Frontal Cluster Research Articles

Structural changes after videogame practice related to a brain network associated with intelligence

Here gray and white matter changes after four weeks of videogame practice were analyzed using optimized voxel-based morphometry (VBM), cortical surface and cortical thickness indices, and white matter integrity computed from several projection, commissural, and association tracts relevant to cognition. Beginning with a sample of one hundred young females, twenty right handed participants were recruited for the study and assigned to a practice or a control group carefully matched by their general cognitive ability scores. After the first scan, the practice group played ‘Professor Layton and The Pandora's Box’ 4h per week during four weeks. A second scan was obtained at the end of practice and intelligence was measured again. Image analyses revealed gray and white matter changes in the practice group. Gray matter changes theoretically relevant for intelligence were observed for the practice group mainly in frontal clusters (Brodmann areas 9 and 10) and also in smaller parietal and temporal regions. White matter findings were focused in the hippocampal cingulum and the inferior longitudinal fasciculus. These gray and white matter changes presumably induced by practice did not interact with intelligence tests' scores.

Dynamic changes of ICA-derived EEG functional connectivity in the resting state.

An emerging issue in neuroscience is how to identify baseline state(s) and accompanying networks termed "resting state networks" (RSNs). Although independent component analysis (ICA) in fMRI studies has elucidated synchronous spatiotemporal patterns during cognitive tasks, less is known about the changes in EEG functional connectivity between eyes closed (EC) and eyes open (EO) states, two traditionally used baseline indices. Here we investigated healthy subjects (n = 27) in EC and EO employing a four-step analytic approach to the EEG: (1) group ICA to extract independent components (ICs), (2) standardized low-resolution tomography analysis (sLORETA) for cortical source localization of IC network nodes, followed by (3) graph theory for functional connectivity estimation of epochwise IC band-power, and (4) circumscribing IC similarity measures via hierarchical cluster analysis and multidimensional scaling (MDS). Our proof-of-concept results on alpha-band power demonstrate five statistically clustered groups with frontal, central, parietal, occipitotemporal, and occipital sources. Importantly, during EO compared with EC, graph analyses revealed two salient functional networks with frontoparietal connectivity: a more medial network with nodes in the mPFC/precuneus which overlaps with the "default-mode network" (DMN), and a more lateralized network comprising the middle frontal gyrus and inferior parietal lobule, coinciding with the "dorsal attention network" (DAN). Furthermore, a separate MDS analysis of ICs supported the emergence of a pattern of increased proximity (shared information) between frontal and parietal clusters specifically for the EO state. We propose that the disclosed component groups and their source-derived EEG functional connectivity maps may be a valuable method for elucidating direct neuronal (electrophysiological) RSNs in healthy people and those suffering from brain disorders.

White matter microstructural alterations in migraine: A diffusion-weighted MRI study

Migraine is a common and disabling neurological disease. The pathomechanism that underlies the disorder is not entirely understood, and reliable biomarkers are missing. In the current analysis we looked for microstructural alterations of the brain white matter in migraine patients by means of diffusion-weighted magnetic resonance imaging. The measurements were carried out with a novel approach based on fine-tuned nonlinear registration and nonparametric permutation test in an alignment-invariant tract representation (Tract-Based Spatial Statistics). We found reduced fractional anisotropy in the right frontal white matter cluster of migraine patients. In the same region we also found increased mean diffusivity and increased radial diffusivity. The probabilistic tractography showed connection of this cluster to other parts of the pain network (orbitofrontal cortex, insula, thalamus, dorsal midbrain). We speculate that these findings reflect maladaptive plastic changes or white matter disintegration.

