These observations were paralleled

by in vitro studies of

These observations were paralleled

by in vitro studies of synaptic plasticity demonstrating a clear requirement for newly synthesized proteins in the long-term modification of synaptic function (see Sutton and Schuman, 2006 for review; Paclitaxel solubility dmso also, Tanaka et al., 2008). This link between protein synthesis and long-term plasticity is most recently reinforced by studies showing that targeted genetic disruption of signaling molecules that regulate protein translation interfere with long-term synaptic or behavioral memories (Costa-Mattioli et al., 2009). The above studies, while indicating a requirement for protein synthesis, do not address the location. We now know dendrites and axons of neurons represent specialized cellular “outposts” that can function with a high degree of autonomy at long distances from the soma, as illustrated by the remarkable ability of growing axons to navigate correctly after soma removal (Harris et al., 1987) or isolated synapses to undergo plasticity (Kang and Schuman, 1996 and Vickers et al., 2005). The identification of polyribosomes at the base or in spines (Steward

and Levy, 1982) together with metabolic labeling experiments that provided the first evidence of de novo synthesis of specific proteins in axons and dendrites (Feig and Lipton, 1993, Giuditta et al., 1968, Koenig, 1967 and Torre and Doxorubicin Steward, 1992) indicated the competence of these compartments for translation. Subsequent studies demonstrated

that specific subsets of mRNAs localize to synaptic sites (Steward et al., 1998) and directly linked synaptic plasticity with local translation in dendrites (Aakalu et al., 2001, Huber et al., 2000, Kang and Schuman, 1996, Martin et al., 1997 and Vickers et al., 2005), providing definitive proof that dendrites are a source of protein during plasticity. In axons, the idea of local protein synthesis has been slower to find acceptance, no doubt hindered by the classical view of axons as information transmitters rather than receivers; so, why would local protein synthesis be required? Although ribosomes were identified in growth cones in early ultrastructural studies (Bunge, 1973 and Tennyson, TCL 1970), they were rarely observed in adult axons. It is now thought that at least part of the explanation for their apparent paucity lies in their localization close to the plasma membrane in axons (Sotelo-Silveira et al., 2008) where ribosomal subunits can associate directly with surface receptors (Tcherkezian et al., 2010). In addition, evidence indicates that myelinated axons can tap into an external supply of ribosomes by the translocation of ribosomal proteins from Schwann cells (Court et al., 2011). Growing and navigating axons are clearly information receivers, like dendrites, since their growth cones steer using extrinsic signals.

, 2010) The open field arena consisted of a polypropylene box (3

, 2010). The open field arena consisted of a polypropylene box (37.6 cm × 30.4 cm × 17 cm) in which the floor was divided into 16 same-sized rectangles (7.6 cm × 9.4 cm), 12 peripheral and 4 central. The experiments were conducted under bright white light illumination during the dark part of the daily cycle, 1–2 h after Pexidartinib solubility dmso its onset. Each mouse was individually placed in the center of the arena. Behaviors in the open field were recorded for 10 min (divided into 1 min

intervals) with an overhead video camera. At the end of the session, the floor and walls were washed with odorless liquid soap, rinsed thoroughly with tap water and dried with a disposable paper towel. Recorded images of the tests were used to analyze behavior. The observer was blind regarding the experimental treatment of the animals. The ambulation was quantified on the basis of the number of rectangles crossed by the animals (Filgueiras et al., 2009). Mice

had to place all four legs on a given rectangle for a crossing to be counted. The following ambulation variables see more were evaluated: ambulation in the center (C), ambulation in the periphery (Pe), C/Pe ratio and total ambulation (C + Pe). In addition, considering that direct comparisons between the activity in the center and in periphery can be influenced by the fact that the number of rectangles in the periphery is greater than that in the center, the rectangles crossed in the center and in the periphery were respectively divided by 4 (C/4) and 12 (Pe/12). A separate group of mice was injected with ethanol or saline as described above. One or 2 h after the second injection (at P4), animals were decapitated and blood was collected (ethanol – 1 h: n = 13, 2 h: n = 9; saline – 1 h: n = 10, 2 h: n = 6). Blood was centrifuged at 2000 rpm for 5 min and the PDK4 supernatant stored at 4 °C until assayed. BEC was assessed using an enzymatic kit (Alcohol Reagent Set, Pointe Scientific Inc., Michigan, USA) in accordance with the manufacturer’s recommendations. After the test, 60 animals (at least 7 per group) were

