Bilateral Parietal Regions Research Articles

Comparison of changes in oxygenated hemoglobin during the tree-drawing task between patients with schizophrenia and healthy controls.

BackgroundTree-drawing test is used as a projective psychological test that expresses the abnormal internal experience in patients with schizophrenia (SZ). Despite the widely accepted view that the cognitive function is involved in characteristic tree-drawing in patients with SZ, no study has psychophysiologically examined it. The present study aimed to investigate the involvement of cognitive function during tree-drawing in patients with SZ. For that purpose, we evaluated the brain function in patients with SZ during a tree-drawing task by using near-infrared spectroscopy (NIRS) and compared them with those in healthy controls.Patients and methodsThe subjects were 28 healthy controls and 28 patients with SZ. Changes in the oxygenated hemoglobin ([oxy-Hb]) concentration in both the groups during the task of drawing a tree imagined freely (free-drawing task) and the task of copying an illustration of a tree (copying task) were measured by using NIRS.ResultsBecause of the difference between the task conditions, [oxy-Hb] levels in controls during the free-drawing task were higher than that during the copying task at the bilateral frontal pole regions and left inferior frontal region. Because of the difference between the groups, [oxy-Hb] levels at the left middle frontal region, bilateral inferior frontal regions, bilateral inferior parietal regions, and left superior temporal region during the free-drawing task in patients were lower than that in controls.Conclusion[oxy-Hb] during the tree-drawing task in patients with SZ was lower than that in healthy controls. Our results suggest that brain dysfunction in patients with SZ might be associated with their tree-drawing.

S178. ALTERED GYRIFICATION IN THE SCHIZOPHRENIA SPECTRUM

BackgroundIncreased gyrification in diverse cortical areas has been reported in patients with schizophrenia, which is considered to reflect deviations in early neurodevelopment. Schizotypal personality disorder (SPD) is thought to be a prototypic disorder within the schizophrenia spectrum, which shares biological and psychological commonalities with schizophrenia as a neurobiological basis for vulnerability factors. However, to the best of our knowledge, no magnetic resonance imaging (MRI) studies have investigated the gyrification pattern in SPD.MethodsT1-weighted structural MRI scans were obtained by 1.5-T scanner from 101 patients with schizophrenia, 46 patients with SPD, and 77 age- and gender- matched healthy control subjects. Using FreeSurfer software (version 5.3.), the local gyrification indices (LGIs) of entire cortex were obtained with the method of Schaer and colleagues. Clinical symptoms of the patients were rated with the Scale for the Assessment of Positive Symptoms (SAPS) and the Scale for the Assessment of Negative Symptoms (SANS) at the time of scanning. A general linear model controlling for age, gender, medication dose, and duration of medication was used to compare the LGIs across the groups and to conduct vertex-by-vertex whole brain LGI correlation analyses with clinical variables. This study was approved by the Committee on the Medical Ethics of Toyama University based on the declaration of Helsinki. After a complete description of the study was provided, written informed consent was obtained from all subjects.ResultsCompared with the controls, the patients with schizophrenia showed significantly higher LGI in widespread cortical areas including the bilateral frontal, parietal, and occipital regions. The patients with SPD demonstrated significantly higher LGI in the bilateral frontal and left parietal regions compared with the controls. Compared with the patients with SPD, the patients with schizophrenia showed significantly higher LGI in the left occipital and right frontal regions. Both SAPS and SANS total scores were positively correlated with LGI in the bilateral temporal regions in patients with schizophrenia, and were negatively correlated with LGI in the bilateral occipital regions in patients with SPD.DiscussionIncreased LGI in the bilateral frontal regions may be the common morphological substrates for the schizophrenia spectrum, possibly representing vulnerability to schizophrenia. In addition, increased LGI in the left occipital and right frontal regions preferentially observed in schizophrenia may have a critical role in manifestation of florid psychotic symptoms.

