Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system. This paper reviews the current knowledge derived from positron emission tomography and single ...photon emission tomography studies quantifying GABA
A
receptor binding in movement disorders of extrapyramidal origin, focusing on essential tremor (ET), Parkinsonism (idiopathic PD and atypical parkinsonian syndromes), dystonia, and Huntington’s disease (HD). In ET, there is evidence to suggest a specific disturbance at the level of the GABA
A
receptor and impairment of GABAergic inhibition to be a driving force for the development of rhythmic overactivity in cerebello-thalamo-cortical networks. In dystonia, GABA
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receptor binding studies have been relevant for unraveling pathophysiological mechanisms causing sensorimotor disinhibition leading to dystonic movements. The role of GABA in idiopathic PD and atypical parkinsonian syndromes is less clear, despite the fact that GABA
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receptors are expressed on virtually all striatal neurons and that GABA exerts important inhibitory influences upon basal outflow pathways. In HD, reductions of GABA
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receptor have been reported in the basal ganglia but were found to be less extensive compared with concomitant metabolic reductions.
Premature-born infants have impaired amygdala structure, presumably due to increased stress levels of premature birth mediated by the amygdala. However, accounting for lifelong plasticity of ...amygdala, it is unclear whether such structural changes persist into adulthood. To address this problem, we stated the following questions: first, are whole amygdala volumes reduced in premature-born adults? And second, as adult anxiety traits are often increased after prematurity and linked with amygdala structure, are alterations in amygdala associated with adults' anxiety traits after premature birth? We addressed these questions by automated amygdala segmentation of MRI volumes in 101 very premature-born adults (< 32 weeks of gestation and/or birth weight below 1500 g) and 108 full-term controls at 26 years of age of a prospectively and longitudinally collected cohort. We found significantly lower whole amygdala volumes in premature-born adults. While premature-born adults had significantly higher T score for avoidant personality reflecting increased social anxiety trait, this trait was not correlated with amygdala volume alterations. Results demonstrate reduced amygdala volumes in premature born adults. Data suggest lasting effects of prematurity on amygdala structure.
OBJECTIVE:To identify biological evidence for Alzheimer disease (AD) in individuals with subjective memory impairment (SMI) and unimpaired cognitive performance and to investigate the longitudinal ...cognitive course in these subjects.
METHOD:Ffluoro-2-deoxyglucose PET (FDG-PET) and structural MRI were acquired in 31 subjects with SMI and 56 controls. Cognitive follow-up testing was performed (average follow-up time35 months). Differences in baseline brain imaging data and in memory decline were assessed between both groups. Associations of memory decline with brain imaging data were tested.
RESULTS:The SMI group showed hypometabolism in the right precuneus and hypermetabolism in the right medial temporal lobe. Gray matter volume was reduced in the right hippocampus in the SMI group. At follow-up, subjects with SMI showed a poorer performance than controls on measures of episodic memory. Longitudinal memory decline in the SMI group was associated with reduced glucose metabolism in the right precuneus at baseline.
CONCLUSION:The cross-sectional difference in 2 independent neuroimaging modalities indicates early AD pathology in SMI. The poorer memory performance at follow-up and the association of reduced longitudinal memory performance with hypometabolism in the precuneus at baseline support the concept of SMI as the earliest manifestation of AD.
GLOSSARYADAlzheimer diseaseAUCarea under the curveBDIBeck Depression InventoryCERADConsortium to Establish a Registry for Alzheimerʼs DiseaseCIconfidence intervalFDG-PET18Ffluoro-2-deoxyglucose PETFWEfamily-wise errorGMgray matterMCImild cognitive impairmentrCGMregional cerebral glucose metabolismROCreceiver operating characteristicROIregion of interestSCIDStructured Clinical Interview for DSM-IVSMIsubjective memory impairmentSVCsmall volume correctionTMTTrail-Making TestVLMTVerbal Learning and Memory TestWMwhite matter
Purpose
Magnetic resonance-guided focused ultrasound (MRgFUS) systems are increasingly used to non-invasively treat tremor; consensus on imaging follow-up is poor in these patients. This study aims ...to elucidate how MRgFUS lesions evolve for a radiological readership with regard to clinical outcome.
Methods
MRgFUS-induced lesions and oedema were retrospectively evaluated based on DWI, SWI, T2-weighted and T1-weighted 3-T MRI data acquired 30 min and 3, 30 and 180 days after MRgFUS (
n
= 9 essential tremor,
n
= 1 Parkinson’s patients). Lesions were assessed volumetrically, visually and by ADC measurements and compared with clinical effects using non-parametric testing.
