Bilateral Superior Parietal Cortex Research Articles

Facial emotion recognition deficits are associated with hypomimia and related brain correlates in Parkinson's disease.

Hypomimia is a frequent manifestation in Parkinson's disease (PD) that can affect interpersonal relationships and quality of life. Recent studies have suggested that hypomimia is not only related to motor dysfunction but also to impairment in emotional processing networks. Therefore, we hypothesized that the severity of hypomimia could be associated with performance on a task aimed at assessing facial emotion recognition. In this study, we explored the association between hypomimia, recognition of facial expressions of basic emotions using the Ekman 60 Faces Test (EF), and brain correlates of both hypomimia and performance on the EF. A total of 94 subjects underwent clinical assessments (neurological and neuropsychological examinations), and 56 of them participated in the neuroimaging study. We found significant correlation between hypomimia, EF Disgust (r = -0.242, p = 0.022) and EF Happiness (r = -0.264, p = 0.012); an independent reduction in Cortical Thickness (Cth) in the postcentral gyrus, insula, middle and superior temporal gyri, supramarginal gyrus, banks of the superior temporal sulcus, bilateral fusiform gyri, entorhinal cortex, parahippocampal gyrus, inferior and superior parietal cortex, and right cuneus and precuneus; and multiple correlations between negative emotions such as EF Disgust or EF Anger and a reduced Cth in fronto-temporo-parietal regions. In conclusion, these results suggest that the association between hypomimia and emotion recognition deficits in individuals with PD might be mediated by shared circuits, supporting the concept that hypomimia is not only the result of the dysfunction of motor circuits, but also of higher cognitive functions.

Association of β‐amyloid, microglial activation, hypermetabolism and hypertrophy in Alzheimer’s disease

AbstractBackgroundPlasma β‐amyloid (Aβ) Aβ42/Aβ40 measured by immunoprecipitation and liquid chromatography‐mass spectrometry assay has been demonstrated useful to identify Aβ PET positive individuals, but the concordance and discordance about the positivity of plasma Aβ42/Aβ40 (Plasma+/‐) and Aβ PET (PET+/‐) have not been fully characterized. Moreover, the association of Aβ deposition, cortical thickness (CTh), glucose metabolism, and microglial activation among different Plasma/PET profiles is poorly understood.MethodIn this study, we classified 173 ADNI participants into Plasma‐/PET‐ (N = 48), Plasma+/PET‐ (N = 43), and Plasma+/PET+ (N = 73) group based on thresholds of composite Aβ PET (18F‐florbetapir, FBP) standardized uptake value ratio (SUVR) (≥1.11) and plasma Aβ42/Aβ40 (≤0.1218). Part of them had longitudinal 18F‐fluorodeoxyglucose (FDG) PET, structural MRI, and CSF soluble Triggering Receptor Expressed on Myeloid Cell 2 (sTREM2) data. Baseline and slopes of FBP SUVRs of 68 Freesurfer‐defined ROIs were compared between different Plasma/PET groups. The associations of regional FBP SUVRs, CSF sTREM2, regional glucose metabolism (reflected in FDG‐SUVR), and CTh (measured using structural MRI) were investigated in different Plasma/PET groups.ResultPlasma Aβ42/Aβ40 might become positive earlier than Aβ PET (Fig.1A, McNemar’s test, p<0.001). Longitudinally, Plasma+/PET‐ participants showed faster rates of Aβ accumulation in bilateral BANKSSTS, supramarginal, and superior parietal cortices whereas demonstrated no difference in baseline FBP SUVRs than Plasma‐/PET‐ participants (Fig.1D‐E). Higher CSF sTREM2 level and faster rate of CSF sTREM2 increase were related to slower rates of Aβ accumulation in BANKSSTS (standardized β (βstd) = ‐0.418, p = 0.002) in Plasma+/PET+ but not in Plasma+/PET‐ individuals (Fig.2A and D). In contrast, thicker CTh (Fig. 4B‐C) and higher glucose metabolism (Fig. 4H‐I) in supramarginal and superior parietal cortices were coupled to faster rates of CSF sTREM2 increase in Plasma+/PET‐ rather than in Plasma+/PET+ individuals.ConclusionThese findings suggest that plasma Aβ42/Aβ40 might become abnormal earlier than Aβ PET, and plasma Aβ42/Aβ40 positive Aβ PET negative (Plasma+/PET‐) individuals accumulate Aβ plaques faster than Plasma‐/PET‐ individuals. Activated microglia may play a role in reducing fibrillar‐Aβ increasing rates in late amyloidosis stage, whereas it may be related to hypertrophy and hypermetabolism in early amyloidosis stages.

