A Weighted and Directed Interareal Connectivity Matrix for Macaque Cerebral Cortex

The quote only partly states this claim.

The G29 × 29 subgraph indicates an unexpectedly high incidence of unidirectional (nonreciprocal) pathways, about 33% of potentially unidirectional pathways.

“The G29 × 29 subgraph suggests an unexpectedly high incidence of unidirectional links.”

• Also stated in: § Introduction · hedged

  “In contrast, our analysis of a 29 × 29 subset of cortical areas indicates an unexpectedly high incidence of unidirectional (nonreciprocal) pathways.”

• Also stated in: § Introduction · plain

  “Our analysis of 1615 connections, including 36% that we consider to be NFP, reveals a high density of cortico-cortical connectivity (66%) and an unexpectedly high incidence (33%) of potentially unidirectional pathways, of which one-third (10% of the total) were shown to originate from corresponding locations within the connected cortical areas.”

May combine two claims.

Newly found projections were weaker on average than known projections, but the two sets had extensively overlapping weight distributions.

“Newly found projections were weaker on average compared with the known projections; nevertheless, the 2 sets of pathways had extensively overlapping weight distributions.”

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Retrograde tracer injections in 29 of the 91 areas of the macaque cerebral cortex revealed 1,615 interareal pathways, about one-third of which had not previously been reported.

“Retrograde tracer injections in 29 of the 91 areas of the macaque cerebral cortex revealed 1,615 interareal pathways, a third of which have not previously been reported.”

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The connectivity profile for each area conformed to a lognormal distribution, in which a majority of projections are moderate or weak in strength.

“The connectivity profile for each area conformed to a lognormal distribution, where a majority of projections are moderate or weak in strength.”

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

In the G29 × 29 interareal subgraph, two-thirds of the connections that can exist do exist, giving a high density of cortico-cortical connectivity of 66%.

“In the G29 × 29 interareal subgraph, two-thirds of the connections that can exist do exist.”

• Also stated in: § Introduction · plain

  “Our analysis of 1615 connections, including 36% that we consider to be NFP, reveals a high density of cortico-cortical connectivity (66%) and an unexpectedly high incidence (33%) of potentially unidirectional pathways, of which one-third (10% of the total) were shown to originate from corresponding locations within the connected cortical areas.”

May combine two claims.

For the 67 areas containing label from at least one area 10 injection, 50 (75%) were labeled by all 4 injections, 7 by 3 injections, 4 by 2 injections, and 6 by only a single injection; 24 areas lacked connections in all 4 cases.

“For the 67 areas containing label from at least one injection, 50 (75%) were labeled by all 4 injections, 7 by 3 injections, 4 by 2 injections and 6 by only a single injection; 24 areas lacked connections to the injection area in all 4 cases.”

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The best-fitting negative binomial curve for area 10 is closer to a geometric distribution, as was seen for injections of areas V1, V2, and V4.

“It is closer to a geometric distribution (blue line), as was seen for injections of areas V1, V2, and V4 (Markov et al. 2011).”

• cites Markov et al. 2011 sourceNot checked yet

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For an exemplar single V1 injection, the difference between the observed single-case value and the mean of 5 injections is generally quite small and in every case lies within the 95% confidence interval predicted by the negative binomial distribution.

“The difference between the observed single-case value and the mean of 5 injections (blue circles) is generally quite small and for this exemplar injection in every case lies within the 95% confidence interval predicted by the negative binomial distribution.”

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FLNe values obtained from single injections are usually within a factor of 3 and highly likely to be within a factor of 10 of the mean value.

“Altogether, this analysis indicates that FLNe values obtained from single injections are usually within a factor of 3 and highly likely to be within a factor of 10 of the mean value.”

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The maximum difference between the single V1 injection and the mean of 5 injections is 0.99 log unit, corresponding to a 9.5-fold difference.

“The maximum difference is 0.99 log unit, corresponding to a 9.5-fold difference between the single-subject and group-average results.”

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Of the 12 cases with probabilities below 0.05, 3 are consistent and had an observed mean exceeding 7 neurons.

“Of the 12 cases with probabilities below 0.05, 3 are consistent and had an observed mean exceeding 7 neurons.”

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Most NFP to F2 are sparse, but several (areas 12, MB, and PGa) are moderate in strength.

