Brain Blood Oxygen Level-dependent Research Articles

Fractal Analysis of Brain Blood Oxygenation Level Dependent (BOLD) Signals from Children with Mild Traumatic Brain Injury (mTBI).

BackgroundConventional imaging techniques are unable to detect abnormalities in the brain following mild traumatic brain injury (mTBI). Yet patients with mTBI typically show delayed response on neuropsychological evaluation. Because fractal geometry represents complexity, we explored its utility in measuring temporal fluctuations of brain resting state blood oxygen level dependent (rs-BOLD) signal. We hypothesized that there could be a detectable difference in rs-BOLD signal complexity between healthy subjects and mTBI patients based on previous studies that associated reduction in signal complexity with disease.MethodsFifteen subjects (13.4 ± 2.3 y/o) and 56 age-matched (13.5 ± 2.34 y/o) healthy controls were scanned using a GE Discovery MR750 3T MRI and 32-channel RF-coil. Axial FSPGR-3D images were used to prescribe rs-BOLD (TE/TR = 35/2000ms), acquired over 6 minutes. Motion correction was performed and anatomical and functional images were aligned and spatially warped to the N27 standard atlas. Fractal analysis, performed on grey matter, was done by estimating the Hurst exponent using de-trended fluctuation analysis and signal summation conversion methods.Results and ConclusionsVoxel-wise fractal dimension (FD) was calculated for every subject in the control group to generate mean and standard deviation maps for regional Z-score analysis. Voxel-wise validation of FD normality across controls was confirmed, and non-Gaussian voxels (3.05% over the brain) were eliminated from subsequent analysis. For each mTBI patient, regions where Z-score values were at least 2 standard deviations away from the mean (i.e. where |Z| > 2.0) were identified. In individual patients the frequently affected regions were amygdala (p = 0.02), vermis(p = 0.03), caudate head (p = 0.04), hippocampus(p = 0.03), and hypothalamus(p = 0.04), all previously reported as dysfunctional after mTBI, but based on group analysis. It is well known that the brain is best modeled as a complex system. Therefore a measure of complexity using rs-BOLD signal FD could provide an additional method to grade and monitor mTBI. Furthermore, this approach can be personalized thus providing unique patient specific assessment.

Randomized trial on the effects of a combined physical/cognitive training in aged MCI subjects: the Train the Brain study

Age-related cognitive impairment and dementia are an increasing societal burden. Epidemiological studies indicate that lifestyle factors, e.g. physical, cognitive and social activities, correlate with reduced dementia risk; moreover, positive effects on cognition of physical/cognitive training have been found in cognitively unimpaired elders. Less is known about effectiveness and action mechanisms of physical/cognitive training in elders already suffering from Mild Cognitive Impairment (MCI), a population at high risk for dementia. We assessed in 113 MCI subjects aged 65–89 years, the efficacy of combined physical-cognitive training on cognitive decline, Gray Matter (GM) volume loss and Cerebral Blood Flow (CBF) in hippocampus and parahippocampal areas, and on brain-blood-oxygenation-level-dependent (BOLD) activity elicited by a cognitive task, measured by ADAS-Cog scale, Magnetic Resonance Imaging (MRI), Arterial Spin Labeling (ASL) and fMRI, respectively, before and after 7 months of training vs. usual life. Cognitive status significantly decreased in MCI-no training and significantly increased in MCI-training subjects; training increased parahippocampal CBF, but no effect on GM volume loss was evident; BOLD activity increase, indicative of neural efficiency decline, was found only in MCI-no training subjects. These results show that a non pharmacological, multicomponent intervention improves cognitive status and indicators of brain health in MCI subjects.

