, 2002) Expression in the Escherichia coli BL21 strain and purif

, 2002). Expression in the Escherichia coli BL21 strain and purification was followed according to Ferreira et al. (2002). Salivary antigen was obtained according to da Silva Vaz Jr et al. (1994). Briefly, partially engorged females from the Porto Alegre strain were dissected in PBS and salivary glands

were separated from other organs and frozen at −70 °C. Salivary glands were macerated CHIR-99021 mouse and sonicated (Ultrasonicator Cole Parmer, 4710, 500 W, 4 and 20% duty cycle) in a solution containing Tris/HCl 10 mM pH 8.2, 1% deoxicolate, leupeptin (8 mg/ml), pepstatin A (1 mg/ml) and TPCK (0.1 mM) and centrifuged at 32,000 × g for 40 min at 4 °C. The soluble fraction (supernatant) was then collected and stored at −70 °C. Sera from six Bos taurus (Hereford) and eight B. indicus (Nelore) bovines from a farm in Pelotas (Brazil), within a region naturally infested with R. microplus, as well as the sera from non-infested

B. indicus animals (negative controls) Selleckchem MLN0128 were kindly provided by the Departamento de Veterinária Preventiva, at the Universidade Federal de Pelotas (Brazil). Additionally, the sera from three bovines (indicated as bovines 1, 2 and 3) submitted to twelve successive experimental infestations were the same described previously by Cruz et al. (2008). Briefly, the infestation regime consisted of six initial heavy infestations with 18,000 larvae (Bagé strain) followed by six light infestations with 800 larvae. All infestations were performed once a month and along the only back. rBmPRM was submitted to SDS–PAGE 10% (58 μg/cm) and transferred to the nitrocellulose membrane at 70 V for 1 h at 4 °C (Dunn, 1986). Nitrocellulose strips of 4 mm were blocked for 1 h at room temperature with blocking buffer (cow non-fat dry milk 5%–PBS). Prior to the overnight incubation at 4 °C with the membrane strips, all sera were diluted 1:50 in an E. coli

BL21 strain lysate expressing the pGEX-4T3 vector and incubated for 2 h at room temperature for removal of contaminating anti-vector and E. coli proteins reactive antibodies. As positive control an anti-rRmPRM hyperimmune serum (1:400) raised in bovine was used. Preparation of the E. coli BL21 strain lysate was performed according to Rott et al. (2000). After 3 washes with blocking buffer, the strips were incubated for 1 h with anti-bovine IgG peroxidase conjugate (Sigma), diluted 1:6000 in blocking buffer. The strips were then washed three times with PBS, and the development buffer (5 mg 3,3-diaminobenzidine in 30 ml PBS plus 150 μl H2O2 30% and 100 μl CoCl2 1%) was added. Microtitration plates were incubated overnight at 4 °C with 0.5 μg of rBmPRM or 1 μg salivary gland protein extract diluted in 50 mM carbonate/bicarbonate buffer pH 9.6 per well. Plates were washed three times with blocking buffer, blocked for 1 h with blocking buffer at 37 °C, and then incubated with bovine sera diluted 1:50 in blocking buffer for 1 h at 37 °C.

Adult E cells are labeled by the cry13-Gal4 driver in combination

Adult E cells are labeled by the cry13-Gal4 driver in combination with a Pdf-Gal80 transgene and, along with LNvs, are required to generate normal behavioral rhythms in 12 hr light:12 hr

dark (LD) cycles ( Stoleru et al., 2004). We found that this driver combination only labeled the two larval DN1s ( Figure 1A and data not shown). Although expression of green fluorescent protein (GFP) was often difficult to detect simultaneously in both larval DN1s (as in Figure 1A), expression of UAS-Diphtheria toxin (UAS-Dti) always ablated both larval DN1s, whereas the PDF+ LNvs, the 5th PDF− LNv, and the two DN2s were still present, as judged by clock protein staining (data not shown). This is consistent with larval DN1s becoming the adult DN1a neurons, a subset of adult E cells ( Grima Z-VAD-FMK mouse et al., 2004 and Stoleru et al., 2004). GFP-labeled DN1 projections terminate in the vicinity of the PDF+ UMI-77 molecular weight LNv axonal termini (Figure 1A). Because the GFP derivative used is a postsynaptic marker (Dscam17.1-GFP; Wang et al., 2004), larval DN1 projections

