Posterior Brain Areas Research Articles

The use of an anterior-posterior atrophy index to distinguish Alzheimer's disease from frontotemporal disorders: an automated volumetric MRI Study.

Alzheimer's disease (AD) and frontotemporal dementia (FTD) require different treatments. Since clinical presentation can be nuanced, imaging biomarkers aid in diagnosis. Automated software such as Neuroreader (NR) provides volumetric imaging data, and indices between anterior and posterior brain areas have proven useful in distinguishing dementia subtypes in research cohorts. Existing indices are complex and require further validation in clinical settings. To provide initial validation for a simplified anterior-posterior index (API) from NR in distinguishing FTD and AD in a clinical cohort. A retrospective chart review was completed. We derived a simplified API: API = (logVA/VP-μ)/σ where is weighted volume of frontal and temporal lobes and of parietal and occipital lobes. and are the mean and standard deviation of logVA/VP computed for AD participants. Receiver operating characteristic (ROC) curves and regression analyses assessed the efficacy of the API versus brain areas in predicting diagnosis of AD versus FTD. A total of 39 participants with FTD and 78 participants with AD were included. The API had an excellent performance in distinguishing AD from FTD with an area under the ROC curve of 0.82 and a positive association with diagnostic classification on logistic regression analysis (B = 1.491, P < 0.001). The API successfully distinguished AD and FTD with excellent performance. The results provide preliminary validation of the API in a clinical setting.

Gamma activity in Autism Spectrum Disorder: Enhanced response to visual input

IntroductionAutism spectrum disorder (ASD) is a childhood onset neurodevelopmental condition, that leads to permanent disability in a high proportion of cases. ASD is associated with a heterogeneous symptom presentation, which - besides social interaction and communication difficulties - encompasses altered sensory reactivity, including excessive hyper-sensitivity to stimuli, especially in the visual domain. Meta-analyses of fMRI studies revealed increased reactivity in visual task conditions in the temporal and occipital brain regions. Neural oscillations in the EEG gamma band are viewed as a candidate neurobiological marker for higher order sensory and perceptual processes, and social interactions.ObjectivesWe investigated changes in gamma activity in the EEG in the eyes open (EO) vs. eyes closed (EC) condition in order to identify the neurobiological underpinning of the enhanced sensitivity to visual input in ASD as compared to typically developing (TD) subjects.MethodsEEGs were obtained in EC and EO condition in ASD (N=23) and TD subjects (N=24) in an ongoing study. For EEG recording we used a high-density 128-channel BioSemi system, with 0.5 Hz frequency resolution. The spectral power in the gamma band (30-100Hz) was quantified by the power spectral density. To investigate whether changes in the gamma band were linked to changes in arousal instead of enhanced visual processing, we also examined alterations in the alpha band (8-13Hz) in the EO condition. Spectral power changes were determined for each EEG channel by computing the difference between the EC and EO conditions (EO-EC).ResultsSpectral power in the gamma band showed changes in the opposite direction in the two study groups: ASD subjects manifested significant (p&lt;0.05) increase, while TD subjects had a decrease in the EO vs. EC condition in the temporal and occipital brain regions. By contrast, the changes in the alpha band were similar, with both groups exhibiting a spectral power decrease in the EO compared to the EC condition.ConclusionsIn ASD, an enhancement of gamma activity is present in the EO as compared to the EC condition in the posterior brain areas. These brain areas are involved in the processing of visual information, and gamma activity is considered as a measure of perceptual processes. Thus, the gamma alterations in the EO vs. EC condition may underlie the hyper-sensitivity symptoms to visual stimuli in ASD, and EEG can offer a simple to use tool to delineate the neurobiological foundation of the symptom presentation.Funding statement: Hungarian Brain Research program,#NAP2022-I-4/2022Disclosure of InterestNone Declared

Alteration of functional connectivity despite preserved cerebral oxygenation during acute hypoxia

