Whole-animal connectomes of both Caenorhabditis elegans sexes

Classified as probably not a substantial claim.

Earlier work described connectivity for parts of the C. elegans nervous system, including major neural centres in the adult hermaphrodite and the posterior region of the adult male.

“Connectivity has been described previously for sections of the C. elegans nervous system that encompasses the major neural centres, including the anterior and posterior body regions and the pharynx of the adult hermaphrodite and the posterior region of the adult male1–4,18.”

• cites [1] White, J. G., Southgate, E., Thomson, J. N. & Brenner, S. The structure of the nervous system of the nematode Caenorhabditis elegans. Phil. Trans. R. Soc. Lond. B 314, 1–340 (1986). sourceNot checked — no full text of the source
• cites [2] Albertson, D. G. & Thomson, J. N. The pharynx of Caenorhabditis elegans. Phil. Trans. R. Soc. Lond. B 275, 299–325 (1976). sourceNot checked — no full text of the source
• cites [3] Jarrell, T. A. et al. The connectome of a decision-making neural network. Science 337, 437–444 (2012). sourceNot checked — no full text of the source
• cites [4] Hall, D. H. & Russell, R. L. The posterior nervous system of the nematode Caenorhabditis elegans: serial reconstruction of identified neurons and complete pattern of synaptic interactions. J. Neurosci. 11, 1–22 (1991). sourcePartly supported

  The paper’s opening passage says earlier reports described the anterior sensory cells, pharynx, ventral nerve cord and nerve ring; it then describes this paper’s reconstruction of synaptic interactions in the adult hermaphrodite tail. That supports the claim about connectivity in parts of the hermaphrodite nervous system, but our copy does not support the adult-male posterior-region component. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [18] Varshney, L. R., Chen, B. L., Paniagua, E., Hall, D. H. & Chklovskii, D. B. Structural properties of the Caenorhabditis elegans neuronal network. PLOS Comput. Biol. 7, e1001066 (2011). sourcePartly supported

  The Introduction and Materials and Methods (Data Acquisition; page unavailable) describe earlier reconstructions of the hermaphrodite nervous system, particularly the anterior, neck, and tail regions. The paper does not establish the claim about previously described connectivity in the adult male’s posterior region; its Results (Reconstruction) also distinguish its somatic wiring diagram from the pharyngeal nervous system. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

May combine two claims.

C. elegans sensory neurons usually respond to several stimuli, so sensory integration starts within the sensory neurons.

“As the sensory neurons of C. elegans generally respond to multiple stimuli, sensory integration begins within the sensory neurons themselves25,26.”

• cites [25] Zou, W. et al. Polymodal responses in C. elegans phasmid neurons rely on multiple intracellular and intercellular signaling pathways. Sci. Rep. 7, 42295 (2017). sourcePartly supported

  The Abstract reports that C. elegans PHA/PHB neurons respond to multiple stimuli and use intracellular and intercellular pathways to process them; the Discussion describes encoding and discrimination in those neurons. This supports sensory processing within particular sensory neurons, but the paper does not establish that C. elegans sensory neurons generally respond to multiple stimuli or that integration always begins within them. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [26] Hart, A. C., Kass, J., Shapiro, J. E. & Kaplan, J. M. Distinct signaling pathways mediate touch and osmosensory responses in a polymodal sensory neuron. J. Neurosci. 19, 1952–1958 (1999). sourcePartly supported

  The Abstract reports that ASH neurons respond to nose touch, hyperosmolarity, and volatile repellents, and distinguish stimuli through distinct signaling pathways within the neurons. This supports stimulus processing within ASH, but the paper does not establish that C. elegans sensory neurons generally respond to multiple stimuli. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Prior functional studies link SMD to Ω-turn amplitude, SMB to sinusoidal movement amplitude, SAB to proprioception, and SIA to flipping behaviour during lethargus.