Changes in Brain Oxygenation in Response to Inhaled 100% Oxygen Are Different in Sickle Cell Disease Patients

Introduction: The prevalence of silent stroke increases monotonically with age in SCD patients, with more than 50% developing detectable white matter hyperintensities on MRI by adulthood. We are exploring the use of inhaled oxygen as a contrast agent to try to identify individuals at risk for silent stroke and to better understand how the brain regulates its own oxygen delivery. In this study, we report changes of brain Blood Oxygen Level Dependent (BOLD) signal and frontal Near Infrared Spectroscopy (NIRs) to 5 minutes of inhaled 100% oxygen in patients with sickle cell disease (SCD), non sickle anemia (ACTL), and control subjects.Method: The study was approved by the institutional review board and performed at Children’s Hospital Los Angeles (CHLA); all patients provided informed consent. Patients with previous stroke, pregnancy, and acute chest pain and crisis hospitalization within one month were excluded. 19 SCD patients (age = 20.7 ± 8.8), 12 patients with non sickle anemia syndromes (age = 25.1 ± 6.9) and 20 ethnicity matched control (CTL) subjects (age = 30.5 ± 12.7) were studied. Peripheral oxygen saturation (SpO2%) was measured by MRI compatible pulse oximeter. A five minute BOLD sequence was acquired with the patient breathing room air for 50 seconds, followed by 100% oxygen for 250 seconds. NIRS recordings of oxygenated hemoglobin change (DOHB), deoxygenated hemoglobin change (DDHB) and tissue oxygenation index (TOI) were recorded from the patient’s forehead. Average BOLD signal was from a 6 cm slab in the middle of the brain. CBC, hemoglobin electrophoresis, and markers of hemolysis were also measured.Results: A representative frontal DOHB signal, and the parameters used to characterize its time-course, are shown in Figure 1. DOHB remained stable until oxygen was administered and then increased over several minutes to a maximum. In many patients, the DOHB signal subsequently declined back toward baseline, representing the effects of compensatory cerebral vasoconstriction. The delay time was shorter in anemic subjects because of increased cerebral blood flow, but the rise times were not different. Peak DOHB increase was greater in SCD patients than in ACTL or non anemic control subjects (1.4 mM ± 0.2mM, 0.8 mM ± 0.2 mM and 0.6 mM ± 0.4 mM, respectively, p <0.0001 by ANOVA). There was no difference in the DOHB vasoconstriction response among the three patient groups.DOHB was highly correlated with DDHB and DTOI in all three patient groups. Consequently, both DDHB and DTOI changes were also larger in SCD patients. All three NIRs signal changes were larger in non-transfused SCD patients than in patients on chronic transfusions. Non-transfused SCD patients had more significant increases in SpO2% than chronically transfused subjects and the effect was proportional to hemoglobin F%, suggesting a p50 effect. After controlling for SpO2%, SCD patients still exhibited larger NIRs changes than ACTL or CTL patients, but the differences between transfused and non transfused SCD patients disappeared.Whole brain %BOLD was also correlated with changes in DOHB, DDHB, TOI, and SpO2%. The relationship between DOHB versus %BOLD is illustrated in Figure 2. %BOLD changes were also significantly higher in SCD patients. However, unlike the NIRS changes, whole brain %BOLD differences could entirely be explained by differences in SpO2% with hyperoxia.Conclusion:100% oxygen administration increases brain oxygenation in SCD patients to a greater degree than in control subjects or patients with anemia of other etiologies. Some of the differences can be explained by differences in resting oxygen saturations but disparities between BOLD and NIRs response suggest regional variation of brain oxygenation in response to this challenge. [Display omitted] [Display omitted] DisclosuresWood:Apopharma: Consultancy; AMAG: Consultancy; World Care Clinical: Consultancy; AMAG: Consultancy; Celgene: Consultancy; Apopharma: Consultancy; Biomed Informatics: Consultancy; Celgene: Consultancy; Ionis Pharmaceuticals: Consultancy; Vifor: Consultancy; Vifor: Consultancy; Ionis Pharmaceuticals: Consultancy; Biomed Informatics: Consultancy; World Care Clinical: Consultancy.

