Peripheral blood pressure changes induced by dobutamine do not alter BOLD signals in the human brain

Altered spontaneous brain activity during dobutamine challenge in healthy young adults: A resting-state functional magnetic resonance imaging study

Introduction

There is a growing interest in exploring brain-heart interactions. However, few studies have investigated the brain-heart interactions in healthy populations, especially in healthy young adults. The aim of this study was to explore the association between cardiovascular and spontaneous brain activities during dobutamine infusion in healthy young adults.

Methods

Forty-eight right-handed healthy participants (43 males and 5 females, range: 22-34 years) underwent vital signs monitoring, cognitive function assessment and brain MRI scans. Cardiovascular function was evaluated using blood pressure and heart rate, while two resting-state functional magnetic resonance imaging (rs-fMRI) methods-regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF)-were used together to reflect the local neural activity of the brain. Logistic regression was used to model the association between brain and heart.

Results

Results showed that blood pressure and heart rate significantly increased after dobutamine infusion, and the performance in brain functional activity was the decrease in ReHo in the left gyrus rectus and in ALFF in the left frontal superior orbital. The results of logistic regression showed that the difference of diastolic blood pressure (DBP) had significant positive relationship with the degree of change of ReHo, while the difference of systolic blood pressure (SBP) had significant negative impact on the degree of change in ALFF.

Discussion

These findings suggest that the brain-heart interactions exist in healthy young adults under acute cardiovascular alterations, and more attention should be paid to blood pressure changes in young adults and assessment of frontal lobe function to provide them with more effective health protection management.

Internet gaming disorder in children and adolescents: a systematic review

AIM

Internet gaming disorder (IGD) is a serious disorder leading to and maintaining pertinent personal and social impairment. IGD has to be considered in view of heterogeneous and incomplete concepts. We therefore reviewed the scientific literature on IGD to provide an overview focusing on definitions, symptoms, prevalence, and aetiology.

METHOD

We systematically reviewed the databases ERIC, PsyARTICLES, PsycINFO, PSYNDEX, and PubMed for the period January 1991 to August 2016, and additionally identified secondary references.

RESULTS

The proposed definition in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition provides a good starting point for diagnosing IGD but entails some disadvantages. Developing IGD requires several interacting internal factors such as deficient self, mood and reward regulation, problems of decision-making, and external factors such as deficient family background and social skills. In addition, specific game-related factors may promote IGD. Summarizing aetiological knowledge, we suggest an integrated model of IGD elucidating the interplay of internal and external factors.

INTERPRETATION

So far, the concept of IGD and the pathways leading to it are not entirely clear. In particular, long-term follow-up studies are missing. IGD should be understood as an endangering disorder with a complex psychosocial background.

WHAT THIS PAPER ADDS

In representative samples of children and adolescents, on average, 2% are affected by Internet gaming disorder (IGD). The mean prevalences (overall, clinical samples included) reach 5.5%. Definitions are heterogeneous and the relationship with substance-related addictions is inconsistent. Many aetiological factors are related to the development and maintenance of IGD. This review presents an integrated model of IGD, delineating the interplay of these factors.

Influence of internal carotid artery stenosis, blood pressure, glycated hemoglobin, and hemoglobin level on fMRI signals of stroke patients

OBJECTIVES

To identify the effect of internal carotid artery (ICA) stenosis, blood pressure (BP), glycated hemoglobin (HbA1c), and hemoglobin level on blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signals in stroke patients.

METHODS

A total of 18 stroke patients with acute cerebral infarction (13 males and 5 females) and 13 age-matched healthy controls (5 males and 8 females) were recruited. Among 18 stroke patients, 8 had significant ICA stenosis (> 50%) and 10 had nonsignificant ICA stenosis (< 50%). During handgrip task, stroke patients and normal controls were allowed to use their hands coincided with infarction and right hands, respectively.

RESULTS

The mean BOLD signals in patients with significant ICA stenosis were significantly less than that in patients with nonsignificant ICA stenosis. Mean arterial pressure (MAP) was significantly correlated with activated voxels of Brodmann area 4 (P < 0.01) and total activated voxels (P  =  0.007), whereas hemoglobin and HbA1c showed no significant correlation with activated voxels of Brodmann area 4 or total activated voxels (P > 0.05).