Resting state networks (RSN), which show the connectivity in the brain in the absence of any stimuli, are increasingly important to assess brain function. Here, we investigate the changes in RSN as well as the hemodynamic changes during acute, global hypoxia. Mice were imaged at different levels of oxygen (21, 12, 10 and 8%) over the course of 10 weeks, with hypoxia and normoxia acquisitions interspersed. Simultaneous GCaMP and intrinsic optical imaging allowed tracking of both neuronal and hemodynamic changes. During hypoxic conditions, we found a global increase of both HbO and HbR in the brain. The saturation levels of blood dropped after the onset of hypoxia, but surprisingly climbed back to levels similar to baseline within the 10-min hypoxia period. Neuronal activity also showed a peak at the onset of hypoxia, but dropped back to baseline as well. Despite regaining baseline sO2 levels, changes in neuronal RSN were observed. In particular, the connectivity as measured with GCaMP between anterior and posterior parts of the brain decreased. In contrast, when looking at these same connections with HbO measurements, an increase in connectivity in anterior–posterior brain areas was observed suggesting a potential neurovascular decoupling.

Origin, synchronization, and propagation of sleep slow waves in children

Study ObjectivesSleep slow wave activity, as measured using EEG delta power (<4 Hz), undergoes significant changes throughout development, mirroring changes in brain function and anatomy. Yet, age-dependent variations in the characteristics of individual slow waves have not been thoroughly investigated. Here we aimed at characterizing individual slow wave properties such as origin, synchronization, and cortical propagation at the transition between childhood and adulthood. MethodsWe analyzed overnight high-density (256 electrodes) EEG recordings of healthy typically developing children (N = 21, 10.3 ± 1.5 years old) and young healthy adults (N = 18, 31.1 ± 4.4 years old). All recordings were preprocessed to reduce artifacts, and NREM slow waves were detected and characterized using validated algorithms. The threshold for statistical significance was set at p = 0.05. ResultsThe slow waves of children were larger and steeper, but less widespread than those of adults. Moreover, they tended to mainly originate from and spread over more posterior brain areas. Relative to those of adults, the slow waves of children also displayed a tendency to more strongly involve and originate from the right than the left hemisphere. The separate analysis of slow waves characterized by high and low synchronization efficiency showed that these waves undergo partially distinct maturation patterns, consistent with their possible dependence on different generation and synchronization mechanisms. ConclusionsChanges in slow wave origin, synchronization, and propagation at the transition between childhood and adulthood are consistent with known modifications in cortico-cortical and subcortico-cortical brain connectivity. In this light, changes in slow-wave properties may provide a valuable yardstick to assess, track, and interpret physiological and pathological development.

Eigenvector centrality dynamics are related to Alzheimer's disease pathological changes in non-demented individuals.

Amyloid-β accumulation starts in highly connected brain regions and is associated with functional connectivity alterations in the early stages of Alzheimer's disease. This regional vulnerability is related to the high neuronal activity and strong fluctuations typical of these regions. Recently, dynamic functional connectivity was introduced to investigate changes in functional network organization over time. High dynamic functional connectivity variations indicate increased regional flexibility to participate in multiple subnetworks, promoting functional integration. Currently, only a limited number of studies have explored the temporal dynamics of functional connectivity in the pre-dementia stages of Alzheimer's disease. We study the associations between abnormal cerebrospinal fluid amyloid and both static and dynamic properties of functional hubs, using eigenvector centrality, and their relationship with cognitive performance, in 701 non-demented participants from the European Prevention of Alzheimer's Dementia cohort. Voxel-wise eigenvector centrality was computed for the whole functional magnetic resonance imaging time series (static), and within a sliding window (dynamic). Differences in static eigenvector centrality between amyloid positive (A+) and negative (A-) participants and amyloid-tau groups were found in a general linear model. Dynamic eigenvector centrality standard deviation and range were compared between groups within clusters of significant static eigenvector centrality differences, and within 10 canonical resting-state networks. The effect of the interaction between amyloid status and cognitive performance on dynamic eigenvector centrality variability was also evaluated with linear models. Models were corrected for age, sex, and education level. Lower static centrality was found in A+ participants in posterior brain areas including a parietal and an occipital cluster; higher static centrality was found in a medio-frontal cluster. Lower eigenvector centrality variability (standard deviation) occurred in A+ participants in the frontal cluster. The default mode network and the dorsal visual networks of A+ participants had lower dynamic eigenvector centrality variability. Centrality variability in the default mode network and dorsal visual networks were associated with cognitive performance in the A- and A+ groups, with lower variability being observed in A+ participants with good cognitive scores. Our results support the role and timing of eigenvector centrality alterations in very early stages of Alzheimer's disease and show that centrality variability over time adds relevant information on the dynamic patterns that cause static eigenvector centrality alterations. We propose that dynamic eigenvector centrality is an early biomarker of the interplay between early Alzheimer's disease pathology and cognitive decline.