Poster - 06: Fractal Analysis of the brain blood oxygenation level dependent (BOLD) signal of mild traumatic brain injury (mTBI) patients

Conventional imaging techniques are unable to detect abnormalities in the brain of Mild traumatic brain injury (mTBI) patients that have shown delayed response on neuropsychological evaluation. Our goal was to explore a novel analysis approach involving measurement of the temporal fractal nature of the resting state blood oxygen level depending (rsBOLD) signal. Fifteen subjects (13.4±2.3 y/o) and 56 age-matched (13.5±2.34 y/o) healthy controls were scanned using a GE-MR750-3T MRI and 32-channel RF-coil. Axial FSPGR-3D images were used to prescribe the rsBOLD. Motion correction was performed and the anatomical and functional images were aligned and spatially warped to a standard space. Fractal analysis, performed over the gray matter, was assessed by calculating the Hurst exponent according to Eke's procedure . Voxel-based fractal dimension (FD) was calculated for every subject in the control group to generate the mean and standard deviation maps for the Z-score analysis. We generated Z-score maps for each mTBI patient and the regions where |Z|>2 were analyzed. We found that the most affected regions were the amygdala, the vermis, the caudate head, the hippocampus, and the hypothalamus, which have been previously reported as dysfunctional after mTBI. This preliminary study suggests that fractal analysis of the rsBOLD signal could possibly provide further information in mTBI. It is well known that the brain is best modeled as a complex system and therefore a measure of complexity using FD could provide an additional method to approach this global problem.

Selective serotonin 5-HT1A receptor biased agonists elicitdistinct brain activation patterns: a pharmacoMRI study.

Serotonin 1A (5-HT1A) receptors are involved in several physiological and pathological processes and constitute therefore an important therapeutic target. The recent pharmacological concept of biased agonism asserts that highly selective agonists can preferentially direct receptor signaling to specific intracellular responses, opening the possibility of drugs targeting a receptor subtype in specific brain regions. The present study brings additional support to this concept thanks to functional magnetic resonance imaging (7 Tesla-fMRI) in anaesthetized rats. Three 5-HT1A receptor agonists (8-OH-DPAT, F13714 and F15599) and one 5-HT1A receptor antagonist (MPPF) were compared in terms of influence on the brain blood oxygen level-dependent (BOLD) signal. Our study revealed for the first time contrasting BOLD signal patterns of biased agonists in comparison to a classical agonist and a silent antagonist. By providing functional information on the influence of pharmacological activation of 5-HT1A receptors in specific brain regions, this neuroimaging approach, translatable to the clinic, promises to be useful in exploring the new concept of biased agonism in neuropsychopharmacology.

The Psychoactive Designer Drug and Bath Salt Constituent MDPV Causes Widespread Disruption of Brain Functional Connectivity

The abuse of 'bath salts' has raised concerns because of their adverse effects, which include delirium, violent behavior, and suicide ideation in severe cases. The bath salt constituent 3,4-methylenedioxypyrovalerone (MDPV) has been closely linked to these and other adverse effects. The abnormal behavioral pattern produced by acute high-dose MDPV intake suggests possible disruptions of neural communication between brain regions. Therefore, we determined if MDPV exerts disruptive effects on brain functional connectivity, particularly in areas of the prefrontal cortex. Male rats were imaged following administration of a single dose of MDPV (0.3, 1.0, or 3.0 mg/kg) or saline. Resting state brain blood oxygenation level-dependent (BOLD) images were acquired at 4.7 T. To determine the role of dopamine transmission in MDPV-induced changes in functional connectivity, a group of rats received the dopamine D1/D2 receptor antagonist cis-flupenthixol (0.5 mg/kg) 30 min before MDPV. MDPV dose-dependently reduced functional connectivity. Detailed analysis of its effects revealed that connectivity between frontal cortical and striatal areas was reduced. This included connectivity between the prelimbic prefrontal cortex and other areas of the frontal cortex and the insular cortex with hypothalamic, ventral, and dorsal striatal areas. Although the reduced connectivity appeared widespread, connectivity between these regions and somatosensory cortex was not as severely affected. Dopamine receptor blockade did not prevent the MDPV-induced decrease in functional connectivity. The results provide a novel signature of MDPV's in vivo mechanism of action. Reduced brain functional connectivity has been reported in patients suffering from psychosis and has been linked to cognitive dysfunction, audiovisual hallucinations, and negative affective states akin to those reported for MDPV-induced intoxication. The present results suggest that disruption of functional connectivity networks involving frontal cortical and striatal regions could contribute to the adverse effects of MDPV.