Results
Thirty minutes after treatment, all lesions could be identified on T2-weighted images. Immediate oedema was rare (
n
= 1). Lesion volume as well as oedema reached a maximum on day 3 with a mean lesion size of 0.4 ± 0.2 cm
3
and an oedema volume 3.7 ± 1.2 times the lesion volume. On day 3, a distinct diffusion-restricted rim was noted that corresponded well with SWI. Lesion shrinkage after day 3 was observed in all sequences. Lesions were no longer detectable on DWI in
n
= 7/10, on T2-weighted images in
n
= 4/10 and on T1-weighted images in
n
= 4/10 on day 180. No infarcts or haemorrhage were observed. There was no correlation between lesion size and initial motor skill improvement (
p
= 0.99). Tremor reduction dynamics correlated strongly with lesion shrinkage between days 3 and 180 (
p
= 0.01,
R
= 0.76).
Conclusion
In conclusion, cerebral MRgFUS lesions variably shrink over months. SWI is the sequence of choice to identify lesions after 6 months. Lesion volume is arguably associated with intermediate-term outcome.
Abstract
The aim of this study was to investigate central pain representations during loading of the periodontium induced by orthodontic and occlusal stress. Nineteen healthy male volunteers (25.7 ± ...2.8 years) were tested on two consecutive days: after phenotyping (questionnaires) and determination of warmth (WPT) and heat (HPT) pain thresholds, functional magnetic resonance imaging was performed as event-related paradigm including 36 tooth clenchings of 3 s duration, alternating with rest periods varying between 20–30 s. The task was performed in absence (T1) and 24 h after placement of an elastic separator between the second bicuspid and the first molar on the right side of the lower jaw (T2). No significant changes in WPT and HPT were observed but pain ratings were significantly elevated at T2. Significantly elevated activation at T2, as compared to T1, was found in bilateral sensorimotor cortex, bilateral secondary sensory cortex, supplementary motor area, right rolandic operculum, and bilateral insula. Our data show for the first time in humans that periodontal stimulation, as tested by tooth clenching in the presence of an elastic separator, goes along with specific expressions of pain at behavioral and neuronal network levels. Findings supplement the existing neuroimaging literature on odontogenic pain.
•Thalamic nuclei volume is globally, not locally, lower in preterm-born adults.•These alterations are linked to the extent of stress exposure after birth.•Lateral, medial, and pulvinar nuclei volume ...aberrations are relevant for cognition.
Lasting thalamus volume reduction after preterm birth is a prominent finding. However, whether thalamic nuclei volumes are affected differentially by preterm birth and whether nuclei aberrations are relevant for cognitive functioning remains unknown.
Using T1-weighted MR-images of 83 adults born very preterm (≤ 32 weeks’ gestation; VP) and/or with very low body weight (≤ 1,500 g; VLBW) as well as of 92 full-term born (≥ 37 weeks’ gestation) controls, we compared thalamic nuclei volumes of six subregions (anterior, lateral, ventral, intralaminar, medial, and pulvinar) across groups at the age of 26 years. To characterize the functional relevance of volume aberrations, cognitive performance was assessed by full-scale intelligence quotient using the Wechsler Adult Intelligence Scale and linked to volume reductions using multiple linear regression analyses.
Thalamic volumes were significantly lower across all examined nuclei in VP/VLBW adults compared to controls, suggesting an overall rather than focal impairment. Lower nuclei volumes were linked to higher intensity of neonatal treatment, indicating vulnerability to stress exposure after birth. Furthermore, we found that single results for lateral, medial, and pulvinar nuclei volumes were associated with full-scale intelligence quotient in preterm adults, albeit not surviving correction for multiple hypotheses testing.
These findings provide evidence that lower thalamic volume in preterm adults is observable across all subregions rather than focused on single nuclei. Data suggest the same mechanisms of aberrant thalamus development across all nuclei after premature birth.
Premature birth bears an increased risk for aberrant brain development concerning its structure and function. Cortical complexity (CC) expresses the fractal dimension of the brain surface and changes ...during neurodevelopment. We hypothesized that CC is altered after premature birth and associated with long-term cognitive development.
One-hundred-and-one very premature-born adults (gestational age <32 weeks and/or birth weight <1500 g) and 111 term-born adults were assessed by structural MRI and cognitive testing at 26 years of age. CC was measured based on MRI by vertex-wise estimation of fractal dimension. Cognitive performance was measured based on Griffiths-Mental-Development-Scale (at 20 months) and Wechsler-Adult-Intelligence-Scales (at 26 years).
In premature-born adults, CC was decreased bilaterally in large lateral temporal and medial parietal clusters. Decreased CC was associated with lower gestational age and birth weight. Furthermore, decreased CC in the medial parietal cortices was linked with reduced full-scale IQ of premature-born adults and mediated the association between cognitive development at 20 months and IQ in adulthood.
Results demonstrate that CC is reduced in very premature-born adults in temporoparietal cortices, mediating the impact of prematurity on impaired cognitive development. These data indicate functionally relevant long-term alterations in the brain’s basic geometry of cortical organization in prematurity.