“Functional studies have shown that SMD encodes the amplitude of a deep ventral bend behaviour known as the Ω-turn; SMB influences the amplitude of sinusoidal movement; SAB is thought to act in proprioception; and the SIA neurons are involved in so-called ‘flipping behaviour’ during lethargus24,29,30.”

• cites [24] Gray, J. M., Hill, J. J. & Bargmann, C. I. A circuit for navigation in Caenorhabditis elegans. Proc. Natl Acad. Sci. USA 102, 3184–3191 (2005). sourceNot checked — no full text of the source
• cites [29] Kratsios, P. et al. Transcriptional coordination of synaptogenesis and neurotransmitter signaling. Curr. Biol. 25, 1282–1295 (2015). sourceSupported
• cites [30] Schwarz, J. & Bringmann, H. Analysis of the NK2 homeobox gene ceh-24 reveals sublateral motor neuron control of left–right turning during sleep. eLife 6, e24846 (2017). sourceSupported

May combine two claims.

The close match between node placement and worm neuroanatomy indicates economical wiring, a common property of nervous systems including C. elegans.

“The notable similarity in the placement of the nodes to the neuroanatomy of the worm reflects economical wiring, a property commonly found for nervous systems, including in C. elegans19–22.”

• cites [19] Ahn, Y.-Y., Jeong, H. & Kim, B. J. Wiring cost in the organization of a biological neuronal network. Physica A 367, 531–537 (2006). sourceSupported
• cites [20] Chen, B. L., Hall, D. H. & Chklovskii, D. B. Wiring optimization can relate neuronal structure and function. Proc. Natl Acad. Sci. USA 103, 4723–4728 (2006). sourceSupported
• cites [21] Wang, I. E. & Clandinin, T. R. The influence of wiring economy on nervous system evolution. Curr. Biol. 26, R1101–R1108 (2016). sourceNot checked — no full text of the source
• cites [22] Gushchin, A. & Tang, A. Total wiring length minimization of C. elegans neural network: a constrained optimization approach. PLoS ONE 10, e0145029 (2015). sourcePartly supported

  The Conclusions (page unavailable) say that total wiring-length minimization has a large influence on C. elegans interneuron placement, supporting the economical-wiring interpretation. But they also note discrepancies between real and optimal positions; the Results report that optimal layouts could reduce real wiring length substantially. The paper does not establish that economical wiring is a common property of nervous systems generally. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

The ASEL-ASER pair is known to be lateralized in chemosensory cue detection.

“The ASEL-ASER pair is known to be lateralized in its ability to sense chemosensory cues34,35.”

• cites [34] Pierce-Shimomura, J. T., Faumont, S., Gaston, M. R., Pearson, B. J. & Lockery, S. R. The homeobox gene lim-6 is required for distinct chemosensory representations in C. elegans. Nature 410, 694–698 (2001). sourceNot checked — no full text of the source
• cites [35] Johnston, R. J. Jr, Chang, S., Etchberger, J. F., Ortiz, C. O. & Hobert, O. MicroRNAs acting in a double-negative feedback loop to control a neuronal cell fate decision. Proc. Natl Acad. Sci. USA 102, 12449–12454 (2005). sourceSupported
  Experimental — accuracy not yet measured

May combine two claims.

AVA and AVB promote backward and forward locomotion and are targeted by male-specific interneurons PVV, PVX, and PVY, which regulate male locomotion during copulation.

“For example, the major layer 1 pre-motor interneurons AVA and AVB, which promote backward and forward locomotion, respectively, are targeted by three major male-specific interneurons, PVV, PVX and PVY, that regulate the locomotion of the male during copulation37,38.”