Characterization of spastic paraplegia in a family with a novel PSEN1 mutation.

Spastic paraparesis has been described to occur in 13.7% of PSEN1 mutations and can be the presenting feature in 7.5%. In this paper, we describe a family with a particularly young onset of spastic paraparesis due to a novel mutation in PSEN1 (F388S). Three affected brothers underwent comprehensive imaging protocols, two underwent ophthalmological evaluations and one underwent neuropathological examination after his death at age 29. Age of onset was consistently at age 23 with spastic paraparesis, dysarthria and bradyphrenia. Pseudobulbar affect followed with progressive gait problems leading to loss of ambulation in the late 20s. Cerebrospinal fluid levels of amyloid-β, tau and phosphorylated tau and florbetaben PET were consistent with Alzheimer's disease. Flortaucipir PET showed an uptake pattern atypical for Alzheimer's disease, with disproportionate signal in posterior brain areas. Diffusion tensor imaging showed decreased mean diffusivity in widespread areas of white matter but particularly in areas underlying the peri-Rolandic cortex and in the corticospinal tracts. These changes were more severe than those found in carriers of another PSEN1 mutation, which can cause spastic paraparesis at a later age (A431E), which were in turn more severe than among persons carrying autosomal dominant Alzheimer's disease mutations not causing spastic paraparesis. Neuropathological examination confirmed the presence of cotton wool plaques previously described in association with spastic parapresis and pallor and microgliosis in the corticospinal tract with severe amyloid-β pathology in motor cortex but without unequivocal disproportionate neuronal loss or tau pathology. In vitro modelling of the effects of the mutation demonstrated increased production of longer length amyloid-β peptides relative to shorter that predicted the young age of onset. In this paper, we provide imaging and neuropathological characterization of an extreme form of spastic paraparesis occurring in association with autosomal dominant Alzheimer's disease, demonstrating robust diffusion and pathological abnormalities in white matter. That the amyloid-β profiles produced predicted the young age of onset suggests an amyloid-driven aetiology though the link between this and the white matter pathology remains undefined.

Oscillatory brain responses to emotional stimuli are effects related to events rather than states.

Emotional cues draw attention, thereby enabling enhanced processing. Electrophysiological brain research in humans suggests that increased gamma band activity and decreased alpha band activity over posterior brain areas is associated with the allocation of attention. However, emotional events can alternate quickly, like rapidly changing news items and it remains unknown whether the modulation of brain oscillations happens in a stimulus induced manner, changing with each individual stimulus, or whether the events lead to prolonged, state-like changes. To investigate this, we measured the electroencephalogram (EEG) during a passive viewing task (N = 32) while emotional pictures International Affective Picture System (IAPS) were presented in blocks containing either pleasant and neutral or unpleasant and neutral pictures. As predicted, we found decreased alpha and increased gamma power over posterior areas in response to unpleasant compared to pleasant pictures (and also compared to neutral pictures for gamma power). When testing the neutral pictures of the unpleasant and pleasant block against each other, we found no significant difference, which speaks to a stimulus induced effect of alpha and gamma power rather than a state effect. In addition, the inter-trial interval (ITI) between the pictures did not differ between the unpleasant and pleasant block either, corroborating this conclusion. Since emotional pictures can at the same time elicit a freezing-like response and we were interested in whether this freezing-like response co-occurs with enhanced attention, we also collected postural sway data. However, within this EEG-setup, postural analyses indicated no stimulus-related effects nor a correlation with EEG-data. We interpret the alpha and gamma band results as reflecting event-related attention toward unpleasant compared to pleasant (and neutral) pictures and discuss this finding in light of previous EEG research and in combination with behavioral research on threat-induced reductions in body sway (freezing-like response).