Common structural correlates of trait impulsiveness and perceptual reasoning in adolescence

Trait impulsiveness is a potential factor that predicts both substance use and certain psychiatric disorders. This study investigates whether there are common structural cerebral correlates of trait impulsiveness and cognitive functioning in a large sample of healthy adolescents from the IMAGEN project. Clusters of gray matter (GM) volume associated with trait impulsiveness, Cloningers' revised temperament, and character inventory impulsiveness (TCI-R-I) were identified in a whole brain analysis using optimized voxel-based morphometry in 115 healthy 14-year-olds. The clusters were tested for correlations with performance on the nonverbal tests (Block Design, BD; Matrix Reasoning, MT) of the Wechsler Scale of Intelligence for Children IV reflecting perceptual reasoning. Cloningers' impulsiveness (TCI-R-I) score was significantly inversely associated with GM volume in left orbitofrontal cortex (OFC). Frontal clusters found were positively correlated with performance in perceptual reasoning tasks (Bonferroni corrected). No significant correlations between TCI-R-I and perceptual reasoning were observed. The neural correlate of trait impulsiveness in the OFC matches an area where brain function has previously been related to inhibitory control. Additionally, orbitofrontal GM volume was associated with scores for perceptual reasoning. The data show for the first time structural correlates of both cognitive functioning and impulsiveness in healthy adolescent subjects.

Remitted major depression is characterized by reward network hyperactivation during reward anticipation and hypoactivation during reward outcomes

Although functional brain imaging has established that individuals with unipolar major depressive disorder (MDD) are characterized by frontostriatal dysfunction during reward processing, no research to date has examined the chronometry of neural responses to rewards in euthymic individuals with a history of MDD. A monetary incentive delay task was used during fMRI scanning to assess neural responses in frontostriatal reward regions during reward anticipation and outcomes in 19 participants with remitted major depressive disorder (rMDD) and in 19 matched control participants. During the anticipation phase of the task, the rMDD group was characterized by relatively greater activation in bilateral anterior cingulate gyrus, in right midfrontal gyrus, and in the right cerebellum. During the outcome phase of the task, the rMDD group was characterized by relatively decreased activation in bilateral orbital frontal cortex, right frontal pole, left insular cortex, and left thalamus. Exploratory analyses indicated that activation within a right frontal pole cluster that differentiated groups during reward anticipation predicted the number of lifetime depressive episodes within the rMDD group. Replication with larger samples is needed. Results suggest a double dissociation between reward network reactivity and temporal phase of the reward response in rMDD, such that rMDD is generally characterized by reward network hyperactivation during reward anticipation and reward network hypoactivation during reward outcomes. More broadly, these data suggest that aberrant frontostriatal response to rewards may potentially represent a trait marker for MDD, though future research is needed to evaluate the prospective utility of this functional neural endophenotype as a marker of MDD risk.

What's the story? The tale of reading fluency told at speed.

Fluent readers process written text rapidly and accurately, and comprehend what they read. Historically, reading fluency has been modeled as the product of discrete skills such as single word decoding. More recent conceptualizations emphasize that fluent reading is the product of competency in, and the coordination of, multiple cognitive sub-skills (a multi-componential view). In this study, we examined how the pattern of activation in core reading regions changes as the ability to read fluently is manipulated through reading speed. We evaluated 13 right-handed adults with a novel fMRI task assessing fluent sentence reading and lower-order letter reading at each participant's normal fluent reading speed, as well as constrained (slowed) and accelerated reading speeds. Comparing fluent reading conditions with rest revealed regions including bilateral occipito-fusiform, left middle temporal, and inferior frontal gyral clusters across reading speeds. The selectivity of these regions' responses to fluent sentence reading was shown by comparison with the letter reading task. Region of interest analyses showed that at constrained and accelerated speeds these regions responded significantly more to fluent sentence reading. Critically, as reading speed increased, activation increased in a single reading-related region: occipital/fusiform cortex (left > right). These results demonstrate that while brain regions engaged in reading respond selectively during fluent reading, these regions respond differently as the ability to read fluently is manipulated. Implications for our understanding of reading fluency, reading development, and reading disorders are discussed.

