Hemodynamic Responses In Prefrontal Cortex Research Articles

Effects of acute exercise on craving and cortical hemodynamics under drug-cue exposure in MA-dependent individuals

BackgroundMethamphetamine (MA) dependent individuals who want to break free of their drug habit or guard against a relapse often find it hard to overcome cravings induced by drug-related cues they are bound to encounter. The purpose of this study was to investigate the effects of acute virtual reality (VR) enhanced physical exercise on cue-induced cravings in MA-dependent individuals. MethodsThirty MA-dependent individuals performed a drug-cue reactivity task both before and after a 10 min VR-enhanced competitive cycling exercise. Functional near-infrared spectroscopy (fNIRS) was recorded during the pre- and post-exercise drug-cue reactivity tasks. ResultsMA dependent individuals show higher hemodynamic responses in prefrontal cortex (PFC) to drug-related cues than to neutral cues. After acute exercise, hemodynamic responses in PFC, including bilateral dorsolateral prefrontal cortex and orbitofrontal cortex, were attenuated under the same drug-related cues exposure. Acute exercise also affected the functional connectivity between PFC and motor cortex in response to drug-related cues versus neutral cues. ConclusionsThese results suggest that a single session of VR-enhanced competitive cycling exercise facilitates MA-dependent individuals’ self-control over their cue-induced cravings by modulating cortical activations and brain functional networks.

Hemodynamic responses in prefrontal cortex and personality characteristics in patients with bulimic disorders: a near-infrared spectroscopy study.

This study sought to identify the prefrontal cortex hemodynamic response that is dependent on cognitive performance in patients with bulimic disorders (BD), and investigate its association with personality characteristics. Nineteen female patients with BD and 23 healthy women were recruited. Their personality characteristics related to eating disorders were examined using a self-reporting questionnaire, namely the eating disorder inventory-2 (EDI-2). Cerebral blood flow response in the prefrontal cortex during the digit span backward task (DSBT) was measured using near-infrared spectroscopy (NIRS). Change in oxygenated hemoglobin concentration (ΔoxyHb), obtained using NIRS, were used as an index of brain activity. Further, the relationship between prefrontal cortical activity and personality characteristics was investigated in patients with BD. The cognitive performance of patients with BD was significantly lower in the DSBT compared with healthy subjects. There was no difference between the groups in ΔoxyHb during the task. Task scores of patients with BD correlated with asceticism and perfectionism. Moreover, the asceticism score was negatively correlated with ΔoxyHb of the bilateral prefrontal cortex in patients with BD. The results suggest that cognitive performance and brain activity induced during DSBT might be affected by asceticism in BD patients. III, case-controlstudy.

Reduced Prefrontal Cortex Hemodynamic Response in Adults with Methamphetamine Induced Psychosis: Relevance for Impulsivity.

Patients with methamphetamine abuse/dependence often exhibit high levels of impulsivity, which may be associated with the structural abnormalities and functional hypoactivities observed in the frontal cortex of these subjects. Although near-infrared spectroscopy (NIRS) is a simple and non-invasive method for characterizing the clinical features of various psychiatric illnesses, few studies have used NIRS to directly investigate the association between prefrontal cortical activity and inhibitory control in patients with methamphetamine-induced psychosis (MAP). Using a 24-channel NIRS system, we compared hemodynamic responses during the Stroop color-word task in 14 patients with MAP and 21 healthy controls matched for age, sex and premorbid IQ. In addition, we used the Barrett Impulsivity Scale-11 (BIS-11) to assess impulsivity between subject groups. The MAP group exhibited significantly less activation in the anterior and frontopolar prefrontal cortex accompanied by lower Stroop color-word task performance, compared with controls. Moreover, BIS-11 scores were significantly higher in the MAP group, and were negatively correlated with the hemodynamic responses in prefrontal cortex. Our data suggest that reduced hemodynamic responses in the prefrontal cortex might reflect higher levels of impulsivity in patients with MAP, providing new insights into disrupted inhibitory control observed in MAP.

Monitoring Mental Fatigue in Analog Space Environment Using Optical Brain Imaging

Accurate assessment of mental fatigue level would improve operational safety and efficacy of astronauts for long-term space flight. Identification of neurophysiological markers can index impending overload or fatigue before performance decrements using neuroimaging technologies. The current study utilized functional near-infrared spectroscopy (fNIR) to investigate the relationship of hemodynamic response in prefrontal cortex with changes of mental fatigue level, task performance (reaction time) during n-back working memory task and routine work task in analog space environment. Results indicated that the information entropy of hemodynamic response is related to task performance and subjective self-reported measures; the reaction time is predicted by regression analysis; and the accuracy of mental fatigue classification approaches 90%. Since fNIR is a portable, wearable and minimally intrusive methodology, it has the potential to be deployed in future space environments to monitoring mental fatigue and assessing the effort of operators in field environments.

19. Effects of target probability changes on hemodynamic responses in prefrontal cortex during a Go-Nogo task

19. Effects of target probability changes on hemodynamic responses in prefrontal cortex during a Go-Nogo task

Category-specific organization of prefrontal response-facilitation during priming

Perceptual priming is a fundamental long-term memory capability that allows more efficient and faster responding to a stimulus as a result of prior exposure to that stimulus. The two major components of priming are facilitated response expression and improved stimulus identification. Recent fMRI studies have identified a potential neural correlate for response-facilitation, namely the repetition-related activity decrements in prefrontal cortex that are linearly correlated with improvements in reaction times. However, the neural processes underlying such response-facilitation are still unclear. They could be stimulus-selective stimulus-response mapping processes or general response-learning mechanisms. In human imaging studies, behavioral priming has been associated with decreased hemodynamic responses in prefrontal cortex and in category-specific brain regions of the ventral visual stream. Currently, it is unclear whether priming-related response decreases in prefrontal cortex are also category-specific. In this fMRI study, 16 subjects performed a repetition priming task employing category-specific identification judgments on pictures of faces (male/female judgment), scenes (indoor/outdoor judgment) and scrambled ‘noise’ pictures (simple button press). The repeated faces and scenes were identified faster than first presentations indicating priming. Hemodynamic decreases for repetitions were observed in a left inferior (near Brodman Area, BA, 44) and middle frontal (BA8) region of the prefrontal cortex, in category-specific areas of the ventral stream (bilateral fusiform face area, FFA, parahippocampal place area, PPA), and two category-specific right lateral occipital (LOC) regions. Hemodynamic increases for repetitions appeared in the caudate and cerebellum. However, the prefrontal areas were the only regions that showed a correlation between repetition-related reaction time improvement and hemodynamic decrease. Importantly, the correlations were category-specific in their relationship to reaction time improvement: in the left inferior frontal cortex the correlations were specific for scenes whereas and in left middle frontal gyrus they were specific for faces. There were no correlations between behavior and repetition suppression for both LOC regions, FFA and PPA. These data reveal that response-facilitation in prefrontal cortex is organized according to stimulus-properties, compatible with learning of stimulus-response mapping rather than response learning in general.