CONCLUSION

It is suggested that both ICA stenosis and arterial BP could influence BOLD signal, while HbA1c and hemoglobin level had no effect on BOLD signal.

Correlation between baseline blood pressure and the brainstem FMRI response to isometric forearm contraction in human volunteers: a pilot study

It has been shown previously that changes in brainstem neural activity correlate with changes in both mean arterial pressure (MAP) and muscle sympathetic nerve activity (MSNA) during static handgrip (SHG). However, the relationship between baseline MAP and brainstem neural activity is unclear. We investigated changes in blood oxygen level-dependent (BOLD) signal induced by SHG in 12 young adults using BOLD functional magnetic resonance imaging (FMRI). An estimation of the blood pressure response to SHG was obtained in seven subjects during a session outside the MRI scanner and was used to model the blood pressure response to SHG inside the scanner. SHG at 40% of maximum grip increased MAP (mean ± s.d.) at the end of the 180-s squeeze from 85 ± 6 mm Hg to 108 ± 15 mm Hg, P = 0.0001. The brainstem BOLD signal change associated with SHG was localised to the ventrolateral medulla. This regional BOLD signal change negatively correlated with baseline MAP, r = -0.61, P = 0.01. This relationship between baseline MAP and brainstem FMRI responses to forearm contraction is suggestive of a possible role for brainstem activity in the control of MAP and may provide mechanistic insights into neurogenic hypertension.

Neuroimaging of the periaqueductal gray: state of the field

This review and meta-analysis aims at summarizing and integrating the human neuroimaging studies that report periaqueductal gray (PAG) involvement; 250 original manuscripts on human neuroimaging of the PAG were identified. A narrative review and meta-analysis using activation likelihood estimates is included. Behaviors covered include pain and pain modulation, anxiety, bladder and bowel function and autonomic regulation. Methods include structural and functional magnetic resonance imaging, functional connectivity measures, diffusion weighted imaging and positron emission tomography. Human neuroimaging studies in healthy and clinical populations largely confirm the animal literature indicating that the PAG is involved in homeostatic regulation of salient functions such as pain, anxiety and autonomic function. Methodological concerns in the current literature, including resolution constraints, imaging artifacts and imprecise neuroanatomical labeling are discussed, and future directions are proposed. A general conclusion is that PAG neuroimaging is a field with enormous potential to translate animal data onto human behaviors, but with some growing pains that can and need to be addressed in order to add to our understanding of the neurobiology of this key region.

Biological markers of the effects of intravenous methylphenidate on improving inhibitory control in cocaine-dependent patients

Prior research points to the importance of psychostimulants in improving self-control. However, the neural substrates underlying such improvement remain unclear. Here, in a pharmacological functional MRI study of the stop signal task, we show that methylphenidate (as compared with placebo) robustly decreased stop signal reaction time (SSRT), an index of improved control, in cocaine-dependent patients (a population in which inhibitory control is impaired). Methylphenidate-induced decreases in SSRT were positively correlated with inhibition-related activation of left middle frontal cortex (MFC) and negatively with activation of the ventromedial prefrontal cortex (vmPFC) in whole brain linear regressions. Inhibition-related MFC but not vmPFC activation distinguished individuals with short and long SSRT in 36 demographically matched healthy individuals, whereas vmPFC but not MFC activation, along with improvement in SSRT, was correlated with a previously implicated biomarker of methylphenidate response (systolic blood pressure). These results implicate a specific neural (i.e., vmPFC) mechanism whereby stimulants improve inhibitory control. Altered ventromedial prefrontal activation and increased blood pressure may represent useful CNS and peripheral biomarkers in individualized treatment with methylphenidate for patients with cocaine dependence.