Abstract 19532: Maternal Hyperoxia Increases Cerebral Oxygenation in Fetuses With Complex Congenital Heart Disease: A Functional MRI Study

Introduction: Fetal brain growth is altered in congenital heart disease (CHD). The role of disturbed placental and fetal blood flow/oxygenation remains poorly understood. We compared the effect of maternal hyperoxia on cerebral and placental oxygenation in CHD vs control fetuses using blood oxygenation level dependent (BOLD) functional MRI (fMRI). Methods: We studied 85 pregnant women (51 healthy /34 CHD fetuses) at 22-39 weeks gestational age (GA), using MRI and Doppler. After 2min baseline recording at normoxia (NO), we made BOLD fMRI measurements in 4 phases, (1) early hyperoxia (HO; 100% O2) for 2min (2) late HO (2min), (3) early return NO (1.75min), (4) late return NO (1.75min). We measured % BOLD signal changes in fetal brain and placenta and correlated these with umbilical artery (UA) pulsatility index (PI) obtained at baseline. Results: Mean GA of CHD vs control fetuses was 32 4/7 and 32 2/7 (p=0.77). 41.2% had 1-ventricle (1V; all HLHS) vs 2-ventricle (2V) physiology. In controls, brain BOLD signal increased in phase 1 HO and remained elevated through phase 4. In CHD fetuses, the BOLD signal increased in phase 1 and continued to rise through phase 4. Differences in brain BOLD elevation in CHD vs controls (3.1% vs 0.9%, p=0.04) was significant in phase 4 (Fig. 1). Brain BOLD differed between 1V (3.4%, p=0.04) and 2V (0.9%, p=0.15) in phases 3 &amp; 4. Placental BOLD signal increased during HO in control (4.4%, p&lt;0.001) and CHD fetuses (6.4%, p&lt;0.001). UA PI in CHD fetuses was higher than controls (1.11 vs 1.03, p=0.03). UA PI correlated with placental BOLD during HO in healthy and CHD fetuses (p&lt;0.05). Conclusions: In this first report of placental and fetal brain responses to maternal HO, we show a significantly increased brain BOLD response in CHD fetuses, specifically 1V. These data suggest that maternal HO improves brain oxygenation in CHD fetuses in the short-term. Studies evaluating the prolonged effects of HO are needed to determine the role of HO management in select CHD fetuses.

Brain Correlates of Self-Evaluation Deficits in Schizophrenia: A Combined Functional and Structural MRI Study.

Self-evaluation plays an important role in adaptive functioning and is a process that is typically impaired in patients with schizophrenia. Underlying neural mechanisms for this dysfunction may be associated with manifested psychosis. However, the brain substrates underlying this deficit are not well known. The present study used brain blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) and gray matter voxel-based morphometry to explore the functional and structural brain correlates of self-evaluation deficits in schizophrenia. Eighteen patients with schizophrenia and 17 healthy controls were recruited and asked to judge whether a set of personality-trait adjectives were appropriate for describing themselves, a familiar other, or whether the adjectives were of positive or negative valence. Patients had slower response times for negative trait attributions than controls did; responses to positive trait attributions were faster than those for negative traits among the patient group, while no differences were observed in the control group. Control subjects showed greater activation within the dorsal medial prefrontal cortex (dMPFC) and the anterior cingulate cortex (ACC) than the patient group during the self-evaluation > semantic positivity-evaluation contrast. Patients showed greater activation mainly within the posterior cingulate gyrus (PCC) as compared to controls for the other-evaluation > semantic positivity-evaluation contrast. Furthermore, gray matter volume was reduced in the MPFC, temporal lobe, cuneus, and the dorsal lateral prefrontal cortex (DLPFC) among the patient group when compared to controls. The present study adds to previous findings regarding self- and other-referential processing in schizophrenia, providing support for neurobiological models of self-reflection impairment.

Global brain blood-oxygen level responses to autonomic challenges in obstructive sleep apnea.