Changes in brain structure in subjects with resistance to thyroid hormone due to THRB mutations

BackgroundBeing critical for brain development and neurocognitive function thyroid hormones may have an effect on behaviour and brain structure. Our exploratory study aimed to delineate the influence of mutations in the thyroid hormone receptor (TR) ß gene on brain structure.MethodsHigh-resolution 3D T1-weighted images were acquired in 21 patients with a resistance to thyroid hormone ß (RTHß) in comparison to 21 healthy matched-controls. Changes in grey and white matter, as well as cortical thickness were evaluated using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI).ResultsRTHß patients showed elevated circulating fT4 & fT3 with normal TSH concentrations, whereas controls showed normal thyroid hormone levels. RTHß patients revealed significantly higher scores in a self-rating questionnaire for attention deficit hyperactivity disorder (ADHD). Imaging revealed alterations of the corticospinal tract, increased cortical thickness in bilateral superior parietal cortex and decreased grey matter volume in bilateral inferior temporal cortex and thalamus.ConclusionRTHb patients exhibited structural changes in multiple brain areas. Whether these structural changes are causally linked to the abnormal behavioral profile of RTHß which is similar to ADHD, remains to be determined.

Mild behavioral impairment linked to phenoconversion to Alzheimer’s disease and cortical thinning in mild cognitive impairment

AbstractBackgroundMild Behavioral Impairment (MBI) is a neurobehavioral syndrome characterized by later life emergence of sustained neuropsychiatric symptoms, as an at‐risk state for dementia (Ismail Z, Alzheimers Dement, 2016). However, the associations between MBI and a risk of phenocoversion to dementia and its neuroanatomical correlates in MCI are still unclear.MethodA total 1326 older adults with MCI was followed for a mean of 3.0 ± 2.0 years. MBI was approximated using a transformation algorithm for the neuropsychiatric inventory at baseline. Two‐step cluster analysis was used to explore classes of 5 MBI domains (decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, abnormal perception/thought content). A Cox regression analysis was applied to investigate the association between the clusters and phenoconversion to AD. A subset of participants (n = 225) underwent 3D T1‐weighted MRI scans and cortical thickness was compared among the clusters of MBI domains.ResultThe cluster analysis identified 3 groups of participants: (1) people without MBI (47.8%, asymptomatic); (2) people with only affective dysregulation (29.3%, affective dysregulation); (3) people with relatively high probability of affective dysregulation, followed by impulse dyscontrol and affective dysregulation (22.9%, multiple domains). Compared to the asymptomatic, multiple domains was associated with a higher risk of phenoconversion to AD (hazard ratio = 2.589 [1.981 – 3.385], p = < 0.001), but affective dysregulation did not predict phenoconversion (1.204 [0.896 – 1.620], p = 0.219) (Fig 1). MCI individuals with symptoms in multiple domains revealed thinning in the bilateral superior and inferior parietal, superior temporal, and prefrontal cortex, and the right precuneus compared to those with only affective dysregulation (Fig 2). We did not find differences in cortical thickness between phenocoverter and non‐phenoconverter, and interaction of clusters of MBI domains and phenoconversion.ConclusionThe multiple co‐occuring MBI domains in individuals with MCI are associated with a higher risk of phenoconversion to AD. Moreover, MCI individuals with symptoms in multiple domains revealed cortical thinning in the superior parietal and precuneus, which have suggested as AD signatures (Dickerson BC, Cereb Cortex, 2009). These results suggest that evaluation of MBI and neuroimaging characteristics could be useful for risk stratification in MCI individuals.

