•EEG alpha asymmetry and fRMI indicative of left frontal hypoactivity in depression.•Asymmetry in non-verbal/emotional dichotic and visual tasks abnormal in depression.•ERPs to emotional stimuli ...indicate right parietotemporal hypoactivity in depression.•Frontal and parietotemporal asymmetries modulated by anxiety and anxious arousal.•Right-left asymmetry related to diagnostic and treatment responsive subtypes.
The right and left side of the brain are asymmetric in anatomy and function. We review electrophysiological (EEG and event-related potential), behavioral (dichotic and visual perceptual asymmetry), and neuroimaging (PET, MRI, NIRS) evidence of right-left asymmetry in depressive disorders. Recent electrophysiological and fMRI studies of emotional processing have provided new evidence of altered laterality in depressive disorders. EEG alpha asymmetry and neuroimaging findings at rest and during cognitive or emotional tasks are consistent with reduced left prefrontal activity in depressed patients, which may impair downregulation of amygdala response to negative emotional information. Dichotic listening and visual hemifield findings for non-verbal or emotional processing have revealed abnormal perceptual asymmetry in depressive disorders, and electrophysiological findings have shown reduced right-lateralized responsivity to emotional stimuli in occipitotemporal or parietotemporal cortex. We discuss models of neural networks underlying these alterations. Of clinical relevance, individual differences among depressed patients on measures of right-left brain function are related to diagnostic subtype of depression, comorbidity with anxiety disorders, and clinical response to antidepressants or cognitive behavioral therapy.
Schizophrenia is characterized by profound and disabling deficits in the ability to recognize emotion in facial expression and tone of voice. Although these deficits are well documented in ...established schizophrenia using recently validated tasks, their predictive utility in at-risk populations has not been formally evaluated.
The Penn Emotion Recognition and Discrimination tasks, and recently developed measures of auditory emotion recognition, were administered to 49 clinical high-risk subjects prospectively followed for 2 years for schizophrenia outcome, and 31 healthy controls, and a developmental cohort of 43 individuals aged 7-26 years. Deficit in emotion recognition in at-risk subjects was compared with deficit in established schizophrenia, and with normal neurocognitive growth curves from childhood to early adulthood.
Deficits in emotion recognition significantly distinguished at-risk patients who transitioned to schizophrenia. By contrast, more general neurocognitive measures, such as attention vigilance or processing speed, were non-predictive. The best classification model for schizophrenia onset included both face emotion processing and negative symptoms, with accuracy of 96%, and area under the receiver-operating characteristic curve of 0.99. In a parallel developmental study, emotion recognition abilities were found to reach maturity prior to traditional age of risk for schizophrenia, suggesting they may serve as objective markers of early developmental insult.
Profound deficits in emotion recognition exist in at-risk patients prior to schizophrenia onset. They may serve as an index of early developmental insult, and represent an effective target for early identification and remediation. Future studies investigating emotion recognition deficits at both mechanistic and predictive levels are strongly encouraged.
Point mutations and deletions of mitochondrial DNA (mtDNA) accumulate in a variety of tissues during ageing in humans, monkeys and rodents. These mutations are unevenly distributed and can accumulate ...clonally in certain cells, causing a mosaic pattern of respiratory chain deficiency in tissues such as heart, skeletal muscle and brain. In terms of the ageing process, their possible causative effects have been intensely debated because of their low abundance and purely correlative connection with ageing. We have now addressed this question experimentally by creating homozygous knock-in mice that express a proof-reading-deficient version of PolgA, the nucleus-encoded catalytic subunit of mtDNA polymerase. Here we show that the knock-in mice develop an mtDNA mutator phenotype with a threefold to fivefold increase in the levels of point mutations, as well as increased amounts of deleted mtDNA. This increase in somatic mtDNA mutations is associated with reduced lifespan and premature onset of ageing-related phenotypes such as weight loss, reduced subcutaneous fat, alopecia (hair loss), kyphosis (curvature of the spine), osteoporosis, anaemia, reduced fertility and heart enlargement. Our results thus provide a causative link between mtDNA mutations and ageing phenotypes in mammals.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Guidelines on histopathological techniques and reporting for adult and paediatric gastrointestinal neuromuscular pathology have been produced recently by an international working group (IWG). These ...addressed the important but relatively neglected areas of histopathological practice of the general pathologist, including suction rectal biopsy and full-thickness intestinal tissue. Recommendations were presented for the indications, safe acquisition of tissue, histological techniques, reporting and referral of such histological material.