Obstructive sleep apnea (OSA) is accompanied by brain injury, perhaps resulting from apnea-related hypoxia or periods of impaired cerebral perfusion. Perfusion changes can be determined indirectly by evaluation of cerebral blood volume and oxygenation alterations, which can be measured rapidly and non-invasively with the global blood oxygen level dependent (BOLD) signal, a magnetic resonance imaging procedure. We assessed acute BOLD responses in OSA subjects to pressor challenges that elicit cerebral blood flow changes, using a two-group comparative design with healthy subjects as a reference. We separately assessed female and male patterns, since OSA characteristics and brain injury differ between sexes. We studied 94 subjects, 37 with newly-diagnosed, untreated OSA (6 female (age mean ± std: 52.1±8.1 yrs; apnea/hypopnea index [AHI]: 27.7±15.6 events/hr and 31 male 54.3±8.4 yrs; AHI: 37.4±19.6 events/hr), and 20 female (age 50.5±8.1 yrs) and 37 male (age 45.6±9.2 yrs) healthy control subjects. We measured brain BOLD responses every 2 s while subjects underwent cold pressor, hand grip, and Valsalva maneuver challenges. The global BOLD signal rapidly changed after the first 2 s of each challenge, and differed in magnitude between groups to two challenges (cold pressor, hand grip), but not to the Valsalva maneuver (repeated measures ANOVA, p<0.05). OSA females showed greater differences from males in response magnitude and pattern, relative to healthy counterparts. Cold pressor BOLD signal increases (mean ± adjusted standard error) at the 8 s peak were: OSA 0.14±0.08% vs. Control 0.31±0.06%, and hand grip at 6 s were: OSA 0.08±0.03% vs. Control at 0.30±0.02%. These findings, indicative of reduced cerebral blood flow changes to autonomic challenges in OSA, complement earlier reports of altered resting blood flow and reduced cerebral artery responsiveness. Females are more affected than males, an outcome which may contribute to the sex-specific brain injury in the syndrome.

Functional magnetic resonance imaging suggests automatization of the cortical response to inspiratory threshold loading in humans

Inspiratory threshold loading (ITL) induces cortical activation. It is sustained over time and is resistant to distraction, suggesting automaticity. We hypothesized that ITL-induced changes in cerebral activation may differ between single-breath ITL and continuous ITL, with differences resembling those observed after cortical automatization of motor tasks. We analyzed the brain blood oxygen level dependent (BOLD) signal of 11 naive healthy volunteers during 5min of random, single-breath ITL and 5min of continuous ITL. Single-breath ITL increased BOLD in many areas (premotor cortices, bilateral insula, cerebellum, reticular formation of the lateral mesencephalon) and decreased BOLD in regions colocalizing with the default mode network. Continuous ITL induced signal changes in a limited number of areas (supplementary motor area). These differences are comparable to those observed before and after overlearning of motor tasks. We conclude that the respiratory-related cortical activation observed in response to ITL is likely due to automated, attention-independent mechanisms. Also, ITL activates cortical circuits right from the first breath.

Functional Magnetic Resonance Imaging (fMRI) with Auditory Stimulation in Songbirds

The neurobiology of birdsong, as a model for human speech, is a pronounced area of research in behavioral neuroscience. Whereas electrophysiology and molecular approaches allow the investigation of either different stimuli on few neurons, or one stimulus in large parts of the brain, blood oxygenation level dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) allows combining both advantages, i.e. compare the neural activation induced by different stimuli in the entire brain at once. fMRI in songbirds is challenging because of the small size of their brains and because their bones and especially their skull comprise numerous air cavities, inducing important susceptibility artifacts. Gradient-echo (GE) BOLD fMRI has been successfully applied to songbirds (1-5) (for a review, see (6)). These studies focused on the primary and secondary auditory brain areas, which are regions free of susceptibility artifacts. However, because processes of interest may occur beyond these regions, whole brain BOLD fMRI is required using an MRI sequence less susceptible to these artifacts. This can be achieved by using spin-echo (SE) BOLD fMRI (7,8) . In this article, we describe how to use this technique in zebra finches (Taeniopygia guttata), which are small songbirds with a bodyweight of 15-25 g extensively studied in behavioral neurosciences of birdsong. The main topic of fMRI studies on songbirds is song perception and song learning. The auditory nature of the stimuli combined with the weak BOLD sensitivity of SE (compared to GE) based fMRI sequences makes the implementation of this technique very challenging.