Brain perfusion alterations in tick-borne encephalitis—preliminary report

BackgroundMagnetic resonance imaging (MRI) changes in tick-borne encephalitis (TBE) are non-specific and the pathophysiological mechanisms leading to their formation remain unclear. This study investigated brain perfusion in TBE patients using dynamic susceptibility-weighted contrast-enhanced magnetic resonance perfusion imaging (DSC-MRI perfusion). MethodsMRI scans were performed for 12 patients in the acute phase, 3–5days after the diagnosis of TBE. Conventional MRI and DSC-MRI perfusion studies were performed. Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP) parametric maps were created. The bilateral frontal, parietal, and temporal subcortical regions and thalamus were selected as regions of interest. Perfusion parameters of TBE patients were compared to those of a control group. ResultsThere was a slight increase in CBF and CBV, with significant prolongation of TTP in subcortical areas in the study subjects, while MTT values were comparable to those of the control group. A significant increase in thalamic CBF (p<0.001) and increased CBV (p<0.05) were observed. Increased TTP and a slight reduction in MTT were also observed within this area. ConclusionsThe DSC-MRI perfusion study showed that TBE patients had brain perfusion disturbances, expressed mainly in the thalami. These results suggest that DSC-MRI perfusion may provide important information regarding the areas affected in TBE patients.

Quality of frequency-following response to speech sounds linked with left prefrontal hemodynamic activity using fNIRS+EEG

Quality of frequency-following response to speech sounds linked with left prefrontal hemodynamic activity using fNIRS+EEG

Food-related salience processing in healthy subjects during word recognition: Fronto-parietal network activation as revealed by independent component analysis.

BackgroundThe study aimed to isolate and localize mutually independent cognitive processes evoked during a word recognition task involving food‐related and food‐neutral words using independent component analysis (ICA) for continuously recorded EEG data. Recognition memory (old/new effect) involves cognitive subcomponents—familiarity and recollection—which may be temporally and spatially dissociated in the brain. Food words may evoke additional attentional salience which may interact with the old/new effect.MethodsSixteen satiated female participants undertook a word recognition task consisting of an encoding phase (learning of presented words, 40 food‐related and 40 food neutral) and a test phase (recognition of previously learned words and new words). Simultaneously recorded 64‐channel EEG data were decomposed into mutually independent components using the Infomax algorithm in EEGLAB. The components were localized using single dipole fitting using a four‐shell BESA head model. The resulting (nonartefactual) components with <15% residual variance were clustered across subjects using the kmeans algorithm resulting in five meaningful clusters localized to fronto‐parietal regions. Repeated‐measures anova was employed to test main effects (old/new and food relevance) and their interaction on cluster time courses.ResultsEarly task‐relevant old/new effects were localized to the medial frontal gyrus (MFG) and later old/new effects to the right parietal regions (precuneus). Food‐related (nontask‐relevant) salience effects were localized to bilateral parietal regions (left precuneus and right postcentral gyrus). Food‐related salience interacted with task relevance, the old/new effect in MFG being significant only for food‐neutral words highlighting central the role of MFG as the converging site of endogenous and exogenous salience inputs.ConclusionOur results indicate ICA to be a valid technique to decompose complex neurophysiological signals involving multiple cognitive processes and implicate the fronto‐parietal network as an important attentional network for processing salience and task demands.

Altered brain morphometry in 7-year old HIV-infected children on early ART.