could receive inputs in this region, including from LNvs. To localize DN1 presynaptic termini, we used UAS-Synaptotagmin-HA (UAS-Syt-HA; Robinson et al., 2002) expressed via the stronger cry16-Gal4 driver in combination with Pdf-Gal80 because cry13-Gal4 expression of Syt-HA was undetectable. The two larval DN1s marked by CD8-GFP expression project to the LNv termini in which Syt-HA is detectable in several foci, some of which are very close to LNv axons ( Figures 1B and 1C). Thus, DN1s could signal to LNvs and receive their inputs. This is consistent with electron microscopy studies of adult small ventral lateral neurons (s-LNvs) that

revealed input synapses to s-LNv projections in the dorsal protocerebrum, the Chlormezanone location of adult DNs ( Yasuyama and Meinertzhagen, 2010). We also detected low levels of CD8-GFP and Syt-HA expression in LNvs when expressed with the cry16-Gal4; Pdf-Gal80 combination, presumably because cry16-Gal4 is not completely repressed by Pdf-Gal80. Because cry16-Gal4 also labels a few nonclock neurons in the brain (data not shown), we did not use cry16-Gal4 in the subsequent behavioral experiments. Given the possibility that DN1s signal to LNvs, we first characterized the contributions of these different groups of clock neurons to light avoidance in larvae raised in 12:12 LD cycles at 25°C. In this assay, 15 larvae are placed on a half-covered Petri dish, and the number of larvae on the dark side are counted after 15 min. At 750 lux, ∼70% of wild-type larvae are in the dark at the end of the assay, and this requires the clock genes period (per) and timeless (tim) ( Gong, 2009, Keene et al., 2011 and Mazzoni et al., 2005).

As demonstrated in several vaccination models, and as observed by

As demonstrated in several vaccination models, and as observed by ourselves in previous experiments (data not shown), recombinant influenza vectors are not efficient inducers of heterospecific immune responses when used in single immunization or homologous vaccination protocols [14], [16], [45], [46], [47] and [48]. Therefore, we chose to test FLU-SAG2 as prime vector, to be administered in combination with a booster dose of Ad-SAG2. To this aim, BALB/c mice were primed intranasally

with vNA or FLU-SAG2. Four weeks later, they were boosted with an IN or a SC dose of Ad-Ctrl or Ad-SAG2. Serum samples were obtained 2 weeks after the prime and boost immunizations. Bronchoalveolar lavage (BAL) samples were obtained from animals sacrificed 2 weeks after boost immunization. Specific anti-SAG2 antibodies were detected by ELISA using a tachyzoite Fulvestrant nmr membrane extract enriched for GPI-anchored proteins (F3 antigenic fraction) [40]. As shown in Fig. 4, when analyzing BAL samples, specific anti-SAG2 antibodies were detected only in animals that received prime and boost by IN route. It is noteworthy that this route of immunization elicited both IgG1 (Fig. 4B) and IgG2a (Fig. 4C) antibodies. Analysis of serum samples showed that significant levels of specific selleck chemical anti-SAG2 antibodies could be obtained by IN or SC vaccination (Fig. 5A). Overall, similar levels of IgG1 and IgG2a antibodies could be found in sera of immunized mice

(Fig. 5B and C). In all vaccination protocols, irrespective of the route of immunization, specific anti-SAG2 IgG antibodies were detected only after the boost immunization (Fig. 5A–C). In our previous experience with Ad-SAG2 and other recombinant adenoviruses, we observed that one immunization with these viruses were also unable to induce significant levels of antibodies against the recombinant antigens [39]. Induction of anti-toxoplasma specific

CD4+ T and CD8+ T cells is considered to be the most important mechanism for protection against toxoplasmosis [31] and [49]. It was demonstrated in different vaccination models that the efficacy of a particular protocol is directly related to its capacity to activate T cells in spleen [4] and [33]. To evaluate whether the heterologous vaccination protocols are able to induce specific anti-SAG2 IFN-γ producing T cells at systemic level, Resminostat spleen cells obtained 3 weeks after the boost immunization were stimulated in vitro with the F3 antigenic fraction of T. gondii in an IFN-γ ELISPOT assay. The results shown in Fig. 5D represent the average of two independent experiments. In mice primed and boosted by IN route, we were unable to detect specific IFN-γ producing T cells. In contrast, the number of antigen specific IFN-γ producing T cells was significantly higher in mice immunized with the combination of IN dose FLU-SAG2 and SC dose Ad-SAG2 recombinant viruses (207 ± 19) than in mice immunized with control viruses (38 ± 11).