“Quantification of each pathway (see Supplementary Table 6) indicates that most NFP to F2 are indeed sparse, but several (areas 12, MB, and PGa) are moderate in strength.”

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NFP from the F2 injection are located in temporal (9), prefrontal (4), and frontal (1) regions.

“NFP are located in temporal (9), prefrontal (4), and frontal (1) regions (blue areal labels in Fig. 6).”

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Fifty-one projections were identified from the F2 injection, of which 14 are considered NFP.

“Fifty one projections were identified from this injection, of which 14 we consider NFP.”

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The strongest connections tend to be from areas close to the injection, but there are exceptions.

“The strongest connections tend to be from areas close to the injection, but there are exceptions.”

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NFP are rare in the immediate vicinity of the injected area, but are common at both intermediate and distant locations and often form a near-continuous belt of areas.

“NFP are rare in the immediate vicinity of the injected area, but are common at both intermediate and distant locations and often form a near-continuous belt of areas, as in Figure 7.”

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The injection in case 27 was in the hindlimb representation and did not lead to labeling in areas V6A, 32, and PIP, whereas more lateral and ventral injections in the arm representation do label these areas.

“For example, the injection in case 27 was in the hindlimb representation and did not lead to labeling in areas V6A, 32, and PIP, whereas more lateral and ventral injections (in the arm representation) do label these areas (Johnson et al. 1996; Matelli et al. 1998; Caminiti et al. 1999; Petrides and Pandya 1999; Tanne-Gariepy et al. 2002).”

• cites Johnson et al. 1996Not checked yet

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• cites Matelli et al. 1998Not checked yet

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• cites Caminiti et al. 1999Not checked yet

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In general, the areas providing inputs to any given target area form a group that covers at least half of the cortical surface and in some cases more than three quarters of the hemisphere.

“In general, the areas providing inputs to any given target area form a group that covers at least half of the cortical surface (e.g. area 24c) and in some cases more than 3 quarters of the hemisphere (e.g. area 7A).”

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126 reciprocal pathways were categorized as symmetric and 88 as asymmetric.

“We categorized 126 reciprocal pathways as symmetric and 88 as asymmetric (see Supplementary Table 4).”

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Of the 108 unidirectional connections, 4 are classified as strong and 36 as medium.

“Of the 108 unidirectional connections, 4 are classified as strong and 36 as medium (see the Materials and Methods section).”

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The 29 × 91 connectivity matrix is asymmetric, in contrast to many connectivity matrices obtained using neuroimaging methods that cannot distinguish the directionality of connections.

“The matrix is asymmetric, in contrast to many connectivity matrices obtained using neuroimaging methods that cannot distinguish the directionality of connections.”

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The curves in Figure 8 illustrate common features in the connectivity profiles, including close tracking of single FLNe values to the lognormal distribution and progressive widening of the 95% confidence interval with decreasing FLNe values.

“The curves shown in Figure 8 illustrate common features in the connectivity profiles including just how closely the single FLNe values track the lognormal distribution as well as the progressive widening of the 95% confidence interval with decreasing FLNe values.”

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For the target areas in each cortical region, NFP constituted a substantial fraction of the total number of connections: limbic 13%, prefrontal 40%, frontal 30%, parietal 30%, temporal 43%, and occipital 37%.

“For the target areas in each cortical region, the NFP constituted a substantial fraction of the total number of connections (limbic 13%, prefrontal 40%, frontal 30%, parietal 30%, temporal 43%, and occipital 37%).”

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Known connections are on average stronger than NFP, but the two populations overlap extensively.

“Known connections are on average stronger than NFP, but the 2 populations overlap extensively.”

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In the G29 × 29 edge-complete matrix, connectivity was bidirectional between 214 projection pairs, unidirectional for 108 pairs, and unconnected for 84 pairs.

“In our G29 × 29 edge-complete matrix, the connectivity was bidirectional between 214 projection pairs, unidirectional for 108 pairs, and unconnected for 84 pairs (see Supplementary Table 4).”

May combine two claims.

For very low FLNe values, NFP correspond up to 90% of the population, but constitute a decreasing fraction of the source areas with increasing FLNe.

“For very low FLNe values, NFP correspond up to 90% of the population, but constitute a decreasing fraction of the source areas with increasing FLNe.”