10-Hz tACS up-regulates a visual attention network and down-regulates the rich club

Abstract Synchronization of oscillatory brain activity may play a critical role in linking distributed neuronal populations into transient functional networks, with up-regulation of engaged networks during task performance accompanied by down-regulation of less salient networks. Can tACS be used to elicit network-specific changes in brain function, given that the distributed nodes of a network may experience varying amplitudes of exogenous current flow? We utilized MEG to characterize brain dynamics following bilateral parietal 10-Hz tACS during a visual attention task (8 healthy adults; 1 mA, verum/sham 20 min/30 s). Regions of interest included a cortico-cerebellar sensory processing network (SP: frontal, parietal, temporal cortex, hippocampus, cerebellum) and the Rich Club (bilateral superior parietal and frontal cortex, precuneus, hippocampus). Persistent changes in local oscillatory dynamics were seen in the SP network across a broad spectrum of frequency bands. Changes in alpha-band activity extended before, during, and after presentation of global/local letter images, consistent with a tonic influence of the 10-Hz tACS on alpha-band dynamics. Up-regulation of alpha and down-regulation of theta throughout the SP network was consistent with results seen in previous working memory studies. Moreover, increases in alpha were accompanied by increased gamma-band activity, consistent with a cross-frequency relationship between these rhythms. In contrast, down-regulation of alpha was characteristic of regions in Rich Club, with the exception of up-regulation in superior parietal cortex. Interestingly, despite a lack of consistency of a reciprocal relationship between alpha and theta in the Rich Club, the stimulation also reduced both theta and gamma-band activity, suggesting a role for theta-gamma coupling in the Rich Club. Our results suggest that tACS may provide a method for identifying and up-/down- regulating individual brain networks. Importantly, identifying tACS parameters that maximize changes to specific networks may be critical to increase efficacy and reduce potential negative side-effects of tACS. Research Category and Technology and Methods Basic Research: 8. Transcranial Alternating Current Stimulation (tACS) Keywords: tACS, MEG, Network, Visual Attention

Brain Anatomy in Boys with Conduct Disorder: Differences Among Aggression Subtypes.

Aggression is a core feature of conduct disorder (CD), but the motivation, execution of aggression may vary. A deeper understanding of the neural substrates of aggressive behaviours is critical for effective clinical intervention. Seventy-six Boys with CD (50 with impulsive aggression (I-CD) and 26 with premeditated aggression (P-CD)) and 69 healthy controls (HCs) underwent a structural MRI scan and behavioural assessments. Whole-brain analyses revealed that, compared to HCs, the I-CD group showed significant cortical thinning in the right frontal cortex, while the P-CD group demonstrated significant folding deficits in the bilateral superior parietal cortex. Both types of aggression negatively correlated with the left amygdala volume, albeit in different ways. The present results demonstrated that the complex nature of aggression relies on differentiated anatomical substrates, highlighting the importance of exploring differential circuit-targeted interventions for CD patients.

Cortical Thickness Alterations in Patients With Tinnitus Before and After Sound Therapy: A Surface-Based Morphometry Study.

This study aimed to explore brain surface-based morphometry cortical thickness changes in patients with idiopathic tinnitus before and after 24 weeks of sound therapy. In this prospective observational study, we recruited 33 tinnitus patients who had undergone 24 weeks of sound therapy and 26 matched healthy controls. For the two groups of subjects, a 3D-BRAVO pulse sequence was acquired both at baseline and at the 24th week. Structural image data preprocessing was performed using the DPABISurf toolbox. The Tinnitus Handicap Inventory (THI) score was assessed to determine the severity of tinnitus before and after treatment. Two-way mixed-model analysis of variance (ANOVA) and Pearson’s correlation analysis were used in the statistical analysis. Student–Newman–Keuls (SNK) tests were used in the post hoc analysis. Significantly lower cortical thickness was found in the left somatosensory and motor cortex (SMC), left posterior cingulate cortex (PCC), and right orbital and polar frontal cortex (OPFC) of the participants in the tinnitus group at baseline than in the participants in the HC group at baseline and after 24 weeks; in the tinnitus group, significantly higher cortical thickness was found after the 24 weeks sound therapy in comparison to the baseline in the left SMC, bilateral superior parietal cortex (SPC), left inferior parietal cortex (IPC), left PCC, and right OPFC. In the HC group, no statistically significant difference in cortical thickness was found after the 24 weeks treatment in comparison to the baseline in the bilateral SMC, bilateral SPC, left IPC, left PCC, or right OPFC. The changes in cortical thickness before and after sound therapy can provide certain reference values for clinical tinnitus treatment. These brain regions could serve as potential targets for neuroimaging.

Cortical Thickness in Alcohol Dependent Patients With Apathy.