sacrificed by cervical dislocation. Frontal cerebral cortices (approximately the rostral third of the cerebral wall) and hippocampi were immediately dissected and incubated for 1 h at 37 °C in minimum essential medium (MEM) buffered with 20 mM HEPES at pH 7.3 and containing 100 mM ascorbic acid, 100 mM pargyline and 0.5 mM Rolipram (Sigma Chemical Co., St. Louis, MO, USA). After incubation, the reaction was interrupted by the addition of TCA to 10% (final concentration). cAMP was purified by removing trichloroacetic acid and endogenous interfering compounds from supernatant solution, using an ion exchange column of AGSOW-X4 (200–400 mesh, hydrogen form, Bio-Rad, Rio de Janeiro, Brazil), previously washed and equilibrated with H2O (Matsuzawa and Nirenberg, 1975). Cyclic AMP concentrations of purified samples were determined by a protein binding assay described previously (de Mello et al., 1982 and Gilman, 1970).

, 1995) An example of the converse situation in which fibers wit

, 1995). An example of the converse situation in which fibers with distinct electrophysical properties innervate a common peripheral end organ has recently come to light: Li et al. (2011a) show that Aβ, Aδ, and C fibers all form lanceolate endings that surround hair follicles. This discovery relied on developing a suite of genetic markers that were exploited in two ways. First, they were used to determine the peripheral endings associated

with marked sensory subtypes. Second, they were used to link electrophysiological properties derived from in vivo intracellular recordings to the marker suite and hence to mechanoreceptor subtype. Thus, knowledge of conduction velocity and force sensitivity may not be sufficient to infer the identity of the peripheral organ check details being stimulated. Genetic deletion of single DEG/ENaC or TRP channel proteins in mice alters sensitivity to mechanical stimulation, but leaves both functions largely intact. While these studies cast doubt Pomalidomide on the idea that DEG/ENaC or TRP channel proteins are essential for mechanotransduction in mammals, they also suggest that the mammalian somatosensory system is robust to genetic deletion. Such robustness could reflect molecular redundancy within or between ion channel gene families. Additionally, robustness could be conferred by functional degeneracy among

mechanoreceptor neurons. The potential for degeneracy arises from the fact that skin dermatomes contain a mixture of peripheral Unoprostone sensory structures and are innervated by multiple classes of somatosensory neurons. For example, low-threshold, rapidly adapting Aβ fibers are thought to innervate both Pacinian and Meissner corpuscles in the skin (Brown and Iggo, 1967, Burgess et al., 1968 and Vallbo et al., 1995). In addition to having distinct morphologies, each of these endings also expresses different DEG/ENaC and TRP channel proteins (Calavia et al., 2010, García-Añoveros et al., 2001, Kwan et al., 2009, Price et al., 2001 and Suzuki et al., 2003b). In this scenario, loss of a single ion channel protein is expected to have only a minor effect on the entire class of such fibers. The acid-sensing ion channels or ASICs

are a vertebrate sub-division of the conserved DEG/ENaC superfamily. Most if not all of the ASIC proteins are expressed in cell bodies in the trigeminal and dorsal root ganglia (reviewed in Deval et al., 2010) and localize to the peripheral endings in the skin (Figure 2C). For instance, ASIC1 is expressed in nerves innervating Pacinian corpuscles in human skin (Calavia et al., 2010 and Montaño et al., 2009). However, genetic deletion of ASIC1 has no effect on the threshold or firing frequency of fibers innervating mouse skin (Page et al., 2004), but alters visceral sensory function (Page et al., 2004 and Page et al., 2005). ASIC2 and ASIC3 are expressed in the majority of mechanoreceptor endings in mouse skin (Figure 2C; García-Añoveros et al., 2001, Price et al.