• cites [37] Sherlekar, A. L. et al. The C. elegans male exercises directional control during mating through cholinergic regulation of sex-shared command interneurons. PLoS ONE 8, e60597 (2013). sourcePartly supported

  The Results section on PVY reports that PVY and PVX target the AVA backward and AVB forward command interneurons, and that PVY promotes backward movement during mating (page unavailable). It does not establish the claimed role for PVV; it also says PVX ablation had no obvious effect on vulva-search behavior, leaving its role subtle or potentially redundant. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [38] Koo, P. K., Bian, X., Sherlekar, A. L., Bunkers, M. R. & Lints, R. The robustness of Caenorhabditis elegans male mating behavior depends on the distributed properties of ray sensory neurons and their output through core and male-specific targets. J. Neurosci. 31, 7497–7510 (2011). sourcePartly supported

  The section “Many male-specific ray neuron targets are not essential for ventral curling” (page unavailable) identifies PVV and PVY as male-specific interneuron/motor neurons, and the Discussion (page unavailable) mentions PVX and PVV as possible contributors to male posterior muscle control. Our copy does not establish that PVV, PVX, and PVY target AVA and AVB, or specify AVA’s and AVB’s respective roles in backward and forward locomotion. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Connectivity reinforcement by circuit activity and experience has been demonstrated but remains little studied.

“Reinforcement of connectivity by circuit activity and hence experience has been demonstrated but little studied so far45.”

• cites [45] Hart, M. P. & Hobert, O. Neurexin controls plasticity of a mature, sexually dimorphic neuron. Nature 553, 165–170 (2018). sourcePartly supported

  In “DVB neurites are experience and activity-dependent” (page unavailable), the paper reports that mating experience and repeated circuit activation increase DVB neurite growth. In “DVB plasticity impacts behavior via dimorphic synaptic connectivity” (page unavailable), it reports an increase in specific synaptic connections with age. It does not directly show that activity reinforces those connections, and its statement that molecular mechanisms are not well understood does not establish that connectivity reinforcement itself has been little studied. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

May combine two claims.

For chemical synapses, the standard deviation of the percentage uncertainty in the number of sections scored was 10% for edge weights of 10 sections or fewer and 2% for edge weights of 40 sections or more.

“the percentage uncertainty (s.d.) in the number of sections scored ranged for chemical synapses between 10% for edge weights of 10 sections or less to 2% for edge weights of 40 sections or more.”

• cites [62] Xu, M. et al. Computer assisted assembly of connectomes from electron micrographs: application to Caenorhabditis elegans. PLoS ONE 8, e54050 (2013). sourcePartly supported

  The Results (page unavailable) give the claimed approximate 10% and 2% uncertainty estimates for chemical-synapse edge weights at the stated thresholds. They describe these as estimated percentage uncertainty from differences between three scorers, however, not as standard deviations. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

C. elegans neurons are largely isopotential, but activity-controlling properties such as calcium levels may be compartmentalized, as shown in one example.

“Although C. elegans neurons are largely isopotential48, the properties of these neurons that control activity, such as calcium levels, may be compartmentalized, as has been previously demonstrated in one example49.”

• cites [48] Goodman, M. B., Hall, D. H., Avery, L. & Lockery, S. R. Active currents regulate sensitivity and dynamic range in C. elegans neurons. Neuron 20, 763–772 (1998). sourceNot checked — no full text of the source
• cites [49] Hendricks, M., Ha, H., Maffey, N. & Zhang, Y. Compartmentalized calcium dynamics in a C. elegans interneuron encode head movement. Nature 487, 99–103 (2012). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

The reproducibility of the annotation was evaluated by comparing results from independent annotators.

“Reproducibility of the annotation has been assessed by comparing the results of independent annotators62.”

• cites [62] Xu, M. et al. Computer assisted assembly of connectomes from electron micrographs: application to Caenorhabditis elegans. PLoS ONE 8, e54050 (2013). sourceSupported

May combine two claims.

Neurite outgrowth and synapse formation in C. elegans continue through larval development, the L4 stage, and adulthood, and ectopic neurite sprouting continues with aging.

