Regional Brain Activation In Response Research Articles

Validation of Emotional Stimuli Flashcards for Conducting ‘Response to Reward’ fMRI Study among Malaysian Undergraduates

Problematic Instagram Use (PIGU) is a specific Internet addiction disorder observed among the youth of today. Functional magnetic resonance imaging (fMRI) can objectively assess regional brain activation in response to addictionspecific rewards, e.g. viewing picture flashcards. Pictures that were uploaded onto Instagram by users with PIGU issue have often been associated with risky behaviors in their efforts to gain more ‘Likes’. Thus, it was hypothesized that individuals with PIGU issue are more drawn to negative emotional cues. To date, no literature on addiction-specific cues found on the local database. The objective of this study was to conduct an out-of-scanner validation study to create a database of pictures with negative emotional cues that evoke responses of arousal among individuals with PIGU issue. Forty-four Malaysian undergraduates (20 undergraduates in the PIGU group, 24 undergraduates in the control group) were randomly recruited as the subjects in the present study. They were grouped into PIGU or control groups based on the evaluation using the Smartphone-Addiction-Scale-Malay version (SAS-M) and modified Instagram Addiction Test (IGAT) and whether they fulfilled the definition of addiction according to Lin et al. (2016). They were administered with 200 content-specific pictures that were multidimensional, i.e. arousal (excitation or relaxation effects), approachavoidance (motivational direction) and emotional valence (positive or negative feelings) to describe their perceptions on the psychological properties of the pictures using a 9-point Likert scale. The results showed that the subjects with PIGU issue, who viewed the negative emotional cues, demonstrated significant positive correlations between arousal and valence (z = 4.834, p < .001, effect size = 0.69) and arousal and avoidance-approach (z = 4.625, p < .001, effect size = 0.66) as compared to the controls and were more frequently aroused by negative emotional type of stimuli. As a conclusion, a database of validated, addiction-specific pictures can be developed to potentiate any future cue-induced response to reward fMRI studies for assessing PIGU.

Regional Cerebral Activation Accompanies Sympathoexcitation in Women With Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is associated with increased sympathetic nervous system activation, but the cerebral pathways involved are unclear. To compare cerebral [blood oxygen level-dependent (BOLD) functional MRI], pressor [blood pressure (BP), heart rate (HR], and muscle sympathetic nerve activity (MSNA) responses to isometric forearm contraction (IFC) in women with PCOS and matched control subjects. Case-control study. Referral center. Patients with PCOS (n = 20; mean ± SD data: age, 29.8 ± 4.8 years; body mass index (BMI), 26.1 ± 4.9 kg/ m2) and 20 age- and BMI-matched control subjects (age, 29.7 ± 5.0 years; BMI, 26.1 ± 4.8 kg/ m2). BP, HR, catecholamine, and MSNA responses to 30% IFC. BOLD signal change was modeled for BP response to 30% IFC. Although HR and BP increased to a similar extent in both groups after IFC, MSNA burst frequency increased by 68% in the PCOS group compared with 11.9% in control subjects (n = 7 in both groups; P = 0.002). Brain activation indexed by the BOLD signal in response to IFC was significantly greater in the PCOS group (n = 15) compared with controls (n = 15) in the right orbitofrontal cortex (P < 0.0001). Adjustment for insulin sensitivity, but not hyperandrogenism, abolished these between-group differences. Our study confirms enhanced sympathoexcitation in women with PCOS and demonstrates increased regional brain activation in response to IFC. The right orbitofrontal cortex BOLD signal change in women with PCOS is associated with insulin sensitivity. Additional studies are warranted to clarify whether this may offer a novel target for cardiovascular risk reduction.