Consensual processes undertaken by the IWG and following established guideline decision group methodologies.
This report presents a contemporary and structured classification of gastrointestinal neuromuscular pathology based on defined histopathological criteria derived from the existing guidelines. In recognition of its origins and first presentation in London at the World Congress of Gastroenterology 2009, this has been named 'The London Classification'. The implementation of this classification should allow some diagnostic standardisation, but should necessarily be viewed as a starting point for future modification as new data become available.
Prior research has identified two resting EEG biomarkers with potential for predicting functional outcomes in depression: theta current density in frontal brain regions (especially rostral anterior ...cingulate cortex) and alpha power over posterior scalp regions. As little is known about the discriminant and convergent validity of these putative biomarkers, a thorough evaluation of these psychometric properties was conducted toward the goal of improving clinical utility of these markers. Resting 71‐channel EEG recorded from 35 healthy adults at two sessions (1‐week retest) were used to systematically compare different quantification techniques for theta and alpha sources at scalp (surface Laplacian or current source density CSD) and brain (distributed inverse; exact low resolution electromagnetic tomography eLORETA) level. Signal quality was evaluated with signal‐to‐noise ratio, participant‐level spectra, and frequency PCA covariance decomposition. Convergent and discriminant validity were assessed within a multitrait‐multimethod framework. Posterior alpha was reliably identified as two spectral components, each with unique spatial patterns and condition effects (eyes open/closed), high signal quality, and good convergent and discriminant validity. In contrast, frontal theta was characterized by one low‐variance component, low signal quality, lack of a distinct spectral peak, and mixed validity. Correlations between candidate biomarkers suggest that posterior alpha components constitute reliable, convergent, and discriminant biometrics in healthy adults. Component‐based identification of spectral activity (CSD/eLORETA‐fPCA) was superior to fixed, a priori frequency bands. Improved quantification and conceptualization of frontal theta is necessary to determine clinical utility.
Magnitude of frontal theta (rostral ACC eLORETA source amplitude) and posterior alpha (spectral components of scalp current source density) at rest have been considered candidate EEG biomarkers of depression outcomes. Given inconsistent findings, we examined the discriminant and convergent validity of these measures in healthy adults. Unlike theta, two distinct alpha components constituted reliable, convergent, and discriminant biometrics. While results have marked implications for clinical utility, we make several recommendations for improving the psychometric properties of resting frontal theta.
Background There is growing evidence that individual differences among depressed patients on electrophysiologic (EEG), neuroimaging, and neurocognitive measures are predictive of therapeutic response ...to antidepressant drugs. This study replicates prior findings of pretreatment differences between selective serotonin reuptake inhibitor (SSRI) responders and nonresponders in EEG alpha power or asymmetry and examines whether these differences normalize or are stable after treatment. Methods Resting EEG (eyes open and closed) was recorded from 28 electrodes (nose reference) in 18 depressed patients when off medication and at the end of 12 weeks of fluoxetine treatment. Clinical response was assessed by an independent rater with the Clinical Global Impression Improvement scale. The EEG data were also obtained for 18 healthy adults matched to patients in gender and age. Results Treatment responders had greater alpha power compared with nonresponders and healthy control subjects, with largest differences at occipital sites where alpha was largest. There were also differences in alpha asymmetry between responders and nonresponders at occipital sites. Responders showed greater alpha (less activity) over right than left hemisphere, whereas nonresponders tended to show the opposite asymmetry. Neither alpha power nor asymmetry changed after treatment, and test-retest correlations were high, particularly for alpha power. Alpha power and asymmetry showed reasonable positive predictive value but less negative predictive value. Conclusions The findings confirm reports of alpha differences between antidepressant responders and nonresponders and raise hopes for developing EEG tests for selecting effective treatments for patients. The stability of alpha power and asymmetry differences between SSRI responders and nonresponders after treatment suggests that they represent state-independent characteristics.