Even with the increased roll out of combination antiretroviral therapy (cART), paediatric HIV infection is associated with neurodevelopmental delays and neurocognitive deficits that may be accompanied by alterations in brain structure. Few neuroimaging studies have been done in children initiating ART before 2years of age, and even fewer in children within the critical stage of brain development between 5 and 11years. We hypothesized that early ART would limit HIV-related brain morphometric deficits at age 7. Study participants were 7-year old HIV-infected (HIV+) children from the Children with HIV Early Antiretroviral Therapy (CHER) trial whose viral loads were supressed at a young age, and age-matched uninfected controls. We used structural magnetic resonance imaging (MRI) and FreeSurfer ( http://www.freesurfer.net/ ) software to investigate effects of HIV and age at ART initiation on cortical thickness, gyrification and regional brain volumes. HIV+ children showed reduced gyrification compared to controls in bilateral medial parietal regions, as well as reduced volumes of the right putamen, left hippocampus, and global white and gray matter and thicker cortex in small lateral occipital region. Earlier ART initiation was associated with lower gyrification and thicker cortex in medial frontal regions. Although early ART appears to preserve cortical thickness and volumes of certain brain structures, HIV infection is nevertheless associated with reduced gyrification in the parietal cortex, and lower putamen and hippocampus volumes. Our results indicate that in early childhood gyrification is more sensitive than cortical thickness to timing of ART initiation. Future work will clarify the implications of these morphometric effects for neuropsychological function.

Asymmetric oculomotor apraxia, optic ataxia, and simultanagnosia with right hemispatial neglect from a predominantly left-sided lesion of the parieto-occipital area

ABSTRACTIntroduction: Bálint’s syndrome involves bilateral damage to the parieto-occipital area. The extent of the effect of unilateral damage on the Bálint’s triad (oculomotor apraxia, optic ataxia, and simultanagnosia) remains unknown.Methods: We examined a 63-year-old, right-handed woman who developed right hemianopia, oculomotor apraxia, optic ataxia, simultanagnosia, and hemispatial neglect (HSN) for the right after a cerebral infarction, with detailed neuropsychological tests, magnetic resonance imaging, and single photon emission computed tomography (SPECT).Results: Neuropsychological examination showed that oculomotor apraxia, optic ataxia, and simultanagnosia were more pronounced in the right hemi-space, probably due to the limited eye movement in the right visual field, whereas HSN was restricted to the right hemi-space. Diffusion-weighted MR images revealed hyperintensity in the left parieto-temporo-occipital region, and several spotty areas of the bilateral frontal and parietal subcortical regions. SPECT revealed hypoperfusion in the left parieto-occipital region and frontal operculum and small areas of the right superior parietal lobule.Conclusions: The case suggests that asymmetric (more pronounced in the right hemi-space) oculomotor apraxia, optic ataxia, and simultanagnosia occur in an extensive lesion of the left parieto-occipital cortices. Although HSN is not a prerequisite for simultanagnosia, the coexistence of HSN aggravates simultanagnosia in the hemi-space opposite the lesion.

The neural development of conditional reasoning in children: Different mechanisms for assessing the logical validity and likelihood of conclusions

Scientific and mathematical thinking relies on the ability to evaluate whether conclusions drawn from conditional (if-then) arguments are logically valid. Yet, the neural development of this ability -- termed deductive reasoning -- is largely unknown. Here we aimed to identify the neural mechanisms that underlie the emergence of deductive reasoning with conditional rules in children. We further tested whether these mechanisms have their roots in the neural mechanisms involved in judging the likelihood of conclusions. In a functional Magnetic Resonance Imaging (fMRI) scanner, 8- to 13-year-olds were presented with causal conditional problems such as “If a baby is hungry then he will start crying; The baby is crying; Is the baby hungry?”. In Validity trials, children were asked to indicate whether the conclusion followed out of necessity from the premises. In Likelihood trials, they indicated the degree of likelihood of the conclusion. We found that children who made accurate judgments of logical validity (as compared to those who did not) exhibited enhanced activity in left and medial frontal regions. In contrast, differences in likelihood ratings between children were related to differences of activity in right frontal and bilateral parietal regions. There was no overlap between the brain regions underlying validity and likelihood judgments. Therefore, our results suggest that the ability to evaluate the logical validity of conditional arguments emerges from brain mechanisms that qualitatively differ from those involved in evaluating the likelihood of these arguments in children.

