Sera from 42 patients allergic to A alternata (18 female and 24

Sera from 42 patients allergic to A. alternata (18 female and 24 male; mean age, 20.5 years; age range, 10–33 years) and 17 control subjects (11 female and six male; mean age, 32.3 years; age range, 14–70 years) were included in the study. Diagnosis of A. alternata allergy was based on a clinical history of recurrent rhinitis (four patients), asthma (four patients), rhinoconjunctivitis (12 patients), rhinitis and asthma (12 patients), rhinoconjunctivitis and asthma (10 patients); a positive cutaneous response to a commercial A. alternata extract (Bial-Arístegui, Bilbao, Spain); and specific IgE to A. alternata extract > 0.35 IU mL−1 according ImmunoCAP (Thermo-Fisher,

Uppsala, Sweden). Eight MDV3100 healthy subjects and nine allergic individuals check details sensitized to different allergenic sources unrelated

to A. alternata, as demonstrated by negative SPT responses and lack of A. alternata-specific IgE, were used as controls. Standard molecular genetic techniques were used (Sambrook et al., 1989). For Southern blotting, genomic DNA was prepared from recombinant yeasts as previously described (Barth & Gaillardin, 1996). Afterwards, DNA was digested, separated on a 0.8% agarose gel, and transferred onto Hybond-N+ nylon membranes (GE-Healthcare, Little Chalfont, Buck, UK). Probes were labeled with [32P]-dCTP using the MegaPrime Kit (GE-Healthcare). The autosomal vector pMM4 was used to express the Alt a 1 allergen. The YlMETII promoter was obtained from plasmid pSG70 (García, 1993; Domínguez et al., 2003) and cloned between the EcoRI-BamHI restriction sites of the pBluescript-SK. The Alt a 1-coding gene sequence (Asturias et al., 2003) 4-Aminobutyrate aminotransferase was cloned after this promoter into the BamHI site, resulting in the pMMR2 vector. As the insertion of the target gene between yeast promoter and terminator sequences produces more efficient expression of heterologous genes in Y. lipolytica (Franke et al., 1998), the YlSTE7 terminator was amplified using specific primers and cloned into the SpeI and XbaI-restriction sites of pMMR2, resulting in the pMMR3 plasmid. This plasmid

was digested with ClaI and XbaI and the 1.8 kb-fragment containing the fusion of the YlMTPII promoter-Alt a 1-YlSTE7-terminator was purified and inserted into the pINA240 plasmid (Barth & Gaillardin, 1996), giving rise to pMMR4. The correct construction was verified by sequencing. The construction of the integrative plasmid pMMR10 was performed as follows. To create the pMMR10 plasmid, the 1.8-kb ClaI-SphI fragment from pMMR4 carrying the YlMTPII promoter-Alt a 1-YlSTE7-terminator fusion was cloned into the pINA62 plasmid. The correct construction was verified by sequencing. Plasmid maps of pMMR4 and pMMR10 and sequences of the specific primers used for YlSTE7 terminator amplification are available as Supporting Information (Fig. S1, Table S1). nAlt a 1 was purified from A. alternata CBS 603.78 spent culture medium after 3 weeks of static growth in Czapeck broth at 25 °C.

Indeed, information on pre-travel

preventive actions shou

Indeed, information on pre-travel

preventive actions should be actively spread to non-Spanish speaking immigrants, and, very 17-AAG solubility dmso particularly, to Moroccan families, which in absolute numbers are currently the first immigrant community in Spain.25 Two main approaches have been considered to carry out these actions: some authors recommend sensitization and specific education of primary care nurses and pediatricians as a key strategy,26 while others encourage community-based or even mass media-based campaigns.27 Typhoid and meningitis vaccines were administered proportionally more among tourist children. This could mainly be attributed to the younger age of CVFR, a feature that often limits its use. On the contrary, live virus vaccinations were administered in a greater proportion among CVFR. The indication for yellow fever vaccine reflects the Neotropical Amazonic region as a frequent LDE225 destination, and to lesser degree, the African Paleotropical areas. The use of the MMR vaccine was however infrequent (6.4%), pointing to some suboptimal indication. Hepatitis A vaccination coverage reached 81% among CVFR. This is a pivotal point if it

is taken into account that the population of CVFR is the main source of hepatitis A clusters in Spain and other EU countries.28,29 Only 18.5% of the tourists were vaccinated against this virus. Nevertheless, it should be considered that this group contains a large proportion of older children already immunized against hepatitis A (included in the Catalan Systematic Vaccinations at 12 years of age) and newly arrived immigrant children in whom vaccination is often useless. The indication of antimalarial chemoprophylaxis is superior among CVFR (74%) thereby reflecting their exposure to rural environments in Montelukast Sodium malaria transmission