•MRI-derived Cortical Complexity is reduced in adults after premature birth.•Bilateral lateral temporal and medial parietal cortices are affected.•Cortical aberrations correlate with gestational age and birth weight.•Medial parietal cortical complexity correlates with full-scale IQ in adulthood.•Cortical complexity mediates cognitive development from infancy to adulthood.
Deep phenotyping and longitudinal assessment of predementia at-risk states of Alzheimer's disease (AD) are required to define populations and outcomes for dementia prevention trials. Subjective ...cognitive decline (SCD) is a pre-mild cognitive impairment (pre-MCI) at-risk state of dementia, which emerges as a highly promising target for AD prevention.
The German Center for Neurodegenerative Diseases (DZNE) is conducting the multicenter DZNE-Longitudinal Cognitive Impairment and Dementia Study (DELCODE), which focuses on the characterization of SCD in patients recruited from memory clinics. In addition, individuals with amnestic MCI, mild Alzheimer's dementia patients, first-degree relatives of patients with Alzheimer's dementia, and cognitively unimpaired control subjects are studied. The total number of subjects to be enrolled is 1000. Participants receive extensive clinical and neuropsychological assessments, magnetic resonance imaging, positron emission tomography, and biomaterial collection is perfomed. In this publication, we report cognitive and clinical data as well as apolipoprotein E (APOE) genotype and cerebrospinal fluid (CSF) biomarker results of the first 394 baseline data sets.
In comparison with the control group, patients with SCD showed slightly poorer performance on cognitive and functional measures (Alzheimer's Disease Assessment Scale-cognitive part, Clinical Dementia Rating, Functional Activities Questionnaire), with all mean scores in a range which would be considered unimpaired. APOE4 genotype was enriched in the SCD group in comparison to what would be expected in the population and the frequency was significantly higher in comparison to the control group. CSF Aβ42 was lower in the SCD group in comparison to the control group at a statistical trend with age as a covariate. There were no group differences in Tau or pTau concentrations between the SCD and the control groups. The differences in all measures between the MCI group and the AD group were as expected.
The initial baseline data for DELCODE support the approach of using SCD in patients recruited through memory clinics as an enrichment strategy for late-stage preclinical AD. This is indicated by slightly lower performance in a range of measures in SCD in comparison to the control subjects as well as by enriched APOE4 frequency and lower CSF Aβ42 concentration.
German Clinical Trials Register DRKS00007966 . Registered 4 May 2015.
Neuroimaging studies with positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have delineated a human pain network in vivo. Despite the recognition of cerebral ...structures engaged in pain transmission, the cerebral mechanisms involved in pain modulation are still not well understood. Here, we investigated healthy volunteers using fMRI during experimental heat pain and distraction induced by a visual incongruent color-word Stroop task. A factorial design permitted categorical and covariation analysis of four conditions, namely innocuous and noxious heat; with and without distraction. Pain without distraction evoked an activation pattern similar to that observed in previous neuroimaging pain studies. Distraction was associated with a significant reduction of the visual analogue scale (VAS) ratings for pain intensity and unpleasantness and a reduction of pain-related activation in multiple brain areas, particularly in the so-called ‘medial pain system’. Distraction significantly increased the activation of the cingulo-frontal cortex including the orbitofrontal and perigenual anterior cingulate cortex (ACC), as well as the periaquaeductal gray (PAG) and the posterior thalamus. Covariation analysis revealed functional interaction between these structures during pain stimulation and distraction, but not during pain stimulation per se. According to our results, the cingulo-frontal cortex may exert top–down influences on the PAG and posterior thalamus to gate pain modulation during distraction.
Physical activity influences psychological well-being. This study aimed to determine the impact of exercise intensity on psychological well-being and alterations in emotion-related brain functional ...connectivity (FC).
Twenty young, healthy, trained athletes performed a low- and high-intensity interval exercise (LIIE and HIIE) as well as a control condition in a within-subject crossover design. Before and after each condition, Positive And Negative Affect Scale (PANAS) was assessed as well as resting-state functional MRI (rs-fMRI). Voxel-wise FC was examined for bilateral amygdala seed region to whole-brain and emotion-related anatomical regions (e.g., insula, temporal pole, precuneus). Data analyses were performed using linear mixed-effect models with fixed factors condition and time.
The PANAS Positive Affect scale showed a significant increase after LIIE and HIIE and a significant reduction in Negative Affect after the control condition. In rs-fMRI, no significant condition-by-time interactions were observed between the amygdala and whole brain. Amygdala-precuneus FC analysis showed an interaction effect, suggesting reduced post-exercise anticorrelation after the control condition, but stable, or even slightly enhanced anticorrelation for the exercise conditions, especially HIIE.
In conclusion, both LIIE and HIIE had positive effects on mood and concomitant effects on amygdala-precuneus FC, particularly after HIIE. Although no significant correlations were found between amygdala-precuneus FC and PANAS, results should be discussed in the context of affective disorders in whom abnormal amygdala-precuneus FC has been observed.
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