“Outgrowth of neurites and establishment of synapses in C. elegans occurs throughout larval development and continues through the L4 larval stage and into adulthood, and ectopic neurite sprouting continues as the nervous system ages45,46.”

• cites [45] Hart, M. P. & Hobert, O. Neurexin controls plasticity of a mature, sexually dimorphic neuron. Nature 553, 165–170 (2018). sourcePartly supported

  The ‘Morphologic plasticity displayed by adult male DVB neuron’ section reports progressive neurite outgrowth from adult days 1 to 5, and ‘DVB plasticity impacts behavior via dimorphic synaptic connectivity’ reports an increase in specific synaptic connections over that period (page numbers not supplied). The paper does not establish continued outgrowth and synapse formation throughout larval development or the L4 stage, or general ectopic sprouting across the aging nervous system; its adult finding concerns the male DVB neuron. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [46] Toth, M. L. et al. Neurite sprouting and synapse deterioration in the aging Caenorhabditis elegans nervous system. J. Neurosci. 32, 8778–8790 (2012). sourcePartly supported

  The Results section, “C. elegans touch receptor neurons exhibit new neurite outgrowth with age” (page unavailable), reports new branches that become more frequent in aging adults, supporting the ectopic-sprouting portion. Our copy does not establish that neurite outgrowth and synapse formation continue throughout larval development, through L4, and into adulthood; its aging-synapse findings concern deterioration rather than new synapse formation. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Other shared neurons in male circuits are extensively differentiated in adult males relative to adult hermaphrodites and larvae, and serve different functions in the two sexes.

“Other shared neurons that participate in the male circuits are extensively differentiated in the adult male compared to the adult hermaphrodite and larval stages, and serve different functions in the two sexes (Fig. 6a–f).”

The quote only partly states this claim.

Gap junction connections were more variable than chemical connections.

“Gap junctions were more variable.”

May combine two claims.

When all edges for both sexes are treated as undirected, the chemical and gap junction graphs are weakly connected.

“Although sparse, if all edges for both sexes are considered to be undirected, both chemical and gap junction graphs are connected, meaning that there is a path connecting every pair of nodes (weakly connected).”

May combine two claims.

The male graph has 5,315 chemical edges and 1,755 gap junction edges.

“and 5,315 chemical and 1,755 gap junction edges in the male”

May combine two claims.

Computational two-dimensional layouts show sensory information pathways, 1-5 synaptic steps from sensory neurons to end organs, and feedforward network organization.

“Two-dimensional layouts of the connectivity graphs based on computational arrangement reveal the pathways of sensory information flow, the small number (1–5) of synaptic steps between the sensory neurons and the end organs, and the feedforward nature of the networks”

May combine two claims.

In the male, 54% of shared neuron classes, 50 of 93, output to the sex-specific component, providing 18% of its input.

“Reciprocally, 54% of the shared neuron classes (50 out of 93 classes) have output onto the sex-specific component, constituting 18% of the input of the sex-specific neurons.”

May combine two claims.

108 neurons in 17 classes, providing 91% of input to body-wall muscles, are classified as motor neurons because much of their output goes to muscle and muscle control appears primary.

“Of these neurons, we classify 108 neurons in 17 classes—accounting for 91% of input to the body-wall muscles—as motor neurons, because a large fraction of their output is to muscle, and muscle control appears to be their primary function”

May combine two claims.

The hermaphrodite has 8 sex-specific neurons and 16 sex-specific muscles; the male has 91 sex-specific neurons and 39 sex-specific muscles.

“In total 8 neurons and 16 sex muscles are specific to the hermaphrodite; 91 neurons and 39 sex muscles are specific to the male.”

May combine two claims.

The main sex differences concern reproduction: vulval and uterine muscles and their motor neurons in the hermaphrodite, and additional male neurons, sex muscles, and tail connections for copulation.

“The primary sex differences are in reproductive functions, the vulval and uterine muscles and the motor neurons that control them in the hermaphrodite and—in the male—the large number of additional neurons, sex muscles and connections in the tail that generate the circuits for copulation3.”