, 1992, Squire and Zola-Morgan, 1991 and Lavenex and Amaral, 2000

, 1992, Squire and Zola-Morgan, 1991 and Lavenex and Amaral, 2000; Figure 1). On this background, it may come as a surprise that these systems contain a set of representations that perfectly match an attribute

of the external world: the animal’s location in space. In the hippocampus, place cells fire specifically at one or a few locations in the animal’s environment (O’Keefe and Dostrovsky, 1971). In the medial part of the entorhinal cortex, grid cells fire at multiple locations that, for each cell, define a hexagonal array across the entire available space (Hafting et al., 2005 and Moser et al., 2008; Figure 2). Grid cells intermingle with head direction cells, which fire specifically Osimertinib price when the animal faces certain directions, and border cells, which fire specifically when animals move along borders of the local environment (Sargolini et al., 2006, Savelli et al., 2008 and Solstad et al., 2008). Collectively, these cell types form the elements of what we will refer to as the entorhinal-hippocampal space circuit. In this review, we shall take a historical perspective and describe the unfolding of a system of elementary

correlates for representation of space in the hippocampus and the entorhinal cortex. We shall discuss mechanisms that might generate this representation, many synapses away from the specific receptive fields of the sensory cortices, and we shall elaborate on how the evolution of a functional architecture within this system might benefit not only mapping of space, but also the formation of high-capacity memory. The study of spatial representation PKC activation and spatial navigation started long before neuroscientists approached the cortex. The notion of an internal spatial map can be traced back to Edward C. Tolman, who in his cognitive theory of learning suggested that behavior was guided by a map-like representation Calpain of stimulus relationships in the environment, rather than by chains of

stimulus-response sequences of the type envisaged by Thorndike and Hull (Tolman, 1948). The internal map was thought to enable animals to navigate flexibly in the environment, taking shortcuts and making detours when previously traveled routes were less effective. Tolman’s ideas remained controversial for decades, partly because scientists did not have tools to determine if the cognitive entities proposed by Tolman actually existed. Tolman’s ideas were revitalized many years after his death, after the development of microelectrodes for extracellular recording from single neurons in behaving animals. This development led Ranck (1973) and O’Keefe and Dostrovsky (1971) to monitor activity from single neurons in the hippocampus of freely moving rats. Both laboratories found reliable links between neural firing and the animal’s behavior, but it was O’Keefe and Dostrovsky who found that the firing depended on the animal’s location in the environment.

, 1997) For each subject, the parameters of functional coupling

, 1997). For each subject, the parameters of functional coupling were estimated separately for the Entity and No_Entity videos in covert and overt viewing Talazoparib nmr conditions (i.e., four multiple regression models in SPM). Together with the signal of the rTPJ ROI, the models included the head motion realignment parameters and, for the Entity video, two predictors modeling the transient effect of the attention grabbing and non-grabbing characters (delta functions, convolved with the HRF). For the covert viewing conditions, the models included losses of fixation as events of no interest. The time series were

high-pass filtered at 0.0083 Hz and prewhitened by means of autoregressive model AR(1). Group-level significance (random effects) was buy Dinaciclib assessed by using a 2 × 2 within-subjects ANOVA modeling the four conditions of interest (Entity/No_Entity videos × overt/covert viewing). Main effects and interactions were tested at a statistical threshold of p-corr. = 0.05,

corrected for multiple comparisons at cluster level (cluster size estimated at p-unc. = 0.005). The Neuroimaging Laboratory, Santa Lucia Foundation, is supported by The Italian Ministry of Health. The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement n. 242809. “
“During the transition from childhood to adolescence, there is a dramatic increase in the amount of time spent with peers (Brown, 2004). This coincides with heightened reward sensitivity, sensation-seeking, preferences for risky behavior, a greater sense of the importance of conforming to peer group norms, and a growing divergence of peer and family values as peers begin to approve of more negative behaviors (Gardner and Steinberg, 2005 and Steinberg, 2008). Together, these changes create the sense that teenagers are less resistant to peer pressure than either children or adults, first although susceptibility to peer influence

per se gradually decreases over the course of adolescence (Steinberg and Monahan, 2007). Parental and societal concerns therefore abound regarding adolescent abilities to resist peer pressure, and whether a teenager’s lack thereof will precipitate his or her engagement in risky behaviors (such as early substance abuse, delinquency, or unsafe sexual activity). Although there are various social explanations for why peers are so influential during this period of development, researchers are increasingly focusing on biological factors that may underlie adolescents’ affective reactivity and emotion regulation ability during interactions with peers (Steinberg, 2008). These biological factors include not only hormonal changes that occur with the onset of puberty but also further brain development (Nelson et al., 2005).