zones. The simplicity of administration (a single dosage once a week) and the null cost of mefloquine to the patients may explain its greater prescription. Children usually tolerate mefloquine better than adults,30 although it must be carefully avoided in children with a history of hyperactivity, seizures, or behavioral alterations. Indeed, adherence to treatment with mefloquine is superior to that to other antimalarial preventive drugs.31,32 The major limitation of this study is that individuals included in the database might not be representative of all traveling children. The Unit is a specialized center located within high-density immigration districts, some of which are underserved. Thus, it may not possible to generalize the results to other populations such as middle-class neighborhood residents or children presenting to primary care pediatricians.33 CVFR showed a greater risk to exposure to infectious diseases compared with tourists. Two types of risk factors were observed.

Indeed, information on pre-travel

preventive actions shou

Indeed, information on pre-travel

preventive actions should be actively spread to non-Spanish speaking immigrants, and, very AZD9291 particularly, to Moroccan families, which in absolute numbers are currently the first immigrant community in Spain.25 Two main approaches have been considered to carry out these actions: some authors recommend sensitization and specific education of primary care nurses and pediatricians as a key strategy,26 while others encourage community-based or even mass media-based campaigns.27 Typhoid and meningitis vaccines were administered proportionally more among tourist children. This could mainly be attributed to the younger age of CVFR, a feature that often limits its use. On the contrary, live virus vaccinations were administered in a greater proportion among CVFR. The indication for yellow fever vaccine reflects the Neotropical Amazonic region as a frequent www.selleckchem.com/products/Bortezomib.html destination, and to lesser degree, the African Paleotropical areas. The use of the MMR vaccine was however infrequent (6.4%), pointing to some suboptimal indication. Hepatitis A vaccination coverage reached 81% among CVFR. This is a pivotal point if it

is taken into account that the population of CVFR is the main source of hepatitis A clusters in Spain and other EU countries.28,29 Only 18.5% of the tourists were vaccinated against this virus. Nevertheless, it should be considered that this group contains a large proportion of older children already immunized against hepatitis A (included in the Catalan Systematic Vaccinations at 12 years of age) and newly arrived immigrant children in whom vaccination is often useless. The indication of antimalarial chemoprophylaxis is superior among CVFR (74%) thereby reflecting their exposure to rural environments in Sitaxentan malaria transmission

zones. The simplicity of administration (a single dosage once a week) and the null cost of mefloquine to the patients may explain its greater prescription. Children usually tolerate mefloquine better than adults,30 although it must be carefully avoided in children with a history of hyperactivity, seizures, or behavioral alterations. Indeed, adherence to treatment with mefloquine is superior to that to other antimalarial preventive drugs.31,32 The major limitation of this study is that individuals included in the database might not be representative of all traveling children. The Unit is a specialized center located within high-density immigration districts, some of which are underserved. Thus, it may not possible to generalize the results to other populations such as middle-class neighborhood residents or children presenting to primary care pediatricians.33 CVFR showed a greater risk to exposure to infectious diseases compared with tourists. Two types of risk factors were observed.


“Fusarium oxysporum is a ubiquitous species complex of soi


“Fusarium oxysporum is a ubiquitous species complex of soil-borne plant pathogens comprising of many different formae speciales, each characterized by a high degree of host specificity. In the present investigation, we surveyed microsatellites in the available express sequence tags and transcript sequences

of three formae speciales of F. oxysporum viz. melonis (Fom), cucumerium (Foc), and lycopersici (Fol). The relative abundance and density of microsatellites were higher in Fom when compared with Foc and Fol. Thirty microsatellite primers were designed, ten from each forma specialis, for genetic characterization of F. oxysporum isolates belonging to five formae speciales. Of the 30 primers, only 14 showed amplification. A see more total of 28 alleles were amplified by 14 primers with an average of two alleles per marker. Eight markers showed 100% polymorphism. The markers were found to be more polymorphic AZD9291 clinical trial (47%) in Fol as compared to Fom and Foc; however, polymorphic information