We used two different types of objectives, with complementary adv

We used two different types of objectives, with complementary advantages and disadvantages. Fluid-immersion

objectives allowed higher numerical apertures but required delivery and removal of fluid at the beginning and end of each head-fixation period. Imaging could not be carried out during the process of fluid delivery or removal (∼500 ms each). In contrast, air objectives have lower numerical apertures but allowed imaging to continue until the end of head restraint on each trial. Both types of objectives allow high-quality cellular resolution SAHA HDAC in vitro functional imaging. For experiments with fluid-immersion objectives, we developed an automated immersion fluid delivery and removal system (Figure 4A). This system consisted of two thin tubes, one for delivery, connected Selleck Fulvestrant to an immersion fluid reservoir,

and one for suction, connected to a vacuum pump. A custom collar mounted on the objective barrel positioned the openings of the tubes at the gap between the imaging region and the face of the objective. To discourage the use of this fluid as a water-reward source, we used 5–10 mM quinine instead of distilled water. Timing of the addition and removal of immersion fluid with each insertion was controlled by solenoid valves, which received commands from behavioral software (Figure 5A). Addition of the immersion fluid began at the initiation of head restraint and lasted 400 ms. Fluid removal began 400 ms before the end of head fixation, concomitant with the end of image acquisition for that trial. An aperture (0.9 cm by 1.5 cm) in the

center of the headplate allowed access to the skull and could accommodate the implantation of an optical window that allowed optical access to the brain. The optical window was designed based on an implantable optical device previously used to perform in vivo cellular resolution imaging in mice with minimal brain motion over long periods of time (Figure 4B; Dombeck et al., 2010). It consisted of a 150-μm-thick, 3.5-mm-diameter circular cover glass that was bonded to a short 9G stainless steel ring using optical adhesive. The height of the ring was designed to match the thickness of the rat skull over the imaging region. In experiments targeting the medial all agranular cortex (AGm), the height of the ring was 400 μm, whereas in experiments targeting the visual cortex (V1), the height was 800 μm. To increase mechanical stability during imaging, we designed the optical window to depress the cortical surface by ∼150 μm below the bottom of the skull when fully implanted (Dombeck et al., 2007). Given the working distance of the imaging objectives (3.3 mm for water, 4.0 mm for air) relative to the combined thickness of the headplate (1.65 mm) and rat skull (0.4–0.8 mm), it became necessary in some cases to move the objective out of the way, prior to the insertion of the headplate on each trial, to prevent the headplate from hitting, and potentially damaging, the objective.

In the stratum radiatum of the hippocampus,

sAC immune-pe

In the stratum radiatum of the hippocampus,

sAC immune-peroxidase labeling was observed in glial processes from wild-type (WT) mice, but not in male Sacytm1Lex/Sacytm1Lex mice (Figure 1E). The number of glial processes stained with R21 antibody was significantly reduced in sAC-C1 KO animals compared to wild-type animals (WT: 191.0 ± 18.0/411 μm2 versus sAC-C1 KO: 6.9 ± 4.6/411 μm2). The quantification is shown in Figure 1F. These data show that astrocytes, as opposed to neurons, are the predominant site for sAC expression in the hippocampus. Because of their selective permeability to K+, astrocytes are exquisitely sensitive to the changes in [K+]ext, which occur as a result of changes in neuronal depolarization generated by synaptic activity and neuronal spiking. Physiological increases in [K+]ext of only a few millimolar cause astrocyte depolarization and permit HCO3− entry through the electrogenic DAPT cell line NBC, resulting in intracellular alkalinization (Pappas and Ransom, 1994). If increases in [K+]ext activate sAC via HCO3− influx, we predict that there should be a corresponding

increase in cAMP that would be inhibited by DIDS, a blocker of NBC. Therefore, we examined the effect of elevated [K+]ext on the production of cAMP in cultured astrocytes expressing a cAMP sensor (GFPnd-EPAC(dDEP)-mCherry) (van der Krogt et al., 2008) using Försters CP-868596 supplier resonance energy transfer (FRET) confocal imaging (green fluorescent protein [GFP] donor/mCherry acceptor) (Figure S2). Elevating Ketanserin [K+]ext from 2.5 mM to 5 or 10 mM progressively increased the cAMP sensor FRET ratio, indicating a rise in intracellular cAMP (control: 0.32% ± 0.27%, n = 13; 5 mM K+: 9.60% ± 1.06%, n = 11, p < 0.001; 10 mM K+: 18.70% ± 1.12%, n = 9, p < 0.001; Figures 2A–2C). Several lines of experiments confirmed that this rise in cAMP was due to sAC activation by HCO3− entry. The increase in the cAMP sensor FRET ratio normally observed in high [K+]ext was significantly inhibited by the sAC-selective inhibitor 2-hydroxyestrone (2-OH, 20 μM) (Hess et al., 2005; Schmid et al., 2007; Steegborn et al., 2005) (3.82% ± 1.09%, n =