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For area triples there are 69 dominating sets (1.88% of 3654), and for sets of 4 areas there are 1,978 (8.33% of 23,751).

“For area triples there are 69 dominating sets (1.88% of 3654), and for sets of 4 areas, there are 1,978 (8.33% of 23 751).”

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The G29 × 29 graph has 536 binary directed links from the maximum possible 812, and is strongly interconnected with a graph density of 0.66 (66%).

“The G29 × 29 graph has M= 536 (binary) directed links from the maximum possible of N(N−1) = 812, and therefore, it is strongly interconnected, with a graph density of ρ= 0.66 (66%).”

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The in-degrees of the G29 × 91 graph range from 26 to 87, and their distribution is concentrated around the mean.

“The in-degrees of the G29 × 91 graph (i.e. the number of source areas projecting to each of 29 target areas, Fig. 12) range from 26 to 87 with a mean of ; their distribution (right side of figure) is concentrated around the mean.”

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The in-degree distribution is inconsistent with a scale-free graph, as is the fact that slightly increasing the size of dominating sets to include 3, 4, and more nodes quickly increases their number.

“The in-degree distribution (Fig. 12) is “inconsistent” with a scale free graph, as is the fact that slightly increasing the size of dominating sets to include 3, 4, and more nodes quickly increases their number.”

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One pair of areas (8l, 7m) receives projections from all 91 areas, revealing an MDS size of 2.

“One pair of areas (8l, 7m) receives projections from all 91 areas, revealing an MDS size of 2.”

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The median number of estimated extrinsic neurons per hemisphere labeled by one repeat injection is 187,000 (interquartile range 98,000-280,000), giving a lower limit to the reliability of the FLNe of <6 × 10−5.

“The median number of estimated extrinsic neurons per hemisphere labeled by one of our repeat injections is 187,000 (interquartile range: 98,000–280,000), which gives a lower limit to the reliability of the FLNe of <6 × 10−5.”

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

Most NFP are long-distance connections.

“Another is that most NFP are long-distance connections that may have been missed in studies that did not closely scrutinize distant cortical regions.”

May combine two claims.

This consistency was previously shown for central visual field injections in areas V1, V2, and V4 and is extended in the present study to area 10, a higher order area with about twice as many inputs as the early visual areas.

“This was previously shown for central visual field injections in areas V1, V2, and V4 (Markov et al. 2011) and is extended in the present study to area 10, a higher order area with about twice as many inputs as the early visual areas (Fig. 11).”

• cites Markov et al. 2011 sourceNot checked yet

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The NFP are sparser than the known connections, but overall their weight distribution overlaps with that of the known connections.

“While the NFP are sparser than the known connections, overall their weight distribution overlaps with that of the known connections (Fig. 9).”

• AssumptionRests on an assumption: The areal parcellation/atlas used is consistent and objective enough to define connections and compare across injections.

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Repeat injections in areas V1, V2, V4, and 10 showed that 58% of NFP are present after each repeat injection and are therefore classified as consistent.

“Further, repeat injections in areas V1, V2, V4, and 10 showed that 58% of NFP are present after each repeat injection and are therefore classified as consistent.”

• AssumptionRests on an assumption: The areal parcellation/atlas used is consistent and objective enough to define connections and compare across injections.

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Projections having more than 10 neurons on average occurred consistently in repeat injections, with just 2 exceptions, and therefore can be considered stable projections.

“Projections having more than 10 neurons on average occurred consistently in repeat injections, with just 2 exceptions, and therefore can be considered stable projections.”

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If the analysis were restricted to previously known connections, the estimated density for the entire hemisphere would decrease to 45%, similar to that predicted for the visual system alone by Felleman and Van Essen (1991) and Jouve et al. 1998.

“If the analysis were restricted to previously known connections, the estimated density for the entire hemisphere would decrease to 45%, similar to that predicted for the visual system alone by Felleman and Van Essen (1991) and Jouve et al. 1998.”

• cites Felleman and Van Essen (1991) sourceNot checked yet

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• cites Jouve et al. 1998Not checked yet

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• AssumptionRests on an assumption: The areal parcellation/atlas used is consistent and objective enough to define connections and compare across injections.

May combine two claims.