Domain-General Brain Regions Do Not Track Linguistic Input as Closely as Language-Selective Regions.

Language comprehension engages a cortical network of left frontal and temporal regions. Activity in this network is language-selective, showing virtually no modulation by nonlinguistic tasks. In addition, language comprehension engages a second network consisting of bilateral frontal, parietal, cingulate, and insular regions. Activity in this "multiple demand" (MD) network scales with comprehension difficulty, but also with cognitive effort across a wide range of nonlinguistic tasks in a domain-general fashion. Given the functional dissociation between the language and MD networks, their respective contributions to comprehension are likely distinct, yet such differences remain elusive. Prior neuroimaging studies have suggested that activity in each network covaries with some linguistic features that, behaviorally, influence on-line processing and comprehension. This sensitivity of the language and MD networks to local input characteristics has often been interpreted, implicitly or explicitly, as evidence that both networks track linguistic input closely, and in a manner consistent across individuals. Here, we used fMRI to directly test this assumption by comparing the BOLD signal time courses in each network across different people (n = 45, men and women) listening to the same story. Language network activity showed fewer individual differences, indicative of closer input tracking, whereas MD network activity was more idiosyncratic and, moreover, showed lower reliability within an individual across repetitions of a story. These findings constrain cognitive models of language comprehension by suggesting a novel distinction between the processes implemented in the language and MD networks.SIGNIFICANCE STATEMENT Language comprehension recruits both language-specific mechanisms and domain-general mechanisms that are engaged in many cognitive processes. In the human cortex, language-selective mechanisms are implemented in the left-lateralized "core language network", whereas domain-general mechanisms are implemented in the bilateral "multiple demand" (MD) network. Here, we report the first direct comparison of the respective contributions of these networks to naturalistic story comprehension. Using a novel combination of neuroimaging approaches we find that MD regions track stories less closely than language regions. This finding constrains the possible contributions of the MD network to comprehension, contrasts with accounts positing that this network has continuous access to linguistic input, and suggests a new typology of comprehension processes based on their extent of input tracking.

Inter-brain network underlying turn-based cooperation and competition: A hyperscanning study using near-infrared spectroscopy

The present study examined neural substrates underlying turn-based cooperation and competition in a real two-person situation. We simultaneously measured pairs of participants’ activations in their bilateral frontal, temporal, and parietal regions using a 96-channel near-infrared spectroscopy (NIRS) system, when participants played a turn-taking disk-game on a computer. NIRS data demonstrated significant inter-brain neural synchronization (INS) across participant pairs’ right posterior superior temporal sulcus (pSTS) in both the cooperation and competition conditions, and the competition condition also involved significant INS in the right inferior parietal lobule (IPL). In addition, competitive dyads’ INS in the bilateral inferior frontal gyrus (IFG) may play as a role of mediation in relationship between their empathy score and disk-manipulation latency, but cooperative dyads’ INS did not. These results suggest that first the right pSTS may be commonly involved in both cooperation and competition due to task demands of joint attention and intention understanding, while the right IPL may be more important for competition due to additional requirements of mentalizing resources in competing contexts. Second, participants’ empathy may promote INS in the bilateral IFG across competitors, and in turn affect their competitive performance.

Overlap between frontotemporal dementia and Alzheimer’s disease: case report

The &lt;em&gt;frontal variant of Alzheimer’s disease&lt;/em&gt; (fv-AD) has been described in patients with prominent behavioral or executive dysfunctions. Subsequently, the spectrum of frontal variant Alzheimer’s disease has been enlarged to comprise patients with early personality and behavioral changes including disinhibition, apathy or compulsiveness. We describe the case of a patient with a history of memory loss and behavioral changes. The neuropsychological profile overlapped with the presence of behavioral disorders such as marked apathy, disinhibition, hostile behavior, agitation, irritability and hyperorality. The results of the neuropsychological examination leaned towards a diagnosis of frontotemporal circuit functional impairment, however, the 18-FDG PET study demonstrated a moderate-to-severe impairment in the bilateral parietal regions. On the basis of the neuropsychological profile and 18-FDG PET imaging, a diagnosis of a probable fv-AD was made, the patient started oral rivastigmine 3 mg/daily and subsequent assessments showed only modest worsening in the cognitive profile and a moderate improvement in behavioral symptoms.