Table 3 presents results from adjusted analyses stratified by sex

Table 3 presents results from adjusted analyses stratified by sex. Girls who attended schools offering one or more sports per 100 students were 47% more likely to participate in sports than girls who attended schools offering fewer sports. However, this was not significant in the boys’ model. In contrast, the percent of unrestricted sports offered at school was positively related to boys’ sports selleckchem team participation, such that boys who attended schools with 100% of the sports unrestricted were 12% more likely to participate in sports

compared to boys who attended schools with less than 85% of the sports unrestricted. This association was also significant when the percent of unrestricted sports was treated as a continuous variables (test of trend, p = 0.005). The percent of unrestricted selleck products sports was not significantly related to girls’ sports

team participation (test of trend, p = 0.57). Our results indicate that, in the U.S., high school sports opportunities differentially affect boys’ and girls’ sports participation. Specifically, we found that the variety of choice in school sports offered predicted girls’ sports participation, whereas the percent of unrestricted sports (access) predicted boys’ sports participation. These effects were statistically significant even after adjusting for adolescent-, parent-, and school/town-level covariates, including adolescents’ previous participation in sports and overweight/obese status. Our finding that girls played on more sports teams if they had a wider variety of options to choose from is consistent with Cohen et al.’s8 finding for both sexes. In contrast, we did not find that boys’ participation was related to the variety of sports teams offered at school. Instead, boys played on more sports teams if their school did not restrict participation in the most popular sports (e.g., soccer, basketball). This sex difference could reflect different motivations among

boys’ and girls’ for participating in sports. A prior study found that boys were generally most interested in competitive aspects of specific sports;34 thus, they may be less willing to switch sports if blocked from participating ADAMTS5 in their preferred sport. It is possible that girls were more willing to participate in a variety of different sports because they are interested in the social and physical benefits of sports as well as the competitive aspects.34 and 35 Alternatively, girls may have broader exposure to different sports at an early age and so they feel more comfortable taking advantage of different sport opportunities compared to boys. Future qualitative research is needed to explore the differential motivations, barriers, and facilitators to boys’ and girls’ participation in sports to help contextualize our findings. School-based obesity prevention intervention studies have demonstrated that comprehensive programs that address multiple components of the school environment are most successful.

, 2010), tunable lenses (Grewe et al , 2011), or multibeam system

, 2010), tunable lenses (Grewe et al., 2011), or multibeam systems (Amir et al., 2007 and Cheng et al., 2011). To rapidly obtain two-photon imaging data from a larger range of depths, we have previously shown that insertion of a sharp, 1 mm glass microprism into the neocortex of an anesthetized mouse can be used for acute, single-session two-photon imaging of anatomical structures across all six cortical layers, including the soma and dendrites of cortical layer 5 pyramidal cells, in a single field-of-view (Chia and Levene, 2009a,

Chia and Levene, 2009b and Chia and Levene, 2010). Here, we describe an improved approach that has enabled chronic anatomical and functional imaging of hundreds of individual neurons and neuronal processes CX-5461 in vitro simultaneously across all cortical layers. The structure and function of neurons at distances >150 μm from the prism face were not qualitatively different after prism insertion and remained stable for months after prism insertion. We also demonstrate that microprisms can be used for simultaneous, high-speed calcium imaging CT99021 datasheet from neurons in layers 2 to 6 during locomotion and for imaging visual responses in long-range axon terminals in deep cortical layers. This approach complements traditional in vivo electrophysiological methods by enabling high-yield,

simultaneous chronic monitoring of subcellular structure and neural activity in superficial and deep-layer cortical neurons in behaving mice. Two parallel approaches have dominated the study of neocortical circuits.

