, 2000, Fransson, 2006, Greicius et al., 2008, Greicius and Menon, 2004, Larson-Prior et al., 2009, Morgan and Price, 2004 and Vincent et al., 2007). It is also supported by the observation that intrinsic BOLD fMRI fluctuations account for variability in task-evoked activity ( Fox et al., 2006) and

associated behavioral performance ( Fox et al., 2007). In the context of MEG BLP-correlation, this second hypothesis predicts maintenance of within/between see more RSN topography during natural vision, and an increase of interaction between RSN as they go from a state of relative segregation at rest to a state of greater integration during task. We focus on networks (visual, dorsal attention, auditory, language) that have been modulated in fMRI during the

HKI-272 in vivo observation of natural scenes (Golland et al., 2007, Hasson et al., 2004 and Nir et al., 2006), and the default mode network (Raichle et al., 2001 and Shulman et al., 1997) that is active at rest but suppressed during task performance. We recorded MEG signals in a group of twelve participants, each performing three different experimental blocks (runs) both during visual fixation (fixation) and the observation of three movie segments (about 5 min each) taken from the Italian version of The Good, the Bad and the Ugly (movie). In a separate recording session, each participant underwent fMRI during fixation and movie conditions ( Figure 1). The MEG data analysis pipeline is the same as in de Pasquale et al., 2010 and de Pasquale

et al., 2012) and Mantini et al. (2011) and returns estimates of band limited power (BLP) from the source-space signals for delta (δ), theta (θ), alpha (α), beta (β), gamma (γ) band (see Supplemental PAK6 Information and Figure S1 available online). To evaluate the modulation produced by movie watching on BLP interaction with respect to fixation, in sensory and attention networks, we computed the total interdependence function from BLP, a global measure of interaction at different frequencies, obtained from all the possible pairs of the principal nodes of each RSN (visual, auditory, and dorsal attention networks) (Experimental Procedures and Supplemental Information). The nodes of each RSN were defined a priori from an independent set based on meta-analyses of task fMRI studies (Baldassarre et al., 2012, He et al., 2007 and Lewis et al., 2009; Table S1). In both α and β bands, the within-network inter-nodal BLP interaction was stronger at lower (<2 Hz) than higher frequencies, with a moderate peak at about 0.1 Hz during fixation in agreement with previous MEG studies (Brookes et al., 2011b, de Pasquale et al., 2010, de Pasquale et al., 2012 and Hipp et al., 2012; Figure 2A). Movie watching decreased the total interdependence compared to fixation, at frequencies below 0.3 Hz in each RSN (Figure 2A, dotted lines; Supplemental Information).

We employed homologous recombination in mouse embryonic stem (ES) cells to generate KI mutant mice with a T to C substitution in the codon sequence

of Munc13-1 residue 464 in exon 11 of the Munc13-1 (Unc13a) gene ( Figures 1A–1E; see Experimental Procedures for details). This substitution causes a tryptophan to arginine exchange (Munc13-1W464R), which abolishes Ca2+-CaM binding ( Junge et al., 2004), and introduces an AgeI restriction site. Homozygous, cre-recombined Munc13-1W464R mice were viable and fertile, had a normal life expectancy, and were indistinguishable from WT littermates in the cage environment. The FRAX597 supplier size and cytoarchitecture of Munc13-1W464R and WT brains were identical (data not shown). Importantly, PARP inhibitor whole brain Munc13-1 expression levels did not differ between Munc13-1W464R and WT mice at postnatal day (P) 9 or 28 (Figure 1F). Likewise, the expression levels of Munc13-2, Munc13-3, and key interaction partners of Munc13-1 such as RIM1 and Syntaxin-1 were similar in Munc13-1W464R and WT mice, and none of the other synaptic markers tested showed altered expression levels (see Figure S1 available online). To confirm that the W464R point mutation interferes with the Ca2+-CaM-Munc13-1 interaction in vivo, we immunoprecipitated Munc13-1 from Munc13-1W464R and WT brains and tested for coprecipitated interaction partners. While Syntaxin-1