Https://he01.tci-thaijo.org/index.php/AIHD-MU/article/view/258521

This study aims to investigate the effects of d-camphor inhalation on psychophysiological parameters among healthy participants. Twenty-four healthy volunteers participated in the trials. d-Camphor was administered to determine the effects on autonomic nervous system (ANS), central nervous system (CNS) through electroencephalography (EEG) recordings as well as psychological parameters through emotional states. EEG recordings were conducted based on 10-20 system and EEG band power was calculated by Fast Fourier Transformation (FFT). For data analysis, d-camphor was inhaled and compared with sweet almond oil as base oil. Paired t-test was employed to measure the oil inhalation. The findings indicated that d-camphor inhalation caused significant changes in ANS parameters, psychological parameters through emotional states and central nervous system (CNS) through electroencephalography (EEG) recordings. After d-camphor inhalation, systolic blood pressure, heart rate, and the respiratory rate decreased significantly. Relaxed and calm feelings increased significantly while active and stressed feelings decreased significantly. The power of the alpha wave over all the brain areas including left anterior, right anterior, center, left posterior and right posterior brain areas increased significantly. d-Camphor caused significant changes in psychophysiological parameters indicating its sedative effects.

Theta-phase connectivity between medial prefrontal and posterior areas underlies novel instructions implementation.

Implementing novel instructions is a complex and uniquely human cognitive ability, which requires the rapid and flexible conversion of symbolic content into a format that enables the execution of the instructed behavior. Preparing to implement novel instructions, as opposed to their mere maintenance, involves the activation of the instructed motor plans, and the binding of the action information to the specific context in which this should be executed. Recent evidence and prominent computational models suggest that this efficient configuration of the system might involve a central role of frontal theta oscillations in establishing top-down long-range synchronization between distant and task-relevant brain areas. In the present EEG study (human subjects, 30 females, 4 males), we demonstrate that proactively preparing for the implementation of novels instructions, as opposed to their maintenance, involves a strengthened degree of connectivity in the theta frequency range between medial prefrontal and motor/visual areas. Moreover, we replicated previous results showing oscillatory features associated specifically with implementation demands, and extended on them demonstrating the role of theta oscillations in mediating the effect of task demands on behavioral performance. Taken together, these findings support our hypothesis that the modulation of connectivity patterns between frontal and task-relevant posterior brain areas is a core factor in the emergence of a behavior-guiding format from novel instructions.

Still Wanting to Win: Reward System Stability in Healthy Aging.

Healthy aging is accompanied by multi-faceted changes. Especially within the brain, healthy aging exerts substantial impetus on core parts of cognitive and motivational networks. Rewards comprise basic needs, such as food, sleep, and social contact. Thus, a functionally intact reward system remains indispensable for elderly people to cope with everyday life and adapt to their changing environment. Research shows that reward system function is better preserved in the elderly than most cognitive functions. To investigate the compensatory mechanisms providing reward system stability in aging, we employed a well-established reward paradigm (Monetary Incentive Delay Task) in groups of young and old participants while undergoing EEG measurement. As a new approach, we applied EEG connectivity analyses to assess cortical reward-related network connectivity. At the behavioral level, our results confirm that the function of the reward system is preserved in old age. The mechanisms identified for maintaining reward system function in old age do not fit into previously described models of cognitive aging. Overall, older adults exhibit lower reward-related connectivity modulation, higher reliance on posterior and right-lateralized brain areas than younger adults, and connectivity modulation in the opposite direction than younger adults, with usually greater connectivity during non-reward compared to reward conditions. We believe that the reward system has unique compensatory mechanisms distinct from other cognitive functions, probably due to its etymologically very early origin. In summary, this study provides important new insights into cortical reward network connectivity in healthy aging.