NFP significantly span greater distances and more frequently link areas in different regions than do the known connections.

“In this respect, we found that NFP signficantly span greater distances and more frequently link areas in different regions than do the known connections (Markov et al. in preparation).”

• cites Markov et al. in preparationNot checked yet

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The negative binomial and lognormal distributions evidently reflect important regularities of neocortical organization.

“Here, we demonstrate that both features, the negative binomial and lognormal distributions, generalize to other cortical areas and evidently reflect important regularities of neocortical organization.”

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Cortico-cortical connections are directed as well as weighted.

“Just as with many other real-world networks (Boccaletti et al. 2006), cortico-cortical connections are directed as well as weighted.”

• cites Boccaletti et al. 2006 sourceNot checked yet

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Classified as probably not a substantial claim.

A seminal analysis across studies concluded that between-animal variability of a given pathway can exceed 2 orders of magnitude.

“A seminal paper analyzed data across studies and concluded that between-animal variability of a given pathway can exceed 2 orders of magnitude (Scannell et al. 2000).”

• cites Scannell et al. 2000Not checked yet

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Classified as probably not a substantial claim.

Only projections that previously were neither depicted nor listed in publications or databases were classified as newly found projections.

“Here, only projections that previously were neither depicted nor listed in publications or databases (cf. see Supplementary Tables 1 and 6) are classified as NFP.”

Classified as probably not a substantial claim.

To identify connections not previously reported, the authors assessed the connections reported in 119 published studies of connectivity.

“To identify connections to the 29 target areas that were not previously reported, we assessed the connections reported in 119 published studies of connectivity (see Supplementary Tables 1 and 6).”

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

Subsequent studies using improved tracers, more systematic methods, and different parcellation schemes revealed numerous additional pathways.

“Subsequent studies using improved tracers, more systematic methods, and different parcellation schemes revealed numerous additional pathways.”

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

The veracity of labeled neurons was checked by senior team members.

“The veracity of labeled neurons were checked by senior team members (H.K., C.D., P.M., N.T.M., and C.L.).”

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

Injections were included in the analysis if they showed little or no involvement of the underlying white matter and were restricted to a single cortical area.

“Injections were included in our analysis if they showed little or no involvement of the underlying white matter and were restricted to a single cortical area.”

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An early systematic study compiled the interareal connectivity of 32 visual areas in the macaque and reported 305 known projections out of 992 possible pathways, giving a link density of 32% for the visual cortex.

“In the resultant 32 × 32 connectivity matrix, these authors reported 305 known projections out of 992 possible pathways, giving a link density (or graph density) of 32% for the visual cortex, that is, one-third of the maximum possible connections among visual areas were reported to exist.”

• cites Felleman and Van Essen 1991 sourceNot checked yet

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When exploring for labeled neurons, 1 section in 2 (at 240 μm intervals) was examined throughout the cortical gray matter, which enabled the identification of many newly found projections.

“Importantly, when exploring for labeled neurons, 1 section in 2 (i.e. at 240 μm intervals) was examined throughout the cortical gray matter, which enabled the identification of many NFP.”

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The latter study also identified many newly found projections, especially with areas outside the classical visual system.

“The latter study also identified many newly found projections (NFP), especially with areas outside the classical visual system.”

• cites Markov et al. 2011 sourceNot checked yet

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Indirect methods of assessing cortical connectivity using diffusion imaging and resting state functional connectivity are insensitive to the direction of connections and are limited in estimating the weight of the underlying anatomical connections.

“Indirect methods of assessing cortical connectivity using diffusion imaging and resting state functional connectivity are insensitive to the direction of connections and are limited in estimating the weight of the underlying anatomical connections (Hagmann et al. 2008).”

• cites Hagmann et al. 2008 sourceNot checked yet

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A recent hemisphere-wide analysis involving retrograde tracers injected into areas V1, V2, and V4 showed interindividual variability typically less than an order of magnitude.

“In contrast, a recent hemisphere-wide analysis involving retrograde tracers injected into areas V1, V2, and V4 showed greater consistency, with interindividual variability typically less than an order of magnitude (Markov et al. 2011).”

• cites Markov et al. 2011 sourceNot checked yet

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

Not all sections were scored when mapping heavily labeled areas.

“However, not all sections were scored when mapping heavily labeled areas.”