One approach involves recordings in living coronal brain slices (typically ∼400 μm thick). Farnesyltransferase Although many long-range axonal inputs to the cortical columns within each slice are severed, this reductionist approach has provided a wealth of insights regarding the layer-specific physiological properties of neurons and the interlaminar flow of neural impulses, using multiple intracellular and extracellular recordings (e.g., Adesnik and Scanziani, 2010, Sanchez-Vives and McCormick, 2000 and Thomson, 2010), two-photon calcium imaging (MacLean et al., 2006), and voltage-sensitive dye imaging (Petersen and Sakmann, 2001). A second common approach involves neuronal recordings from the intact brain, where it is possible to correlate neural activity with sensory perception and with behavior. Two-photon imaging has provided a means for monitoring neural activity and structural plasticity across days and weeks in awake animals (e.g., Dombeck et al., 2007, Andermann et al., 2010, Mank et al., 2008 and Trachtenberg et al., 2002). However, many aspects of cortical processing remain out of reach because of the challenges in imaging deep-layer neurons and in simultaneous in vivo imaging across all layers.

Furthermore, their intact performance on the Low Interference con

Furthermore, their intact performance on the Low Interference conditions, particularly the second Low Interference condition, demonstrates that their deficits were specific to the buildup of interfering features, rather than fatigue or generic task-practice BTK inhibitor effects. The hippocampal cases were not impaired on any condition (all t(7) < 0.4, p > 0.3). To address the potential concern that differences in task difficulty across conditions could have confounded our results, we analyzed the accuracy and reaction time data of control participants (shown in Figures 5 and 6; Tables S1 and S7; all reported t tests are two-tailed). Importantly, the planned interaction contrast revealed

no greater difference in d′ between High Ambiguity and Low Ambiguity Objects than between Difficult and Easy Size (the interaction was not significant in experiment 2, t(19) = 1.1, p = 0.3, and was driven by a bigger drop in performance for Difficult than Easy size conditions in experiments 1 and 3, both t > 2.0, p < 0.06). In experiment 4, the condition on which the MTL patients were impaired (High Interference) was not the condition that controls found to be the most difficult: the High Interference condition was matched in difficulty to Low Interference 2 (t(21) = 0.3, p = 0.8) and significantly easier than the selleck chemical Low Interference 1 (t(21) = 3.1, p < 0.01). These results suggest that our observed

eye movement patterns (expt 1), fMRI effects of feature ambiguity (expt 2), and patient deficits (expts 3–4) were not due to global differences in task difficulty. In terms almost of reaction times, the increase in RTs for High Ambiguity versus Low Ambiguity Objects was significantly greater than the increase for Difficult versus Easy Size in experiments 1–3 (a trend in expt 1: t(15) = 1.9, p = 0.07; expts 2 and 3: both t > 2.2, p < 0.05). In experiment 4, reaction times for the High Interference condition were significantly longer relative to the second Low Interference condition (t(21) = 3.0, p < 0.01),

but were not significantly different from the first Low Interference condition (t(21) = 1.5, p = 0.2). These results suggest that at least for experiment 4, differences in reaction times cannot explain the patients’ deficits. Nonetheless, the finding that in experiments 1–3 the High Ambiguity Object conditions were associated with longer reaction times relative to the Size Control conditions merits further consideration in light of the idea that working memory demands may have differed across conditions. Several studies have reported impairments of short-term memory in amnesia (e.g., Hannula et al., 2006, Nichols et al., 2006, Olson et al., 2006, Warren et al., 2010, Warren et al., 2011 and Warren et al., 2012), and neuroimaging studies have observed hippocampal activity in tasks typically considered to assess short-term memory (e.g., Cabeza et al., 2002, Cashdollar et al., 2009, Hannula and Ranganath, 2008, Karlsgodt et al.

, 2010) In this manner, intercellular interactions among SCN neu

, 2010). In this manner, intercellular interactions among SCN neurons (i.e., coupling) determine the population-level properties that are required for the transmission of coherent output signals to downstream tissues

and adjustment to changing environmental conditions ( Meijer et al., 2010 and Meijer et al., 2012). Although it is critical for pacemaker function, the process by which SCN neurons interact remains ill-defined. Candidates for SCN coupling factors FK228 have been identified (Aton and Herzog, 2005 and Maywood et al., 2011), with vasoactive intestinal polypeptide (VIP) known to play an especially important role. Without competent VIP signaling, SCN neurons display desynchronized rhythms and a lower propensity for sustained cellular oscillations (Aton et al., 2005). However, SCN neurons also communicate through other signaling pathways that can compensate for the lack of VIP (Brown et al., 2005,