Detecting overlapped functional clusters in resting state fMRI with Connected Iterative Scan: A graph theory based clustering algorithm

The brain is a complex neural network with interleaving functional connectivity among anatomical regions. However, current functional parcellation algorithms usually emphasize independence or orthogonality between the spatial components, with the interleaving nature underrepresented. This study investigates a method, Connected Iterative Scan (CIS), for identifying functionally overlapped anatomical groups with resting state fMRI. CIS iteratively optimizes a grouping of vertexes in a weighted graph, using a density metric computed based on the input and output weights of a candidate cluster. In this study, CIS is able to detect the overlapped clusters in a simulated dataset. CIS also detects that the default mode network and the task positive network, which were known as two anti-correlated networks, are overlapped at the posterior cingulate cortex and the lateral parietal cortex. CIS also detects the conventional functional clusters in the whole brain neural network (e.g., the visual cluster, the motor cluster, the frontal cluster, etc.), as well as meaningful overlaps, and also revealed the possible existence of an emotional memory functional cluster. CIS was able to identify several hub regions actively participating in many clusters. With the ability to reveal overlapping functional clusters, CIS is potentially useful in revealing the delicate architecture of the brain neural network.

Broadband high-frequency EEG power modulations vary with behavioral task

Event Abstract Back to Event Broadband high-frequency EEG power modulations vary with behavioral task Julie A. Onton1*, Klaus Gramann1 and Scott Makeig1 1 UC San Diego, United States Broadband high frequency modulations of spectral power appear frequently in ECoG recordings from the cortical surface, but are typically considered difficult to differentiate from muscle when recorded from EEG scalp electrodes. Recently, we reported using independent component analysis (ICA) to find independent sources of EEG brain activity, followed by ICA decomposition of the spectrogram of each independent component process. This returned broadband high-frequency (bhf) modulations (~30 to 150-250 Hz) that were neither in phase nor co-modulated with broadband power fluctuations from scalp muscle activities. Further, mean bhf power levels from brain components exhibited different values when subjects were imagining various emotional states (Onton, 2009). Here, we collected EEG data during different behavioral task conditions to explore how and where bhf modulations were regulated under varying cognitive demands. In a letter two-back continuous performance task including auditory feedback signals after every manual response, bhf modulators in bilateral occipital areas showed a dip in power after feedback and before the next letter presentation. In the same task, left superior temporal IC phf power increased after 'incorrect' feedback. In a separate task involving a physical orienting response (head turn plus pointing) a bhf power in a frontal midline component cluster was activated during the acceleration phase of the head turn (Gramann, in preparation). These results show that broadband high frequency-modulations of power in source EEG activities are readily detectable in high-density scalp EEG recordings and are regulated differently depending on task demands. Funding: Supported by Swartz Foundation. Keywords: brain oscillations, EEG Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Quantitative Analysis of EEG, MEG & Brain Oscillations Citation: Onton JA, Gramann K and Makeig S (2011). Broadband high-frequency EEG power modulations vary with behavioral task. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00137 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Julie A Onton, UC San Diego, San Diego, United States, jonton@ucsd.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Julie A Onton Klaus Gramann Scott Makeig Google Julie A Onton Klaus Gramann Scott Makeig Google Scholar Julie A Onton Klaus Gramann Scott Makeig PubMed Julie A Onton Klaus Gramann Scott Makeig Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Age- and performance related modulations in spectral event-related dynamics during a working memory task