Human NREM Sleep Promotes Brain-Wide Vasomotor and Respiratory Pulsations.

The physiological underpinnings of the necessity of sleep remain uncertain. Recent evidence suggests that sleep increases the convection of cerebrospinal fluid (CSF) and promotes the export of interstitial solutes, thus providing a framework to explain why all vertebrate species require sleep. Cardiovascular, respiratory and vasomotor brain pulsations have each been shown to drive CSF flow along perivascular spaces, yet it is unknown how such pulsations may change during sleep in humans. To investigate these pulsation phenomena in relation to sleep, we simultaneously recorded fast fMRI, magnetic resonance encephalography (MREG), and electroencephalography (EEG) signals in a group of healthy volunteers. We quantified sleep-related changes in the signal frequency distributions by spectral entropy analysis and calculated the strength of the physiological (vasomotor, respiratory, and cardiac) brain pulsations by power sum analysis in 15 subjects (age 26.5 ± 4.2 years, 6 females). Finally, we identified spatial similarities between EEG slow oscillation (0.2–2 Hz) power and MREG pulsations. Compared with wakefulness, nonrapid eye movement (NREM) sleep was characterized by reduced spectral entropy and increased brain pulsation intensity. These effects were most pronounced in posterior brain areas for very low-frequency (≤0.1 Hz) vasomotor pulsations but were also evident brain-wide for respiratory pulsations, and to a lesser extent for cardiac brain pulsations. There was increased EEG slow oscillation power in brain regions spatially overlapping with those showing sleep-related MREG pulsation changes. We suggest that reduced spectral entropy and enhanced pulsation intensity are characteristic of NREM sleep. With our findings of increased power of slow oscillation, the present results support the proposition that sleep promotes fluid transport in human brain.SIGNIFICANCE STATEMENT We report that the spectral power of physiological brain pulsation mechanisms driven by vasomotor, respiration, and cardiac rhythms in human brain increase during sleep, extending previous observations of their association with glymphatic brain clearance during sleep in rodents. The magnitudes of increased pulsations follow the rank order of vasomotor greater than respiratory greater than cardiac pulsations, with correspondingly declining spatial extents. Spectral entropy, previously known as vigilance and as an anesthesia metric, decreased during NREM sleep compared with the awake state in very low and respiratory frequencies, indicating reduced signal complexity. An EEG slow oscillation power increase occurring in the early sleep phase (NREM 1–2) spatially overlapped with pulsation changes, indicating reciprocal mechanisms between those measures.

The cognitive phenotypes of Creutzfeldt-Jakob disease: comparison with secondary metabolic encephalopathy.

Rapidly progressive cognitive impairment is a diagnostic criterion in Creutzfeldt-Jakob disease (CJD), but the diagnosis is usually reached when an analysis of cognitive aspects is no longer possible. This study aims to delineate the cognitive phenotypes preceding severe dementia in CJD compared to secondary metabolic encephalopathies (SME) with rapid cognitive impairment. Patients with rapidly progressive neurological symptoms underwent neuropsychological evaluation, analysis of cerebrospinal fluid (CSF) and codon 129 polymorphism of the prion protein gene (PRNP), magnetic resonance imaging (MRI), and single positron emission computed tomography (99mTcSPECT). CSF real-time quaking-induced conversion analysis was applied in CJD patients. Based on literature and clinical expertise, cognitive profiles were correlated with brain areas. Thirty-one patients were diagnosed with CJD (n = 17) or SME; 77 cases of CJD were extracted from the literature. In patients with CJD, verbal initiative, lexical search, long-term memory, attention, and abstract reasoning were the most frequently impaired abilities. Cognitive profiles were mainly related to dysfunction in fronto-temporal areas. Furthermore, they were consistent with areas of hypoperfusion detected by 99mTc SPECT in six patients and cortical and subcortical MRI hyperintensities in eight and 14 patients, respectively, and were similar to those described in the literature. In contrast, cognitive profiles were different from those in SME characterized by visuospatial and constructive deficits relating to posterior brain areas. In CJD, clinical and neuropsychological analyses outline a salient cognitive phenotype suggestive of fronto-temporal dysfunction preceding severe dementia. This phenotype is different from that observed in other rapidly progressive encephalopathies.