13, p < 0.001; Figures 2A–2C) and was prevented by inhibiting the electrogenic NBC with DIDS (450 μM) (0.71% ± 0.60%, n = 9, p < 0.001; Figures 2B and 2C). Furthermore, the cAMP sensor FRET ratio increased when the external solution was changed from HCO3−-free (replaced with HEPES buffered) to one containing HCO3−, which should increase sAC activity (6.51% ± 1.79%, n = 13, p < 0.001; Figure 2C). As a control for our FRET-cAMP measurement and to provide a comparison with other stimulators of cAMP synthesis, we measured the cAMP sensor FRET ratio when we increased cAMP via sAC-independent pathways by directly stimulating transmembrane adenylyl cyclases (tmACs) with forskolin (25 μM) (31.3% ± 1.8% increase in the cAMP sensor FRET ratio, n = 5; Figure 2C) or the beta-adrenergic agonist isoproterenol (100 μM) (Figure S3).

Also, cholinergic modulation can change thresholds by several mil

Also, cholinergic modulation can change thresholds by several millivolts even with a constant baseline (Figenschou et al., 1996). Alternatively, having a higher proportion of APs triggered by dendritic spikes (Gasparini et al., 2004) could lead to an apparently lower threshold, with the proportion itself affected by differences in inputs and/or intrinsic factors. Selleck Pomalidomide Second, while the random input-based model predicts a continuum of “peak – threshold” values (regardless of whether the AP threshold is fixed or varies across cells) with higher values

for place cells, instead we found a bimodal distribution with a large, clear gap separating place fields from silent (Figure 4G) as well as active from nonactive (Figure S1V) directions. This was the feature that most clearly separated the two classes and, contrary to the random input-based model, suggests that place and silent

cells qualitatively differ within a given environment. This qualitative difference is further supported by the surprising flatness of the silent cells’ subthreshold fields (Figures 4A, 4E, and 4H). A nonrandom distribution of inputs could explain the lack of a continuum, but would be unlikely to explain the following result, as it involved somatic current injection. Third, even prior to any sensory input from the maze, future place and silent cells unexpectedly displayed differing burst propensities (Figures 5 and S1J) as did future active and non-active cells (Figure S1A′). Raf inhibitor Thus intrinsic properties may predetermine the division into place and silent cells. Does this mean that a fixed fraction of cells will have place fields regardless of the size of the environment? While fewer cells may express place fields in smaller and/or simpler mazes (Thompson and Best, 1989), in larger environments the number of place cells appears to be limited,

with additional spatial coverage achieved primarily by having each place cell express multiple fields (Fenton et al., 2008 and Davidson et al., 2009). Therefore, what intrinsic factors may predetermine is the restricted subset of cells that could potentially have place fields. Moreover, among the set of possible place cells, Histone demethylase the relative locations of their place fields also appear to be predetermined (Dragoi and Tonegawa, 2011). In the simple input-based model, the subthreshold field would essentially reflect the net synaptic conductance as a function of the animal’s location and be largely independent of properties such as the threshold or burst propensity, but these results show that they are all interrelated. Indeed, direct comparison of the “peak – baseline” and threshold shows that these features were negatively correlated (Figures S1O and S1F′) as opposed to uncorrelated (or positively correlated, which could occur if the input and threshold were uncorrelated but the threshold acted as a ceiling on the subthreshold peak).

Serotonergic blockers did not prevent the disappearance of slow w

Serotonergic blockers did not prevent the disappearance of slow waves upon waking (Figures 5E, blue; Figure S5C), validating a role for norepinephrine in switching cortical dynamics. We conclude that arousal dramatically transforms the temporal pattern of spontaneous synaptic inputs in cortical networks. Local

recurrent networks appear able to generate a relatively constant level of background synaptic input. Our study demonstrates that wakeful patterns of synaptic input can occur independent of primary and secondary sensory thalamic nuclei, contrary to the idea that global brain states PF-06463922 in vivo influence local cortical networks via thalamic afferents (Hirata and Castro-Alamancos, 2010 and Steriade et al., 1993b). Cholinergic selleck products modulation was also unnecessary to achieve awake cortical dynamics. We found that ACh more noticeably impacts sensory-evoked responses, a capacity that may subserve attentional focusing on selected stimuli. In contrast, the powerful influence of arousal on cortical dynamics required norepinephrine. Electrical stimulation

