex and precuneus. Our results suggest that different brainstem FC patterns underlie the objective and subjective vigilance declines induced by TSD.

Regional Homogeneity Alterations in Patients with Impaired Consciousness. An Observational Resting-State fMRI Study.

PURPOSE: It is always challenging to correctly differentiate between minimally conscious state (MCS) and vegetative state/unresponsive wakefulness syndrome (VS/UWS) among disorders of consciousness (DOC) patients. However, the underlying neural mechanisms of awareness identification remain incompletely understood. METHODS: Using regional homogeneity (ReHo) analysis, we evaluated how regional connectivity of brain regions is disrupted in MCS and VS/UWS patients. Resting-state functional magnetic resonance imaging was conducted in 14 MCS patients, 25 VS/UWS patients, and 30 age-matched healthy individuals. RESULTS: We found that MCS and VS/UWS patients demonstrated DOC-dependent reduced ReHo within widespread brain regions including posterior cingulate cortices (PCC), medial prefrontal cortices (mPFC), and bilateral fronto-parieto-temporal cortices and showed increased ReHo in limbic structures. Moreover, a positive correlation between Coma Recovery Scale-Revised (CRS-R) total scores and reduced ReHo in the left precuneus was observed in VS/UWS patients, despite the linear trend was not found in MCS patients. In addition, ReHo were also observed reduced in three mainly intrinsic connectivity networks (ICNs), including default mode network (DMN), executive control network (ECN), and salience network (SN). Notably, as the clinical symptoms of consciousness disorders worsen from MCS to VS/UWS, ReHo in dorsal DMN, left ECN, and posterior SN became significantly reduced. CONCLUSION: These findings make a further understanding of the underlying neural mechanism of regional connectivity among DOC patients and provide additional neuroimaging-based biomarkers for the clinical diagnosis of MCS and VS/UWS patients.

Brain structural plasticity in visual and sensorimotor areas of airline pilots: A voxel-based morphometric study.

BACKGROUND AND PURPOSE: Airline pilot is a highly specialized profession that requires to response quickly and accurately in the presence of a wide variety of visual information. Although functional imaging studies have employed virtual simulation to identify brain areas that underlie various flying-related tasks, little is known about the specific patterns of structural plasticity in the airline pilot's brain. MATERIALS AND METHODS: In this study, we examined differences of gray matter and white matter volumes between 42 airline pilots and 39 non-pilots by using voxel-based morphometry, and further assessed the association between magnitude of structural alterations and flight time in the pilots. RESULTS: We found significantly increased white matter volume in the cuneus area in the pilot group compared to the non-pilot group (p < 0.05, FWE corrected). Using a relaxed threshold, it was also observed that the pilots had increased gray matter volume in the lingual gyrus, inferior frontal gyrus, supramarginal gyrus, cuneus, and postcentral gyrus, and increased white matter volume in the postcentral area (p < 0.001, uncorrected). Moreover, the pilots' flight time was positively correlated with gray matter volume in the postcentral gyrus and white matter volume in the cuneus area (p < 0.001, uncorrected). CONCLUSIONS: The morphological changes in specific visual and sensorimotor areas may provide airline pilots with neural efficiency in the visuo-motor processing related to flight.

Cognitive and neural bases of decision-making causing civilian casualties during intergroup conflict.

Civilian casualties occur during military attacks. Such 'collateral damage' is prohibited by international laws but increases with substantial consequences when intergroup conflict escalates. Here, we investigate cognitive and neural bases of decision-making processes resulting in civilian harm, using a task that simulates punishment decision-making during intergroup conflict. We test two groups of Chinese participants in a laboratory setting, and members of two ethnic groups (Jewish and Palestinian) in Israel. The results dissociate two psychological constructs, harm preference and harm avoidance, which respectively characterize punishment decision-making related to outgroup combatants and outgroup noncombatants during intergroup conflict. In particular, individuals show decreased avoidance of harming outgroup noncombatants when conflict escalates. Brain imaging (functional magnetic resonance imaging) reveals that decreased harm avoidance is predicted by inhibition of the left middle frontal activity during selection of punishment decisions. Our findings provide insight into the cognitive and neural bases of decision-making involving civilian harm during intergroup conflict.