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While cortico-cortical pathways vary widely in weight, surprisingly little quantitative data are available on quantitative connectivity profiles in nonhuman primates.

“While it is well known that cortico-cortical pathways vary widely in their weight (connection strength), surprisingly little data are available on quantitative connectivity profiles in nonhuman primates (Falchier et al. 2002; Barbas et al. 2005; Burman et al. 2011; Markov et al. 2011).”

• cites Falchier et al. 2002Not checked yet

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• cites Barbas et al. 2005Not checked yet

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• cites Burman et al. 2011Not checked yet

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

Previous studies reported that the vast majority of pathways between cortical areas are reciprocal; Felleman and Van Essen identified only 5 unidirectional pathways out of 126 explicitly tested pairs.

“Felleman and Van Essen (1991) identified only 5 unidirectional pathways out of the 126 explicitly tested pairs.”

• cites Felleman and Van Essen (1991) sourceNot checked yet

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Classified as probably not a substantial claim.

Complete scanning of the hemisphere made it possible to determine the full set of ipsilateral cortical source areas projecting to each injected area.

“Complete scanning of the hemisphere made it possible to determine the full set of ipsilateral cortical source areas projecting to each injected area.”

May combine two claims.

Comparison of variability of repeat injections in V1, V2, V4, and 10 with variability when areas are grouped into larger regions shows only a modest reduction in variability, suggesting that areal delineation is not the major source of variability.

“Comparisons of the slopes in Figure 3C,D show only a modest reduction in variability, suggesting that areal delineation is not the major source of variability.”

Classified as probably not a substantial claim.

Increasing the sampling rate reduces the variability in estimates of the FLNe.

“Elsewhere we have shown that increasing the sampling rate reduces the variability in estimates of the FLNe (Vezoli et al. 2004).”

• cites Vezoli et al. 2004 sourceNot checked yet

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

Area F2 is located anterior to F1 (area 4), extends rostrally up to 3 mm in front of the genu of the arcuate sulcus, and is bordered ventrally by the spur of the arcuate sulcus.

“It is located anterior to F1 (area 4), extends rostrally up to 3 mm in front of the genu of the arcuate sulcus and is bordered ventrally by the spur of the arcuate sulcus (Matelli et al. 1998).”

• cites Matelli et al. 1998Not checked yet

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Area F2 is located in the dorso-caudal part of Brodmann's premotor area, area 6.

“Area F2 is located in the dorso-caudal part of Brodmann's premotor area, area 6.”

• cites Matelli et al. 1998Not checked yet

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The availability of 29 injections analyzed using the same parcellation scheme enabled testing for the existence of all pathways and generating an edge-complete graph, G29 × 29.

“The availability of 29 injections analyzed using the same parcellation scheme enabled us to test for the existence of all pathways and to generate an edge-complete graph, which we call G29 × 29.”

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

The curves in each plot are based only on the mean and SDs of the log10(FLNe) values and the number of projections; no free parameters were used to constrain the shape of the curves.

“The curves in each plot are based only on the mean and SDs of the log10 (FLNe) values and the number of projections; no free parameters were used to constrain the shape of the curves.”

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

The evidence for the existence of the known connections is generally relatively good, insofar as most projections are reported in several studies.

“The evidence for the existence of the known connections is generally relatively good, insofar as most projections are reported in several studies.”

May combine two claims.

Some cortical areas have nonuniform connectivity across their extent, and this could impact assessments of reciprocity.

“As already noted, some cortical areas have nonuniform connectivity across their extent, and this could impact assessments of reciprocity.”

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Foveal V1 and V4 are reciprocally connected, whereas peripheral V4 projects to V1 but does not receive a projection from V1.

“For example, whereas foveal V1 and V4 are reciprocally connected (Zeki 1978; Zeki 1980; Van Essen et al. 1986), peripheral V4 projects to V1 but does not receive a projection from V1 (Kennedy and Bullier 1985; Perkel et al. 1986).”

• cites Zeki 1978 sourceNot checked yet

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• cites Zeki 1980Not checked yet

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• cites Van Essen et al. 1986Not checked yet

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There are many alternative parcellation schemes for the macaque cortex, some of which are finer-grained than the 91-area parcellation used.