ObjectivesMany studies reported structural brain changes in patients with alcohol dependence (PADs). However, no studies identified structural correlates of apathy that might aggravate alcohol misuse. Here, we explored regional differences in cortical thickness in PADs relative to healthy controls (HCs), and examined the potential correlation of regional thickness with the severity of apathy.MethodsMagnetic resonance imaging data were collected from 33 male PADs and 35 male age- and education-matched HCs. We used the FreeSurfer software to investigate group differences in cortical thickness across 148 regions. Apathy was evaluated using the Lille Apathy Rating Scale-Informant (LARS-I). Regression analyses examined the relationship between cortical thickness of regions of interest and apathy score in PADs.ResultsCompared to HCs, PADs showed significant decreases in the cortical thickness of occipito-temporal cortex (OTC), including the left middle occipital gyrus and occipital pole, right superior occipital gyri, and bilateral lingual gyrus; bilateral superior parietal cortex (SPC), including the right intraparietal sulcus; and bilateral inferior parietal cortex (IPC). Furthermore, the cortical thickness of all of the three regions was negatively correlated with the apathy total scores. The cortical thickness of the IPC was also negatively correlated with the action initiation subscore of the LARS-I.ConclusionsThe current results suggest the thickness of bilateral parietal and occipital temporal cortices as neural markers of apathy in PADs. These findings add to the literature by identifying the neural bases of a critical clinical feature of individuals with alcoholism.

Corrigendum: Enhanced Topological Network Efficiency in Preschool Autism Spectrum Disorder: A Diffusion Tensor Imaging Study.

[This corrects the article DOI: 10.3389/fpsyt.2018.00278.].

The neural basis of hand choice: An fMRI investigation of the Posterior Parietal Interhemispheric Competition model

The current study investigates a new neurobiological model of human hand choice: The Posterior Parietal Interhemispheric Competition (PPIC) model. The model specifies that neural populations in bilateral posterior intraparietal and superior parietal cortex (pIP-SPC) encode actions in hand-specific terms, and compete for selection across and within hemispheres. Actions with both hands are encoded bilaterally, but the contralateral hand is overrepresented. We use a novel fMRI paradigm to test the PPIC model. Participants reach to visible targets while in the scanner, and conditions involving free choice of which hand to use (Choice) are compared with when hand-use is instructed. Consistent with the PPIC model, bilateral pIP-SPC is preferentially responsive for the Choice condition, and for actions made with the contralateral hand. In the right pIP-SPC, these effects include anterior intraparietal and superior parieto-occipital cortex. Left dorsal premotor cortex, and an area in the right lateral occipitotemporal cortex show the same response pattern, while the left inferior parietal lobule is preferentially responsive for the Choice condition and when using the ipsilateral hand. Behaviourally, hand choice is biased by target location – for targets near the left/right edges of the display, the hand in ipsilateral hemispace is favoured. Moreover, consistent with a competitive process, response times are prolonged for choices to more ambiguous targets, where hand choice is relatively unbiased, and fMRI responses in bilateral pIP-SPC parallel this pattern. Our data provide support for the PPIC model, and reveal a selective network of brain areas involved in free hand choice, including bilateral posterior parietal cortex, left-lateralized inferior parietal and dorsal premotor cortices, and the right lateral occipitotemporal cortex.

Changes in sensorimotor network activation after botulinum toxin type A injections in patients with cervical dystonia: a functional MRI study

Botulinum toxin type A (BoNT) is considered an effective therapeutic option in cervical dystonia (CD). The pathophysiology of CD and other focal dystonias has not yet been fully explained. Results from neurophysiological and imaging studies suggest a significant involvement of the basal ganglia and thalamus, and functional abnormalities in premotor and primary sensorimotor cortical areas are considered a crucial factor in the development of focal dystonias. Twelve BoNT-naïve patients with CD were examined with functional MRI during a skilled hand motor task; the examination was repeated 4 weeks after the first BoNT injection to the dystonic neck muscles. Twelve age- and gender-matched healthy controls were examined using the same functional MRI paradigm without BoNT injection. In BoNT-naïve patients with CD, BoNT treatment was associated with a significant increase of activation in finger movement-induced fMRI activation of several brain areas, especially in the bilateral primary and secondary somatosensory cortex, bilateral superior and inferior parietal lobule, bilateral SMA and premotor cortex, predominantly contralateral primary motor cortex, bilateral anterior cingulate cortex, ipsilateral thalamus, insula, putamen, and in the central part of cerebellum, close to the vermis. The results of the study support observations that the BoNT effect may have a correlate in the central nervous system level, and this effect may not be limited to cortical and subcortical representations of the treated muscles. The results show that abnormalities in sensorimotor activation extend beyond circuits controlling the affected body parts in CD even the first BoNT injection is associated with changes in sensorimotor activation. The differences in activation between patients with CD after treatment and healthy controls at baseline were no longer present.