A neurobiological association of revenge propensity during intergroup conflict.

Revenge during intergroup conflict is a human universal, but its neurobiological underpinnings remain unclear. We address this by integrating functional MRI and measurements of endogenous oxytocin in participants who view an ingroup and an outgroup member's suffering that is caused mutually (Revenge group) or by a computer (Control group). We show that intergroup conflict encountered by the Revenge group is associated with an increased level of oxytocin in saliva compared to that in the Control group. Furthermore, the medial prefrontal activity in response to ingroup pain in the Revenge group but not in the Control group mediates the association between endogenous oxytocin and the propensity to give painful electric shocks to outgroup members, regardless of whether they were directly involved in the conflict. Our findings highlight an important neurobiological correlate of revenge propensity, which may be implicated in conflict contagion across individuals in the context of intergroup conflict.

Thoughts of death affect reward learning by modulating salience network activity.

Thoughts of death substantially influence human behavior and psychological well-being. A large number of behavioral studies have shown evidence that asking individuals to think about death or mortality salience leads to significant changes of their behaviors. These findings support the well-known terror management theory to account for the psychological mechanisms of existential anxiety. However, despite increasing findings of mortality salience effects on human behavior, how the brain responds to reminders of mortality and changes the activity underlying subsequent behavior remains poorly understood. By scanning healthy adults (N = 80) of both sexes using functional magnetic resonance imaging, we showed that, relative to reading emotionally neutral sentences, reading sentences that evoke death-related thoughts decreased the salience network activity, reduced the connectivity between the cingulate cortex and other brain regions during a subsequent resting state, and dampened the speed of learning reward-related objects and cingulate responses to loss feedback during a subsequent reward learning task. In addition, the decreased resting-state cingulate connectivity mediated the association between salience network deactivations in response to reminders of mortality and suppressed cingulate responses to loss feedback. Finally, the suppressed cingulate responses to loss feedback further predicted the dampened speed of reward learning. Our findings demonstrate sequential modulations of the salience network activity by mortality salience, which provide a neural basis for understanding human behavior under mortality threat.

Optimal Delay Time of CT Perfusion for Predicting Cerebral Parenchymal Hematoma After Intra-Arterial tPA Treatment.

Background and Purpose: Cerebral hemorrhage is a serious potential complication of stroke revascularization, especially in patients receiving intra-arterial tissue-type plasminogen activator (tPA) therapy. We investigated the optimal pre-intervention delay time (DT) of computed tomography perfusion (CTP) measurement to predict cerebral parenchymal hematoma (PH) in acute ischemic stroke (AIS) patients after intra-arterial tissue plasminogen activator (tPA) treatment. Methods: The study population consisted of a series of patients with AIS who received intra-arterial tPA treatment and had CTP and follow-up computed tomography/magnetic resonance imaging (CT/MRI) to identify hemorrhagic transformation. The association of increasing DT thresholds (>2, >4, >6, >8, and >10 s) with PH was examined using receiver operating characteristic (ROC) analysis and logistic regression. Results: Of 94 patients, 23 developed PH on follow-up imaging. Receiver operating characteristic analysis revealed that the greatest area under the curve for predicting PH occurred at DT > 4 s (area under the curve, 0.66). At this threshold of > 4 s, DT lesion volume ≥ 30.85 mL optimally predicted PH with 70% sensitivity and 59% specificity. DT > 4 s volume was independently predictive of PH in a multivariate logistic regression model (P < 0.05). Conclusions: DT > 4 s was the parameter most strongly associated with PH. The volume of moderate, not severe, hypo-perfusion on DT is more strongly associated and may allow better prediction of PH after intra-arterial tPA thrombolysis.

Prognostication of chronic disorders of consciousness using brain functional networks and clinical characteristics.