A functional MRI study of deception among offenders with antisocial personality disorders

Deceit is a core feature of antisocial personality disorder (ASPD), and the study of deception in ASPD has important implications for identifying the underlying mechanism of ASPD. A great deal of functional neuroimaging literature has described the neural correlates of deception in healthy volunteers, but there have been few imaging studies examining people with ASPD. The neural correlates of lie-telling in ASPD, and which specific brain activities are related to the capacity to lie, are unclear. In this study, 32 offenders who satisfied the Personality Diagnostic Questionaire-4 and PDI-IV (Personality Disorder Interview) criteria for ASPD were divided into three groups based on their capacity for deception, which was evaluated based on the deceitfulness criterion of the PDI-IV ASPD. All offenders underwent functional magnetic resonance imaging (fMRI) while responding to questions in a truthful, inverse, or deceitful manner. We primarily created contrasts in the brain activities between truth-telling and lie-telling, and then computed the Pearson’s correlation coefficients between activities contrasts of individual, i.e. BOLD (blood-oxygen-level-dependent) strength during deception minus that during truth-telling, and the capacity for deception. Our results indicated that the bilateral dorsolateral prefrontal cortex extending to the middle frontal gyrus, the left inferior parietal lobule, and the bilateral anterior cingulate gyrus/medial superior frontal gyrus were associated with deception among people with ASPD. As the capacity for deception increased, the contrasted brain activities of the above regions decreased. This study found that truthful and untruthful communications of ASPD subjects can be differentiated in terms of brain BOLD activities, and more importantly, this study is the first to use fMRI to discover that BOLD activities during deception are correlated with the capacity to lie. The latter finding might challenge the diagnostic accuracy of lie detection and may also caution that greater attention should be given to detecting untruths in individuals who are skilled at lying.

Functional MRI analysis of deception among people with antisocial personality disorders

To investigate the functional magnetic resonance imaging (fMRI) data of deception in antisocial personality disorders (ASPD). A total of 32 criminals meeting the criteria for ASPD underwent fMRI at 1.5T while responding truthfully questions or lying. We compared the brain activities between truth-telling and lie-telling, and then computed the correlation coefficient between the contrast brain activities and the inclination to deception. The left anterior cingulate gyrus, the bilateral dorsolateral prefrontal cortex, and left inferior parietal lobule were associated with the executive aspects of deception among people with ASPD. But with the greater inclination to deception, the blood oxygen level dependent (BOLD) activities in those regions decreased. Evaluations of truthful and untruthful communications pertaining to ASPD subjects may be differentiated in terms of brain BOLD activities, though those activities may decrease in habitual liars, which remains a challenge to the diagnostic accuracy in lie detection.

Correlating brain blood oxygenation level dependent (BOLD) fractal dimension mapping with magnetic resonance spectroscopy (MRS) in Alzheimer’s disease

To correlate temporal fractal structure of resting state blood oxygen level dependent (rsBOLD) functional magnetic resonance imaging (fMRI) with in vivo proton magnetic resonance spectroscopy ((1)H-MRS), in Alzheimer's disease (AD) and healthy age-matched normal controls (NC). High temporal resolution (4 Hz) rsBOLD signal and single voxel (left putamen) magnetic resonance spectroscopy data was acquired in 33 AD patients and 13 NC. The rsBOLD data was analyzed using two types of fractal dimension (FD) analysis based on relative dispersion and frequency power spectrum. Comparisons in FD were performed between AD and NC, and FD measures were correlated with (1)H-MRS findings. Temporal fractal analysis of rsBOLD, was able to differentiate AD from NC subjects (P = 0.03). Low FD correlated with markers of AD severity including decreased concentrations of N-acetyl aspartate (R = 0.44, P = 0.015) and increased myoinositol (mI) (R = -0.45, P = 0.012). Based on these results we suggest fractal analysis of rsBOLD could provide an early marker of AD.