Decreased regional brain activity in response to sleep‐related sounds after cognitive behavioral therapy for psychophysiological insomnia

Patients with psychophysiological insomnia (PI) experience hyperarousal, especially as a reaction to sound stimuli. In the current study, we explored brain activity changes in response to sleep-related sounds (SS) in patients with insomnia after cognitive behavioral therapy for insomnia (CBT-I). In 14 drug-free PI patients, regional brain activity in response to SS, and to white noise sound (NS) as neutral stimuli, was investigated before and after individual CBT-I using functional magnetic resonance imaging. Blood oxygen level-dependent (BOLD) signals to SS and NS were compared before and after CBT-I. In addition, the association between clinical improvement after CBT-I and changes in brain activity in response to SS and NS was analyzed. Compared with baseline, regional brain activity in response to SS after CBT-I decreased in the left middle temporal and left middle occipital gyrus. In regression analysis, a reduction in the Dysfunctional Beliefs and Attitudes about Sleep (DBAS) Scale score after CBT-I was associated with decrease in brain activity in response to SS in both thalami. However, brain activity in response to NS showed no BOLD signal changes and no association with DBAS change. Cortical hyperactivity, which may cause hyperarousal in PI, was found to decrease after CBT-I. CBT-I targeting changes in beliefs and attitudes about sleep may induce its therapeutic effects by reducing thalamic brain activity in response to sleep-related stimuli.

The effects of exercise on cigarette cravings and brain activation in response to smoking-related images

Smokers show heightened activation toward smoking-related stimuli and experience increased cravings which can precipitate smoking cessation relapse. Exercise can be effective for modulating cigarette cravings and attenuating reactivity to smoking cues, but the mechanism by which these effects occur remains uncertain. The objective of the study was to assess the effect of exercise on regional brain activation in response to smoking-related images during temporary nicotine abstinence. In a randomised crossover design, overnight abstinent smokers (n = 20) underwent an exercise (10-min moderate-intensity stationary cycling) and passive control (seating for the same duration) treatment, following 15h of nicotine abstinence. After each treatment, participants underwent functional magnetic resonance imaging (fMRI) brain scanning while viewing a random series of blocked smoking or neutral images. Self-reported cravings were assessed at baseline, mid-, and post-treatments. There was a significant interaction effect (treatment × time) for desire to smoke, F (2,32) = 12.5, p < 0.001, with significantly lower scores following the exercise at all time points compared with the control treatment. After both exercise and rest, significant areas of activation were found in areas of the limbic lobe and in areas associated with visual attention in response to smoking-related stimuli. Smokers showed increased activation to smoking images in areas associated with primary and secondary visual processing following rest, but not following a session of exercise. The study shows differing activation towards smoking images following exercise compared to a control treatment and may point to a neuro-cognitive process following exercise that mediates effects on cigarette cravings.

Effect of Bupropion Treatment on Brain Activation Induced by Cigarette-Related Cues in Smokers

Nicotine-dependent smokers exhibit craving and brain activation in the prefrontal and limbic regions when presented with cigarette-related cues. Bupropion hydrochloride treatment reduces cue-induced craving in cigarette smokers; however, the mechanism by which bupropion exerts this effect has not yet been described. To assess changes in regional brain activation in response to cigarette-related cues from before to after treatment with bupropion (vs placebo). Randomized, double-blind, before-after controlled trial. Academic brain imaging center. Thirty nicotine-dependent smokers (paid volunteers). Participants were randomly assigned to receive 8 weeks of treatment with either bupropion or a matching placebo pill (double-blind). Subjective cigarette craving ratings and regional brain activations (blood oxygen level-dependent response) in response to viewing cue videos. Bupropion-treated participants reported less craving and exhibited reduced activation in the left ventral striatum, right medial orbitofrontal cortex, and bilateral anterior cingulate cortex from before to after treatment when actively resisting craving compared with placebo-treated participants. When resisting craving, reduction in self-reported craving correlated with reduced regional brain activation in the bilateral medial orbitofrontal and left anterior cingulate cortices in all participants. Treatment with bupropion is associated with improved ability to resist cue-induced craving and a reduction in cue-induced activation of limbic and prefrontal brain regions, while a reduction in craving, regardless of treatment type, is associated with reduced activation in prefrontal brain regions.

Mapping of regional brain activation in response to fatigue-load and recovery in rats with c-Fos immunohistochemistry

Fatigue is known to be accompanied by a feeling of extreme physical or mental tiredness, resulting from severe stress and hard physical or mental work. To investigate the functional localization of neural activity related to fatigue and recovery, we examined brain c-Fos expression patterns in a rat in a state of fatigue in which rats kept in a cage filled with water to a height of 2.2 cm for 1–5 days. A significant increase in the number of c-Fos-immunopositive cells was observed in the retrosplenial granular b cortex during the fatigue-loading and in the dentate gyrus of the ventral hippocampus after a 24-h recovery. In addition, variable increases in the number of c-Fos-immunopositive cells were observed in the cingulate cortex area 2, ventral part of the lateral septum nucleus, median preoptic nucleus, anterior part of the paraventricular thalamic nucleus, medial parvicellular part of the paraventricular hypothalamic nucleus, and lateral and ventrolateral periaqueductal gray during the fatigue-load period. These results indicate that such regional brain activity would be involved in fatigue or in subsequent recovery and might provide a foothold for further research into the nature of fatigue.