Increased Occipital Gyrification and Development of Psychotic Disorders in Individuals With an At-Risk Mental State: A Multicenter Study

BackgroundAnomalies of brain gyrification have been reported in schizophrenia, possibly reflecting its neurodevelopmental pathology. However, it remains elusive whether individuals at risk for psychotic disorders exhibit deviated gyrification patterns, and whether such findings, if present, are predictive of transition to psychotic disorders. MethodsThis multicenter magnetic resonance imaging study investigated brain gyrification and its relationship to later transition to psychotic disorders in a large sample of at-risk mental state (ARMS) individuals. T1-weighted magnetic resonance imaging scans were obtained from 104 ARMS individuals, of whom 21 (20.2%) exhibited the transition to psychotic disorders during clinical follow-up (mean = 4.9 years, SD = 2.6 years), and 104 healthy control subjects at 4 different sites. The local gyrification index (LGI) of the entire cortex was compared across the groups using FreeSurfer software. ResultsCompared with the control subjects, ARMS individuals showed a significantly higher LGI in widespread cortical areas, including the bilateral frontal, temporal, parietal, and occipital regions, which was partly associated with prodromal symptomatology. ARMS individuals who exhibited the transition to psychotic disorders showed a significantly higher LGI in the left occipital region compared with individuals without transition. ConclusionsThese findings suggested that increased LGI in diverse cortical regions might represent vulnerability to psychopathology, while increased LGI in the left occipital cortex might be related to subsequent manifestation of florid psychotic disorders as a possible surrogate marker.

Neural activity during attentional conflict predicts reduction in tinnitus perception following rTMS

BackgroundSubjective idiopathic tinnitus is an intrusive, distracting, and potentially disabling disorder characterized by phantom perception of sounds. Although tinnitus has no approved pharmacologic treatment, recent evidence supports the use of repetitive transcranial magnetic stimulation (rTMS) to alleviate tinnitus symptoms. Objective/HypothesisRepetitive TMS delivered over the middle superior temporal gyrus (STG) may alter ratings of tinnitus awareness and annoyance more than loudness due to change in attentional processing. STG has reciprocal connections to regions of the prefrontal cortex that mediate attention. To probe the hypothesized influence of STG stimulation on attention, a subset of patients with tinnitus enrolled in an rTMS clinical trial [n = 12, 9 male, mean (sd) age = 49 (15) years] underwent an attentional conflict task before and after rTMS treatment in a repeated-measures functional magnetic resonance imaging (fMRI) study. MethodsThe Multi-Source Interference Task (MSIT), a Stroop-based visual attentional conflict fMRI task, was used to map participants' neural processing of attentional conflict prior to rTMS intervention (Baseline) and after three rTMS intervention arms: Sham, 1 Hz, and 10 Hz (four sessions per arm, 1800 pulses per session, delivered @110% of the motor threshold over the posterior superior temporal gyrus). ResultsAll measures of tinnitus severity (awareness, loudness, and annoyance) improved with 1 Hz rTMS intervention; however, the greatest and most robust changes were observed for ratings of tinnitus awareness (mean 16% reduction in severity from Baseline, p < 0.01). The MSIT elicited a similar pattern of neural activation among tinnitus participants at Baseline compared to an independent sample of 43 healthy comparison adults (r = 0.801, p = 0.001). Linear regression with bootstrap resampling showed that greater recruitment of bilateral prefrontal and bilateral parietal regions by MSIT at Baseline corresponded with poorer treatment response. Individual regions' activities explained 37–67% variance in participant treatment response, with left dorsolateral prefrontal cortex's MSIT activity at Baseline explaining the greatest reduction in tinnitus awareness following 1 Hz stimulation. Although left dorsolateral prefrontal cortex activity at Baseline also predicted reduction in tinnitus loudness and annoyance (∼50% variance explained), these symptoms were more strongly predicted by right middle occipital cortex (∼70% variance explained) – suggesting that the neural predictors of symptom-specific treatment outcomes may be dissociable. ConclusionThese candidate neural reactivity markers of treatment response have potential clinical value in identifying tinnitus sufferers who would or would not therapeutically benefit from rTMS intervention.

