Altered interregional molecular associations of the serotonin transporter in attention deficit/hyperactivity disorder assessed with PET

Altered serotonergic neurotransmission has been found to cause impulsive and aggressive behavior, as well as increased motor activity, all exemplifying key symptoms of ADHD. The main objectives of this positron emission tomography (PET) study were to investigate the serotonin transporter binding potential (SERT BP_ND) in patients with ADHD and to assess associations of SERT BP_ND between the brain regions. 25 medication‐free patients with ADHD (age ± SD; 32.39 ± 10.15; 10 females) without any psychiatric comorbidity and 25 age and sex matched healthy control subjects (33.74 ± 10.20) were measured once with PET and the highly selective and specific radioligand [¹¹C]DASB. SERT BP_ND maps in nine a priori defined ROIs exhibiting high SERT binding were compared between groups by means of a linear mixed model. Finally, adopted from structural and functional connectivity analyses, we performed correlational analyses using regional SERT binding potentials to examine molecular interregional associations between all selected ROIs. We observed significant differences in the interregional correlations between the precuneus and the hippocampus in patients with ADHD compared to healthy controls, using SERT BP_ND of the investigated ROIs (P < 0.05; Bonferroni corrected). When correlating SERT BP_ND and age in the ADHD and the healthy control group, we confirmed an age‐related decline in brain SERT binding in the thalamus and insula (R² = 0.284, R² = 0.167, Ps < 0.05; Bonferroni corrected). The results show significantly different interregional molecular associations of the SERT expression for the precuneus with hippocampus in patients with ADHD, indicating presumably altered functional coupling. Altered interregional coupling between brain regions might be a sensitive approach to demonstrate functional and molecular alterations in psychiatric conditions. Hum Brain Mapp 38:792–802, 2017. © 2016 Wiley Periodicals, Inc.     

MEG biomarker of Alzheimer's disease: Absence of a prefrontal generator during auditory sensory gating

Magnetoencephalography (MEG), a direct measure of neuronal activity, is an underexplored tool in the search for biomarkers of Alzheimer's disease (AD). In this study, we used MEG source estimates of auditory gating generators, nonlinear correlations with neuropsychological results, and multivariate analyses to examine the sensitivity and specificity of gating topology modulation to detect AD. Our results demonstrated the use of MEG localization of a medial prefrontal (mPFC) gating generator as a discrete (binary) detector of AD at the individual level and resulted in recategorizing the participant categories in: (1) controls with mPFC generator localized in response to both the standard and deviant tones; (2) a possible preclinical stage of AD participants (a lower functioning group of controls) in which mPFC activation was localized to the deviant tone only; and (3) symptomatic AD in which mPFC activation was not localized to either the deviant or standard tones. This approach showed a large effect size (0.9) and high accuracy, sensitivity, and specificity (100%) in identifying symptomatic AD patients within a limited research sample. The present results demonstrate high potential of mPFC activation as a noninvasive biomarker of AD pathology during putative preclinical and clinical stages. Hum Brain Mapp 38:5180–5194, 2017. © 2017 Wiley Periodicals, Inc.     

Comparison of cerebral activation between motor execution and motor imagery of self-feeding activity

Motor imagery is defined as an act wherein an individual contemplates a mental action of motor execution without apparent action. Mental practice executed by repetitive motor imagery can improve motor performance without simultaneous sensory input or overt output. We aimed to investigate cerebral hemodynamics during motor imagery and motor execution of a self-feeding activity using chopsticks. This study included 21 healthy right-handed volunteers. The self-feeding activity task comprised either motor imagery or motor execution of eating sliced cucumber pickles with chopsticks to examine eight regions of interest: pre-supplementary motor area, supplementary motor area, bilateral prefrontal cortex, premotor area, and sensorimotor cortex. The mean oxyhemoglobin levels were detected using near-infrared spectroscopy to reflect cerebral activation. The mean oxyhemoglobin levels during motor execution were significantly higher in the left sensorimotor cortex than in the supplementary motor area and the left premotor area. Moreover, significantly higher oxyhemoglobin levels were detected in the supplementary motor area and the left premotor area during motor imagery, compared to motor execution. Supplementary motor area and premotor area had important roles in the motor imagery of self-feeding activity. Moreover, the activation levels of the supplementary motor area and the premotor area during motor execution and motor imagery are likely affected by intentional cognitive processes. Levels of cerebral activation differed in some areas during motor execution and motor imagery of a self-feeding activity. This study was approved by the Ethical Review Committee of Nagasaki University(approval No. 18110801) on December 10, 2018.     

Hippocampus-specific fMRI group activation analysis using the continuous medial representation

We present a new shape-based approach for regional group activation analysis in fMRI studies. The method restricts anatomical normalization, spatial smoothing and random effects statistical analysis to the space inside and around a structure of interest. Normalization involves finding intersubject correspondences between manually outlined masks, and it leverages the continuous medial representation, which makes it possible to extend surface-based shape correspondences to the space inside and outside of structures. Our approach is an alternative to whole-brain normalization in cases where the latter may fail due to anatomical variability or pathology. It also provides an opportunity to analyze the shape and thickness of structures concurrently with functional activation. We apply the technique to the hippocampus and evaluate it using data from a visual scene encoding fMRI study, where activation in the hippocampus is expected. We produce detailed statistical maps of hippocampal activation, as well as maps comparing activation inside and outside of the hippocampus. We find that random effects statistics computed by the new approach are more significant than those produced using the Statistical Parametric Mapping framework (Friston, K.J., Holmes, A.P., Worsley, K.J., Poline, J.-P., Firth, C.D., Frackowiak, R.S.J. 1994, Statistical parametric maps in functional imaging: a general linear approach. Human Brain Mapping, 2(4): 189-210) at low levels of smoothing, suggesting that greater specificity can be achieved by the new method without a severe tradeoff in sensitivity.     