was coprecipitated with WT Munc13-1 and Munc13-1W464R, we did not detect any Ca2+-CaM binding to Munc13-1W464R, although the levels of CaM in WT and Munc13-1W464R brains were indistinguishable (Figure 1G). These data show that the KI mutation has a specific and selective effect restricted to the interaction of Munc13-1 with Ca2+-CaM, does not interfere with

gene transcription, mRNA translation, protein stability and turnover, or other protein-protein interactions of Munc13-1, and does not have overt effects on brain structure. In preparation for functional analyses, we studied the expression and localization of Munc13-1 already at the calyx of Held of WT and Munc13-1W464R mice (Figure 2). Munc13-1 was previously reported to localize to AZs of most glutamatergic and GABAergic synapses in the brain (Augustin et al., 1999a; Varoqueaux et al., 2005). Correspondingly, immunostaining for Munc13-1 in sections containing the medial nucleus of the trapezoid body (MNTB) from WT mice at P9–P11 (before hearing onset) or P15–P17 (after hearing onset) revealed punctate immunopositive structures that surrounded postsynaptic cell bodies. Colabeling with antibodies to the AZ marker Bassoon (Dondzillo et al., 2010) indicated that Munc13-1 is localized at AZs of calyx of Held synapses (Figures 2A and 2C). The same staining pattern for Munc13-1 was observed in calyces of Munc13-1W464R mice (Figures 2B and 2D).

Horseradish peroxidase-conjugated goat anti-mouse IgG antibody (Sigma) diluted 1:7500 in 2.5% BLOTTO was then added to all wells and incubated for 1 h at room temperature. All reactions were detected using TMB Microwell ELISA substrate (Kirkegaard and Perry Laboratories, Gaithersburg, Md.). The substrate was allowed to react for 10 min at room temperature, and then the reaction was stopped by adding an equal buy Target Selective Inhibitor Library volume of 1 M H3PO4. Optical densities (OD) at 450 nm were determined with a Spectra Max 190 Plate Reader (Molecular Devices, Inc., Palatine, IL). End point titer values were determined as the reciprocal

of the highest dilution that had an absorbance value greater than or equal to 0.1 above the background value. End point titers

of antigen-specific antibody responses were determined for each individual animal. The geometric mean titers (GMTs) were determined for each group of mice. Standard errors were calculated for log-transformed titers. Statistical analyses were performed with SPSS version 10.0 for Windows (SPSS, Inc., Chicago, IL). Antibody titers or levels of antibodies between groups were compared by using the Kruskal–Wallis test followed by the Mann–Whitney U rank sum test. Animals immunized with 100 μg of KLH and either a 6 or 20 μg dose of full-length NSP4 as an adjuvant. Both doses of NSP4 exhibited a statistically significant (p = 0.04 Mann–Whitney U Test) 6-fold increase in KLH-specific serum IgG titers (GMT = 72,839) compared to the Compound Library purchase group of mice receiving KLH alone (GMT = 11,494) ( Fig. 1A) and so the lower dose was chosen for future experiments. In addition, those animals also showed significantly higher (p = 0.05, Mann–Whitney U Test) (>30-fold increase) KLH-specific fecal IgA antibody responses (GMT = 2302 ng/ml) compared to the antigen alone group (GMT = 71 ng/ml) ( Fig. 1B). Serum IgG and fecal IgA specific antibody levels decreased approximately 20-fold and 30-fold, respectively, when mice were inoculated with KLH co-administered with NSP4 compared to mLT (GMT; IgG = 1,447,738;