Enhanced Topological Network Efficiency in Preschool Autism Spectrum Disorder: A Diffusion Tensor Imaging Study.

Background: The functional mechanism behind autism spectrum disorder (ASD) is not clear, but it is related to a brain connectivity disorder. Previous studies have found that functional brain connectivity of ASD is linked to both increased connections and weakened connections, and the inconsistencies in functional brain connectivity may be related to age. The functional connectivity in adolescents and adults with ASD is generally less than in age-matched controls; functional connectivity in younger children with the disorder appears to be higher. As the basis of the functional network, the structural network is less studied. This study intends to further study the pathogenesis of ASD by analyzing the white matter network of ASD preschool children.Materials and Methods: In this study, Diffusion Tensor Imaging (DTI) was used to scan preschool children (aged 2–6 years, 39 children with ASD, 19 children as controls), and graph theory was used for analysis.Result: Enhanced topological network efficiency was found in the preschool children with ASD. A higher nodal efficiency was found in the left precuneus, thalamus, and bilateral superior parietal cortex, and the nodal efficiency of the left precuneus was positively associated with the severity of ASD.Conclusion: Our research shows the white matter network efficiency of preschoolers with ASD. It supports the theory of excessive early brain growth in ASD, and it shows left brain lateralization. It opens the way for new research perspectives of children with ASD.

Neural Correlates underlying Size Constancy in Virtual Three-Dimensional Space

The perceived size of an object remains relatively constant although its retinal size keeps decreasing as the object moves away along the depth dimension of the 3D space, i.e. size constancy. Neural mechanisms generating size constancy in virtual 3D space, however, remain poorly understood. By constructing a virtual 3D world in the MR scanner, we positioned the same 3D objects either near or far from the observers so that the near and far objects were perceived as having the same physical size despite their differences in retinal size. To control for the effect of differential retinal size, an additional 2D condition was introduced: a large and a small object, with matched retinal images as the near and far objects in the 3D condition, respectively, were presented on a 2D screen. Differences in retinal size activated overlapped areas in bilateral inferior occipital gyrus (IOG) in both experiments. The overlapped areas in IOG, however, showed different patterns of functional connectivity with different neural networks, depending on the perceived size of objects. In particular, IOG showed enhanced connectivity with bilateral superior parietal cortex in the 2D condition, but with inferior temporal and prefrontal cortex in the virtual 3D condition, i.e., size constancy.

Treatment effect of methylphenidate on intrinsic functional brain network in medication-naïve ADHD children: A multivariate analysis

Methylphenidate is a first-line therapeutic option for treating attention-deficit/hyperactivity disorder (ADHD); however, elicited changes on resting-state functional networks (RSFNs) are not well understood. This study investigated the treatment effect of methylphenidate using a variety of RSFN analyses and explored the collaborative influences of treatment-relevant RSFN changes in children with ADHD. Resting-state functional magnetic resonance imaging was acquired from 20 medication-naïve ADHD children before methylphenidate treatment and twelve weeks later. Changes in large-scale functional connectivity were defined using independent component analysis with dual regression and graph theoretical analysis. The amplitude of low frequency fluctuation (ALFF) was measured to investigate local spontaneous activity alteration. Finally, significant findings were recruited to random forest regression to identify the feature subset that best explains symptom improvement. After twelve weeks of methylphenidate administration, large-scale connectivity was increased between the left fronto-parietal RSFN and the left insula cortex and the right fronto-parietal and the brainstem, while the clustering coefficient (CC) of the global network and nodes, the left fronto-parietal, cerebellum, and occipital pole-visual network, were decreased. ALFF was increased in the bilateral superior parietal cortex and decreased in the right inferior fronto-temporal area. The subset of the local and large-scale RSFN changes, including widespread ALFF changes, the CC of the global network and the cerebellum, could explain the 27.1% variance of the ADHD Rating Scale and 13.72% of the Conner's Parent Rating Scale. Our multivariate approach suggests that the neural mechanism of methylphenidate treatment could be associated with alteration of spontaneous activity in the superior parietal cortex or widespread brain regions as well as functional segregation of the large-scale intrinsic functional network.