• cites [3] Jarrell, T. A. et al. The connectome of a decision-making neural network. Science 337, 437–444 (2012). sourceNot checked — no full text of the source

May combine two claims.

The graphs are sparse, containing 3.2% of possible edges in the hermaphrodite and 2.4% in the male.

“They are sparse graphs with respectively 3.2% (for the hermaphrodite) and 2.4% (for the male) of all possible edges.”

May combine two claims.

In the cell-class connectivity graph, median degree values near 19 indicate extensive cross-connectivity and both convergence and divergence across the nervous system.

“Considering the graph of connectivity between cell classes, median degree values of around 19 illustrate the extensive cross-connectivity and thus indicate both convergence and divergence throughout the nervous system.”

May combine two claims.

In the hermaphrodite, 37% of neuron classes are targeted by HSN and VC, but this is only 1.4% of total input to the shared component.

“In the hermaphrodite, 37% of the neuron classes are targeted by the two sex-specific neuron classes, HSN and VC, but this constitutes only 1.4% of total input of the shared component.”

May combine two claims.

The hermaphrodite graph has 4,887 chemical edges and 1,447 gap junction edges.

“The respective graphs have 4,887 chemical (or directed) edges and 1,447 gap junction (or undirected) edges in the hermaphrodite”

Probably not a substantial claim: may not pass S3 (load-bearing).

In the N2U hermaphrodite anterior reconstruction, 7,446 chemical and gap junction synapses fell roughly equally into three regions: 2,578 not nerve ring, 2,472 nerve ring 45°, and 2,396 nerve ring in-plane.

“Of7,446 synapses (chemical plus gap junctions), the synapses fell roughly equally into these three regions (2,578 not nerve ring, 2,472 nerve ring 45°, 2,396 nerve ring in-plane).”

May combine two claims.

The study scored more synapses than previous papers for two reasons.

“We scored more synapses compared to the previous papers for two reasons (Extended Data Fig. 1).”

• cites Extended Data Fig. 1Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

In the hermaphrodite, the best anterior series N2U ends around the midbody vulva, while the best posterior series JSE extends anteriorly only to the junction between the ventral cord and the pre-anal ganglion.

“In the hermaphrodite, the best anterior series (N2U) ends around the midbody vulva whereas the best posterior series (JSE) extends anteriorly only as far as the junction between the ventral cord and the pre-anal ganglion”

• cites Supplementary Information 10Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

In the male, the anterior series N930 extends posteriorly through the ventral ganglion, while the posterior series N2Y extends anteriorly to near the border between the seminal vesicle and the vas deferens.

“In the male, the anterior series (N930) extends posteriorly through the ventral ganglion, whereas the posterior series (N2Y) extends anteriorly to a position near the border between the seminal vesicle and the vas deferens”

• cites Supplementary Information 10Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The gap contains gap junctions between adjacent muscles, neuromuscular junctions linking ventral cord motor neurons to dorsal and ventral body-wall muscles, connections between successive ventral cord motor neurons, and connections from premotor interneurons AVA and AVB to ventral cord motor neurons.

“This gap includes gap junctions between adjacent muscles, neuromuscular junctions between the ventral cord motor neurons and dorsal and ventral body-wall muscles, connections from one ventral cord motor neuron to the next, and connections between the major premotor interneurons AVA and AVB and ventral cord motor neurons.”

Probably not a substantial claim: may not pass S3 (load-bearing).

N2U includes only the anterior part of the dorsal nerve cord where neuromuscular junctions to dorsal muscle quadrants are located.

“N2U includes only the anterior portion of the dorsal nerve cord where the neuromuscular junctions to the dorsal muscle quadrants are located.”

May combine two claims.

Chemical synapse sizes span 1 to 23 sections in the hermaphrodite and 1 to 41 sections in the male; gap junction sizes span 1 to 20 sections in the hermaphrodite and 1 to 30 sections in the male.