IgA = 74,083 ng/ml). those When full-length NSP4 was given with TT (10 μg), it enhanced serum TT-specific total immunoglobulin (GMT = 11,143) responses (17-fold increase) to a greater extent than to those seen with KLH, when compared to the antigen alone group (Fig. 2A). However, in contrast to the enhanced fecal antibody responses observed when KLH was given as the antigen, there was no significant increase (p > 0.05, Mann–Whitney U Test) of TT-specific fecal antibody response in the group of animals that received NSP4 and TT as compared to TT alone ( Fig. 2B). In contrast to the observations with KLH and TT, NSP4 did not enhance serum antibody responses to OVA (GMT = 28,963) compared to the antigen alone (GMT = 15,521) group (Fig. 2C). However, a significantly higher level (11-fold increase; (p = 0.

, 2012). To generate a bait construct with the peptide AC domain without the signal sequence (Asn27–Cys211) of EtROM3 (GenBank DQ323509), the cDNA was amplified by PCR (sense 5′-CCGGAATTCAACATTTCACTGGACAAGTCG-3′, antisense 5′-CGGGATCCACACGTTACTGCGAACCCGCA–3′) from E. tenella cDNA ( Zheng et al., 2011), and inserted into the EcoRI–BamHI site of pGBKT7. The cDNAs encoding cleavage site VA domain (Val462–Ala675) of EtMIC1 (GenBank EU093966) and GG domain (Glu2175–Gln2340) of EtMIC4 (GenBank AJ306453) were ligated into the EcoRI–BamHI site of pGADT7 (EtMIC1-VA: sense 5′-C GGAATTCGTTGGTGATTGGGAAGACTGGGGGC-3′,

antisense 5′-CGCGGATCCT GCCCACATCTCTGATTGTTCACC-3′; EtMIC4-GG: sense 5′-CGGAATTCGAAGGC GAGACAGGGAAACCTGG-3′, antisense 5′-CGCGGATCCCTACTGGATGTCACCA

CHIR-99021 in vivo CTGTCTGCC-3′). The recombinant vector sequences were confirmed by Sangon Biotech (Shanghai). AH109 yeasts were transformed with 1 μg of the following plasmids: pGBKT7-ROM3, positive ABT263 control pCL1, and negative control pGBKT7, respectively. Co-transformations were performed with pGBKT7-ROM3 and pGADT7-MIC1, pGBKT7-ROM3 and pGADT7-MIC4, pGBKT7-53 and pGADT7-T, pGBKT7-Lam and pGADT7-T. Yeast cells from a single transformation of DNA binding domain constructs were spread on SD/-Leu plates and SD/-Leu/-His plates. All co-transformed yeasts were plated on SD/-Trp/-Leu plates and SD plates lacking tryptophan, leucine, histidine HCl monohydrate and adenine hemisulfate salt (SD/-Trp/-His/-Leu/-Ade). The activation of transformants was detected by the filter assay for β-galactosidase activity. For Western found blot analysis, positive single colony was picked from SD/-Trp/-Leu plates, cultured in SD liquid medium lacking tryptophan and leucine at 30 °C with rotation at 250 rpm until OD600 > 1.0. The yeast cells were pelleted and lysed by votexing with glass beads (0.5 mm in diameter, Sigma) at 4 °C in 200 μL of cell lysis buffer with freshly added protease inhibitors. Twenty micrograms of each sample was run on SDS-PAGE and electroblotted onto Protran

nitrocellulose membrane (Whatmann, UK). Anti-c-Myc monoclonal antibody (1:500) and anti-HA polyclonal antibody (1:1000) (Santa Cruz, CA) was used for Western blot analysis. AC domain of EtROM3 was subcloned into pcDNA3.1-Myc and GG domain of EtMIC4 was subcloned into pcDNA3.1-HA. All constructs were confirmed by DNA sequencing. Hela cells were cultured in DMEM plus 10% FBS and glutamine in 6-well plate at a density of 3 × 105/well. After 24 h, cells were transformed with recombinant plasmids pcDNA-Myc-ROM3, pcDNA-HA-MIC4, pcDNA-Myc-ROM3 and pcDNA-HA-MIC4 using Lipofectamine 2000 (Invitrogen) as described (Pascall et al., 2002). Forty-eight hours after transfections, Hela cells were harvested and lysed on ice in lysis buffer for 20 min (20 mmol/L Tris–HCl (pH 7.4), 150 mmol/L NaCl, 0.5% NP-40, supplemented with a protease inhibitor cocktail from Roche).