of nonspecific intralaminar thalamic nuclei, which diffusely project across cortex, initially implicated them in arousal (reviewed in Van der Werf et al., 2002). Lesions of intralaminar nuclei do not, however, alter EEG patterns (Buzsaki et al., 1988 and Vanderwolf and Stewart, 1988). Indeed, we found that wakefulness still profoundly affected cortical dynamics after our thalamic lesions, which severed connections between cortex and the central lateral intralaminar nucleus, the most investigated for a role in arousal. Our results do not rule out possible contributions of the central medial nucleus, parafascicular complex, or rhomboid nucleus. These, much however, seem unlikely given that sparse axons

from these intralaminar nuclei avoid L4 (Van der Werf et al., 2002), where we investigated mechanism. Moreover, these projections would have to act through L2/3-L4 and L5/6-L4 synapses, which are also anatomically sparse and, in those rare instances when observed, substantially (∼2–6 fold) weaker than L4-L4 synapses (Gottlieb and Keller, 1997, Lefort et al., 2009 and Schubert et al., 2003). A more likely explanation for the switch in cortical dynamics, therefore, is that NE directly modulates synapses among L4 neurons. Electrical stimulation of cholinergic nuclei is sufficient to produce awake-like cortical activity in anesthetized animals (Goard and Dan, 2009, Metherate et al., 1992 and Steriade et al., 1993a). We found, however, that cholinergic modulation is unnecessary to achieve wakeful cortical dynamics. Our experiments do not rule out possible behavioral contexts in which natural ACh release could alter dynamics.

, 2009 and Ryan et al , 2008) Some of the effects were substanti

, 2009 and Ryan et al., 2008). Some of the effects were substantial, particularly those in ShaB. Interestingly, the overall effect of editing at multiple sites within the same transcript could not be predicted from the effects of the individual sites, a phenomenon known as functional epistasis. Thus the functional outcomes of editing can be exceptionally complex. In a different study, editing was shown to decrease the sensitivity of a GABA-gated

Cl- channel to GABA, an effect predicted to increase excitability ( Jones et al., 2009). With hundreds of editing sites BIBF1120 in Drosophila yet to be investigated, these studies are obviously just the beginning. On the other end of the physiological spectrum from molecular structure-function studies, there have been several investigations into how RNA editing affects Drosophila behavior. These have been aided by the fact that Drosophila contains a single ADAR Selleckchem Erlotinib locus and its removal results in viable flies, although just barely ( Palladino et al., 2000a and Palladino et al., 2000b). The Drosophila ADAR locus resides at the tip of the X chromosome, and the protein that it encodes closely resembles vertebrate ADAR2. Null mutants for Drosophila ADAR (dADAR) appear morphologically normal, have a normal

life-span and, when maintained under favorable conditions, can be coaxed into reproducing. However, adult flies are obviously compromised ( Palladino et al., 2000b). Problems include seizures, whose severity increase with age, poorly coordinated locomotion, compulsive preening, abnormal posture, tremors, and a reluctance to jump and fly. On a morphological level, conspicuous neurodegeneration is evident in the brain and retinas. Although dADAR is expressed outside of the nervous system, and has activities beyond editing mRNAs, it has been demonstrated that much of the dADAR null phenotype results from a lack of editing of brain messages ( Jepson

and Reenan, 2009). Because a complete dADAR knockout results in such a severe phenotype, it is difficult to assess the importance of editing for complex behaviors using these flies. To address this problem, Reenan and colleagues engineered flies in which dADAR expression was greatly Dipeptidyl peptidase reduced but not abolished ( Jepson et al., 2011). Interestingly, although the severe locomotor phenotypes of the null mutants were not evident, defects in courtship and circadian behavior were evident and a knockdown of editing in a specific neuronal subset was sufficient to alter the male courtship song. Now that we know the more or less complete set of edited targets in Drosophila, due to the genetic manipulations that are possible in this system, we can begin to design experiments that link the mechanistic changes caused by RNA editing with the complex behaviors that these changes regulate.