Acute exercise modulates cigarette cravings and brain activation in response to smoking-related images: an fMRI study

Substances of misuse (such as nicotine) are associated with increases in activation within the mesocorticolimbic brain system, a system thought to mediate the rewarding effects of drugs of abuse. Pharmacological treatments have been designed to reduce cigarette cravings during temporary abstinence. Exercise has been found to be an effective tool for controlling cigarette cravings. The objective of this study is to assess the effect of exercise on regional brain activation in response to smoking-related images during temporary nicotine abstinence. In a randomized crossover design, regular smokers (n = 10) undertook an exercise (10 min moderate-intensity stationary cycling) and control (passive seating for same duration) session, following 15 h of nicotine abstinence. Following treatments, participants entered a functional Magnetic Resonance Imaging (fMRI) scanner. Subjects viewed a random series of smoking and neutral images for 3 s, with an average inter-stimulus-interval (ISI) of 10 s. Self-reported cravings were assessed at baseline, mid-, and post-treatments. A significant interaction effect (time by group) was found, with self-reported cravings lower during and following exercise. During control scanning, significant activation was recorded in areas associated with reward (caudate nucleus), motivation (orbitofrontal cortex) and visuo-spatial attention (parietal lobe, parahippocampal, and fusiform gyrus). Post-exercise scanning showed hypo-activation in these areas with a concomitant shift of activation towards areas identified in the 'brain default mode' (Broadmanns Area 10). The study confirms previous evidence that a single session of exercise can reduce cigarette cravings, and for the first time provides evidence of a shift in regional activation in response to smoking cues.

Application of Kalman Filter to Remove TMS-Induced Artifacts from EEG Recordings

Transcranial magnetic stimulation (TMS) is a technique in which a pulsed magnetic field created by a coil positioned next to the scalp is used to locally depolarize neurons in brain cortex. TMS can be combined with electroencephalography (EEG) to visualize regional brain activity in response to direct cortical stimulation, making it a promising tool for studying brain function. A technical drawback of EEG/TMS coregistrations is that the TMS impulse generates high amplitude and long-lasting artifacts that corrupt the EEG trace. In this brief, an offline Kalman filter approach to remove TMS-induced artifacts from EEG recordings is proposed. The Kalman filter is applied to the linear system arising from the combination of the dynamic models describing EEG and TMS signals generation. Time-varying covariance matrices suitably tuned on the physical parameters of the problem allow us to model the non-stationary components of the EEG/TMS signal, (neglected by conventional stationary filters). Experimental results show that the proposed approach guarantees an efficient deletion of TMS-induced artifacts while preserving the integrity of EEG signals around TMS impulses.

Reciprocal Effects of Antidepressant Treatment on Activity and Connectivity of the Mood Regulating Circuit: An fMRI Study

Reciprocal Effects of Antidepressant Treatment on Activity and Connectivity of the Mood Regulating Circuit: An fMRI Study

Imaging treatment effects in Alzheimer's disease

Alzheimer's disease (AD) is the commonest form of degenerative dementia and is characterised by progressive cognitive decline. Despite extensive research, the cause of AD is unknown and there is no cure at present. Of the deficits found in AD, that affecting the cholinergic neurotransmitter system is the best established and the only one translated into symptomatic treatment. Cholinergic enhancement with cholinesterase inhibitor (ChEI) drugs has been achieved and their efficacy and safety ascertained by conventional clinical trials. The mechanism of action of these drugs, however, is not well understood. Imaging with SPECT, PET, MRI and fMRI after treatment has clarified what happens in the brains of those AD patients treated with ChEI drugs. Studies with these techniques have identified increases in brain blood flow and glucose metabolism, restoration of nicotinic receptor function and re-establishment of task-related regional brain activation in response to cognitive stimulation after treatment. Structural MRI studies have explained, to some degree, why only a proportion of patients benefits from ChEI treatment and there is some evidence that some ChEI drugs might be neuroprotective. There are, however, many unsolved problems. Timing of treatment intervention to obtain maximum response and the determinants of treatment response are mostly unknown. It is also unclear whether administration of treatment in those patients who have no potential for response accelerates disease progression. These issues cannot be solved by conventional clinical trials. Pharmacoimaging studies could assist the development and refinement of drugs to treat those diseases, such as AD, which affect the central nervous system.