Perceptual and neural response to affective tactile texture stimulation in adults with autism spectrum disorders.

Autism spectrum disorders (ASD) are associated with differences in sensory sensitivity and affective response to sensory stimuli, the neural basis of which is still largely unknown. We used psychophysics and functional magnetic resonance imaging (fMRI) to investigate responses to somatosensory stimulation with three textured surfaces that spanned a range of roughness and pleasantness in a sample of adults with ASD and a control group. While psychophysical ratings of roughness and pleasantness were largely similar across the two groups, the ASD group gave pleasant and unpleasant textures more extreme average ratings than did controls. In addition, their ratings for a neutral texture were more variable than controls, indicating they are less consistent in evaluating a stimulus that is affectively ambiguous. Changes in brain blood oxygenation level-dependent (BOLD) signal in response to stimulation with these textures differed substantially between the groups, with the ASD group exhibiting diminished responses compared to the control group, particularly for pleasant and neutral textures. For the most unpleasant texture, the ASD group exhibited greater BOLD response than controls in affective somatosensory processing areas such as the posterior cingulate cortex and the insula. The amplitude of response in the insula in response to the unpleasant texture was positively correlated with social impairment as measured by the Autism Diagnostic Interview-Revised (ADI-R). These results suggest that people with ASD tend to show diminished response to pleasant and neutral stimuli, and exaggerated limbic responses to unpleasant stimuli, which may contribute to diminished social reward associated with touch, perpetuating social withdrawal, and aberrant social development.

Effects of mobile phone signals over BOLD response while performing a cognitive task

Objective The aim of this study was to investigate the effects induced by an exposure to a GSM signal (Global System for Mobile Communication) on brain BOLD (blood-oxygen-level dependent) response, as well as its time course while performing a Go–NoGo task. Methods Participants were tested twice, once in presence of a “real” exposure to GSM radiofrequency signal and once under a “sham” exposure (placebo condition). BOLD response of active brain areas and reaction times (RTs) while performing the task were measured both before and after the exposure. Results RTs to the somatosensory task did not change as a function of exposure (real vs sham) to GSM signal. BOLD results revealed significant activations in inferior parietal lobule, insula, precentral and postcentral gyri associated with Go responses after both ‘‘real’’ and ‘‘sham’’ exposure, whereas no significant effects were observed in the ROI analysis. Conclusions The present fMRI study did not detect any brain activity changes by mobile phones. Also RTs in a somatosensory task resulted unaffected. Significance No changes in BOLD response have been observed as a consequence of RF-EMFs exposure.

Functional Cortical and Subcortical Abnormalities in Pedophilia: A Combined Study Using a Choice Reaction Time Task and fMRI

Pedophiles show sexual interest in prepubescent children but not in adults. Research into the neurofunctional mechanisms of paraphilias has gathered momentum over the last years. To elucidate the underlying neural processing of sexual interest among pedophiles and to highlight the differences in comparison with nonparaphilic sexual interest in adults. Nine pedophilic patients and 11 nonpedophilic control subjects underwent functional magnetic resonance imaging (fMRI) while viewing pictures of nude (prepubescents, pubescents, and adults) and neutral content, as well as performing a concomitant choice reaction time task (CRTT). Brain blood oxygen level-dependent (BOLD) signals and response latencies in the CRTT during exposure to each picture category. Analysis of behavioral data showed group differences in reaction times regarding prepubescent and adult but not pubescent stimuli. During stimulation with pictures displaying nude prepubescents, pedophiles showed increased BOLD response in brain areas known to be involved in processing of visual sexual stimuli. Comparison of pedophilic patients with the control group discovered differences in BOLD responses with respect to prepubescent and adult but not to pubescent stimuli. Differential effects in particular occurred in the cingulate gyrus and insular region. The brain response of pedophiles to visual sexual stimulation by images of nude prepubescents is comparable with previously described neural patterns of sexual processing in nonpedophilic human males evoked by visual stimuli depicting nude adults. Nevertheless, group differences found in the cingulate gyrus and the insular region suggest an important role of these brain areas in pedophilic sexual interest. Furthermore, combining attention-based methods like CRTT with fMRI may be a viable option for future diagnostic procedures regarding pedophilia.