These athlete-specific questionnaires were the Weight Pressures in Sport Scale for Male Athletes (WPSS-MA),39 the ATHLETE Questionnaire (AQ),40 and the Athletic

Milieu Direct Questionnaire (AMDQ).41 These assessments were each used once in the studies reviewed. Table 1, Table 2 and Table 3 indicate the eating disorder measure(s) used, the authors, sample sizes, sport, and whether the coefficient was calculated and/or cited for each male athlete, female athlete, and combined-gender athlete study, respectively. Only seven studies calculated validity coefficients within the study (r = −0.51–0.88) whereas 47 cited the validity coefficient (r = −0.51–0.99) of the measure of that was established in studies with non-athlete populations. Twenty-six calculated a reliability coefficient (α = 0.51–0.96)

while 47 cited the reliability (α = 0.81–0.98) of measures obtained, 5 FU again, from studies on non-athlete populations. Three studies attempted Veliparib in vivo to validate the less frequently used WPSS-MA,39 the AQ,40 and the AMDQ41 in an athlete population. Of the studies using the EAT, EDI, BULIT-R, QEDD, and EDE-Q, only four studies reported both validity and reliability coefficients in these commonly used questionnaires when assessing athletes for ED. Doninger et al.42 found validity evidence for the EAT in a population of female athletes while Petrie et al.4 and 6 found validity evidence of the QEDD in populations of male athletes. Finally, Sanford-Martens

et al.7 also found validity evidence for the QEDD in a population of male and female athletes. Table 4 presents the frequency with which different types of validity and reliability coefficients were calculated/cited for the 50 selected studies. Regarding the seven studies that calculated validity coefficients, a majority of these studies calculated convergent validity (n = 5). Studies that cited validity coefficients primarily did so with convergent validity as well (n = 31) followed Cediranib (AZD2171) by citations of discriminant validity (n = 13). Although, convergent validity and discriminant validity were the most calculated/cited types of validity coefficients, concurrent, predictive, and other indices of construct validity were also reported/cited. Across gender, only three studies evaluated the same eating disorder measure (i.e., BULIT-R) and calculated convergent validity coefficients within the study; two studies used male college athletes4 and 6 with validity coefficients ranging from −0.51 to 0.70 (Table 1), and one used female athletes with validity coefficients ranging from 0.55 to 0.62 (Table 2). Although many studies included athletes from different sports, no study examined the validity of an eating disorder measure in a specific sport type or compared validity across sport types.

In fact, we estimate that fewer than 15% of such high-risk families with two children, at least one with autism, would be excluded by the study design, and fewer than 30% of those with three children. Accordingly, we studied the SSC families for 3-Methyladenine concentration evidence

of transmitted risk factors. We saw no statistically significant difference between probands and sibs when we looked at total numbers of transmitted copy-number events or the numbers of genes hit by transmission (Table S7). We explored evidence for transmission distortion of many individual common copy-number polymorphisms, but found no statistically significant signal when adjusted for multiple hypotheses (data not shown). However, a role for transmission can be seen if carefully restricted to extremely rare events Ibrutinib price (Xu et al., 2008). We limited ourselves to the 510 HQ quads: families with high-quality data and exactly one