Mn–Al–C is intended to be one of the “gap magnets” with magnetic performance in-between ferrites and Nd-Fe-B. These magnets are based on the metastable ferromagnetic
τ
-phase with L1
0
structure, ...which requires well controlled synthesis to prevent the formation of secondary phases, detrimental for magnetic properties. Here, we investigate the formation of
τ
-phase in Mn–Al–C using Spark Plasma Sintering (SPS) and compare with conventional annealing. The effect of SPS parameters (pressure and electric current) on the phase formation is also studied. Single
τ
-phase is obtained for annealing 5 min at
500
∘
C
with SPS. In addition, we show that the initial grain size of the
ϵ
-phase is influencing the
τ
-phase transformation and fraction at a given annealing condition, independently of the annealing method used. A faster transformation was observed for smaller initial
ϵ
-grains. The samples obtained by SPS showed comparable magnetic properties with the conventional annealed ones, reaching coercivity of 0.18 T and saturation magnetization of 114 Am
2
/kg in the optimized samples. The similarity in coercivity is related to the microstructure, as we reveal the presence of structure defects like twin boundaries and dislocations in both materials.
Graphical abstract
Highlights · An algorithm was developed to identify bridged electrodes using characteristics of electrical distance frequency distributions. · Using this tool on five publically-available datasets, ...electrode bridges were detected in 54% of sessions. · If used routinely, this automated approach offers feedback required to protect against spatial distortion and smoothing that might contaminate an EEG or ERP topography.
Resting and task-related EEG alpha are used in studies of cognition and psychopathology. Although Laplacian methods have been applied, apprehensions about loss of global activity dissuade researchers ...from greater use except as a supplement to reference-dependent measures. The unfortunate result has been continued reliance on reference strategies that differ across labs, and a systemic preference for a montage-dependent average reference over true reference-free measures. We addressed these concerns by comparing resting- and task-related EEG alpha using three EEG transformations: nose- (NR) and average-referenced (AR) EEG, and the corresponding CSD. Amplitude spectra of resting and prestimulus task-related EEG (novelty oddball) and event-related spectral perturbations were scaled to equate each transformation. Alpha measures quantified for 8–12Hz bands were: 1) net amplitude (eyes-closed minus eyes-open) and 2) overall amplitude (eyes-closed plus eyes-open); 3) task amplitude (prestimulus baseline) and 4) task event-related desynchronization (ERD). Mean topographies unambiguously represented posterior alpha for overall, net and task, as well as poststimulus alpha ERD. Topographies were similar for the three transformations, but differed in dispersion, CSD being sharpest and NR most broadly distributed. Transformations also differed in scale, AR showing less attenuation or spurious secondary maxima at anterior sites, consistent with simulations of distributed posterior generators. Posterior task alpha and alpha ERD were positively correlated with overall alpha, but not with net alpha. CSD topographies consistently and appropriately represented posterior EEG alpha for all measures.
•CSD, nose- (NR) and average-referenced (AR) alpha were quantified and compared.•CSD consistently and appropriately represented posterior alpha for all measures.•AR topographies were intermediate in dispersion, but had spurious secondary maxima.•Overall resting alpha was strongly correlated with task alpha for all transformations.•Posterior net and task alpha were negatively correlated.
Gene discovery using massively parallel sequencing has focused on phenotypes diagnosed postnatally such as well‐characterized syndromes or intellectual disability, but is rarely reported for fetal ...disorders. We used family‐based whole‐exome sequencing in order to identify causal variants for a recurrent pattern of an undescribed lethal fetal congenital anomaly syndrome. The clinical signs included intrauterine growth restriction (IUGR), severe microcephaly, renal cystic dysplasia/agenesis and complex brain and genitourinary malformations. The phenotype was compatible with a ciliopathy, but not diagnostic of any known condition. We hypothesized biallelic disruption of a gene leading to a defect related to the primary cilium. We identified novel autosomal recessive truncating mutations in KIF14 that segregated with the phenotype. Mice with autosomal recessive mutations in the same gene have recently been shown to have a strikingly similar phenotype. Genotype–phenotype correlations indicate that the function of KIF14 in cell division and cytokinesis can be linked to a role in primary cilia, supported by previous cellular and model organism studies of proteins that interact with KIF14. We describe the first human phenotype, a novel lethal ciliary disorder, associated with biallelic inactivating mutations in KIF14. KIF14 may also be considered a candidate gene for allelic viable ciliary and/or microcephaly phenotypes.
PDF