Disorders of consciousness are a heterogeneous mixture of different diseases or injuries. Although some indicators and models have been proposed for prognostication, any single method when used alone carries a high risk of false prediction. This study aimed to develop a multidomain prognostic model that combines resting state functional MRI with three clinical characteristics to predict one year-outcomes at the single-subject level. The model discriminated between patients who would later recover consciousness and those who would not with an accuracy of around 88% on three datasets from two medical centers. It was also able to identify the prognostic importance of different predictors, including brain functions and clinical characteristics. To our knowledge, this is the first reported implementation of a multidomain prognostic model that is based on resting state functional MRI and clinical characteristics in chronic disorders of consciousness, which we suggest is accurate, robust, and interpretable.

Neural activation in response to the two sides of emotion.

Emotions are at the core of human cognition and behavior. Traditionally, emotions have been classified dichotomously as being either positive or negative. However, recent behavioral research (An et al., 2017) suggests that emotions contain both positivity and negativity. The current work investigated neural correlates of experiencing positive and negative emotions in response to happy and sad photos. Functional MRI revealed the precuneus and posterior cingulate cortex showed stronger activation when experiencing positivity compared to negativity of sadness, but not happiness, whereas the bilateral cerebellum showed greater response to positivity than negativity regardless of emotion. Results suggest that there are similarities and differences in the neural activation of positivity and negativity of happiness and sadness, consistent with previous findings (An et al., 2017). Emotion from both the neural and psychological perspectives were investigated. Further implications are discussed.

Disrupted Interactions Between Arousal and Cortical Awareness Networks in MCS and VS/UWS Patients: Evidence from Resting-state Functional Imaging Connectivity.

Clinical patients in a vegetative state or unresponsive wakefulness syndrome (VS/UWS) demonstrate distinct arousal-awareness dissociation; the neuropathological mechanisms underlying such dissociation remain poorly understood. Here, we systematically examined how functional connectivity from the brainstem areas regulating arousal to the cortical networks supporting internal and external awareness is disrupted in minimally conscious state (MCS) and VS/UWS patients. Resting-state functional imaging was conducted in 23 MCS patients, 31 VS/UWS patients, and 20 age-matched healthy individuals. A hierarchical cluster analysis was conducted using all voxel-based signals in the brainstem to identify the specific areas for arousal. We found that the pontine tegmentum area (PTA) and caudal midbrain area persistently formed a distinct cluster that exclusively showed extensive connections with the cortical networks supporting internal and external awareness in healthy individuals, confirming their role in arousal. We show that functional connectivity from the PTA and caudal midbrain area to the cortical-awareness-supporting networks were significantly reduced in MCS and VS/UWS patients; importantly, as the clinical symptoms of consciousness disorders deepen from MCS to VS/UWS, functional connectivity strength became significantly reduced, changing from presenting no significant connections in MCS to widespread negative connections in VS/UWS. Additionally, we observed increased connectivity from the PTA and caudal midbrain area to limbic structures, the brainstem areas, and the cerebellum in MCS and VS/UWS patients, consistent with prior studies. These findings offer important insights into the neural network mechanisms underlying the long-observed arousal-awareness dissociation in VS/UWS patients and provide additional neuroimaging-based biomarkers for the clinical diagnosis of MCS and VS/UWS patients.

Could Arterial Spin Labeling Distinguish Patients in Minimally Conscious State from Patients in Vegetative State?

PURPOSE: Diagnostic error is common among patients with vegetative state (VS) and minimally conscious state (MCS). The purpose of this article is to use three-dimensional pseudo-continuous arterial spin labeling (pcASL) to compare cerebral blood flow (CBF) patterns in patients in MCS with those in VS. METHODS: Patients meeting MCS and VS criteria were identified. Two post-labeling delay (PLD) time pcASL on 3.0-Tesla magnetic resonance imaging scanner system were performed with patients in the resting awake state. After registration to T1WI structure imaging, multiple brain regions of interest of ASL CBF map were automatically separated. The average CBF value of every brain region was calculated and compared between the MCS and VS groups with t-tests. RESULTS: Fifteen patients with VS were identified, with ages ranging from 33 to 71 years. Eight patients who met the MCS criteria ranged in age from 23 to 61 years. Compared with VS, the regional CBF for MCS had a pattern of significantly increased CBF in the regions including the putamen, anterior cingulate gyrus, and medial frontal cortex. A left-lateralized pattern was observed to differentiate MCS from VS. CBF with PLD 2.5 s could find more regions of pattern differentiating MCS from VS than with PLD 1.5 s, except for the pallidum. CONCLUSION: MCS might be differentiated from VS by different ranges of regional CBF as measured by ASL. Multi-PLD ASL may serve as an adjunct method to separate MCS from VS and assess functional reserve in patients recovering from severe brain injuries.