affected and one unaffected child. To minimize false signal, we considered only events of at least 20 probes. Operationally, we define the “family hit count” for each RefSeq gene as the number of families in which we observe a transmitted event that overlaps an exon of that gene. In Table S8 we list all genes with a positive family hit count and provide counts for each time a given gene had an exon within an event transmitted to a sib or a proband. We define an “ultrarare gene” as a gene with a family hit count of one and then define an ultrarare event as an event that overlaps at least one exon of an ultrarare gene. In other words, an ultrarare event is one that hits at least one gene that is not hit by any other transmitted event over the population of HQ quads. The 458 ultrarare events are summarized in Table S9. These events are further characterized by the gender of the recipient children, their affected status, and by the pattern of transmission (“singly” transmitted, either to a proband or a sib, or

“doubly” transmitted, to both). Additional features are listed, such as parent of origin, the ultrarare genes overlapping the event, and whether the event is a duplication or deletion. One strong asymmetry is between the counts Ribonucleotide reductase of ultrarare deletions (178) and duplications (432), in excess of the overall bias in all transmitted events (3119 deletions versus 3875 duplications, p value = 3 × 10−15). Note that this bias for duplications is the opposite bias seen for de novo events in male probands, for which deletions exceed duplications. For singly transmitted ultrarare events, we find a slight excess of events going to the proband rather than the sib (Table 4). The signal is even stronger when we consider the number of ultrarare gene hits (p value = 0.23 for events, p value = 0.13 for genes). We see no bias in families with female siblings, in keeping with the hypothesis that females are less likely to display the symptoms of ASDs.

, 2004 and Ruiz et al., 2008). Here, we have investigated functional alterations of the synaptic vesicle cycle at the very initial stages of degeneration in CSP-α KO mice. We have found that in motor nerve terminals CSP-α is essential to maintain priming for exocytosis and, surprisingly, recycling of synaptic vesicles. CSP-α KO junctions show normal probability of release (p) but a decreased number of release sites (n). Such a phenotype is probably caused by a functional impairment in vesicle XAV-939 manufacturer priming. The strong reduction

in SNAP-25 (Figure 2) at the CSP-α KO motor terminals likely reduces the number of functional SNARE complexes that limits priming. Although we cannot completely rule out that the phenotype is just secondary to early degeneration, we think that the rescue of quantal content upon forskolin treatment (Figure 3) points toward a functional defect in priming rather than to structural degeneration of nerve terminals. A vesicle pool model in chromaffin cells (Nagy et al., 2004) proposes that PKA-dependent phosphorylation of SNAP-25 inhibits depriming and that there is a late step in priming regulated by an additional, as yet unknown, PKA target that could be CSP-α (Evans et al., 2001 and Nagy et al., 2004). One possibility is that SNAP-25

is functionally impaired due to a conformational change before selleckchem it becomes degraded (Sharma et al., 2011b). In such a situation, SNAP-25 would be a poor substrate for PKA phosphorylation and the basal levels of PKA activity would be insufficient to maintain the normal amount of phosphorylated SNAP-25. else The balance between phosphorylated and nonphosphorylated forms of SNAP-25

would be shifted toward the nonphosphorylated species in the absence of CSP-α. The overstimulation of PKA activity could overcome such a situation by promoting the phosphorylation of SNAP-25 and improving its functionality. Although our most parsimonious explanation focuses on SNAP-25, we cannot rule out that, alternatively or additionally to SNAP-25, forskolin activates another PKA-dependent or PKA-independent cAMP-regulated targets to promote vesicle priming in parallel to or downstream to SNAP-25 (Gekel and Neher, 2008 and Nagy et al., 2004). In any case, our experiments demonstrate that such a target is not CSP-α. In addition, it has been recently proposed that synaptic vesicle endocytosis is required to preserve the number of release sites (Hosoi et al., 2009). Therefore, the alteration of dynasore-sensitive endocytosis that we have observed (Figure 6) could also contribute to the decrease in the number of release sites in CSP-α mice. In addition, it is intriguing that the reduction in the number of synaptic release sites does not translate into a reduction in the frequency of MEPPs in the CSP-α KO fibers (Figure S1A). Future experiments will have to investigate if that apparent discrepancy could be explained by a mechanistic segregation of spontaneous and action-potential-driven synaptic signaling (Kavalali et al., 2011).

