Electrophysiology, behavioral, and neuroimaging studies have revealed sex-related differences in autonomic cardiac control, as reflected in measurements of heart rate variability (HRV). Imaging ...studies indicate that the neurobiological correlates of autonomic nervous system (ANS) function can be investigated by measuring indices of HRV during the performance of mildly strenuous motor tasks or mildly stressful cognitive tasks. In this preliminary study, fifteen male and seven female healthy subjects underwent H
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15O-positron emission tomography (PET) and electrocardiograph (ECG) recording while performing a handgrip motor task and an n-back task. Indices of HRV were calculated and correlated with regional cerebral blood flow (rCBF). We hypothesized that sex differences would be evident in brain regions known to participate in autonomic regulation: the anterior insula, the anterior cingulate cortex, the orbitofrontal cortex, and the amygdala. Our study found that associations between rCBF and parasympathetic indices differed significantly between female and male subjects in the amygdala. Females showed a positive correlation between rCBF and parasympathetic indices while males exhibited negative correlations. This differential correlation of amygdala rCBF and parasympathetic activity between males and females may reflect differences in parasympathetic/sympathetic balance between sexes, consistent with known sexual dimorphism in the amygdala and closely related structures such as the hypothalamus. These preliminary imaging results are consistent with earlier reports of significant correlation between brain activity and HRV, and extend these findings by demonstrating prominent sex differences in the neural control of the ANS. While the generalizability of our results was limited by the small size of the study samples, the relatively robust effect size of the differences found between groups encourages further work in larger samples to characterize sex differences in the neural correlates of autonomic arousal.
► Autonomic responses to stressful tasks differ between males and females. ► Females show more parasympathetic withdrawal during task performance. ► The relationship between blood flow and autonomic response differs between genders. ► The differences in this relationship are evident in the amygdala and insula.
Hippocampal volumes obtained from a group of medication-free, remitted subjects with recurrent major depressive disorder (MDD) were compared against corresponding measures from healthy controls.
...Thirty-one subjects with recurrent MDD in full remission, and 57 healthy controls underwent high resolution magnetic resonance imaging (MRI) on a GE 3T scanner. Eight patients with MDD were medication-naive, and twenty-three MDD patients were off antidepressant medications for a mean of 30 months at the time of the MRI study.
Patients showed smaller total and posterior hippocampal volume relative to controls. Anterior hippocampal volume did not differ between patients and controls.
Recurrent depression is associated with smaller hippocampal volume which is most prominent in the posterior hippocampus. Smaller hippocampal volume appears to be a trait characteristic for MDD.
Recent animal models suggest that disturbances in serotonin type-1A receptor (5-HT(1A)R) function may contribute to chronic anxiety, although it is not clear at all whether such models constitute ...relevant models for panic disorder (PD) in humans. The selective 5-HT(1A)R radioligand 18Ftrans-4-fluoro-N-2-4-(2-methoxyphenyl)piperazin-1-ylethyl-N-(2-pyridyl)cyclohexanecarboxamide (FCWAY) permits in vivo assessment of central 5-HT(1A)R binding using positron emission tomography (PET). We studied 16 unmedicated symptomatic outpatients with PD and 15 matched healthy controls. Seven patients had an additional diagnosis of a current major depressive episode, however PD was the primary diagnosis. A 120 min PET study of 5-HT(1A)R binding was acquired using a GE Advance scanner in three-dimensional mode. Using quantitative PET image analysis, regional values were obtained for 18F-FCWAY volume of distribution (DV), corrected for plasma protein binding, and K1, the delivery rate of 18F-FCWAY from plasma to tissue. MRI scanning was performed using a GE Signa Scanner (3.0 Tesla) to provide an anatomical framework for image analysis and partial volume correction of PET data. PD patients showed lower DV in the anterior cingulate (t = 4.3; p < 0.001), posterior cingulate (t = 4.1; p < 0.001), and raphe (t = 3.1; p = 0.004). Comparing patients with PD, patients with PD and comorbid depression, and healthy controls revealed that DVs did not differ between PD patients and PD patients with comorbid depression, whereas both patient groups differed significantly from controls. These results provide for the first time in vivo evidence for the involvement of 5-HT(1A)Rs in the pathophysiology of PD.
Abstract
The NIMH Healthy Research Volunteer Dataset is a collection of phenotypic data characterizing healthy research volunteers using clinical assessments such as assays of blood and urine, mental ...health assessments, diagnostic and dimensional measures of mental health, cognitive and neuropsychological functioning, structural and functional magnetic resonance imaging (MRI), along with diffusion tensor imaging (DTI), and a comprehensive magnetoencephalography battery (MEG). In addition, blood samples of healthy volunteers are banked for future analyses. All data collected in this protocol are broadly shared in the OpenNeuro repository, in the Brain Imaging Data Structure (BIDS) format. In addition, task paradigms and basic pre-processing scripts are shared on GitHub. There are currently few open access MEG datasets, and multimodal neuroimaging datasets are even more rare. Due to its depth of characterization of a healthy population in terms of brain health, this dataset may contribute to a wide array of secondary investigations of non-clinical and clinical research questions.
Objective
A critical need exists to identify objective markers of suicide ideation. One potential suicide risk marker is the Suicide Implicit Association Task (S‐IAT), a behavioral task that uses ...differential reaction times to compare the implicit association between the self and death to the implicit association between the self and life. Individuals with a stronger association between the self and death on the S‐IAT are more likely to attempt suicide in the future. To better understand the neural underpinnings of the implicit association between self and either life or death, a functional magnetic resonance imaging (fMRI) version of the S‐IAT was adapted and piloted in healthy volunteers.
Method
An fMRI version of the S‐IAT was administered to 28 healthy volunteers (ages 18–65, 14F/14M).