Self-construals moderate associations between trait creativity and social brain network.

Creativity is an adaptive way of thinking and plays a key role in problem solving. Recent brain imaging studies focused on structural and functional characteristics of the brain that are correlated with creativity. But whether and how the association between creativity and the brain is moderated by individuals' cultural traits remains unclear. We integrated functional magnetic resonance imaging (fMRI) and questionnaire measures (Williams creativity aptitude test) of trait creativity and self-construal (e.g., interdependence) in male adults to examine whether trait creativity is associated with neural activities underlying social cognition and whether and how the association is moderated by individuals' self-construals. We found that interdependence moderates the association between trait creativity and neural activities in the left superior temporal sulcus, right anterior insular, right temporal-parietal junction and right precentral gyrus engaged in reflection of one's own social attributes. Interdependence also moderates the association between trait creativity and neural activities in the left superior temporal sulcus and right posterior insular involved in reflection of a friend's social attributes. The link of trait creativity and the functional connectivity between the medial prefrontal cortex and postcentral gyri during reflection of a friend's social attributes is also moderated by interdependence. Participants with high and low creativity traits can be dissociated in a three-dimension space defined by integration of interdependence and the brain activity underlying reflection of one's own and the friend's attributes. Our findings suggest that trait creativity is imprinted on the social brain and the link between trait creativity and the neural activities underlying the processing of self and others is moderated by a cultural trait.

White matter integrity correlates with residual consciousness in patients with severe brain injury.

Previous studies have suggested that white matter disruption plays an important role in disorders of consciousness (DOC) after severe brain injury. Nevertheless, the integrity of white matter architecture supporting consciousness and its relations with clinical severity in patients with DOC remain to be established. In this study, diffusion tensor imaging (DTI) data was collected from 14 DOC patients and 15 healthy control subjects. We combined tract-based spatial statistics (TBSS) with region of interest (ROI) analysis to examine differences of DTI metrics on white matter skeletons between DOC patients and healthy controls, and the association between white matter integrity and patients' residual consciousness assessed by Coma Recovery Scale-Revised (CRS-R). We found that: (1) patients with DOC had widespread white matter integrity disruptions, especially in the fornix; (2) the alteration of white matter microstructure was mainly attributed to the increase in radial diffusivity, possibly reflecting demyelination; (3) the behavioral CRS-R assessment score was positively correlated with white matter integrity in the fornix, uncinate fasciculus, pontine crossing tract, and posterior limb of internal capsule. Our results suggest that despite the widespread abnormalities of white matter following severe brain injury, the impairment of consciousness is likely to result from disruptions of key pathways that link brain regions in distributed networks.

Linearity, Bias, and Precision of Hepatic Proton Density Fat Fraction Measurements by Using MR Imaging: A Meta-Analysis.

Purpose To determine the linearity, bias, and precision of hepatic proton density fat fraction (PDFF) measurements by using magnetic resonance (MR) imaging across different field strengths, imager manufacturers, and reconstruction methods. Materials and Methods This meta-analysis was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic literature search identified studies that evaluated the linearity and/or bias of hepatic PDFF measurements by using MR imaging (hereafter, MR imaging-PDFF) against PDFF measurements by using colocalized MR spectroscopy (hereafter, MR spectroscopy-PDFF) or the precision of MR imaging-PDFF. The quality of each study was evaluated by using the Quality Assessment of Studies of Diagnostic Accuracy 2 tool. De-identified original data sets from the selected studies were pooled. Linearity was evaluated by using linear regression between MR imaging-PDFF and MR spectroscopy-PDFF measurements. Bias, defined as the mean difference between MR imaging-PDFF and MR spectroscopy-PDFF measurements, was evaluated by using Bland-Altman analysis. Precision, defined as the agreement between repeated MR imaging-PDFF measurements, was evaluated by using a linear mixed-effects model, with field strength, imager manufacturer, reconstruction method, and region of interest as random effects. Results Twenty-three studies (1679 participants) were selected for linearity and bias analyses and 11 studies (425 participants) were selected for precision analyses. MR imaging-PDFF was linear with MR spectroscopy-PDFF (R2 = 0.96). Regression slope (0.97; P < .001) and mean Bland-Altman bias (-0.13%; 95% limits of agreement: -3.95%, 3.40%) indicated minimal underestimation by using MR imaging-PDFF. MR imaging-PDFF was precise at the region-of-interest level, with repeatability and reproducibility coefficients of 2.99% and 4.12%, respectively. Field strength, imager manufacturer, and reconstruction method each had minimal effects on reproducibility. Conclusion MR imaging-PDFF has excellent linearity, bias, and precision across different field strengths, imager manufacturers, and reconstruction methods. © RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on October 2, 2017.

