Amygdala structure and core dimensions of the affective personality

Neuro-Navigated rTMS Improves Sleep and Cognitive Impairment via Regulating Sleep-Related Networks' Spontaneous Activity in AD Spectrum Patients

Study Objectives

By examining spontaneous activity changes of sleep-related networks in patients with the Alzheimer's disease (AD) spectrum with or without insomnia disorder (ID) over time via neuro-navigated repetitive transcranial magnetic stimulation (rTMS), we revealed the effect and mechanism of rTMS targeting the left-angular gyrus in improving the comorbidity symptoms of the AD spectrum with ID.

Methods

A total of 34 AD spectrum patients were recruited in this study, including 18 patients with ID and the remaining 16 patients without ID. All of them were measured for cognitive function and sleep by using the cognitive and sleep subscales of the neuropsychiatric inventory. The amplitude of low-frequency fluctuation changes in sleep-related networks was revealed before and after neuro-navigated rTMS treatment between these two groups, and the behavioral significance was further explored.

Results

Affective auditory processing and sensory-motor collaborative sleep-related networks with hypo-spontaneous activity were observed at baseline in the AD spectrum with ID group, while substantial increases in activity were evident at follow-up in these subjects. In addition, longitudinal affective auditory processing, sensory-motor and default mode collaborative sleep-related networks with hyper-spontaneous activity were also revealed at follow-up in the AD spectrum with ID group. In particular, longitudinal changes in sleep-related networks were associated with improvements in sleep quality and episodic memory scores in AD spectrum with ID patients.

Conclusion

We speculated that left angular gyrus-navigated rTMS therapy may enhance the memory function of AD spectrum patients by regulating the spontaneous activity of sleep-related networks, and it was associated with memory consolidation in the hippocampus-cortical circuit during sleep.

Clinical Trial Registration

The study was registered at the Chinese Clinical Trial Registry, registration ID: ChiCTR2100050496, China.

Vasoactive intestinal polypeptide plasma levels associated with affective symptoms and brain structure and function in healthy females

Vasoactive intestinal polypeptide (VIP) is a neuroendocrine peptide distributed throughout the human body, including the CNS, where it is particularly abundant in brain regions associated with anxiety and depression. Based on earlier studies indicating that peripheral VIP may cross through the blood–brain barrier, we hypothesized plasma VIP levels to be associated with symptoms of anxiety and depression, as well as brain volume and resting-state functional connectivity in the amygdala, hippocampus, parahippocampus, and orbitofrontal cortex. Plasma VIP concentrations and anxiety/depression symptoms were measured in 37 healthy females. Functional and structural magnetic resonance imaging were used to evaluate functional connectivity and brain volume respectively, and their associations with VIP concentrations within brain regions associated with anxiety and depression. Negative correlations were found between VIP levels and symptoms of anxiety (r = − 0.44, p = 0.002) and depression (r = − 0.50, p = 0.001). Functional connectivity demonstrated significant VIP-dependent positive associations between the amygdala seed region with both the right parahippocampus (t₍₃₃₎ = 3.1, p_FDR = 0.02) and right lateral orbitofrontal cortex (OFC; t₍₃₃₎ = 2.9, p_FDR = 0.02). Moreover, VIP concentrations were significantly, positively correlated with brain volume in the left amygdala (r = 0.28, p = 0.007) and left lateral OFC (r = 0.29, p = 0.004). The present findings highlight a potential role for VIP in the neurobiology of affective symptoms.

Newborn left amygdala volume associates with attention disengagement from fearful faces at eight months

After 5 months of age, infants begin to prioritize attention to fearful over other facial expressions. One key proposition is that amygdala and related early-maturing subcortical network, is important for emergence of this attentional bias - however, empirical data to support these assertions are lacking. In this prospective longitudinal study, we measured amygdala volumes from MR images in 65 healthy neonates at 2-5 weeks of gestation corrected age and attention disengagement from fearful vs. non-fearful facial expressions at 8 months with eye tracking. Overall, infants were less likely to disengage from fearful than happy/neutral faces, demonstrating an age-typical bias for fear. Left, but not right, amygdala volume (corrected for intracranial volume) was positively associated with the likelihood of disengaging attention from fearful faces to a salient lateral distractor (r = .302, p = .014). No association was observed with the disengagement from neutral or happy faces in equivalent conditions (r = .166 and .125, p = .186 and .320, respectively). These results are the first to link the amygdala volume with the emerging perceptual vigilance for fearful faces during infancy. They suggest a link from the prenatally defined variability in the amygdala size to early postnatal emotional and social traits.

Marijuana and the hippocampus: A longitudinal study on the effects of marijuana on hippocampal subfields

The psychoactive effects of cannabis, one of the most commonly used narcotics, have been documented extensively. Despite multiple studies being undertaken, there have been only a few longitudinal studies investigating the effect of long term usage of cannabis on various subcortical structures. This study aims at looking deeper into the effects of long term usage of cannabis on different hippocampus subfields.² Participants were split into two groups, cannabis users and healthy controls. All the test subjects filled out the Cannabis Usage and Disorder Identification Test (CUDIT) and underwent T1-structural MRI scans twice, at a baseline and a followup 3 years later. The subfield volumes were measured using the software package Freesurfer with the LongitudinalHippocampalSubfields (v6.0) Module. Lifetime usage in grams was calculated for each participant until baseline and followup, independently, using linear interpolation. Usage of cannabis (lifetime consumption score) was correlated to increased volumes in certain subfields: the CA3 and CA4 in the right hemisphere and the presubiculum in both, the left and right hemispheres at baseline. Other tests including student's t-test and multivariate analysis of covariance were performed. Tests to understand the effects of varying consumption were also performed. Persistent usage of cannabis, however, did not result in atrophy of the subfields over time. Rather, there were lower growth rates observed in the healthy controls group as compared to that of the cannabis users in certain subfields.

Neurocircuitry of impaired affective sound processing: A clinical disorders perspective

Decoding affective meaning from sensory information is central to accurate and adaptive behavior in many natural and social contexts. Human vocalizations (speech and non-speech), environmental sounds (e.g. thunder, noise, or animal sounds) and human-produced sounds (e.g. technical sounds or music) can carry a wealth of important aversive, threatening, appealing, or pleasurable affective information that sometimes implicitly influences and guides our behavior. A deficit in processing such affective information is detrimental to adaptive environmental behavior, psychological well-being, and social interactive abilities. These deficits can originate from a diversity of psychiatric and neurological disorders, and are associated with neural dysfunctions across largely distributed brain networks. Recent neuroimaging studies in psychiatric and neurological patients outline the cortical and subcortical neurocircuitry of the complimentary and differential functional roles for affective sound processing. This points to and confirms a recently proposed distributed network rather than a single brain region underlying affective sound processing, and highlights the notion of a multi-functional process that can be differentially impaired in clinical disorders.