“This varies from 1 to 23 sections in the hermaphrodite and from 1 to 41 sections in the male for chemical synapses, and from 1 to 20 sections in the hermaphrodite and from 1 to 30 sections in the male for gap junction synapses”

• cites Supplementary Information 3Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Reconstruction completeness is variable and influences weight values.

“The completeness of the reconstructions varies and will affect the values of the weights.”

May combine two claims.

Because no single EM series covered a whole animal, whole-animal connectomes were made by combining series and filling gaps by extrapolating connectivity across repetitive regions.

“As none of the EM series cover an entire single animal, to generate whole-animal connectomes, data from different reconstruction series were combined and the remaining gaps were filled by extrapolating known connectivity across repetitive regions (Methods).”

• AssumptionThe authors state this as an assumption: Connections that were not observed in a given sex can be assumed present because certain regions are repetitive.

May combine two claims.

Sex-specific neurons connect into head central circuitry to regulate behaviour during overt reproduction and to mediate sex-specific appetitive decisions.

“Sex-specific neurons connect into the sex-shared central circuitry in the head with two functions: to regulate behaviour during overt reproductive activity and to mediate sex-specific, appetitive decision-making.”

May combine two claims.

The male copulation control network contains 85 male-specific neurons and 64 shared neurons.

“This is most notable in the male, in which the neural network that controls copulation consists of 85 male-specific and 64 shared neurons3,36.”

• cites [3] Jarrell, T. A. et al. The connectome of a decision-making neural network. Science 337, 437–444 (2012). sourceNot checked — no full text of the source
• cites [36] Emmons, S. W. Neural circuits of sexual behavior in Caenorhabditis elegans. Annu. Rev. Neurosci. 41, 349–369 (2018). sourceNot checked — no full text of the source

May combine two claims.

The reconstructions are quantitative and use synapse sizes, which allows graph and network analysis.

“The reconstructions are quantitative and based on the sizes of the synapses (Methods, Extended Data Fig. 2 and Supplementary Information 2, 3), thus making graph and network analysis possible.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Sublateral motor neurons were previously incompletely described because their axons pass through regions not fully imaged by high-magnification EM.

“The sublateral motor neurons have been incompletely described heretofore, because their axons run through body regions that have not been fully imaged by EM at high magnification.”

May combine two claims. The quote only partly states this claim.

Major motor neurons and their primary pre-motor interneurons are highly interconnected and receive input from most other neurons, making motor output hard to interpret simply.

“The major motor neurons as well as their primary pre-motor interneurons are highly interconnected and receive some input from most of the remaining neurons, defying simple interpretation of motor output.”

May combine two claims.

Connectivity can help deduce some neuron functions and identify previously unknown cell classes.

“The function of some neurons may be deduced from their connectivity, which can identify them as a previously unknown cell class.”

May combine two claims.

Annotation differences come from outright errors and from different interpretations of ambiguous structures.

“Differences arise from out-and-out errors and from differing interpretations of ambiguous structures.”

Classified as probably not a substantial claim. May combine two claims.

Observed differences may reflect developmental variability, age disparity, rearing conditions, experience, errors, or differing reconstruction completeness.

“Differences may be due to developmental variability, as assessed above (Fig. 5a), or to age disparity, rearing conditions or experience, not to mention differences due to errors and differing degrees of completeness in the reconstructions themselves.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

EM-level ultrastructures can indicate neuronal functions such as sensory perception or hormone secretion.

“EM-level ultrastructures can indicate neuronal functions such as sensory perception or hormone secretion.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Gap junctions are harder to score overall, but the difficulty is similar across all animals in the study.

“Gap junctions are more difficult to score overall, but those difficulties are similar across all animals used in this study.”

May combine two claims.

These possible sex differences involve both chemical and gap junction connections and occur at all network levels.