content was the maximum (0.899) in FocSSR-3. Nine polymorphic markers obtained in this study clearly demonstrate the utility of newly developed markers in establishing genetic relationships among different isolates of F. oxysporum. Fusarium oxysporum is an economically important soil-borne pathogen with worldwide distribution (Santos et al., 2002). The fungus causes vascular wilt in about 80 botanical species by invading epidermal tissues of the root, extends to the vascular bundles, produces mycelia and/or spores in the vessels, and ultimately results in death of the plants (Namiki et al., 1994). Individual pathogenic strain within the species has a limited host range, and strains with similar or identical host range are assigned to intraspecific groups, called forma specialis (Namiki et al., 1994). To understand the evolutionary history and genomic constituents of the formae speciales

within F. oxysporum requires knowledge of the phylogenetic relationships among isolates (Appel & Gordon, 1996). Over the past several years, genetic diversity in F. oxysporum has been examined using various genetic markers, such as isozyme profiles (Bosland & Williams, 1987), restriction fragment length polymorphisms (RFLP) in mitochondria and nuclear DNA (Jacobson & Gordon, Thiamine-diphosphate kinase 1990) and inter-simple sequence repeat (ISSR), (Baysal et al., 2009). Phylogenetic analyses based on DNA sequences of housekeeping genes such as the mitochondrial small subunit (mtSSU), ribosomal RNA gene, rDNA intergenic spacer (IGS) region, and translation elongation factor (TEF)-1α gene were extensively studied for genetic and evolutionary relationships within and among the formae speciales of F. oxysporum (O’Donnell et al., 1998; Lievens et al., 2009). Microsatellites or simple sequence repeats (SSRs) are composed of tandemly repeated 1–6 bp long units (Tautz, 1989).

, 2001), gingival fibroblasts and T cells (Belibasakis et al, 20

, 2001), gingival fibroblasts and T cells (Belibasakis et al., 2010), which are crucial for the induction of cytokine responses and the establishment of chronic inflammation in periodontitis (Holzhausen et al., 2010; Fagundes et al., 2011). Gingipains can also stimulate IL-6 production by oral

epithelial cells PS-341 solubility dmso (Lourbakos et al., 2001) and IL-8 production by gingival fibroblasts (Oido-Mori et al., 2001), enhancing the inflammatory responses. However, they can also proteolytically inactivate both anti-inflammatory (IL-4, IL-5) and pro-inflammatory (IL-12, IFN-γ) cytokines (Yun et al., 1999, 2001, 2002; Tam et al., 2009). A number of particularly interesting effects are exerted by the gingipains on components of the complement system. Arg-X gingipains can cleave the C5 molecule, resulting in release of its C5a component, which is crucial for enhancing learn more the recruitment of PMNs (Wingrove et al., 1992; Imamura et al., 2001). On the other hand, Lys-X can inactivate the C5a receptor on PMNs, an action that may actually impair their recruitment (Jagels et al., 1996a, b). Along this line, the Arg-X gingipains can degrade the C3 molecule, potentially contributing to decreased bacterial opsonization (Schenkein et al., 1995). This property could confer increased resistance of P. gingivalis to bactericidal activity. Apart from their effect on immune responses, gingipains may

also be involved in the binding of P. gingivalis to host cells, as Rgp–Kgp complexes have been shown to mediate adherence on gingival epithelial cells and gingival fibroblasts (Chen et al., 2001; Grenier et al., 2003; Andrian et al., 2004). Interestingly, when P. gingivalis intracellularly invades Selleck MG-132 gingival epithelial cells, expression of gingipain is downregulated (Xia et al., 2007). Gingipains may also affect vascular permeability and bleeding at the periodontal site. They can proteolytically activate plasma kallikrein and bradykinin, or alternatively increase the release of thrombin and prothrombin,

which can result in increased vascular permeability and PMN influx (Imamura et al., 1994, 1995a). Moreover, by degrading fibrinogen (Scott et al., 1993), they may contribute to inhibition of blood coagulation and increase bleeding at the site (Imamura et al., 1995a) , thus enhancing the availability of hemin required for P. gingivalis growth. Collectively, studies in various experimental systems indicate that gingipains have seemingly contradicting actions on the innate immune responses, hampering interpretation of their role in the pathogenesis of periodontitis. Nevertheless, such differences may be reconciled by the existence of a concentration gradient of gingipains in the tissue (Pathirana et al., 2010). Closer to the gingival epithelial barrier where the biofilm resides, gingipain concentrations are high, causing degradation or deregulation of various components of the immune response.