Assessing human 5-HT function in vivo with pharmacoMRI

A number of novel ways of using magnetic resonance imaging (MRI) to visualise the action of drugs on animal and human brain (pharmacoMRI or phMRI) are becoming established tools in translational psychopharmacology. Using drugs with known pharmacology it is possible to investigate how neurotransmitter systems are involved in neural systems engaged by other processes, such as cognitive challenge (modulation phMRI) or to examine the acute effects of the drug itself in the brain (challenge phMRI). In this article we discuss the principles behind phMRI and review studies investigating the effect of serotonin (5-HT) manipulations. 5-HT modulation phMRI studies show the involvement of 5-HT in a broad range of neural processes ranging from motor function through 'cold' cognition, such as memory and response inhibition, to emotional processing. We highlight findings in brain areas that show some consistency or complementarity across studies, such as the ventrolateral orbitofrontal cortex where modulation by 5-HT is task-specific, and the amygdala in emotional processing where 5-HT is predominantly inhibitory. 5-HT challenge phMRI is promising but as yet few studies have been carried out. New ways of analysing phMRI data include connectivity analysis which holds the promise of going beyond identifying isolated areas of activation/modulation to understanding functional circuits and their neurochemistry. 5-HT phMRI now needs to be taken into patient populations and methods of investigating treatment effects need to be developed. If this is successful then phMRI will provide a genuinely exciting opportunity for the rapid development of better treatments for psychiatric conditions.

Cerebrovascular support for cognitive processing in hypertensive patients is altered by blood pressure treatment

Hypertension is associated with mild decrements in cognition. In addition, regional cerebral blood flow responses during memory processing are blunted in parietal and thalamic areas among untreated hypertensive adults, who, compared with normotensive subjects, manifest greater correlation in blood flow response across task-related brain regions. Here, we test whether pharmacological treatment of hypertension normalizes regional cerebral blood flow responses and whether it does so differentially according to drug class. Treatment with lisinopril, an angiotensin-converting enzyme blocker, known to enhance vasodilative responsivity, was compared with treatment with atenolol, a beta-blocker. Untreated hypertensive volunteers (n=28) were randomly assigned and treated for 1 year. Whole brain and regional cerebral flow responses to memory processing and acutely administered acetazolamide, a vasodilator, were assessed pretreatment and posttreatment. Peripheral brachial artery dilation during reactive hyperemia was also measured. Quantitative blood flow measures showed no difference in the magnitude of regional cerebral blood flow responses pretreatment and posttreatment to either memory tasks or acetazolamide injection. Brachial artery flow-mediated dilation increased with treatment. No differences between medications were observed. In brain regions active in memory processing, however, regional cerebral blood flow responses were more highly correlated after treatment. Specificity of cerebral blood flow to different regions appears to decline with treatment of hypertension. This greater correlation among active brain regions, which is present as well in untreated hypertensive relative to normotensive volunteers, may represent compensation in the face of less region-specific responsivity in individuals with hypertension.

Expectation modulates human brain responses to acute cocaine: a functional magnetic resonance imaging study

BACKGROUND

Human expectation of psychoactive drugs significantly alters drug effects and behavioral responses. However, their neurophysiological mechanisms are not clear. This study investigates how cocaine expectation modulates human brain responses to acute cocaine administration.

METHODS

Twenty-six right-handed non-treatment-seeking regular cocaine abusers participated in this study. Changes in blood oxygenation level-dependent (BOLD) signals were measured, and online behavioral ratings during cocaine expectation and acute cocaine administration were recorded.

RESULTS

Distinct regional characteristics in BOLD responses to expected and unexpected cocaine infusions were observed in the medial orbitofrontal gyrus (Brodmann area [BA] 11), frontal pole (BA 10), and anterior cingulate gyrus regions. Active engagement in the amygdala and the lateral orbitofrontal cortex (OFC; BA 47) by unexpected but not expected cocaine infusion was discovered. Cocaine expectation did not change BOLD responses to acute cocaine administration in a set of subcortical substrates, the nucleus accumbens, ventral putamen, ventral tegmental area, and thalamus.

CONCLUSIONS

These results suggest that cocaine expectation modulates neural-sensitivity adaptation between the expected events and the actual outcomes but did not modulate the pharmacological characteristics of cocaine. In addition, the amygdala-lateral OFC circuitry plays an important role in mediating stimulus-outcome relations and contextual factors of drug abuse.