Cognitive control inhibition networks in adulthood are impaired by early iron deficiency in infancy

Iron deficiency, a common form of micronutrient deficiency, primarily affects children and women. The principal cause of iron deficiency is undernutrition in low-income countries and malnutrition in middle to upper income regions. Iron is a key element for myelin production, neuronal metabolism, and dopamine functions. Iron deficiency in early life can alter brain development and exert long-lasting effects. Control inhibition is an executive function that involves several brain regions, including the prefrontal cortex and caudate and sub-thalamic nuclei. Dopamine is the prevalent neurotransmitter underlying cognitive inhibition. We followed cohort study participants who had iron deficiency anemia in infancy as well non-anemic controls. At 22 years of age, the participants were subjected to functional magnetic resonance imaging (fMRI) to evaluate the correlation between functional connectivity and performance on an inhibitory cognitive task (Go/No-Go). We hypothesized that former iron deficient anemic (FIDA) participants demonstrate less strength in functional connectivity compared with controls (C). There were not significant group differences in the behavioral results in terms of accuracy and response time. A continuous covariate interaction analysis of functional connectivity and the Go/No-Go scores demonstrated significant differences between the FIDA and C groups. The FIDA participants demonstrated less strength in connectivity in brain regions related to control inhibition, including the medial temporal lobe, impairment in the integration of the default mode network (indicating decreased attention and alertness), and an increase in connectivity in posterior brain areas, all of which suggest slower circuitry maturation. The results support the hypothesis that FIDA young adults show differences in the connectivity of networks related to executive functions. These differences could increase their vulnerability to develop cognitive dysfunctions or mental disorders in adulthood.

Effects of fitness and sedentarism on a biomarker of early AD progression

AbstractBackgroundGiven the lack of an effective treatment for Alzheimer’s Disease (AD), research on factors that might prevent it or delay its symptoms is needed. Physical activity (PA) stands as a means for favourably altering cognitive performance and neuropathologic processes and has been identified as a relevant and easily modifiable lifestyle factor against AD progression. This study thrives to understand the effects of both cardiorespiratory fitness (CRF) and sedentary behaviours (SB) in adult controls through the assessment of magnetoencephalography (MEG).Method30 healthy adults (age between 50 and 70 years) participated in the study. The sample underwent a five minutes of eyes‐closed resting MEG recording (NMEG = 24), a cycloergometer incremental exercise test to evaluate CRF through VO2peak (Nstress = 17), and carried an accelerometer for one week to estimate SB (NACC = 26). The alpha peak frequency at posterior brain areas was extracted, and then its partial correlation to VOpeak and the relative sedentary time from the accelerometer data were calculated, respectively, while also controlling for age. Partial correlation between VO2max and relative sedentary time was calculated as well.ResultStatistical analysis yielded a significant direct correlation between VO2peak and Alpha peak frequency (N=17, rho = 0.504, p‐value = 0.023), while relative sedentary time and Alpha peak frequency showed a significant inverse correlation (N = 20, rho = ‐0.435, p‐value = 0.032). Partial correlation between VO2peak and relative sedentary time was not significant (N = 17, rho = ‐0.404, p‐value = 0.120).ConclusionDespite the small cohort, results pinpoint a strong influence of both CRF and SB. Greater CRF, described as higher VO2peak, appears associated with increased alpha frequency in posterior brain regions, a robust biomarker of brain health which is negatively affected in AD. At the same time, higher levels of sedentarism show a strong relation to decreased alpha peak frequency, indicating that low levels of PA might put subjects entering old age at risk.