Introduction of the flhD4131 allele into YK410 (λPmcb-lacZ) by tr

Introduction of the flhD4131 allele into YK410 (λPmcb-lacZ) by transduction with phage P1vir also did not change the levels of β-galactosidase expression. The difference in Pmcb-lacZ expression between YK410 and YK4131 is not dependent on the thyA allele present (data not shown). Using Hfr mapping, we have localized the region in YK4131 that is responsible for decreased stationary-phase activity of Pmcb to between 9 and 36 min on the

E. coli chromosome. Our results suggest that more than one mutation may be needed for the phenotype as we recover I-BET-762 datasheet three classes of exconjugants. In addition to recombinants that have the expected high and low levels of β-galactosidase activity, we recovered recombinants with intermediate levels of β-galactosidase activity. We plan to sequence the genomes of YK410 and YK4131 in order to identify the mutation(s). In addition to the mcb operon, five E. coli genes or operons have been reported to be regulated by FlhD independent of FlhC (Prüßet al., 2003). Because these genes were identified using YK410, YK4131, and YK4136 (an flhC derivative of YK410), the observed effects on gene expression may also be due to the same unidentified mutation(s) in strain YK4131 that affects expression from Pmcb. Further study is needed to answer this

question. This work was supported in part by a National Institutes of Health James A. Shannon Director’s Award (GM49770) to D.A.S. The authors thank Philip Matsumura and Birgit Prüß for strains, Mike Manson and

Susan Van Way for strains LDK378 and advice on swarm assays, Daren Zentz, Yen Hoang Nong, Sylvia Ontiveros, and Rami Weaver for help performing growth assays, and Jim Hu and Matt Sachs for critical comments on the manuscript. “
“Captive snakes, that is, a Jamaican boa (Epicrates subflavus) a yellow anaconda (Eunectes notaeus) and a corn snake (Pantherophis guttatus guttatus), died with signs of bacteraemia including the presence of petechial haemorrhages in the mouth and gums and haemorrhages in the lung, spleen and intestines. The abdomen and anus were swollen with bloody-tinged mucus in the colon. Aeromonas hydrophila was recovered in dense virtually pure culture growth from the internal organs. Characterization of the isolates was by phenotyping and sequencing of the 16S rRNA gene (sequence homology of 99% with A. hydrophila) with outputs confirming Cell press the identity as A. hydrophila. Pathogenicity experiments confirmed virulence to frogs (Rana esculenta) and rainbow trout (Oncorhynchus mykiss). The genus Aeromonas comprises Gram-negative, oxidase and catalase-positive, heterotrophic, nonhalophilic and facultative anaerobic bacilli, which are widely distributed in natural waters (Holmes et al., 1996). The group is often associated with aquatic animals, and several species are primary or opportunistic pathogens of invertebrates and vertebrates, including humans (Martin Carnahan & Joseph, 2005).

1), but the cells appeared as visible clumps at 10–20 days after

1), but the cells appeared as visible clumps at 10–20 days after they were introduced into the fluids (Fig. 2). Xylella fastidiosa cell densities in grapevine xylem fluid were higher than those in the other tested xylem fluids by 20 days after inoculation (Fig. 1), but the

cell densities increased by 20 days in all xylem fluids. Bacterial cells grown in each xylem fluid were then inoculated to PD3 medium and confirmed to be X. fastidiosa species by specific PCR (data not shown). These data showed that X. fastidiosa can grow in the pure xylem fluid of citrus and grapevine in vitro. The percentage of aggregated cells of X. fastidiosa in grapevine xylem fluid was similar to that in PD3 medium, but significantly higher than that seen in citrus xylem fluid (Fig. 3). The bacterial cells aggregated to form tight clumps Bortezomib research buy in the xylem fluid of grapefruit, orange, and lemon. In contrast, bacterial cells were loosely clumped in grapevine xylem fluid (Fig. 2). Bacteria cells were more loosely clumped in PD3 medium than in the xylem fluids (Fig. 2). After 20 days of culturing, X. fastidiosa cells in the grapevine xylem fluid formed more biofilm than those in the citrus xylem fluid (Fig. 4). Of 111 selected

genes from X. fastidiosa tested in a DNA macroarray, 27 genes were differentially expressed in grapevine xylem fluid vs. citrus xylem fluid (Table 1). Most had a higher expression in the grapevine xylem fluid, but two genes had SB203580 purchase a higher expression in the citrus xylem fluid. Using RT-PCR, several genes putatively involved in virulence were validated based on differential expression in the xylem fluid of grapevine vs. citrus (Fig. 5). rRNA was detected at similar levels in bacteria grown

