Regional Cerebral Blood Flow Abnormalities in Neurosyphilis: A Pilot SPECT Study

Objective: Clinical and radiological findings on neurosyphilis are fairly non-specific and there is a paucity of functional neuroimaging studies on neurosyphilis other than case reports and case series. The purpose of this study was to investigate brain perfusion abnormalities in patients with neurosyphilis. Methods: Four HIV-negative neurosyphilis patients and 4 healthy controls underwent clinical evaluation, brain technetium-99m ethyl cysteinate dimer (99mTc-ECD) single-photon emission computed tomography (SPECT) imaging, and neuropsychological assessments which included the Mini-Mental State Examination (MMSE), Clinical Dementia Rating (CDR), Clinical Dementia Rating-Sum of Boxes (CDR-SOB), and Global Deterioration Scale (GDS). Voxel-wise differences in regional cerebral blood flow were compared between the two groups. Results: Neuropsychological test results indicated cognitive impairment in all patients. SPECT analysis revealed multifocal hypoperfusion predominantly in the frontal, insular, and posterior cingulate regions in neurosyphilis patients compared with healthy controls (family-wise error corrected p < 0.05). Conclusions: Together with previous findings, our results suggest that the hypoperfusion in the frontal, insular, and posterior cingulate regions may reflect cognitive impairments observed in neurosyphilis patients. Further studies with larger samples are needed to confirm our findings.

Astrocytic water channel aquaporin-4 modulates brain plasticity in both mice and humans: a potential gliogenetic mechanism underlying language-associated learning

The role of astrocytes in brain plasticity has not been extensively studied compared with that of neurons. Here we adopted integrative translational and reverse-translational approaches to explore the role of an astrocyte-specific major water channel in the brain, aquaporin-4 (AQP4), in brain plasticity and learning. We initially identified the most prevalent genetic variant of AQP4 (single nucleotide polymorphism of rs162008 with C or T variation, which has a minor allele frequency of 0.21) from a human database (n=60 706) and examined its functionality in modulating the expression level of AQP4 in an in vitro luciferase reporter assay. In the following experiments, AQP4 knock-down in mice not only impaired hippocampal volumetric plasticity after exposure to enriched environment but also caused loss of long-term potentiation after theta-burst stimulation. In humans, there was a cross-sectional association of rs162008 with gray matter (GM) volume variation in cortices, including the vicinity of the Perisylvian heteromodal language area (Sample 1, n=650). GM volume variation in these brain regions was positively associated with the semantic verbal fluency. In a prospective follow-up study (Sample 2, n=45), the effects of an intensive 5-week foreign language (English) learning experience on regional GM volume increase were modulated by this AQP4 variant, which was also associated with verbal learning capacity change. We then delineated in mice mechanisms that included AQP4-dependent transient astrocytic volume changes and astrocytic structural elaboration. We believe our study provides the first integrative evidence for a gliogenetic basis that involves AQP4, underlying language-associated brain plasticity.

Superficial Siderosis of the Central Nervous System due to Spinal Ependymoma

A 75-year-old woman presented with a 3-year history of progressive hearing loss, gait ataxia, and cognitive impairment. Brain magnetic resonance imaging (MRI) with a time gradient echo sequence showed deposition of hemosiderin along the surface of the cerebral cortex, brainstem, and cerebellum, as well as severe atrophy in the diffuse cerebral cortex and cerebellum. We established the diagnosis of superficial siderosis of the central nervous system on the grounds of former pathognomonic MRI findings. The thoraco-lumbar spine MRI demonstrated a myxopapillary ependymoma in the T11-L2 spinal canal that was considered to be the cause of a chronic subarachnoid hemorrhage, affecting the leptomeninges and subpial layers of the central nervous system.

Brain structural changes in cynomolgus monkeys administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine: A longitudinal voxel-based morphometry and diffusion tensor imaging study

In animal models of Parkinson's disease (PD), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is one of the most widely used agents that damages the nigrostriatal dopaminergic pathway. However, brain structural changes in response to MPTP remain unclear. This study aimed to investigate in vivo longitudinal changes in gray matter (GM) volume and white matter (WM) microstructure in primate models administered with MPTP. In six cynomolgus monkeys, high-resolution magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) scans were acquired 7 times over 32 weeks, and assessments of motor symptoms were conducted over 15 months, before and after the MPTP injection. Changes in GM volume and WM microstructure were estimated on a voxel-by-voxel basis. Mixed-effects regression models were used to examine the trajectories of these structural changes. GM volume initially increased after the MPTP injection and gradually decreased in the striatum, midbrain, and other dopaminergic areas. The cerebellar volume temporarily decreased and returned to its baseline level. The rate of midbrain volume increase was positively correlated with the increase rate of motor symptom severity (Spearman rho = 0.93, p = 0.008). Mean, axial, and radial diffusivity in the striatum and frontal areas demonstrated initial increases and subsequent decreases. The current multi-modal imaging study of MPTP-administered monkeys revealed widespread and dynamic structural changes not only in the nigrostriatal pathway but also in other cortical, subcortical, and cerebellar areas. Our findings may suggest the need to further investigate the roles of inflammatory reactions and glial activation as potential underlying mechanisms of these structural changes.