Anatomical and Functional Assemblies of Brain BOLD Oscillations

Brain oscillatory activity has long been thought to have spatial properties, the details of which are unresolved. Here we examine spatial organizational rules for the human brain oscillatory activity as measured by blood oxygen level-dependent (BOLD) signal. Resting-state BOLD signal was transformed into frequency space (Welch's method) and averaged across subjects, and its spatial distribution was studied as a function of four frequency bands, spanning the full BOLD bandwidth. The brain showed anatomically constrained distribution of power for each frequency band. This result was replicated on a repository dataset of 195 subjects. Next, we examined larger-scale organization by parceling the neocortex into regions approximating Brodmann areas (BAs). This indicated that BAs of simple function/connectivity (unimodal), versus complex properties (transmodal), are dominated by low-frequency BOLD oscillations, and within the visual ventral stream we observe a graded shift of power to higher-frequency bands for BAs further removed from the primary visual cortex (increased complexity), linking BOLD frequency properties to hodology. Additionally, BOLD oscillation properties for the default mode network demonstrated that it is composed of distinct frequency-dependent regions. When the same analysis was performed on a visual-motor task, frequency-dependent global and voxelwise shifts in BOLD oscillations could be detected at brain sites mostly outside those identified with general linear modeling. Thus, analysis of BOLD oscillations in full bandwidth uncovers novel brain organizational rules, linking anatomical structures and functional networks to characteristic BOLD oscillations. The approach also identifies changes in brain intrinsic properties in relation to responses to external inputs.

Neural correlates of evaluations of lying and truth-telling in different social contexts

The present study examined the neural correlates of evaluations of both lying and truth-telling in different social contexts using fMRI methodology. The results demonstrated the differentiation between lying and truth-telling and between different types of lying in a network of brain regions. These regions included bilateral superior frontal gyrus (SFG), bilateral inferior parietal lobule (IPL), bilateral cuneus, right lingual gyrus (LG), right precuneus, and left postcentral gyrus (PoCG). Additionally, we found that activations in the right LG, the left IPL and the left PoCG were correlated with the off-line evaluations of truthful and untruthful communications about good and bad acts in different social contexts. These results suggest that the judgments of lying and truth-telling involving a third party might not be emotion-arousing but involve rational processing. This study is among the first to demonstrate that evaluations of truthful and untruthful communications in different social contexts can be differentiated in terms of brain BOLD (blood-oxygen-level-dependent) activities.

Brain functional magnetic resonance imaging response to glucose and fructose infusions in humans

In animals, intracerebroventricular glucose and fructose have opposing effects on appetite and weight regulation. In humans, functional brain magnetic resonance imaging (fMRI) studies during glucose ingestion or infusion have demonstrated suppression of hypothalamic signalling, but no studies have compared the effects of glucose and fructose. We therefore sought to determine if the brain response differed to glucose vs. fructose in humans independently of the ingestive process. Nine healthy, normal weight subjects underwent blood oxygenation level dependent (BOLD) fMRI measurements during either intravenous (IV) glucose (0.3 mg/kg), fructose (0.3 mg/kg) or saline, administered over 2 min in a randomized, double-blind, crossover study. Blood was sampled every 5 min during a baseline period and following infusion for 60 min in total for glucose, fructose, lactate and insulin levels. No significant brain BOLD signal changes were detected in response to IV saline. BOLD signal in the cortical control areas increased during glucose infusion (p = 0.002), corresponding with increased plasma glucose and insulin levels. In contrast, BOLD signal decreased in the cortical control areas during fructose infusion (p = 0.006), corresponding with increases of plasma fructose and lactate. Neither glucose nor fructose infusions significantly altered BOLD signal in the hypothalamus. In normal weight humans, cortical responses as assessed by BOLD fMRI to infused glucose are opposite to those of fructose. Differential brain responses to these sugars and their metabolites may provide insight into the neurologic basis for dysregulation of food intake during high dietary fructose intake.