in each of the xylem fluids. No RNA was detected in the water and pure xylem fluid controls. The observation that X. fastidiosa cells growing in a pure xylem fluid from citrus and grapevine and appearing as visible clumps at 20 days after introduction into the fluid was consistent with previous studies using a mixture (1 : 1) of PD3 and xylem fluid (Bi et al., 2007). Xylella fastidiosa cells have been reported elsewhere to grow in 100% grapevine xylem fluid (Andersen et al., 2007; Zaini et al., Arachidonate 15-lipoxygenase 2009), and in the present study, xylem fluid of citrus supported the growth of a PD strain of X. fastidiosa, although this strain does not cause disease in citrus. This supports the hypothesis that citrus may serve as an asymptomatic reservoir for X. fastidiosa in southern California (Perring et al., 2001; Bi et al., 2007). Biofilm formation is a major factor in X. fastidiosa virulence (Marques et al., 2002), and our measurements of enhanced biofilm formation in grapevine xylem fluid are consistent with the recent report of Zaini et al. (2009). The observation that more biofilm was formed in the grapevine xylem fluid than in the citrus xylem fluids (Fig. 4) would be compatible with the observation that infections of citrus species by X.

, 2004) PratA consists of nine consecutive tetratricopeptide rep

, 2004). PratA consists of nine consecutive tetratricopeptide repeat (TPR) units, a motif that is known to mediate protein–protein interactions. Thereby, it could form a bridge connecting multiple proteins and serve as a scaffold factor for correct assembly of PSII

CDK inhibitor (Schottkowski et al., 2009a). PratA directly interacts with the C-terminus of the D1 reaction center protein of PSII, and its inactivation affects the C-terminal processing of D1, an early step of PSII biogenesis. This D1 maturation occurs in almost all photosynthetic organisms, and it is required for the subsequent docking of the subunits of the oxygen-evolving complex to the lumenal side of PSII. Most intriguingly, PratA was shown to be a soluble protein

located in the periplasm, which forms part of a ∼200 kDa complex of an as yet unknown composition and function (Fulda et al., 2000; Klinkert et al., 2004; Schottkowski et al., 2009a). However, a minor fraction (10–20%) of PratA was found to associate with membranes in a D1-dependent manner. Cellular fractionation experiments using two consecutive sucrose gradients revealed that the membrane-bound PratA is apparently not associated with either the PM or TMs, but co-sediments with an intermediate membrane subfraction, which was therefore named PratA-defined membrane (PDM) subfraction (Schottkowski et al., 2009a). Albeit the different density of PDMs as compared with that of PMs, it cannot be ruled out that PDMs might be identical to previously described specialized PM subregions, in which PSII subunits tend to accumulate (Srivastava et al., 2006). Membrane fractions resembling PDMs with regard www.selleckchem.com/products/AG-014699.html to their density have already been observed in earlier

studies, where they have been postulated to be linked to so-called thylakoid centers (Hinterstoisser et al., 1993). Based on electron microscopic analyses, thylakoid centers were initially described in some cyanobacteria as tubular structures found at the inner face of the Enzalutamide research buy PM, at points where thylakoids extend projections into the cytoplasm (Kunkel, 1982). Recently, this idea was revisited based on a more detailed cryo-electron tomography analysis in Synechocystis 6803 (van de Meene et al., 2006). Interestingly, PratA inactivation and, thus, defective PSII assembly leads to a significant accumulation of the pD1 precursor protein in PDM fractions (Schottkowski et al., 2009a). This suggests that PratA function is required for efficient membrane flow from PDMs to TMs, underlining the role of PDMs for PSII reaction-center assembly. Interestingly, related ‘biogenesis regions/centers’ have recently been observed in the eukaryotic green alga Chlamydomonas reinhardtii, where they are formed by membranes surrounding the pyrenoid structure of the chloroplast (Uniacke & Zerges, 2007). This might indicate an evolutionary conservation of the molecular principles that underlie TM biogenesis.

The video contained 300 frames and each frame was presented to th

The video contained 300 frames and each frame was presented to the model for 40 ms of simulation time. Each image was originally 256 × 256 pixels. Because our cortical model is made up of single columns, however, the input size was reduced to Target Selective Inhibitor Library 20 × 20 pixels (see Fig. 2B) to approximate the visual space that would drive neurons in a receptive field of a V1 cortical column. This was an assumed approximation given the 100 deg2 receptive field and 36 × 36 (64 × 64 pixel) input from the Goard and Dan experiment.