Fat poor angiomyolipoma differentiation from renal cell carcinoma at 320-slice dynamic volume CT perfusion.

PURPOSE: To compare various CT perfusion features of fat poor angiomyolipoma (AML) with those of size-matched renal cell carcinoma (RCC). METHODS: One hundred and seventy-four patients [16 with fat poor AML (mean diameter, 3.1 cm; range, 1.5-5.5 cm) and 158 with RCC (mean diameter, 3.2 cm; range, 2.4-5.4 cm)] who had undergone 320-slice dynamic volume CT perfusion were evaluated. Equivalent blood volume (BV Equiv), permeability surface-area product (PS), and blood flow (BF) of tumor were measured and analyzed. Fat poor AML was compared with each subtype of RCC (132 clear cell, 9 papillary, and 17 chromophobe). Receiver operating characteristic (ROC) curve analysis was performed for the comparison of fat poor AML and RCC. ROC curve analysis was not performed for the papillary RCC subtype because of the small number of masses of this subtype. RESULTS: BV Equiv and BF were significantly lower in fat poor AML than in clear cell RCC (P < 0.05 for both). Fat poor AML had higher BV Equiv, PS, and BF than papillary RCC (P < 0.05 for all). PS and BF in fat poor AML significantly exceeded those in chromophobe RCC (P < 0.05 for both). For differentiating fat poor AML from clear cell RCC, area under the ROC curve (AUC) of BV Equiv and BF were 0.82 and 0.69. Using the optimal threshold value, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 0.82, 0.81, 0.35, 0.97 for BV Equiv and 0.71, 0.75, 0.24, 0.96 for BF, respectively. For differentiating fat poor AML from chromophobe RCC, AUC of PS and BF were 0.77 and 0.79, respectively. The optimal sensitivity, specificity, PPV, and NPV were 0.77, 0.75, 0.75, 0.76 for PS and 0.71, 0.81, 0.72, 0.80 for BF, respectively. CONCLUSIONS: Fat poor AML and subtypes of RCCs demonstrate different perfusion features at 320-slice dynamic volume CT, allowing their differentiations with BV Equiv, PS, and BF being valuable perfusion parameters.

Oxytocin effects on self-referential processing: behavioral and neuroimaging evidence.

Oxytocin (OT) influences other-oriented mental processes (e.g. trust and empathy) and the underlying neural substrates. However, whether and how OT modulates self-oriented processes and the underlying brain activity remains unclear. Using a double-blind, placebo-controlled between-subjects design, we manipulated memory encoding and retrieval of trait adjectives related to the self, a friend and a celebrity in a self-referential task in male adults. Experiment 1 (N = 51) found that OT vs placebo treatments reduced response times during encoding self-related trait adjectives but increased recognition scores of self-related information during memory retrieval. Experiment 2 (N = 50) showed similar OT effects on response times during encoding self-related trait adjectives. Moreover, functional magnetic resonance imaging (fMRI) results revealed that OT vs placebo treatments decreased the activity in the medial prefrontal cortex (MPFC) involved in encoding of self-related trait adjectives and weakened the coupling between the MPFC activity and a cultural trait (i.e. interdependence). Experiment 3 (N = 52) revealed that OT vs placebo treatments increased the right superior frontal activity during memory retrieval of self-related information. The results provide behavioral and fMRI evidence for OT effects on self-referential processing and suggest distinct patterns of OT modulations of brain activities engaged in encoding and retrieval of self-related information.