Immune surveillance of the BBB is critical for the organism to respond to threats to the CNS. Leukocytes in the circulation bind endothelial cells of the BBB through adhesion molecules such as VCAM-1 and ICAM-1, sensing for distress signals from the CNS. Such a signal may be mediated via chemokines and cytokines released by microglia, astrocytes, and pericytes (Takeshita and Ransohoff, 2012). The exact

mechanisms of transmigration RAD001 ic50 into the CNS are still unknown, although it is believed to occur by paracellular means, implying a loosening of the TJ between endothelial cells of the BBB (Sagar et al., 2012). While detrimental in certain pathological cases such as multiple sclerosis, the recruitment of leukocytes into the CNS can play a beneficial role to help resident microglia in resolving certain insults (Simard et al., 2006) or even in gene therapy replacements (Cartier et al., 2009). The BBB, however, is not without fault. Under constant attack by pathogens, tightly regulated processes can become detrimental and actually contribute to the development of an infection. Pathogens enter into the CNS either by paracellular (between endothelial cells) or by trans-cellular (through them) mechanisms ( Ley et al., 2007; Bencurova et al., 2011). As a basic first line of defense, TJs are challenged by some infectious agents in order to weaken the physical properties

of the BBB and infiltrate the CNS. The viral glycoprotein gp120 of HIV has been shown to breach the BBB by activating Roxadustat the chemokine receptors C-C chemokine receptor type 5 (CCR5) and C-X-C chemokine receptor type 4 (CXCR4) ( Kanmogne et al., 2005; András et al., 2005), resulting in TJ protein proteolytic degradation via proteasome ( Nakamuta Rolziracetam et al., 2008; Wang et al., 2011). On the other hand, the meningococcal type IV pili bacteria have been reported to

infiltrate into the CNS by recruiting the polarity complex Par3/Par6/PKCzeta that governs TJ formation at the luminal side of the BBB. This results in the formation of ectopic intercellular junctional domains at the site of bacteria-cerebral endothelial cell interaction, depleting TJ proteins and consequently breaching the BBB ( Coureuil et al., 2009). Moreover, these bacteria can take advantage of the biased β2-adrenoceptor/β-arrestin signaling pathway in endothelial cells in order to tightly adhere to the luminal side of BBB and to delocalize TJ proteins, thus creating anatomical gaps through the BBB that bacteria can use to infiltrate into the CNS ( Coureuil et al., 2010). Transport mechanisms can also be used to trick cerebral endothelial cells into letting infectious agents cross the BBB. The adsorptive endocytosis takes place when glycoproteins in cerebral endothelial cell membrane bind other glycoprotein ligands in a lectin-like fashion.

Wheel running tended to attract individuals who are highly motivated to engage in frequent, sustained exercise, which Doxorubicin cell line reflected a voluntary, active physical and mental state, while treadmill running attracts those that are forced to exercise, which reflects an attitude

towards exercise.41 Only very recently have there been studies demonstrating the sex differences in exercise intervention for drug addiction and rehabilitation. In one such study, Sanchez and colleagues42 found that 10-day wheel running after the formation of rat SA attenuated nicotine-seeking in male rats only under the conditions of access to unlocked wheels. However, access to either locked or unlocked wheels was sufficient to suppress nicotine-seeking during extinction in females. Also 14-day wheel running during abstinence on subsequent