Altered resting-state EEG complexity in children with Tourette syndrome: A preliminary study.

Tourette syndrome is a developmental neuropsychiatric disorder in children, and abnormal corticobasal ganglion connectivity is implied for the pathophysiology. Multiscale entropy, an entropy-based method to measure dynamic complexity at multiple temporal scales, is helpful to disclose the information of brain connectivity. This preliminary study investigated the complexity of resting-state electroencephalogram signals using multiscale entropy in children with Tourette syndrome. Resting-state electroencephalographic (EEG) signals were analyzed by sample entropy and multiscale entropy methods in 10 children with Tourette syndrome and 10 healthy gender- and age-matched controls. Except for the Fp2 channel, the complexity index values in all channels were reduced in children with Tourette syndrome compared with those in normal controls. A statistically significant reduction in EEG complexity was found in the bilateral central, parietal, occipital, and left temporal regions, indicating disturbed brain connectivity in Tourette syndrome. Although there was no difference of complexity in the higher frequency spectra, there was a statistically significant difference of complexity in lower frequency in F3 channel, pointing to the importance of examining a range of time scales in exploring EEG signals. Our preliminary study demonstrated that EEG complexity was significantly lower in children with Tourette syndrome than in normal controls. This difference may serve as a marker of disturbed brain connectivity in such individuals and suggests that further clinical studies are warranted. (PsycINFO Database Record

Restriction Spectrum Imaging As a Potential Measure of Cortical Neurite Density in Autism.

Autism postmortem studies have shown various cytoarchitectural anomalies in cortical and limbic areas including increased cell packing density, laminar disorganization, and narrowed minicolumns. However, there is little evidence on dendritic and axonal organization in ASD. Recent imaging techniques have the potential for non-invasive, in vivo studies of small-scale structure in the human brain, including gray matter. Here, Restriction Spectrum Imaging (RSI), a multi-shell diffusion-weighted imaging technique, was used to examine gray matter microstructure in 24 children with ASD (5 female) and 20 matched typically developing (TD) participants (2 female), ages 7–17 years. RSI extends the spherical deconvolution model to multiple length scales to characterize neurite density (ND) and organization. Measures were examined in 48 cortical regions of interest per hemisphere. To our knowledge, this is the first time that a multi-compartmental diffusion model has been applied to cortical gray matter in ASD. The ND measure detected robust age effects showing a significant positive relationship to age in all lobes except left temporal when groups were combined. Results were also suggestive of group differences (ASD<TD) in anterior cingulate, right superior temporal lobe and much of the parietal lobes, but these fell short of statistical significance. For MD, significant group differences (ASD>TD) in bilateral parietal regions as well as widespread age effects were detected. Our findings support the value of multi-shell diffusion imaging for assays of cortical gray matter. This approach has the potential to add to postmortem literature, examining intracortical organization, intracortical axonal content, myelination, or caliber. Robust age effects further support the validity of the ND metric for in vivo examination of gray matter microstructure in ASD and across development. While diffusion MRI does not approach the precision of histological studies, in vivo imaging measures of microstructure can complement postmortem studies, by allowing access to large sample sizes, a whole-brain field of view, longitudinal designs, and combination with behavioral and functional assays. This makes multi-shell diffusion imaging a promising technique for understanding the underlying cytoarchitecture of the disorder.