Predictive Feedback, Early Sensory Representations, and Fast Responses to Predicted Stimuli Depend on NMDA Receptors.

Learned associations between stimuli allow us to model the world and make predictions, crucial for efficient behavior (e.g., hearing a siren, we expect to see an ambulance and quickly make way). While there are theoretical and computational frameworks for prediction, the circuit and receptor-level mechanisms are unclear. Using high-density EEG, Bayesian modeling, and machine learning, we show that inferred "causal" relationships between stimuli and frontal alpha activity account for reaction times (a proxy for predictions) on a trial-by-trial basis in an audiovisual delayed match-to-sample task which elicited predictions. Predictive β feedback activated sensory representations in advance of predicted stimuli. Low-dose ketamine, an NMDAR blocker, but not the control drug dexmedetomidine, perturbed behavioral indices of predictions, their representation in higher-order cortex, feedback to posterior cortex, and pre-activation of sensory templates in higher-order sensory cortex. This study suggests that predictions depend on alpha activity in higher-order cortex, β feedback, and NMDARs, and ketamine blocks access to learned predictive information.SIGNIFICANCE STATEMENT We learn the statistical regularities around us, creating associations between sensory stimuli. These associations can be exploited by generating predictions, which enable fast and efficient behavior. When predictions are perturbed, it can negatively influence perception and even contribute to psychiatric disorders, such as schizophrenia. Here we show that the frontal lobe generates predictions and sends them to posterior brain areas, to activate representations of predicted sensory stimuli before their appearance. Oscillations in neural activity (α and β waves) are vital for these predictive mechanisms. The drug ketamine blocks predictions and the underlying mechanisms. This suggests that the generation of predictions in the frontal lobe, and the feedback pre-activating sensory representations in advance of stimuli, depend on NMDARs.

Learning Faces as Concepts Improves Face Recognition by Engaging the Social Brain Network.

Face recognition benefits from associating social information to faces during learning. This has been demonstrated by better recognition for faces that underwent social than perceptual evaluations. Two hypotheses were proposed to account for this effect. According to the feature-elaboration hypothesis, social evaluations encourage elaborated processing of perceptual information from faces. According to a social representation hypothesis, social evaluations convert faces from a perceptual representation to a socially meaningful representation of a person. To decide between these two hypotheses, we ran a functional magnetic resonance imaging (fMRI) study in which we functionally localized the posterior face-selective brain areas and social processing brain areas. Participants watched video-clips of young adults and were asked to study them for a recognition test, while making either perceptual evaluations or social evaluations about them. During the fMRI scan, participants performed an old/new recognition test. Behavioural findings replicated better recognition for faces that underwent social then perceptual evaluations. fMRI results showed higher response during the recognition phase for the faces that were learned socially than perceptually, in the social-brain network but not in posterior face-selective network. These results support the social-representation hypothesis and highlight the important role that social processing mechanisms, rather than purely perceptual processes, play in face recognition.

Temporal-parietal-occipital epilepsy in GEFS+ associated with SCN1A mutation.

Most families with genetic epilepsy with febrile seizures plus show a mutation in the sodium channel alpha1 subunit gene, however, but there is much phenotypic heterogeneity and focal epilepsy remains relatively rare. Here, we report a family with electroclinical features indicative of temporal-parietal-occipital carrefour epilepsy with common occurrence of post-ictal migraine. We studied a four-generation family including nine affected subjects by means of EEG and MRI. Genetic testing was performed by targeted re-sequencing (gene panel). In most patients, seizure semiology included cognitive, autonomic, and emotional symptoms, eventually evolving towards sensory visual phenomena. Focal sensory vestibular seizures and changes in body perception were also reported in some cases. Post-ictal migraine was common, occurring in five out of the six (83%) epilepsy patients. A missense mutation (c.1130 G>A; p.R377Q) affecting the S5-S6 segment (pore region) of the sodium channel alpha1 subunit was identified in all affected and four unaffected subjects. Temporal-parietal-occipital carrefour epilepsy is part of the genetic epilepsy with febrile seizures plus spectrum. The electroclinical features in this family support the involvement of a genetically impaired neural network. High prevalence of post-ictal migraine suggests the role of posterior brain areas in the clinical expression of this gene defect.