Brain activation measured using functional magnetic resonance imaging during the Tower of London task.

Individuals with traumatic brain injury (TBI) often suffer from a number of enduring cognitive impairments such as in attention, memory, speed of processing information and dual-task performance. The aim of this study was to assess the patterns of regional brain activation in response to the Tower of London (ToL) task in a group of patients suffering from chronic TBI using functional magnetic resonance imaging (fMRI). fMRI was performed during performance of the ToL planning task in 10 patients suffering from severe TBI and in 10 age- and sex-matched controls using a 3 T magnetic resonance scanner. Performance data showed no difference in response accuracy between the TBI group and the healthy control group. Statistical parametric brain maps showed that the TBI group activates larger and additional areas of the cerebral cortex than the healthy control group both for tasks and for a subtraction contrast between the tasks. The results of this study are interpreted as a cortical reorganization inside the executive system of vigilance and working memory in patients with TBI. Both parietal and frontal areas are recruited to compensate for damaged brain tissue.

Recognition of happy facial affect in panic disorder: An fMRI study

Background This study investigated activation of the anterior cingulate cortex (ACC) and amygdala during the presentation of happy facial affect images in patients with panic disorder (PD) as measured by blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI). Methods Eight patients with PD and eight sex-matched controls were recruited for the study. Scanning was performed on a general electric (GE) Signa 1.5 T scanner retrofitted with a whole body echo planar coil. Using a quadrature head coil, echo planar images and high-resolution MR images were acquired. Results After covarying for age, examination of group differences revealed greater ACC activation bilaterally in patients with PD compared to controls in response to happy faces. However, there were no differences in amygdala activation between the groups. These findings contrasted with regional brain activation in response to neutral faces where there were was also greater bilateral ACC activation in the PD group, but only 44 ACC voxels showed significant increases as opposed to 509 voxels for the happy condition. There were no between group differences in activation in the amygdala. Conclusion This is the first fMRI study to our knowledge that demonstrates ACC abnormalities in response to happy facial affect recognition in PD.

Auditory cortical response to monaural stimulation detected by functional magnetic resonance imaging

Few reports have characterized auditory processing in monaural listening, which is important for the understanding of auditory brain activity in subjects with hearing loss. We measure regional brain activity in response to monaural audition of 95 dB sound pressure level (SPL) monosyllables using functional magnetic resonance imaging (fMRI) in the 10 subjects with normal hearing and four subjects with unilateral deafness as controls for “cross-hearing”. Images were analyzed by statistical parametric mapping software. In subjects without hearing loss, the stimuli elicited cortical activation in the primary auditory and auditory association regions, particularly contralaterally where extent of activation was approximately 2.5 times the ipsilateral extent. All patients with profound unilateral deafness showed no statistically apparent response in the primary auditory and auditory association regions, ruling out an important influence from cross-hearing. We found fMRI to be a useful technique for analysis of auditory processing that should be applicable to patients with various hearing abnormalities.

A TMS coil positioning/holding system for MR image-guided TMS interleaved with fMRI.

Transcranial magnetic stimulation (TMS) can be interleaved with fMRI to visualize regional brain activity in response to direct, non-invasive, cortical stimulation, making it a promising tool for studying brain function. A major practical difficulty is accurately positioning the TMS coil within the MRI scanner for stimulating a particular area of brain cortex. The objective of this work was to design and build a self-contained hardware/software system for MR-guided TMS coil positioning in interleaved TMS/fMRI studies. A compact, manually operated, articulated TMS coil positioner/holder with 6 calibrated degrees of freedom was developed for use inside a cylindrical RF head coil, along with a software package for transforming between MR image coordinates, MR scanner space coordinates, and positioner/holder settings. Phantom calibration studies gave an accuracy for positioning within setups of dx=+/-1.9 mm, dy=+/-1.4 mm, dz=+/-0.8 mm and a precision for multiple setups of dx=+/-0.8 mm, dy=+/-0.1 mm, dz=+/-0.1 mm. This self-contained, integrated MR-guided TMS system for interleaved TMS/fMRI studies provides fast, accurate location of motor cortex stimulation sites traditionally located functionally, and a means of consistent, anatomy-based TMS coil positioning for stimulation of brain areas without overt response.