Attenuation of cortical activity triggering descending pain inhibition in chronic low back pain patients: a functional magnetic resonance imaging study

A considerable portion of chronic low back pain (cLBP) patients lack anatomical abnormality, resist conventional therapeutic interventions, and their symptoms are often complicated with psychological and social factors. Such patients have been reported to show cerebral abnormalities both in anatomy and function by neuroimaging studies. Here we examined differences in cerebral reactivity to a simulated low back pain stimulus between cLBP patients and healthy controls by functional magnetic resonance imaging (fMRI), and their behavioral correlates from a psychophysical questionnaire. Eleven cLBP patients and 13 healthy subjects (HS) were enrolled in this study. After psychophysical evaluation on-going pain with McGill Pain Questionnaire Short Form (MPQ), they underwent whole-brain fMRI in a 3-Tesla MRI scanner while receiving three blocks of 30-s mechanical pain stimuli at the left low back with a 30-s rest in between, followed by a three-dimensional anatomical imaging. Functional images were analyzed with a multi-subject general linear model for blood oxygenation level-dependent (BOLD) signal changes associated with pain. Individual BOLD signal amplitudes at activated clusters were examined for correlation with psychophysical variables. Two in the cLBP and five data sets in the HS groups were excluded from analysis because of deficient or artifactual data or mismatch in age. The HS group showed LBP-related activation at the right insular cortex, right dorsolateral prefrontal cortex (DLPFC), left anterior cingulate cortex (ACC), and left precuneus; and deactivation in a large area over the parietal and occipital cortices, including the bilateral superior parietal cortex. On the other hand, the cLBP group did not show any significant activation at those cortical areas, but showed similar deactivation at the bilateral superior parietal cortex and part of the premotor area. An HS>cLBP contrast revealed significantly less activity at the ACC and DLPFC in the cLBP group, which was negatively correlated with higher MPQ scores. The cLBP patients showed attenuated reactivity to pain at the ACC and DLPFC, known cortical areas mediating affective component, and top-down modulation, of pain. The present results might be associated with possible dysfunction of the descending pain inhibitory system in patients with chronic low back pain, which might possibly play a role in chronification of pain.

P126 Spatiotemporal and task dependence of broadband aftereffects observed following parietal 10-Hz tACS: A MEG study

Introduction Rhythmic tACS is known to entrain brain oscillations. Less well characterized are aftereffects of tACS that may result from stimulation-driven entrainment and/or cross-frequency coupling or more generally from broadband responses determined by intrinsic and/or task-dependent local and brain network properties ( Veniero2015 ). Objective To characterize aftereffects of 10-Hz tACS within multiple cortical and subcortical brain regions. Materials & methods 10-Hz active (1 mA, 20 min) and sham (1 mA, 30 s) tACS was applied in separate experimental sessions over bilateral parietal cortex (P3/P4) during performance of a visual global/local attention task. Structural MRI/MEG data were obtained from 8 healthy adult participants. Images presented were “global” letters (H or S) composed of smaller, “local” letters (H or S). A visual cue switched motor responses between global and local features. MEG data were cleaned with Elekta Neuromag MaxFilterTM. Brainstorm was used to remove eyeblink and cardiac artifacts and to extract Morlet time–frequency (TF) waveforms for brain regions in the Desikan-Killany atlas. Power TF plots were averaged across participants and compared (active vs. sham, t-test p 0.05) for a subset of 1612 sham/active global/local trials recorded ∼5 and ∼10 min post stimulation. Results Significant increases in alpha and beta were seen in bilateral inferior parietal cortex, with increased left hemisphere gamma for “local” but not “global” trials. Task-related decreased activation at alpha, beta, ∼30 Hz and gamma was observed in left hippocampus for both “local” and “global” trials. Aftereffects were also observed in bilateral superior parietal, superior frontal and lateral occipital cortex as well as medial orbitofrontal cortex, precuneus and cerebellum. Conclusion We found complex frequency- and task-dependence of oscillatory activity following 10-Hz tACS, supporting the notion that aftereffects are modulated by intrinsic and/or task-dependent local and network properties. Download : Download high-res image (210KB) Download : Download full-size image Download : Download high-res image (227KB) Download : Download full-size image

Common and distinct brain networks underlying verbal and visual creativity.