Event Abstract Back to Event Age- and performance related modulations in spectral event-related dynamics during a working memory task Thomas Fischer1*, Alexander Strobel1 and Sergei Schapkin2 1 Technical University of Dresden, Germany 2 Federal Institute for Occupational Safety and Health, Germany Age-dependent changes in event-related spectral perturbations (ERSP) and decrements in performance have previously been reported for several cognitive paradigms. However, the relationship between ERSP modulations, performance and age has not been well documented until now. Using a 2-back working memory task, we compared ERSPs between 44 healthy younger subjects (aged 29±3 years) and 44 older subjects (aged 55±3 years). Based on the d’ scores in the 2-back condition participants of each age group were divided into high and low performers. For event-related beta synchronization (ERS; 800-1000 ms after target), the ANOVA showed significant main effects for the factor age and the factor performance in the left frontal cluster (F3, FC3). The beta ERS was significantly larger in the high-performer group (the younger and older subjects taken together) than in the low-performer group as well as larger in younger than in older adults. No interaction effects were obtained. Additionally, age differences in the alpha event-related desynchronisation (ERD; 600-800 ms after target) in the parietal cluster (P3; Pz, P4) were found: the alpha ERD increased in younger adults as compared to older adults. Moreover, alpha ERS was larger in low performers than in high performers.Our results show that working memory processes are associated with left frontal event-related beta-synchronization and suggest that frontal beta synchronization could be an informative indicator for age-related changes in neuronal processes underlying working memory. Keywords: Aging, ERSP Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Cognitive Aging Citation: Fischer T, Strobel A and Schapkin S (2011). Age- and performance related modulations in spectral event-related dynamics during a working memory task. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00547 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 15 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Thomas Fischer, Technical University of Dresden, Dresden, Germany, fischer.tho@googlemail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Thomas Fischer Alexander Strobel Sergei Schapkin Google Thomas Fischer Alexander Strobel Sergei Schapkin Google Scholar Thomas Fischer Alexander Strobel Sergei Schapkin PubMed Thomas Fischer Alexander Strobel Sergei Schapkin Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Detecting overlapped functional clusters in resting state fMRI with connected iterative scan: A graph theory based clustering algorithm

The brain is a complex neural network with interleaving functional connectivity among anatomical regions. However, current functional parcellation algorithms usually emphasize independence or orthogonality between the spatial components, with the interleaving nature underrepresented. This study investigates a method, connected iterative scan (CIS), for identifying functionally overlapped anatomical groups with resting state fMRI. CIS iteratively optimizes a grouping of vertexes in a weighted graph, using a density metric computed based on the input and output weights of a candidate cluster. In this study, CIS is able to detect the overlapped clusters in a simulated dataset. CIS also detects that the default mode network and the task positive network, which were known as two anti-correlated networks, are overlapped at the posterior cingulate cortex and the lateral parietal cortex. CIS also detects the conventional functional clusters in the whole brain neural network (e.g., the visual cluster, the motor cluster, the frontal cluster, etc.), as well as meaningful overlaps, and also revealed the possible existence of an emotional memory functional cluster. CIS was able to identify several hub regions actively participating in many clusters. With the ability to reveal overlapping functional clusters, CIS is potentially useful in revealing the delicate architecture of the brain neural network.

Effects of nicotine withdrawal on verbal working memory and associated brain response

Previous literature has reported effects of nicotine withdrawal on brain function during cognitive tasks such as verbal working memory (VWM). Mechanisms of these withdrawal effects have not been clearly identified. Functional neuroimaging offers an objective method to examine brain mechanisms associated with observable behavior and subjective reports. To investigate these mechanisms, 12 smokers were administered a 2-Back VWM challenge during two functional magnetic resonance imaging sessions. Participants abstained from smoking prior to both sessions; however, they applied a nicotine patch before one session and a placebo patch prior to the other. Among regions that exhibited a significant response to the 2-Back during either session, withdrawal was associated with significantly greater deactivation in left and right temporal poles and left medial frontal gyrus. The magnitude of task-related activation showed a significant inverse relationship to craving in the majority of regions during placebo administration. Also, individual brain responses varied more during placebo, suggesting inefficient neural processing. Results suggest that differences in brain response to a VWM challenge during abstinence may be attributed to increased craving. Further deactivation of regions associated with the default network (medial frontal and anterior temporal clusters) during the placebo condition suggests further suspension of default activity, possibly to compensate for inefficient neural processing.