Regional brain activation in response to rectal distension in patients with irritable bowel syndrome and the effect of a history of abuse.

Previous studies have demonstrated alterations in brain response to rectal distension in patients with irritable bowel syndrome (IBS) compared to controls. Our aim was to compare regional brain activity in response to rectal balloon distension in patients with IBS and healthy controls. We studied six patients with IBS and six healthy controls. Positron emission tomography scans were obtained during rectal balloon distensions. Statistical parametric mapping and region of interest analysis were performed to identify and compare differences in regional cerebral blood flow (CBF) for each distension pressure within and between the groups of interest. In post-hoc analyses, patients with a history of sexual or physical abuse were compared to patients without abuse. In response to rectal distension, controls exhibit a greater increase in anterior cingulate cortex (ACC) activity compared to the IBS group (Z = 3.2, P = 0.001). Thalamic activity was higher in the IBS patients relative to the control group (Z = 3.3, P < 0.001). Increased ACC activity was observed in IBS patients with no history of abuse (Z = 5.2, P < 0.001) similar to controls, whereas no such increased activity was noticed in the abused group. In conclusion, this study replicates previous findings showing alterations in brain response to rectal distension in patients with IBS. The observations on the effect of abuse suggest a possible modulating role of abuse history on this brain response.

Chapter 5 Interleaving fMRI and rTMS

Transcranial magnetic stimulation (TMS) can be interleaved with functional magnetic resonance imaging (fMRI) to visualize regional brain activity in response to direct, non-invasive, TMS stimulation. It is a promising tool for studying brain function. This chapter provides an overview of the methodology and some of the recent work. Issues involved in performing interleaved fMRI and repetitive TMS include safety, the problems with static and dynamic artifacts, the problem of radiofrequency interference, and the requirements for minimizing the interaction between the TMS pulse and MR image acquisition. A major practical difficulty is the accurate positioning of the TMS coil within the MRI scanner for stimulating a particular area of an individual's brain cortical anatomy, especially when there is no overt response associated with that area.

Cortical and subcortical activation with monaural monosyllabic stimulation by functional MRI

Few reports have characterized auditory processing in monaural stimulation, which is important to the understanding of auditory brain activity in subjects with hearing loss. We therefore measured regional brain activity in response to monaural stimulation of 95 dB SPL monosyllables using functional magnetic resonance imaging (fMRI) in subjects with normal hearing and five with unilateral deafness as controls for ‘cross-hearing’. Images were analyzed by statistical parametric mapping software. In subjects without hearing loss, the stimuli elicited cortical activation in the primary auditory (BA 41) and auditory association regions (BA 42, 22), particularly contralaterally where extent of activation was approximately 2.5 times the ipsilateral extent. All patients with profound unilateral deafness showed no statistically apparent response in the primary auditory and auditory association regions, ruling out an important influence from cross-hearing. We found fMRI to be a useful technique for analysis of auditory processing that should be applicable to patients with various hearing abnormalities.

Lateralized response to diazepam predicts temperamental style in rhesus monkeys.

Based on previous findings in humans and rhesus monkeys suggesting that diazepam has asymmetrical effects on frontal lobe activity and other literature supporting a role for the benzodiazepine system in the mediation of individual differences in anxiety and fearfulness, the relation between asymmetrical changes in scalp-recorded regional brain activity in response to diazepam and the temperamental dimension of behavioral inhibition indexed by freezing time in 9 rhesus monkeys was examined. Animals showed greater relative left-sided frontal activation in response to diazepam compared with the preceding baseline. The magnitude of this shift was strongly correlated with an aggregate measure of freezing time (r = .82). The implications of these findings for understanding the role of regional differences in the benzodiazepine system in mediating individual differences in fearfulness are discussed.