Reliability and validity of the korean version of the lifespan sibling relationship scale

The sibling relationship and its potential impact on neurodevelopment and mental health are important areas of neuroscientific research. Validation of the tools assessing the quality of the sibling relationship would be the first essential step for conducting neurobiological and psychosocial studies related to the sibling relationship. However, to the best of our knowledge, no sibling relationship assessment tools have been empirically validated in Korean. We aimed to evaluate the psychometric properties of the Korean version of the Lifespan Sibling Relationship Scale (LSRS), which is one of the most commonly used self-report questionnaires to assess the quality of the sibling relationship. A total of 109 adults completed a series of self-report questionnaires including the LSRS, the mental health subscale of the Medical Outcomes Study-Short Form 36 version 2 (SF36v2), the Satisfaction with Life Scale (SLS), and the Marlowe-Crowne Social Desirability Scale (MC-SDS). The internal consistency, subscale intercorrelations, one-week test-retest reliability, convergent validity, divergent validity, and the construct validity were assessed. All six subscale scores and the total score of the LSRS demonstrated good internal consistency (Cronbach's α=0.85-0.94) and good test-retest reliability (intraclass correlation coefficient=0.77-0.92). Correlations of the LSRS with the SF36v2 mental health score (r=0.32, p=0.01) and with the SLS (r=0.27, p=0.04) supported the good convergent validity. The divergent validity was shown by the non-significant correlation of the LSRS with the MC-SDS (r=0.15, p=0.26). Two factors were extracted through factor analysis, which explained 78.63% of the total variance. The three Adult subscales loaded on the first factor and the three Child subscales loaded on the second factor. Results suggest that the Korean version of the LSRS is a reliable and valid tool for examining the sibling relationship.

Deficits in conditioned fear extinction in obsessive-compulsive disorder and neurobiological changes in the fear circuit

IMPORTANCE

Obsessive-compulsive disorder (OCD) may be characterized by impaired self-regulation and behavioral inhibition. Elevated fear and anxiety are common characteristics of this disorder. The neurobiology of fear regulation and consolidation of safety memories have not been examined in this patient population.

OBJECTIVE

To examine the psychophysiological and neurobiological correlates of conditioned fear extinction in patients with OCD.

DESIGN

Cross-sectional, case-control, functional magnetic resonance imaging study.

SETTING

Academic medical center.

PARTICIPANTS

Twenty-one patients with OCD and 21 healthy participants.

MAIN OUTCOMES AND MEASURES

Skin conductance responses and blood oxygenation level-dependent responses.

RESULTS

The between-group difference noted in our psychophysiological measure (skin conductance responses) was during extinction recall: patients with OCD showed impaired extinction recall relative to control subjects. Regarding the functional magnetic resonance imaging data, patients with OCD showed significantly reduced activation in the ventromedial prefrontal cortex across training phases. Moreover, reduced activation in the patients with OCD was noted in the caudate and hippocampus during fear conditioning, as well as in the cerebellum, posterior cingulate cortex, and putamen during extinction recall. Contrary to our prediction, OCD symptom severity was positively correlated with the magnitude of extinction memory recall. Also contrary to our prediction, functional responses of the ventromedial prefrontal cortex were positively correlated with symptom severity, and functional responses of the dorsal anterior cingulate cortex were inversely correlated with symptom severity.

CONCLUSIONS AND RELEVANCE

As expected, our study showed that fear extinction and its neural substrates are impaired in patients with OCD. However, this study also yielded some surprising and unexpected results regarding the correlates between extinction capacity and its neural substrates and the severity of symptoms expressed in this disorder. Thus, our data report neural correlates of deficient fear extinction in patients with OCD. The negative correlations between fear extinction deficits and Yale-Brown Obsessive-Compulsive Scale symptoms in OCD suggest that there may be other factors, in addition to fear extinction deficiency, that contribute to the psychopathology of OCD.

A new rehabilitation training system for postural balance control using virtual reality technology

A new rehabilitation training system, designated as a virtual cycling system, was developed to improve postural balance control by combining virtual reality (VR) technology with a bicycle. Several parameters including path deviation, path deviation velocity, cycling time, and head movement were extracted and evaluated to quantify the extent of control. The system was effective as a training device and, in addition, the technology might have a wider applicability to the rehabilitation field.