There Is More to Mindfulness Than Emotion Regulation: A Study on Brain Structural Networks.

Dispositional mindfulness and emotion regulation are two psychological constructs closely interrelated, and both appear to improve with the long-term practice of mindfulness meditation. These constructs appear to be related to subcortical, prefrontal, and posterior brain areas involved in emotional processing, cognitive control, self-awareness, and mind wandering. However, no studies have yet discerned the neural basis of dispositional mindfulness that are minimally associated with emotion regulation. In the present study, we use a novel brain structural network analysis approach to study the relationship between structural networks and dispositional mindfulness, measured with two different and widely used instruments [Mindfulness Attention Awareness Scale (MAAS) and Five Facet Mindfulness Questionnaire (FFMQ)], taking into account the effect of emotion regulation difficulties. We observed a number of different brain regions associated with the different scales and dimensions. The total score of FFMQ and MAAS overlap with the bilateral parahippocampal and fusiform gyri. Additionally, MAAS scores were related to the bilateral hippocampus and the FFMQ total score to the right insula and bilateral amygdala. These results indicate that, depending on the instrument used, the characteristics measured could differ and could also involve different brain systems. However, it seems that brain areas related to emotional reactivity and semantic processing are generally related to Dispositional or trait mindfulness (DM), regardless of the instrument used.

Temporo-parietal brain regions are involved in higher order object perception

Lesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also with impairments in the processing of objects presented under demanding viewing conditions. Evidence from neuroimaging studies and lesion patterns observed in patients with simultanagnosia and agnosia for object orientation suggest similar brain regions to be involved in perception of global shapes and processing of objects in atypical (‘non-canonical’) orientation. In a localizer experiment, we identified individual temporo-parietal brain areas involved in global shape perception and found significantly higher BOLD signals during the processing of non-canonical compared to canonical objects. In a multivariate approach, we demonstrated that posterior temporo-parietal brain areas show distinct voxel patterns for non-canonical and canonical objects and that voxel patterns of global shapes are more similar to those of objects in non-canonical compared to canonical viewing conditions. These results suggest that temporo-parietal brain areas are not only involved in global shape perception but might serve a more general mechanism of complex object perception. Our results challenge a strict attribution of object processing to the ventral visual stream by suggesting specific dorsal contributions in more demanding viewing conditions.

Neural correlates of memory recovery: Preliminary findings in children and adolescents with acquired brain injury.

Background:After acquired brain injury (ABI), patients show various neurological impairments and outcome is difficult to predict. Identifying biomarkers of recovery could provide prognostic information about a patient’s neural potential for recovery and improve our understanding of neural reorganization. In healthy subjects, sleep slow wave activity (SWA, EEG spectral power 1–4.5 Hz) has been linked to neuroplastic processes such as learning and brain maturation. Therefore, we suggest that SWA might be a suitable measure to investigate neural reorganization underlying memory recovery.Objectives:In the present study, we used SWA to investigate neural correlates of recovery of function in ten paediatric patients with ABI (age range 7–15 years).Methods:We recorded high-density EEG (128 electrodes) during sleep at the beginning and end of rehabilitation. We used sleep EEG data of 52 typically developing children to calculate age-normalized values for individual patients. In patients, we also assessed every-day life memory impairment at the beginning and end of rehabilitation.Results:In the course of rehabilitation, memory recovery was paralleled by longitudinal changes in SWA over posterior parietal brain areas. SWA over left prefrontal and occipital brain areas at the beginning of rehabilitation predicted memory recovery.Conclusions:We show that longitudinal sleep-EEG measurements are feasible in the clinical setting. While posterior parietal and prefrontal brain areas are known to belong to the memory “core network”, occipital brain areas have never been related to memory. While we have to remain cautious in interpreting preliminary findings, we suggest that SWA is a promising measure to investigate neural reorganization.