A total of 23 figure positions were presented (the distance of th

A total of 23 figure positions were presented (the distance of the RF center relative to the figure center ranged from −5.5° to 5.5° with 0.5° steps, see Figure 2B). For 9 of the 46 V4 recording sites, we did not present figures at all

these CX-5461 molecular weight positions, but we used a subset of five positions (one center, two edge, and two background positions), and the data from these recording sites were not included in the space-time plots (Figures 6C and 6D). The stimulus also contained two curves (width 0.27°, luminance 82 cd·m-2) and two red circles (size 1.5°) in the hemifield opposite to the figure (upper hemifield for monkeys B and J and right hemifield for monkey C). One of the curves was connected to the fixation point (target curve) and the other curve was not (distracter Cilengitide concentration curve). A small change close to the fixation point switched the target and distracter curve (in the example of Figures 2A and 2C the left curve is the target curve but in other trials the right curve was connected to the fixation point). All 23 figure positions × 2 curve configurations were presented in a randomly interleaved

sequence in both tasks. The animals underwent two surgeries under general anesthesia that was induced with ketamine (15 mg kg-1 injected intramuscularly) and maintained after intubation by ventilation with a mixture of 70% N2O and 30% O2, supplemented with 0.8% isoflurane, fentanyl (0.005 mg kg-1 intravenously), unless and midazolam (0.5 mg kg-1 h-1 intravenously). In the first operation a head

holder was implanted and a gold ring was inserted under the conjunctiva of one eye for the measurement of eye position. In the second operation, arrays of 4 × 5 electrodes (Cyberkinetics Neurotechnology Systems Inc.) were chronically implanted in areas V1 and V4 (see Figure S1). All procedures complied with the NIH Guide for Care and Use of Laboratory Animals (National Institutes of Health, Bethesda, Maryland), and were approved by the institutional animal care and use committee of the Royal Netherlands Academy of Arts and Sciences. Details about the recording methods and information about the measurement of RFs in V1 and V4 can be found in Supplemental Experimental Procedures. We quantified visual responsiveness by first calculating the spontaneous mean activity, Sp, and the standard deviation, s, across trials in a 200 ms time window preceding stimulus onset. We then computed the peak response, Pe, by smoothing the average response over conditions with a moving window of 25 ms and taking the maximum during the stimulus period (0–600 ms after stimulus onset). The visual responsiveness index was then given by VR = (Pe-Sp)/s.

It is possible that some degree-based hubs (like those in the pre

It is possible that some degree-based hubs (like those in the precuneus) are provincial hubs that play central roles in particular systems.

It is also possible that these hubs do not have hub-like roles in information processing and that their “hubness” arises from the factors discussed above. We shall return to this topic. In the areal network, nodes represent our current best estimate of buy Protease Inhibitor Library the centers of brain areas (Power et al., 2011). If a node has a high participation index, it has modest-to-high correlations with multiple communities. Since these communities correspond reasonably well to systems (Power et al., 2011), we infer that such nodes likely have access to a variety of types of different information processing represented among different systems. In the modified voxelwise network, nodes do not correspond to any “unit” of brain organization. Here, the peaks in community density represent points of spatial articulation between multiple brain systems. These peaks do not represent areas but rather locations where areas from multiple systems exist in close proximity to one another. Cortex in such regions does not necessarily compound screening assay integrate different types of information but would be well-situated to perform

such integration. Regions with high community density tend to have high participation coefficients (Figure 8A). Convergence between measures is especially prominent at some regions in the anterior insula, dorsal medial prefrontal cortex, dorsal prefrontal cortex, lateral occipito-temporal

cortex, and superior many parietal cortex. There are also some regions where the measures diverge, such as the inferior parietal sulcus (high participation coefficient, low community density) or the midcingulate (low participation coefficient, high community density). Differences between the measures in these latter regions may be of eventual interest, but our present focus is on regions where both measures are congruent. The methods advocated in this report generally highlight different parts of the brain than do degree-based methods. Indeed, community density and node strength (normalized and summed across thresholds) are negatively correlated (r = −0.37, Figure S8), as are participation coefficient and node strength (r = −0.12, Figure S8). No analog of community density exists in the real-world graphs, but the relationship between participation coefficient and node strength seen across networks in Figure S1 is instructive: it is strongly negative in the three real-world correlation networks, mildly negative in the RSFC networks and in a few real-world noncorrelation networks, but usually positive in real-world noncorrelation networks. This is consistent with the idea that RSFC networks occupy a conceptual space somewhere between the computer and birdsong networks of Figure 1.