The Potentially Deleterious Impact of Muscle Activity on Gamma Band Inferences

Sir,In an exciting study recently reported in Neuropsychophar-macology, Barr et al (2009) found that the application ofhigh-frequency repetitive transcranial magnetic stimulation(TMS) amplified the gamma band (30–50Hz) brainelectrical activity associated with performance of an n-backworking memory (WM) task.As a precursor to the analyses of TMS effects, WM-relatedgamma activity was examined. Critically, gamma activityduring the delay period showed a significant effect of load(2-back41-back40-back) in an a priori frontal cluster ofelectrodes (AF3/4, F3/4, F5/6, F1/2, Fz). This effect isconsistent with observations made using hemodynamictechniques and intracranial measures of gamma activity (eg,Axmacher et al, 2008).But are load-dependent changes in gamma activityactually generated in the brain or are they simply anartifact of changes in cranial muscle tension? It is clear thatthe facial muscles, in particular, are exquisitely sensitive to avariety of cognitive and affective processes, includingcognitive load (Shackman et al, 2009). The electromyo-graphic (EMG) activity generated by these muscles ispresent at virtually all frequencies, extending as low as2Hz, and can be detected across the entire scalp (Shackmanet al, 2009).Unfortunately, it is difficult to judge whether the load-dependent gamma band effects reported by Barr et al aremyogenic because the key figures (Figures 3 and 4) onlyshow TMS-induced changes in activity, rather than thesimple effect of load. It also would have been helpful toknow whether the activity at higher frequencies, which arepresumably more sensitive to the EMG, exhibited a similardependence on load. Broadly similar concerns apply toearlier scalp-recorded electroencephalography studies thatreported observing amplified gamma activity during theperformance of WM tasks (eg, Haenschel et al, 2009; Tallon-Baudry et al, 1999).DISCLOSUREThe authors declare no conflict of interest.REFERENCES

Cerebral Representation of the Relief of Itch by Scratching

Cerebral processing of itch-scratching cycles was studied with functional magnetic resonance imaging (fMRI) in healthy volunteers. The back of the hand was repetitively scratched in the absence and presence of itch induced by histamine applied close to the scratched site. Blood-oxygenation-level-dependent (BOLD) effects were assessed in predefined cortical and subcortical brain regions of interest. Scratch-related activation clusters were found in cortical and subcortical areas which had been associated before with pain processing, namely S1, S2, parietal association cortex, motor and premotor cortex, anterior and posterior insula, anterior and medial cingulum, lateral and medial frontal areas, ipsilateral cerebellum and contralateral putamen. Cortical activations were generally stronger in the contralateral hemisphere. General linear model (GLM) analysis and GLM contrast analysis revealed stronger activations during itch-related trials in the motor and premotor cortex, in lateral frontal fields of both sides, and in a left medial frontal cluster. Subcortically, stronger activation during itch-related scratching trials was found in the contralateral putamen and in the ipsilateral cerebellum. Time course analysis showed significantly higher BOLD levels during the last 3-6 s before the start of scratching when the itch intensity was strongest. This effect was found in frontal areas, in the putamen, and in the somatosensory projection areas. During the scratching, no significant differences were found between itch and control conditions with the exception of the putamen, which showed stronger activations during itch-related scratch bouts. We interpret these itch-related activations anticipating the scratching as possible cerebral correlates of the itch processing and the craving for scratch.

Assessment of mental deterioration with the Cognitive Abilities Screening Instrument (CASI) and glucose hypometabolism in Alzheimer’s disease: The Osaki-Tajiri Project

The Cognitive Abilities Screening Instrument (CASI) is a screening test for dementia consisting of 9 domains. We investigated the relationships between CASI domain scores and cerebral glucose metabolism (CMRglc) as shown by positron emission tomography. Fifteen patients with very mild Alzheimer’s disease (AD) and 15 with mild AD were studied using the [ 18F]fluoro-deoxyglucose method. The 9 CASI domains were classified into four clusters (recent memory, frontal cortex cluster, posterior cortex cluster, and orientation). Using the region of interest method, the recent memory cluster was correlated with the bilateral hippocampal CMRglc, the frontal cortex cluster was correlated with the bilateral anterior and right inferior frontal CMRglc, the posterior cortex cluster was correlated with the bilateral temporo-parieto-occipital and occipital CMRglc, and the orientation cluster was correlated with the left anterior frontal CMRglc (Spearman’s correlations). The use of statistical parametric mapping showed that most CASI domains were correlated with CMRglc of the left frontal lobe, the temporal lobe, and the angular gyrus. These findings show that the mental dysfunction assessed using CASI in AD patients has a neurobiological basis.