[Quantitative evaluation of white matter development in fetus with growth restriction by diffusion tensor imaging].

OBJECTIVE: To investigate whether fetal growth restriction (FGR) has an adverse effect on white matter development. METHODS: A total of 28 full-term small for gestational age (SGA) infants were enrolled as study subjects and 15 full-term appropriate for gestational age infants were enrolled as control group. Conventional head magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) were performed for all infants. The white matter was divided into 122 regions. The two groups were compared in terms of fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity of different brain regions. RESULTS: Compared with the control group, the SGA group had a significantly lower fractional anisotropy in 16 brain regions (P<0.01), a significantly higher mean diffusivity in 7 brain regions (P<0.05), a significantly higher axial diffusivity in 8 brain regions (P<0.05), and a significantly higher radial diffusivity in 16 brain regions (P<0.05). CONCLUSIONS: FGR may cause abnormalities in the maturity and integrity of white matter fiber tracts.

Differentiation of low- and high-grade clear cell renal cell carcinoma: Tumor size versus CT perfusion parameters.

PURPOSE: To compare the utility of tumor size and CT perfusion parameters for differentiation of low- and high-grade clear cell renal cell carcinoma (RCC). MATERIALS AND METHODS: Tumor size, Equivalent blood volume (Equiv BV), permeability surface-area product (PS), blood flow (BF), and Fuhrman pathological grading of clear cell RCC were retrospectively analyzed. RESULTS: High-grade clear cell RCC had significantly higher tumor size and lower PS than low grade. Tumor size positively correlated with Fuhrman grade, but PS negatively did. CONCLUSIONS: Tumor size and PS were significantly independent indexes for differentiating high-grade from low-grade clear cell RCC.

Empathy for pain motivates actions without altruistic effects: evidence of motor dynamics and brain activity.

Empathy has been supposed to be a proximate mechanism of altruistic behavior. We investigated whether empathy for pain drives actions without altruistic effects and how such actions modulate neural responses to others' pain. In two experiments, we asked healthy adults to press a button for no reason when viewing video clips showing faces with pain expressions receiving needle penetration or faces with neutral expressions receiving a cotton swab touch. Experiment 1 found that participants pressed a button with greater response force when watching painful than non-painful stimuli. Participants who reported greater unpleasant feelings pressed the button harder when viewing painful stimuli. Experiment 2 revealed that passively viewing painful vs non-painful stimuli increased blood-oxygen-level-dependent signals in the middle cingulate cortex, supplementary motor cortex, and bilateral second somatosensory and inferior frontal cortex, which, however, were reduced by the action of button press without altruistic effects. In addition, individuals who reported higher personal distress illustrated greater decrease of the second somatosensory activity induced by button press. Our results indicate that empathy for pain motivates simple actions without altruistic effects that in turn reduce neural responses to others' pain, suggesting a functional role of action execution in self distress relief when viewing others' suffering.

Neural correlates of increased risk-taking propensity in sleep-deprived people along with a changing risk level.

Risky decision-making under a changing risk level is a complex process involving contextual information. The neural mechanism underlying how sleep deprivation (SD) influences risky decision-making behaviors with a changing risk level has yet to be elucidated. In this study, we used the Balloon Analogue Risk Task (BART) during functional magnetic resonance imaging to investigate the neural correlates of SD-induced changes on decision-making behaviors at different risk levels. Thirty-seven healthy male adults were recruited in this within-subjects, repeat-measure, counterbalanced study. These individuals were examined during a state of rested wakefulness state and after nearly 36 h of total SD. The results showed that SD increased the activation of risk modulation in the left inferior frontal gyrus and were positively correlated with risk-taking propensity after SD. Activation in the ventral striatum and thalamus during cash out was increased, and activation in the middle temporal gyrus after explosion (loss of money) was decreased in sleep-deprived subjects, providing additional evidence for greater risk-taking propensity after SD. These results extend our understanding of the neural mechanism underlying alteration of the risk-taking propensity in sleep-deprived individuals.