Tumor-to-tumor metastasis: pathology and neuroimaging considerations

The phenomenon of tumor-to-tumor metastasis has been reported in the literature for over a century. However, it remains fairly uncommon, with fewer than 100 cases being described during that time. Virtually any benign or malignant tumor can be a recipient, but meningiomas have been implicated as the most common intracranial neoplasm to harbor metastasis. The donor neoplasm is most frequently lung or breast carcinoma, while rare cases of metastasis from other primary tumors have been reported. We report here three examples of such rare metastases. This case series reports the first documented instance involving rectal adenocarcinoma. In addition, we report two cases of metastatic prostate adenocarcinoma to a meningioma; to date of which only three cases have been published. The terms "tumor-to-tumor metastasis" and "collision tumor" are addressed, as are details of the pathology. The limitations of standard radiological imaging techniques, such as standard CT and MR, which cannot reliably identify the presence of metastasis within a meningioma are compared with physiology-based neuroimaging methods, such as perfusion MR and MR spectroscopy, which may be more useful in noninvasively differentiating tumor histology.     

There and up again: On the uses and misuses of neuroimaging in psychology

The aim of this article is to discuss the conditions under which functional neuroimaging can contribute to the study of higher cognition. We begin by presenting two case studies—on moral and economic decision making—which will help us identify and examine one of the main ways in which neuroimaging can help advance the study of higher cognition. We agree with critics that functional magnetic resonance imaging (fMRI) studies seldom “refine” or “confirm” particular psychological hypotheses, or even provide details of the neural implementation of cognitive functions. However, we suggest that neuroimaging can support psychology in a different way—namely, by selecting among competing hypotheses of the cognitive mechanisms underlying some mental function. One of the main ways in which neuroimaging can be used for hypothesis selection is via reverse inferences, which we here examine in detail. Despite frequent claims to the contrary, we argue that successful reverse inferences do not assume any strong or objectionable form of reductionism or functional locationism. Moreover, our discussion illustrates that reverse inferences can be successful at early stages of psychological theorizing, when models of the cognitive mechanisms are only partially developed.     

基于MRN技术的下腰椎Kambin三角的解剖学研究

目的 测量分析正常成人下腰椎Kambin三角工作区磁共振神经显像（magnetic resonance neurography,MRN）的相关解剖数据,为下腰椎微创手术的选择和安全性评估提供参考。 方法 采用3.0 T磁共振对20名健康成年志愿者（男10例,女10例）进行腰椎L4~S1节段的MRN扫描,通过Osirix软件对图像进行神经成像并测量以下数据：神经节与上位椎弓根间距（A）、神经节与下位椎弓根间距（B）、神经根与硬膜囊夹角（α）、Kambin三角的面积（S）,并对所测数据进行统计学分析。 结果 自L4~S1,同侧神经节与上位椎弓根的距离逐渐减小（P<0.05）,而同侧神经节与下位椎弓根的距离无统计学差异（P>0.05）;自L4~S1,同侧出口神经根与硬膜囊夹角逐渐变小,差异有统计学意义（P<0.05）;自L4~S1,Kambin三角面积逐渐增大（P<0.05）;此外,所有测量指标同节段左右两侧对比无统计学差异（P>0.05）。 结论 MRN技术对下腰椎Kambin三角各组成结构的解剖关系显像清晰准确,便于相关解剖测量并指导临床腰椎微创手术方法的选择和手术安全性的评估。     

Depressive symptoms in adolescents: associations with white matter volume and marijuana use

BACKGROUND: Depressed mood has been associated with decreased white matter and reduced hippocampal volumes. However, the relationship between brain structure and mood may be unique among adolescents who use marijuana heavily. The goal of this study was to examine the relationship between white matter and hippocampal volumes and depressive symptoms among adolescent marijuana users and controls. METHODS: Data were collected from marijuana users (n = 16) and demographically similar controls (n = 16) aged 16-18. Extensive exclusionary criteria included psychiatric and neurologic disorders, including major depression. Substance use, mood, and anatomical measures were collected after 28 days of monitored abstinence. RESULTS: Marijuana (MJ) users demonstrated more depressive symptoms than controls (p < .05). MJ use (beta = .42, p < .005) and smaller white matter volume (beta = -.34, p < .03) each predicted higher levels of depressive symptoms on the Hamilton Depression Rating Scale. MJ use interacted with white matter volume (beta = -.55, p < .03) in predicting depression scores on the Beck Depression Inventory: among MJ users, but not controls, white matter volume was negatively associated with depressive symptoms. CONCLUSIONS: Marijuana use and white matter volume were additive and interactive in predicting depressive symptoms among adolescents. Subtle neurodevelopmental white matter abnormalities may disrupt the connections between areas involved in mood regulation.     

内隐记忆的研究证据及临床意义

内隐记忆 (ｉｍｐｌｉｃｉｔｍｅｍｏｒｙ)一词最初由Ｇｒａｆ与Ｓｃｈａｃｔｅｒ于 1985年提出 ,指对特定的过去经验进行有意识或外显的回忆测验中表现出来的对先前获得信息的无意识提取 ,也就是说 ,在有意或无意间获得的信息、技能或习惯 ,虽不能有意识地回忆和再认 ,但会影响类似作业的成效和行为的有效性。这一概念的提出扩大了记忆研究的内涵 ,因此迅速成为记忆研究的热点之一。目前内隐记忆的研究在测量方法与理论解释方面都取得了一些进展 ,大量证据表明它与外显记忆存在质的不同 ,是一个相对独立的记忆系统。不过现存的问题也很多 ,…