Statistical Analysis of Parieto-Frontal Cognitive-Motor Networks

Considerable information has been gathered on the anatomical connectivity within the parieto-frontal network of the primate brain. To examine the statistical regularities in this connectivity, we carried out hierarchical cluster analysis and found statistically significant clusters of areas: four in the parietal and six in the frontal lobe. Clusters were based on patterns of inputs from all cortical areas. Both parietal and frontal clusters were composed of sets of spatially contiguous architectonic areas. The four parietal clusters were composed of sets of anterior (somatosensory), dorsal, inferior, and medio-lateral parietal cortical areas. The six frontal clusters were composed of sets of dorsal premotor, ventral premotor, primary motor, cingulate motor, and dorsal and ventral prefrontal cortical areas. Furthermore, connectivity between frontal and parietal clusters was topographic and reciprocal. Thus we found substantial statistical structure and organization in the parieto-frontal network that gives a simplified but accurate description of this system.

Synoptic, thermodynamic and agroeconomic aspects of severe hail events in Cyprus

Abstract. Hail is a hazardous weather element often accompanying a thunderstorm, as a result of either thermal instability or instability associated with baroclinic synoptic-scale systems (i.e. frontal depressions). Nevertheless, instability of any kind and thunderstorm activity does not always lead to the formation of hail of adequate size to reach the ground. The broader the knowledge concerning hail events the better the understanding of the underlying thermodynamic and dynamic mechanisms, as well as the physical processes associated with its formation. In the present study, the severe hail events that were recorded in Cyprus during the ten-year period from 1996 until 2005 were examined, first by grouping them into two clusters, namely, the "thermal instability cluster" and the "frontal depression cluster". Subsequently, the spatial and temporal evolution of the synoptic, dynamic and thermodynamic characteristics of these hail events was studied in depth. Also, the impact of hailstorms on the local economy of the island is presented in terms of the compensations paid by the Agricultural Insurance Organization of the country.

Neuropsychiatric Symptom Clusters and Functional Disability in Cognitively-Impaired-Not-Demented Individuals

Previous research has shown that cognitively-impaired-not-demented (CIND) individuals with at least one neuropsychiatric symptom (NPS) have more functional disability than individuals without any NPSs. The objectives of the present study were to determine whether there are consistent clusters of NPS in CIND individuals and whether certain NPS clusters are more strongly associated with measures of functional disability than other NPS clusters in this population. This was a cross-sectional baseline study of NPS using the Neuropsychiatric Inventory (NPI) in a national clinic-based observational cohort study (the Canadian Cohort Study of Cognitive Impairment and Related Dementias study). The present investigation focuses on a subset of CIND subjects (73%) whose informant endorsed the presence of at least one NPI item. A hierarchical cluster analysis identified two NPS clusters. One consisted of mood factors (i.e., depression, anxiety, apathy, irritability, and problems with sleep) and the other cluster captured frontal symptoms (i.e., aberrant motor behavior, disinhibition, agitation, and problems with appetite). NPSs grouped within the mood cluster were more common than the frontal cluster (95% of subjects had at least one NPS within the mood cluster versus 53% in the frontal cluster). However, the frontal cluster was more strongly associated with functional disability measures even after controlling for cognitive status (i.e., the Mini-Mental State Exam) and the mood cluster score. The frontal cluster of NPSs was more strongly associated with functional disability than the mood cluster.