“Such possible differences involve both chemical and gap junctional connections and occur at all levels throughout the network (Extended Data Fig. 13).”

May combine two claims.

If synapse size is ignored, judging connectivity strength by counting synapses alone will underestimate strong connections and overestimate weaker ones.

“If synapse size is not taken into account, judging connectivity strength by counting synapses alone will therefore underestimate the strength of strong connections and overestimate the strength of weaker connections.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

The connectome is complex enough to require dynamic homeostatic control, so an EM-based connectome is a snapshot of a dynamic structure.

“The connectome is too complex not to be under the control of dynamic, homeostatic mechanisms; an EM-based connectome should be considered a snapshot of a dynamic structure.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The scoring method may or may not affect larger synapses depending on their position relative to section boundaries; only larger synapses have a definite effect.

“It may or may not have any effect on larger synapses, depending on where they lie with respect to section boundaries; there is only a definite effect on larger synapses.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Whether neurons are chemically or electrically coupled informs how they signal.

“How neurons signal emerges from whether they are chemically or electrically coupled.”

May combine two claims.

Including end organs is important because, at least in C. elegans, they are electrically coupled, which strongly affects their activity.

“Inclusion of the end organs is important as—at least in the case of C. elegans—they are electrically coupled, which will have a marked effect on their activity.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Similar reproducibility results are expected for gap junctions.

“Similar results are expected for gap junctions.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Signalling may not be uniform or simultaneous at all synapses.

“Thus, signalling may not be uniform or simultaneous at all synapses.”

May combine two claims.

The gaps in the adjacency matrices leave some muscle cells and motor neurons without innervation; they align precisely with the unreconstructed region and are therefore unquestionably artefactual.

“These gaps in the adjacency matrices, which leave some muscle cells and some motor neurons without any innervation, precisely line up with the unreconstructed region and thus are unquestionably artefactual.”

Probably not a substantial claim: may not pass S3 (load-bearing).

This conclusion might not hold for a particular connection.

“However, this conclusion might not be true for a particular connection.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Neuron identification in the N930 male reconstruction did not rely on synaptic partnerships.

“Synaptic partnerships were not used to identify neurons.”

May combine two claims.

Since the male graph shares the hermaphrodite's major pathways and shows verifiable sex differences, missing synapses must be spread relatively evenly across connections.

“Considering that the male graph contains the same major pathways as the hermaphrodite and verifiable sex differences can be identified, the missing synapses must be distributed relatively uniformly over the connections.”

May combine two claims.

This simplification has little effect on weight values but could matter for particular connections.

“Notably, this has little effect on the values of the weights but it could be important for particular connections.”

May combine two claims.

Chemical synaptic features were not stained exactly as in earlier images, but they remain identifiable and measurable in size in animals from both sources.

“Although our efforts failed to stain chemical synaptic features exactly as in the previously published images, they are still identifiable and measurable in size in animals from both sources.”

May combine two claims.

The whole-animal C. elegans connectomes are a conceptualization built from multiple animals, with some connections taken from the opposite sex and some assumed present from repetitive regions.

“These whole-animal C. elegans connectomes should be considered a conceptualization, being constructed as they are from multiple animals and including some connections that are observed in the opposite sex and some that are not observed at all but assumed to be present based on the repetitive nature of certain regions.”

• AssumptionThe authors state this as an assumption: Connections that were not observed in a given sex can be assumed present because certain regions are repetitive.

Classified as probably not a substantial claim.

Every anterior image was scored without knowledge of sex.

“All anterior images were scored blind to sex.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Because tail anatomy differs by sex, scoring posterior PAG images could not be blinded to sex.

“Sexually dimorphic tail anatomy precluded blinding to sex when scoring posterior images of the PAG.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In most cases, using distinct fluorescent markers for the presynaptic neurite made genotype blinding impossible.

“Use of different fluorescence markers to label the presynaptic neurite prevented blinding to genotype in most instances.”