Ciarleglio et al., 2009, Maywood et al., 2006 and Maywood et al., 2011). GABA, the most abundant neurotransmitter within the SCN (Abrahamson and Moore, 2001), is also a putative coupling factor whose role remains unclear, since GABAA signaling is sufficient (Liu and Reppert, 2000) but not required for synchrony (Aton et al., 2006). One obstacle in the attempt to develop a mechanistic understanding of the role of different SCN coupling factors is the lack of analytical paradigms that are well suited for this purpose. Previous studies have relied largely on techniques that eliminate cellular interactions via physical, pharmacological, BKM120 or genetic means to determine

which forms of intercellular signaling are necessary or sufficient for period synchrony. Although this approach is informative, it typically entails compromised neural function, which can complicate interpretation of the precise role played by the Rolziracetam candidate coupling factor. Furthermore, this approach is unable to provide insight into how the intact, functional SCN network uses and integrates different coupling signals. Here, we developed a functional assay for SCN interactions that uses genetically intact animals with competent neuronal oscillatory and coupling mechanisms. Our research strategy was modeled on one previously employed to investigate coupling within an invertebrate pacemaker system (Roberts and Block, 1985), which involved shifting one of two coupled pacemakers and then tracking resynchronization between the pair over time in vitro. Although it remains difficult to shift specific SCN subpopulations in vitro, the pacemaker network can be temporally reorganized in vivo by a variety of environmental lighting conditions (de la Iglesia et al., 2004, Inagaki et al., 2007, Meijer et al., 2010 and Yan et al., 2005). Based on previous theoretical and experimental research (Inagaki et al.

” Although it is not yet known whether or how microglia target sp

” Although it is not yet known whether or how microglia target specific “weaker” synapses, these data are consistent with previous work demonstrating that such a competition results in decreased territory of the “weaker” inputs and increased territory of “stronger” inputs within the dLGN (Del Rio and Feller, 2006, Huberman et al., 2008, McLaughlin selleck chemicals et al., 2003, Penn et al., 1998, Shatz, 1990, Shatz and Stryker, 1988, Stellwagen and Shatz, 2002, Stellwagen et al., 1999 and Torborg and Feller, 2005). In the retina, spontaneous, correlated neuronal activity from both eyes (i.e., retinal waves) drives the elimination of synapses and segregation of inputs into eye-specific

territories in the dLGN (Del Rio and Feller, 2006, ZD1839 Feller, 1999, Huberman et al., 2008, McLaughlin et al., 2003, Penn et al., 1998, Stellwagen

and Shatz, 2002 and Torborg and Feller, 2005). Interestingly, complement and complement receptor-deficient mice have similar pruning deficits to mice in which this correlated firing has been disrupted (e.g., cAMP-analog injection, β2nAChR−/− mice, etc.) ( Stevens et al., 2007), suggesting the intriguing possibility that complement cascade activation and function is regulated by neural activity. Neural activity could also directly regulate microglia function (i.e., activation, recruitment, phagocytic capacity) Astemizole through complement-independent mechanisms. Alternatively, neural activity may drive the elimination of synapses by other mechanisms which ultimately lead to complement activation and/or microglia-mediated

engulfment. Future studies will aim to address how neural activity, complement, and microglia may interact to contribute to developmental synaptic pruning ( Figure S7). Synaptic pruning likely involves several mechanisms that cooperatively interact to establish precise synaptic circuits. We suggest that microglia may be a common link and identify CR3/C3 signaling as one pathway underlying microglia-synapse interactions and microglia-dependent pruning in the developing CNS. One of the major questions raised by these findings is precisely how secreted complement proteins mediate the selective elimination of synapses by microglia. In the immune system, C3 is cleaved into an activated form, iC3b, which covalently binds to the surface of cells or debris and targets them for elimination by macrophages via specific phagocytic receptor signaling (e.g., CR3) (Lambris and Tsokos, 1986 and van Lookeren Campagne et al., 2007). Similar to the immune system, we propose that activated C3 (iC3b/C3b) could selectively “tag” weak synapses (Figure S7). Consistent with C3 “tagging” subsets of RGC terminals, previous confocal analysis revealed colocalization of C3 with pre and postsynaptic markers in the developing dLGN (Stevens et al., 2007).