“For instance, there are many alternative parcellation schemes for the macaque cortex, some of which are finer-grained than the 91-area parcellation we used.”

May combine two claims.

When combined with close section intervals and full hemisphere scanning, the tracers revealed many NFP for each area injected and enabled estimation of connection weight for each projection.

“When combined with close section intervals and full hemisphere scanning, these tracers revealed many NFP for each area injected and enabled estimation of connection weight for each projection.”

May combine two claims.

Altogether, this provides a reasonably accurate portrayal of the connectivity profiles for the 29 injected areas and provides G29 × 29 and G29 × 91 subgraphs constructed with consistent criteria.

“Altogether, this provides a reasonably accurate portrayal of the connectivity profiles for the 29 injected areas and provides G29 × 29 and G29 × 91 subgraphs constructed with consistent criteria.”

May combine two claims.

The many deviations from the diagonal suggest that some areas having similar input profiles have distinctly different output profiles, and vice versa.

“However, the many deviations from the diagonal suggest that some areas having similar input profiles have distinctly different output profiles, and vice versa.”

May combine two claims.

Most injection sites were entirely restricted to the cortical gray matter; in a few there was minor encroachment into immediately subjacent white matter.

“While most of the injection sites were entirely restricted to the cortical gray matter, in a few there was minor encroachment into immediately subjacent white matter (see the Materials and Methods section and Supplementary Fig. 6).”

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

Nearly a thousand of these projections had been previously described, but published data on interareal connection weights has been extremely limited.

“While nearly a thousand of these projections had been previously described, published data on interareal connection weights has been extremely limited.”

May combine two claims.

The study chose an alternative strategy of sampling histological sections at high density and across the entire hemisphere, capturing as much data as feasible and reducing variability related to brain morphology.

“We chose an alternative strategy that includes sampling histological sections at high density and across the entire hemisphere, thereby capturing as much data as are feasible and also reducing variability related to brain morphology (Falchier et al. 2002; Vezoli et al. 2004; Markov et al. 2011).”

• cites Falchier et al. 2002Not checked yet

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• cites Vezoli et al. 2004 sourceNot checked yet

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• cites Markov et al. 2011 sourceNot checked yet

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The retrograde tracers used show high sensitivity and restricted uptake zones, making it possible to verify their restriction to a single cortical area.

“We used retrograde tracers that show high sensitivity and restricted uptake zones, the latter making it possible to verify their restriction to a single cortical area (for a detailed discussion of the relative merits of the tracers used here, see Supplementary material in Markov et al. 2011).”

• cites Markov et al. 2011 sourceNot checked yet

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

Our analysis provides valuable inferences regarding statistical characteristics of the entire cortical connectivity graph.

“Our analysis also provides valuable inferences regarding statistical characteristics of the entire cortical connectivity graph.”

May combine two claims.

As more injections add links but not new nodes, they can only enhance these strong domination effects, confirming that the FIN is a dense graph in terms of binary connectivity.

“As more injections add links but not new nodes, they can only enhance these strong domination effects, confirming that the FIN is indeed a dense graph when considered in terms of binary connectivity.”

May combine two claims.

Assuming that non-injected nodes have the same average in-degree as the 29 injected nodes leads to a predicted FIN density of 62%, which is of the same order as the density of G29 × 29.

“We lack data on the in-links to nodes that were not injected, but we can assume that they are characterized by the same average in-degree as the 29 injected nodes. Assuming for the FIN (G91 × 91) leads to the prediction (62%), which is of the same order as the density for the edge-complete graph G29 × 29.”

• AssumptionThe authors state this as an assumption: Nodes that were not injected have the same average in-degree as the 29 injected nodes.

May combine two claims.

Both G29 × 91 and G29 × 29 contain complete information about the status of their edges and would not be influenced by injections into additional areas elsewhere in the cortex.

“Both G29 × 91 and G29 × 29 contain complete information about the status of their edges and would not be influenced by injections into additional areas elsewhere in the cortex.”

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

In such cases, a small proportion of labeled neurons may have arisen from fibers of passage.

“In such cases, a small proportion of labeled neurons may have arisen from fibers of passage.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Existing databases do not provide reliable estimates of the density of the network of cortical areas, nor has there been a concerted effort to extrapolate from existing data to the connectivity of the full interareal network.