A Simplified Electroencephalogram Monitoring System in the Emergency Room.

The study aims to assess the clinical usefulness and related limitations of our simplified emergency electroencephalography (eEEG) as an assessment tool of lethal abnormal brain waves in the emergency room (ER). Electrodes were placed on 4 places: bilateral frontal poles and parietal regions. The derivations to judge consisted of only 2 bipolar leads on the left and right. Abnormal wave was defined as either persistent rhythmic waves or persistent high-amplitude slow waves (<2 Hz). The indications of eEEG were as follows: prolonged impairment of consciousness, suspected subclinical or subtle seizure, and requirement of evaluation of consciousness or seizure during administration of muscle relaxants for endotracheal intubation. We performed eEEG for 86 patients between July 2013 and February 2014. The persistent rhythmic waves were observed in 7 (8.1%), whereas high-amplitude slow waves were observed in 10 (11.6%). Among 69 patients with normal eEEG, 2 were diagnosed with encephalopathy after hospitalization. The mean time taken to attach electrodes was 5.4 minutes. For the ER physician, the simple EEG, such as eEEG, is useful as a biological monitor because it enables quick assessment of lethal abnormal brain waves in the ER. The clinical usefulness and limitations of our eEEG method should be investigated further in a large population.

In need of constraint: Understanding the role of the cingulate cortex in the impulsive mind

Impulsive behavior often occurs without forethought and can be driven by strong emotions or sudden impulses, leading to problems in cognition and behavior across a wide range of situations. Although neuroimaging studies have explored the neurocognitive indicators of impulsivity, the large-scale functional networks that contribute to different aspects of impulsive cognition remain unclear. In particular, we lack a coherent account of why impulsivity is associated with such a broad range of different psychological features. Here, we use resting state functional connectivity, acquired in two independent samples, to investigate the neural substrates underlying different aspects of self-reported impulsivity. Based on the involvement of the anterior cingulate cortex (ACC) in cognitive but also affective processes, five seed regions were placed along the caudal to rostral gradient of the ACC. We found that positive urgency was related to functional connectivity between subgenual ACC and bilateral parietal regions such as retrosplenial cortex potentially highlighting this connection as being important in the modulation of the non-prospective, hastiness – related aspects of impulsivity. Further, two impulsivity dimensions were associated with significant alterations in functional connectivity of the supragenual ACC: (i) lack of perseverance was positively correlated to connectivity with the bilateral dorsolateral prefrontal cortex and right inferior frontal gyrus and (ii) lack of premeditation was inversely associated with functional connectivity with clusters within bilateral occipital cortex. Further analysis revealed that these connectivity patterns overlapped with bilateral dorsolateral prefrontal and bilateral occipital regions of the multiple demand network, a large-scale neural system implicated in the general control of thought and action. Together these results demonstrate that different forms of impulsivity have different neural correlates, which are linked to the functional connectivity of a region of anterior cingulate cortex. This suggests that poor perseveration and premeditation might be linked to dysfunctions in how the rostral zone of the ACC interacts with the multiple demand network that allows cognition to proceed in a controlled way.

Effects of ankyrin 3 gene risk variants on brain structures in patients with bipolar disorder and healthy subjects.

The intronic single-nucleotide polymorphism rs10994336 of the ankyrin 3 gene (ANK3 ) is one of the genome-wide supported risk variants for bipolar disorder (BD), and the T-allele of rs10761482 is also reported to have relevance to BD. We investigated the effect of ANK3 rs10761482 genetic variation on brain structure. Subjects were 43 BD patients and 229 healthy volunteers. We evaluated the effects of ANK3 rs10761482 genetic variation on diagnosis, and of the genotype-by-diagnosis interaction on the brain structure and the degree of age-related brain atrophy on magnetic resonance imaging data evaluated by voxel-based morphometry. BD patients showed significantly lower fractional anisotropy value in the bilateral parietal regions, left fronto-occipital fasciculus, and corpus callosum, compared to healthy subjects. Further, we found considerable decreases of fractional anisotropy in the forceps minor in non-T-allele BD patients compared with the T-carrier patient group. We also found significant lessening of age-related brain atrophy in the T-allele carrier groups compared with the non-T-allele carrier groups in the area around the cerebrospinal space, cingulate cortices, and cerebellum. Our results suggest the influence of the ANK3 on age-related brain atrophy. The ankyrin 3 genotype may be associated with pathogenesis of age-related neurodegeneration, and, in part, of BD.