Creativity is imperative to the progression of human civilization, prosperity, and well-being. Past creative researches tends to emphasize the default mode network (DMN) or the frontoparietal network (FPN) somewhat exclusively. However, little is known about how these networks interact to contribute to creativity and whether common or distinct brain networks are responsible for visual and verbal creativity. Here, we use functional connectivity analysis of resting-state functional magnetic resonance imaging data to investigate visual and verbal creativity-related regions and networks in 282 healthy subjects. We found that functional connectivity within the bilateral superior parietal cortex of the FPN was negatively associated with visual and verbal creativity. The strength of connectivity between the DMN and FPN was positively related to both creative domains. Visual creativity was negatively correlated with functional connectivity within the precuneus of the pDMN and right middle frontal gyrus of the FPN, and verbal creativity was negatively correlated with functional connectivity within the medial prefrontal cortex of the aDMN. Critically, the FPN mediated the relationship between the aDMN and verbal creativity, and it also mediated the relationship between the pDMN and visual creativity. Taken together, decreased within-network connectivity of the FPN and DMN may allow for flexible between-network coupling in the highly creative brain. These findings provide indirect evidence for the cooperative role of the default and executive control networks in creativity, extending past research by revealing common and distinct brain systems underlying verbal and visual creative cognition. Hum Brain Mapp 38:2094-2111, 2017. © 2017 Wiley Periodicals, Inc.

Fronto-Parietal Contributions to Phonological Processes in Successful Artificial Grammar Learning.

Sensitivity to regularities plays a crucial role in the acquisition of various linguistic features from spoken language input. Artificial grammar learning paradigms explore pattern recognition abilities in a set of structured sequences (i.e., of syllables or letters). In the present study, we investigated the functional underpinnings of learning phonological regularities in auditorily presented syllable sequences. While previous neuroimaging studies either focused on functional differences between the processing of correct vs. incorrect sequences or between different levels of sequence complexity, here the focus is on the neural foundation of the actual learning success. During functional magnetic resonance imaging (fMRI), participants were exposed to a set of syllable sequences with an underlying phonological rule system, known to ensure performance differences between participants. We expected that successful learning and rule application would require phonological segmentation and phoneme comparison. As an outcome of four alternating learning and test fMRI sessions, participants split into successful learners and non-learners. Relative to non-learners, successful learners showed increased task-related activity in a fronto-parietal network of brain areas encompassing the left lateral premotor cortex as well as bilateral superior and inferior parietal cortices during both learning and rule application. These areas were previously associated with phonological segmentation, phoneme comparison, and verbal working memory. Based on these activity patterns and the phonological strategies for rule acquisition and application, we argue that successful learning and processing of complex phonological rules in our paradigm is mediated via a fronto-parietal network for phonological processes.

Widespread structural brain involvement in ALS is not limited to the C9orf72 repeat expansion

BackgroundIn patients with a C9orf72 repeat expansion (C9+), a neuroimaging phenotype with widespread structural cerebral changes has been found. We aimed to investigate the specificity of this neuroimaging phenotype in...

The neural circuits recruited for the production of signs and fingerspelled words

Signing differs from typical non-linguistic hand actions because movements are not visually guided, finger movements are complex (particularly for fingerspelling), and signs are not produced as holistic gestures. We used positron emission tomography to investigate the neural circuits involved in the production of American Sign Language (ASL). Different types of signs (one-handed (articulated in neutral space), two-handed (neutral space), and one-handed body-anchored signs) were elicited by asking deaf native signers to produce sign translations of English words. Participants also fingerspelled (one-handed) printed English words. For the baseline task, participants indicated whether a word contained a descending letter. Fingerspelling engaged ipsilateral motor cortex and cerebellar cortex in contrast to both one-handed signs and the descender baseline task, which may reflect greater timing demands and complexity of handshape sequences required for fingerspelling. Greater activation in the visual word form area was also observed for fingerspelled words compared to one-handed signs. Body-anchored signs engaged bilateral superior parietal cortex to a greater extent than the descender baseline task and neutral space signs, reflecting the motor control and proprioceptive monitoring required to direct the hand toward a specific location on the body. Less activation in parts of the motor circuit was observed for two-handed signs compared to one-handed signs, possibly because, for half of the signs, handshape and movement goals were spread across the two limbs. Finally, the conjunction analysis comparing each sign type with the descender baseline task revealed common activation in the supramarginal gyrus bilaterally, which we interpret as reflecting phonological retrieval and encoding processes.