“Existing databases do not provide reliable estimates of the density of the network of cortical areas, nor has there been a concerted effort to extrapolate from the existing data to the connectivity of the full interareal network (FIN).”

May combine two claims.

The M132 parcellation has been mapped to the macaque F99 atlas, which contains accurate surface maps for 15 other published parcellations, enabling detailed cross-parcellation comparisons.

“Nevertheless, our M132 parcellation has been mapped to the macaque F99 atlas, which contains accurate surface maps for 15 other published parcellations (Van Essen, Glasser, Dierker, Harwell 2011), thereby enabling detailed cross-parcellation comparisons.”

• cites Van Essen, Glasser, Dierker, Harwell 2011Not checked yet

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

Few experimental studies have directly tested unidirectionality because it is technically not easy.

“However, few experimental studies have directly tested unidirectionality because it is technically not easy.”

May combine two claims.

Shifting borders could reduce the NFP, but it would mean abandoning a consistent atlas with an objective parcellation for one where area dimensions are dictated by labeling patterns.

“So while shifting borders could reduce the NFP, it would mean that we abandon a consistent atlas with an objective parcellation for one where area dimensions are dictated by labeling patterns.”

• AssumptionRests on an assumption: The areal parcellation/atlas used is consistent and objective enough to define connections and compare across injections.

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

The connection strength values might vary for other macaque species, including the rhesus macaque.

“We also note that the connection strengths reported here are (except in one case, see Supplementary Table 2) specifically for M. fascicularis; the values might vary for other macaque species, including the widely studied rhesus macaque (M. mulatta).”

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

Some of the variability may be attributable to imperfect delineation of areal boundaries for the various source areas.

“Some of the variability may be attributable to imperfect delineation of areal boundaries for the various source areas.”

Classified as probably not a substantial claim.

We scrutinized the entire hemisphere for labeled cells at high magnification and at close section intervals (240 μm).

“One factor is that we scrutinized the entire hemisphere for labeled cells at high magnification and at close section intervals (240 µm).”

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

Previous reports provided scant evidence of unidirectional connectivity in the cortex.

“Previous reports provided scant evidence of unidirectional connectivity in the cortex (Felleman and Van Essen 1991).”

• cites Felleman and Van Essen 1991 sourceNot checked yet

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

Some connections reported as NFP might reflect cross-study differences in the designation of areal boundaries in individual cases.

“Finally, as already noted, some connections we report as NFP might reflect cross-study differences in the designation of areal boundaries in individual cases.”

May combine two claims.

There are genuine individual differences in connection strength that, along with the lognormal distribution, are a characteristic feature of interareal pathways.

“For the above reasons, we consider it highly likely that there are genuine individual differences in connection strength that along with the lognormal distribution is a characteristic feature of interareal pathways.”

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

The caution about internal heterogeneity also applies to other topographically organized sensory-motor areas and might apply to higher-order areas.

“This cautionary note also applies to other topographically organized sensory-motor areas, and it might apply to higher-order areas as well (Burman et al. 2011).”

• cites Burman et al. 2011Not checked yet

  Not checked in the free run.

May combine two claims.

The error in testing reciprocity cannot at present be overcome given that diffusion tensor imaging and tractography do not detect direction and existing tracing techniques, including BDA and labeled amino acids, show bidirectional transport.

“However, this error cannot at present be overcome given that diffusion tensor imaging and tractography do not detect direction and existing tracing techniques, including BDA and labeled amino acids, show bidirectional transport (LeVay and Sherk 1983; da Costa and Martin 2011).”

• cites LeVay and Sherk 1983Not checked yet

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• cites da Costa and Martin 2011Not checked yet

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

Low cortical matrix densities have been reported in estimates based on large data sets compiled across studies, with Young (1993) reporting a density of ∼15%.

“Low cortical matrix densities have been reported in estimates based on large data sets compiled across studies (e.g. Young 1993, who reported a density of ∼15%).”

• cites Young 1993Not checked yet

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May combine two claims.

A reduction in connectivity could be associated with lower weights of long-range pathways with respect to local connectivity or with a reduction in the number of pathways.

“A reduction in connectivity could be associated with lower weights of long-range pathways with respect to local connectivity or with a reduction in the number of pathways (at least in relation to the total number of area-to-area combinatorial possibilities).”