Gamma-band activity reflects attentional guidance by facial expression

Facial expressions attract attention due to their motivational significance. Previous work focused on attentional biases towards threat-related, fearful faces, although healthy participants tend to avoid mild threat. Growing evidence suggests that neuronal gamma (>30Hz) and alpha-band activity (8–12Hz) play an important role in attentional selection, but it is unknown if such oscillatory activity is involved in the guidance of attention through facial expressions. Thus, in this magnetoencephalography (MEG) study we investigated whether attention is shifted towards or away from fearful faces and characterized the underlying neuronal activity in these frequency ranges in forty-four healthy volunteers. We employed a covert spatial attention task using neutral and fearful faces as task-irrelevant distractors and emotionally neutral Gabor patches as targets. Participants had to indicate the tilt direction of the target. Analysis of the neuronal data was restricted to the responses to target Gabor patches. We performed statistical analysis at the sensor level and used subsequent source reconstruction to localize the observed effects. Spatially selective attention effects in the alpha and gamma band were revealed in parieto-occipital regions. We observed an attentional cost of processing the face distractors, as reflected in lower task performance on targets with short stimulus onset asynchrony (SOA <150ms) between faces and targets. On the neuronal level, attentional orienting to face distractors led to enhanced gamma band activity in bilateral occipital and parietal regions, when fearful faces were presented in the same hemifield as targets, but only in short SOA trials. Our findings provide evidence that both top-down and bottom-up attentional biases are reflected in parieto-occipital gamma-band activity.

Topographical APOE ɛ4 Genotype Influence on Cerebral Metabolism in the Continuum of Alzheimer's Disease: Amyloid Burden Adjusted Analysis.

APOE ɛ4 contributes to Alzheimer's disease (AD) pathogenesis by amyloid-beta (Aβ)-dependent and Aβ-independent processes. We investigated the APOE ɛ4 influence on regional cerebral glucose metabolism (rCMglc) in the continuum of AD after Aβ adjustment. We included 318 cognitively normal (CN) elderly, 498 mild cognitive impairment (MCI), and 178 AD from the Alzheimer's Disease Neuroimaging Initiative database. They had [18F] florbetapir positron emission tomography (PET) and [18F] fluorodeoxyglucose (FDG)-PET conducted within 3 months of a clinical and cognitive assessment visit and APOE genotype. At first, the rCMglc differences between APOE ɛ4 carriers (ɛ4+) and non-carriers (ɛ4-) were estimated on a voxel-based analysis using a 'two-sample t-test' design. In the second analysis, Aβ was added as covariate. In CN, ɛ4+ showed reduced rCMglc compared to ɛ4-in the bilateral frontal, temporal, and the left parietal regions. In MCI, ɛ4+ showed reduced rCMglc compared to ɛ4- in the bilateral posterior parietal, temporal, and left frontal regions. In AD, ɛ4+ showed reduced rCMglc in the left hippocampus, right insular, and right temporal gyrus. However, after Aβ adjustment, the significant differences in the temporal regions were absent in CN and MCI, and none of the areas detected as significant in the first analysis were statistically significant in AD. Our study demonstrated that Aβ-independent APOE ɛ4 influence on rCMglc is limited to the parietal and frontal, but not temporal lobes. These results suggest that APOE ɛ4 may predispose for regional vulnerability according to Aβ-independent and Aβ-dependent processes.