Neural correlates of Dutch Verb Second in speech production

Dutch speakers with agrammatic Broca’s aphasia are known to have problems with the production of finite verbs in main clauses. This performance pattern has been accounted for in terms of the specific syntactic complexity of the Dutch main clause structure, which requires an extra syntactic operation (Verb Second), relative to the basic Subject–Object–Verb order surfacing in Dutch subordinate clauses. We report an fMRI study into the question whether this syntactic complexity is reflected in increased brain activation correlated with the production of Dutch main clause word order, in speakers without language impairment. Nineteen healthy subjects performed a covert sentence completion task, during which main and subordinate clauses were alternately elicited in a block design. Results show a left middle to superior frontal cluster of activation correlated to production of Verb-Second over Verb-Final clauses, with no activation in the opposite contrast. This activation pattern is counter to what might be expected from the frequency distribution of main and subordinate clauses. We conclude that the Verb-Second deviation from the basic Dutch SOV word order costs extra neural resources and that this also underlies the agrammatic problems with the production of finite verbs in Dutch main clauses.

Speed of lexical decision correlates with diffusion anisotropy in left parietal and frontal white matter: Evidence from diffusion tensor imaging

Speed of visual word recognition is an important variable affecting linguistic competence. Although speed of visual word recognition varies widely between individuals, the neural basis of reaction time (RT) differences is poorly understood. Recently, a magnetic resonance technique called diffusion tensor imaging (DTI) has been shown to provide information about white matter (WM) microstructure in vivo. Here, we used DTI to explore whether visual word recognition RT correlates with regional fractional anisotropy (FA) values in the WM of healthy young adults. Participants completed a speeded lexical decision task that involved visual input, linguistic processes, and a motor response output. Results indicated that lexical decision RT was correlated negatively with FA in WM of inferior parietal and frontal language regions rather than in WM of visual or motor regions. Voxels within the inferior parietal and frontal correlation clusters were composed primarily of DTI-based tracts oriented in the anterior–posterior orientation at or near the superior longitudinal fasciculus (SLF) and likely including other smaller association fibers. These results provide new microstructural evidence demonstrating that speed of lexical decision is associated with the degree to which portions of frontal and parietal WM are directionally oriented.

Neurohormones as putative circadian clock output signals in the central nervous system of two cricket species

Antisera to the neuropeptides corazonin (Crz) and crustacean cardioactive peptide (CCAP) and to the diapause hormone (DH) react with small sets of neurones in the cephalic ganglia of the crickets Dianemobius nigrofasciatus and Allonemobius allardi. The distribution of their immunoreactivities is similar in the two species and overlaps with the locations of presumed circadian clock components in the optic lobes, protocerebrum, tritocerebrum, suboesophageal ganglion (SOG) and frontal ganglion. D. nigrofasciatus contains two Crz-immunoreactive (Crz-ir) cells in each optic lobe, six cell groups in the protocerebrum, four in the tritocerebrum, and one in SOG, whereas A. allardi harbours only five Crz-ir groups in the protocerebrum and four in the tritocerebrum. CCAP immunoreactivity occurs in both species in four protocerebrum cell clusters, four tritocerebrum cell clusters, four SOG cell clusters, one frontal ganglion cell cluster, and two optic lobe cell clusters; D. nigrofasciatus possesses two additional cells with unique links to the lamina in the optic lobe. DH-related antigens are present in four cell clusters in the optic lobe, six (D. nigrofasciatus) or eight (A. allardi) in the protocerebrum, four in the tritocerebrum, and three (A. allardi) or five (D. nigrofasciatus) in the SOG. Some of the detected cells also react with antibody to the clock protein Period (PER) or lie close to PER-ir cells. Crickets reared at two different photoperiods do not differ in the distribution and intensity of immunoreactivities. No changes have been detected during the course of diurnal light/dark cycles, possibly because the antisera react with persistent prohormones, whereas circadian fluctuations may occur at the level of their processing or of hormone release. The projection of immunoreactive fibres to several brain regions, the stomatogastric nervous system and the neurohaemal organs indicates multiple functions of the respective hormones.