In the 256 × 256 pixel image, RF1 received input from pixels (121–140) × (121–140) and RF2 received input from pixels (141–160) × (121–140). Figure 3 shows the architecture of RF1 and RF2. It has been shown that retinal neurons remove linear correlations by ‘whitening’ images before they reach the cortex (Simoncelli & Olshausen, 2001). To simulate this, all the images were whitened and normalised before being presented to the network (Fig. 2B). Whitening was achieved by applying a Gaussian filter to the Fourier-transformed image (see http://redwood.berkeley.edu/bruno/npb261b/). This flattens the power spectrum of the image PLX4720 and is essentially equivalent to convolving the image with an on-center off-surround filter, as is observed in retinal

ganglion cells and the lateral geniculate nucleus (LGN). As we were not interested in modeling orientation selectivity development, we assumed that the simulated V1 columns, RF1 and RF2, were selective to vertical edges. Therefore, the images were convolved with a vertical Gabor filter after whitening.

The Gabor filter was constructed by modulating a Gabor kernel with a sinusoidal wave as shown in Eqn. (1), where σx and σy determine the spatial extent of the Gaussian in x and y and f specifies the preferred spatial wavelength Immune system (Dayan & Abbott, 2001). Excitatory Poisson spike generators converted the images into spike trains in the input layer. (1) To develop our model, we used a publicly available simulator, which has been shown to simulate large-scale spiking neural networks efficiently and flexibly (Richert et al., 2011). The model contained a TRN, LGN, BF, two prefrontal cortex areas (providing top-down attention) and two, four-layered cortical microcircuits (Fig. 3). The cortical microcircuit architecture was adapted from Wagatsuma et al. (2011), which was able to account for experimental observations of attentional effects on visual neuronal responses and showed that top-down signals enhanced responses in layers 2/3 and 5. All connections that occur between layers in a microcircuit are shown in Fig. 3. Within each layer, there are excitatory–excitatory, excitatory–inhibitory, inhibitory-excitatory and inhibitory–inhibitory connections (data not shown). Connection probabilities in our cortical model were the same as used in Wagatsuma et al. (2011) and are given in Table 1. All subcortical and top-down connection probabilities were set to 0.

The ROI comprised 419 voxels, each one being 4 × 4 × 4 mm in size

The ROI comprised 419 voxels, each one being 4 × 4 × 4 mm in size. We computed the whole-brain RSFC associated with each of the 419 voxels within the ventrolateral ROI, using the same methods described above. We then computed the similarity between every possible pairing of the 419 RSFC maps, using eta squared (η2). The η2 statistic was

recently applied to RSFC data for this purpose by Cohen et al. (2008), and varies between 0 (no similarity) and 1 (identical). Cohen et al. suggested that η2 provides a better measure of similarity selleckchem between two images than spatial correlation, because it can take into account differences in scaling and offset between two images, while correlation is unaffected by these factors. We computed a 419 × 419 η2 matrix describing the similarity between each pair of the 419 RSFC maps for every participant (36 in total). We used the spectral clustering toolbox written for Matlab by Verma and Meila (available at http://www.stat.washington.edu/spectral/) this website to partition the left ventrolateral frontal ROI into K clusters, where K ranged from 2 to 10. Specifically, we used the Meila–Shi (multicut) algorithm (Meila & Shi, 2001), which performs a generalized Eigen decomposition of the normalized Lagrangian of similarity matrix A (here, the 419 × 419 matrix

of η2 values), then applies the k-means clustering algorithm to partition the data on the basis of K highest eigenvectors. The eigenvectors of the similarity matrix provide information about the data’s structure. By performing partitional clustering (with k-means)

on the basis of these eigenvectors, spectral clustering makes use of this information (the data’s spectrum) to form clusters of voxels that maximize intra-cluster similarity (here, η2) and minimize inter-cluster similarity. For comparison, we also partitioned the data using standard hierarchical clustering, as implemented in the Matlab Statistics toolbox. Hierarchical clustering is an agglomerative method, which starts by treating each data point as a singleton cluster, then, as K decreases, successively merges previously established PAK6 clusters (visualized as a dendrogram or tree). Here, we formed clusters of voxels on the basis of average linkage, i.e. the unweighted average of the distances (1−η2) between all pairs of voxels, where one member of the pair is assigned to one cluster and the other member is assigned to a different cluster. At each iteration, K clusters are formed by merging the two clusters (from the K + 1 solution) exhibiting the smallest average distances. In order to determine the optimal K for the ventrolateral ROI, we used a split-half comparison procedure. First, we randomly assigned each of the 36 participants to one of two groups of 18 participants.