May combine two claims.

Graph theoretic analysis allowed us to infer that the binary FIN is dense and that this is therefore a characteristic feature of the macaque cortex.

“Further graph theoretic analysis allowed us to infer that the binary FIN is dense and that this is therefore a characteristic feature of the macaque cortex.”

• AssumptionRests on an assumption: The areal parcellation/atlas used is consistent and objective enough to define connections and compare across injections.

Classified as probably not a substantial claim.

The combination of weight and distance of connections may be important for understanding large-scale temporal dynamics.

“The combination of weight “and” distance of connections may be important for understanding large-scale temporal dynamics (Honey et al. 2007).”

• cites Honey et al. 2007Not checked yet

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

Increasing brain size has been suggested to result in decreased connectivity.

“Increasing brain size has been suggested to result in decreased connectivity (Ringo 1991).”

• cites Ringo 1991Not checked yet

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

The wide range of densities might reflect either differences in thresholding or technical difficulties.

“The wide range of densities might reflect either differences in thresholding or technical difficulties (Jones 2010; Jbabdi and Johansen-Berg 2011; Behrens and Sporns 2012; Van Essen and Ugurbil 2012).”

• cites Jones 2010Not checked yet

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• cites Jbabdi and Johansen-Berg 2011Not checked yet

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• cites Behrens and Sporns 2012Not checked yet

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May combine two claims.

High densities are necessarily accompanied by a short average path length across the cortex and will impact on large-scale models of cortical networks.

“High densities are necessarily accompanied by a short average path length across the cortex and will impact on large-scale models of cortical networks (Young 1993; Sporns et al. 2000; Honey et al. 2007).”

• cites Young 1993Not checked yet

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• cites Sporns et al. 2000Not checked yet

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• cites Honey et al. 2007Not checked yet

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

The human cerebral cortex probably contains a maximum of 150-200 cortical areas compared with the estimated maximum of 130-140 in the macaque.

“The human cerebral cortex is 9-fold greater in surface area than the macaque and probably contains a maximum of 150–200 cortical areas compared with the estimated maximum of 130–140 in the macaque (Van Essen, Glasser, Dierker, Harwell 2011; Van Essen, Glasser, Dierker, Harwell, Coalson 2011).”

• cites Van Essen, Glasser, Dierker, Harwell 2011Not checked yet

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• cites Van Essen, Glasser, Dierker, Harwell, Coalson 2011Not checked yet

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

While there is evidence for a good correlation between functional connectivity and strong short-distance connections, this is not the case for the more numerous long-distance connections.

“For instance, while there is evidence for a good correlation between functional connectivity and strong short-distance connections, this is not the case for the more numerous long-distance connections (Honey et al. 2009; Adachi et al. 2012).”

• cites Honey et al. 2009 sourceNot checked yet

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• cites Adachi et al. 2012 sourceNot checked yet

  Not checked in the free run.

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

The human cerebral cortex is 9-fold greater in surface area than the macaque.

“The human cerebral cortex is 9-fold greater in surface area than the macaque and probably contains a maximum of 150–200 cortical areas compared with the estimated maximum of 130–140 in the macaque (Van Essen, Glasser, Dierker, Harwell 2011; Van Essen, Glasser, Dierker, Harwell, Coalson 2011).”

• cites Van Essen, Glasser, Dierker, Harwell 2011Not checked yet

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• cites Van Essen, Glasser, Dierker, Harwell, Coalson 2011Not checked yet

  Not checked in the free run.

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

Sparse long-distance connections, conceivably via nonlinear phenomena such as "contraction dynamics", may have disproportionate effects relative to the far more dense intrinsic and intermediate-distance connections.

“Sparse long-distance connections, conceivably via nonlinear phenomena such as “contraction dynamics”, may have disproportionate effects relative to the far more dense intrinsic and intermediate-distance connections (Wang and Slotine 2005).”

• cites Wang and Slotine 2005Not checked yet

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Classified as probably not a substantial claim.

A recent modeling study showed that including anatomical directionality and weight led to more realistic biologically modeled brain dynamics.

“A recent modeling study showed that including anatomical directionality and weight led to more realistic biologically modeled brain dynamics (Knock et al. 2009).”

• cites Knock et al. 2009Not checked yet

  Not checked in the free run.