Results
Behavioral results were comparable to those seen in non‐scanner versions of the task. The task was associated with patterns of neural activation in areas relevant to emotional processing, specifically the insula and right ventrolateral prefrontal cortex.
Conclusions
Performance on the S‐IAT fMRI task may reflect scores obtained outside of the scanner. In future evaluations, this task could help assess whether individuals at increased risk of suicide display a different pattern of neural activation in response to self/death and self/life stimuli.
To ascertain the mechanisms of neuropsychiatric illnesses and their treatment, accurate and reliable imaging techniques are required; proton magnetic resonance spectroscopy ((1) H-MRS) can ...noninvasively measure glutamatergic function. Evidence suggests that aberrant glutamatergic signaling plays a role in numerous psychopathologies. Until recently, overlapping glutamatergic signals (glutamate, glutamine, and glutathione) could not easily be separated. However, the advent of novel pulse sequences and higher field magnetic resonance imaging (MRI) allows more precise resolution of overlapping glutamatergic signals, although the question of signal reliability remains undetermined.
At 7T MR, we acquired (1) H-MRS data from the medial pregenual anterior cingulate cortex of healthy volunteers (n = 26) twice on two separate days. An adapted echo time optimized point-resolved spectroscopy sequence, modified with the addition of a J-suppression pulse to attenuate N-acetyl-aspartate multiplet signals at 2.49 ppm, was used to excite and acquire the spectra. In-house software was used to model glutamate, glutamine, and glutathione, among other metabolites, referenced to creatine. Intraclass correlation coefficients (ICCs) were computed for within- and between-session measurements.
Within-session measurements of glutamate, glutamine, and glutathione were on average reliable (ICCs ≥0.7). As anticipated, ICCs for between-session values of glutamate, glutamine, and glutathione were slightly lower but nevertheless reliable (ICC >0.62). A negative correlation was observed between glutathione concentration and age (r(24) = -0.37; P < 0.05), and a gender effect was noted on glutamine and glutathione.
The adapted sequence provides good reliability to measure glutamate, glutamine, and glutathione signals.
Significant controversy has emerged concerning pediatric anxiety disorders. Some researchers question the justification for diagnosing and treating pediatric anxiety disorders, owing to concerns ...about the inappropriate medicalization of social problems. Others note the importance of diagnosis and treatment, given that pediatric anxiety disorders represent a strong risk factor for serious adult mental disorders. We examine the neural correlates of pediatric anxiety disorders, to consider the validity of the categorization scheme used in recent treatment studies.
Using inclusion criteria derived from recent treatment trials, we compared gray matter volume throughout the brain in children with and without anxiety. Morphometric analyses used optimized voxel-based morphometry, an automated method for examining structural changes throughout the brain.
Reductions in left amygdala gray matter volume were noted for patients with anxiety disorders relative to comparison subjects.
We discuss implications of these findings for current controversies.
Anhedonia—defined as loss of interest or pleasure—is one of two core symptoms of major depressive disorder (MDD). Anhedonia may involve decreased enjoyment of potentially rewarding activities and ...decreased motivation to engage in such activities. Increased engagement with reinforcers—activities with the potential to be positive experiences—is a frequent target of cognitive-behavioral therapies. Nevertheless, how environmental reinforcers are perceived, and how decisions to approach or avoid them are made by individuals with MDD, is largely unknown. We developed an experimental Behavioral Approach Motivation Paradigm to study how activities are evaluated and approached in MDD. Twenty-one MDD participants and 23 healthy controls performed an experimental task that rated activity words for their hedonic value, then engaged in an approach-avoidance joystick task with each individual's unique set of ‘liked’ and ‘disliked’ activity words. A negative correlation was observed between anhedonia and the number of ‘liked’ activities across participants. No significant difference between approach and avoidance behavior was found in direct comparisons between healthy controls and MDD participants; however, weaker avoidance and greater approach toward ‘disliked’ activities was found in MDD participants. This suggests negative bias in selecting environmental opportunities, potentially further compromising access to hedonic experiences in MDD.
•Depressed individuals rated fewer activities as ‘liked’ than healthy controls.•Depressed individuals showed a negative bias in their approach behavior.•Anhedonia may involve altered approach and avoidance patterns toward reinforcers.•A larger range of reinforcement opportunities is a valid therapeutic target.•Individual patterns of approach and avoidance are potentially important in MDD.
Abstract Background Shank3, a post-synaptic density protein involved in N-methyl- d -aspartate (NMDA) receptor tethering and dendritic spine rearrangement, is implicated in the pathophysiology of ...bipolar disorder. We hypothesized that elevated baseline plasma Shank3 levels might predict antidepressant response to the NMDA receptor antagonist ketamine. Methods Twenty-nine subjects with bipolar depression received a double-blind, randomized, subanesthetic dose (.5 mg/kg) ketamine infusion. Of the patients for whom Shank3 levels were collected, 15 completed baseline 3-Tesla MRI and 17 completed post-ketamine 18 F-FDG PET. Results Higher baseline Shank3 levels predicted antidepressant response at Days 1 ( r =−.39, p =.047), 2 ( r =−.45, p =.02), and 3 ( r =−.42, p =.03) and were associated with larger average ( r =.58, p =.02) and right amygdala volume ( r =.65, p =.009). Greater baseline Shank3 also predicted increased glucose metabolism in the hippocampus ( r =.51, p =.04) and amygdala ( r =.58, p =.02). Limitations Limitations include the small sample size, inability to assess the source of peripheral Shank3, and the lack of a placebo group for baseline Shank3 levels and comparative structural/functional neuroimaging. Conclusions Shank3 is a potential biomarker of antidepressant response to ketamine that correlates with baseline amygdala volume and increased glucose metabolism in the amygdala and hippocampus.
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