cocaine-seeking of rat’s SA can effectively reduce relapse vulnerability in a dose HSP inhibitor dependent manner, and this effect differs by sex and estrous cycle.43 Since females perform wheel and treadmill running differently than males, it is important to include the consideration of sex-specific effectiveness of exercise on drug rehabilitation in animal experiments. In addition to wheel and treadmill running, forced swimming has also been used for studies of exercise rehabilitation. Forced swimming exercises could be evaluated for exercise performance, psychological status (anxiety and stress), cognition (learning and memory), etc. 44 and 45 It also showed the same effectiveness as displayed in voluntary wheel running in alcohol conditioned place aversion (CPA), 46 and 47 suggesting that forced swimming may be one mode for exercise intervention for drug addiction. Again, compared to male rats, female rats were more active in water 48 and swam faster in speed with less sign of fatigue. 49 and 50 Exercises attenuate drug-seeking behaviors during drug initiation, escalation, extinction, abstinence, and relapse.51 and 52 It is crucial to decrease the susceptibility (preventive effect) at an early stage of drug addiction and reduce the

drug craving (therapeutic effect) at later stages in order to prevent relapse. Montelukast Sodium As most of animal studies in biology research show, researches about exercise as a means of prevention on drug abuse are limited by investigating male animals only,53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67 and 68 with a few studies on female animals,69, 70, 71, 72, 73 and 74 while the others did not specify the gender.75 and 76 In regard to the sex differences as shown in Table 1, the results of these studies have been inconsistent. One study found that chronic forced treadmill exercise for 6 weeks induced reduction of drug craving behavior in adolescent female and male rats, but only male rats showed inhibited CPP.

, 2005). Although the physiological significance of this form of plasticity is not fully delineated, these data suggest that vesicles in muscle fuse and release a soluble signal that traverses the synaptic cleft and signals to the presynaptic release machinery. Some of the first evidence that synaptic see more plasticity requires

postsynaptic exocytosis came from experiments where various factors that inhibit SNARE-mediated membrane fusion were infused into postsynaptic neurons via a recording pipette (Lledo et al., 1998). Each of these factors, which included N-ethylmaleimide, botulinum toxin B, and a short peptide designed to interfere with the binding of NSF to SNAP, blocked LTP triggered by stimulating nearby Schaffer collateral axons. This early observation led

to a model where intradendritic vesicles harboring AMPA-type glutamate receptors fuse with the plasma membrane upon LTP induction. Synaptic strength increases as newly inserted AMPA receptors become incorporated into synapses ( Newpher and Ehlers, 2008). In addition to functional selleck chemicals plasticity, several studies have shown that postsynaptic exocytosis is critical for morphological plasticity at glutamatergic synapses ( Kopec et al., 2006, Kopec et al., 2007, Park et al., 2004, Park et al., 2006 and Yang et al., 2008). Dendritic spines, the micron-sized protrusions ever contacted by axonal terminals at excitatory synapses, stably increase their volume by ∼2-fold following NMDA receptor activation ( Matsuzaki et al., 2004). Infusion of botulinum toxin B, which cleaves VAMP family SNARE proteins, or expression of dominant-negative SNARE proteins in postsynaptic neurons blocks stimulus-induced spine growth ( Kopec et al., 2007, Park et al., 2006 and Yang et al., 2008), indicating that morphological plasticity requires membrane fusion. More recent experiments have sought to define the identity of the intracellular membrane stores, location of activity-triggered

exocytosis, the cargo responsible for synapse potentiation, and the SNARE molecules involved in postsynaptic vesicle fusion. Serial reconstruction electron microscopy studies demonstrated the presence of membrane-bound structures, including recycling endosomes, throughout dendrites and in a large fraction of dendritic spines (Figure 1B) (Cooney et al., 2002). This observation, along with experiments demonstrating that AMPA receptors are endocytosed and reinserted upon synaptic activation, suggested that dendritic recycling endosomes are the internal membrane stores mobilized to the plasma membrane in response to LTP-inducing stimuli (Beattie et al., 2000, Carroll et al., 1999, Ehlers, 2000 and Lüscher et al., 1999).