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Cited by 142Advanced Neuroimaging Techniques and ApplicationsMedical and Biological SciencesFunctional Brain Connectivity Studies

Cortical Terminations of the Inferior Fronto-Occipital and Uncinate Fasciculi: Anatomical Stem-Based Virtual Dissection

Open access
Hau, Janice, Sarubbo, Silvio, Perchey, Guy, Crivello, Fabrice, Zago, Laure, Mellet, Emmanuel, Jobard, Gaël, Joliot, Marc +3 more·2016·Frontiers in Neuroanatomy
DOI 10.3389/fnana.2016.00058PMC PMC4877506
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Abstract

We combined the neuroanatomists' approach of defining a fascicle as all fibers passing through its compact stem with diffusion-weighted tractography to investigate the cortical terminations of two association tracts, the inferior fronto-occipital fasciculus (IFOF) and the uncinate fasciculus (UF), which have recently been implicated in the ventral language circuitry. The aim was to provide a detailed and quantitative description of their terminations in 60 healthy subjects and to do so to apply an anatomical stem-based virtual dissection, mimicking classical post-mortem dissection, to extract with minimal a priori the IFOF and UF from tractography datasets. In both tracts, we consistently observed more extensive termination territories than their conventional definitions, within the middle and superior frontal, superior parietal and angular gyri for the IFOF and the middle frontal gyrus and superior, middle and inferior temporal gyri beyond the temporal pole for the UF. We revealed new insights regarding the internal organization of these tracts by investigating for the first time the frequency, distribution and hemispheric asymmetry of their terminations. Interestingly, we observed a dissociation between the lateral right-lateralized and medial left-lateralized fronto-occipital branches of the IFOF. In the UF, we observed a rightward lateralization of the orbito-frontal and temporal branches. We revealed a more detailed map of the terminations of these fiber pathways that will enable greater specificity for correlating with diseased populations and other behavioral measures. The limitations of the diffusion tensor model in this study are also discussed. We conclude that anatomical stem-based virtual dissection with diffusion tractography is a fruitful method for studying the structural anatomy of the human white matter pathways.

AI snapshot

Written from the paper’s full text.

TL;DR

Using anatomical stem-based virtual dissection of diffusion tractography in 60 healthy adults, this study maps cortical terminations of the inferior fronto-occipital fasciculus (IFOF) and uncinate fasciculus (UF) and finds more extensive territories than conventional definitions. It reports branch-specific termination frequency, density, and hemispheric asymmetries, including right-lateralized lateral IFOF/UF branches and left-lateralized medial IFOF branches.

Key findings

  • IFOF terminations extended beyond conventional definitions: inferior frontal gyrus in 100% bilaterally, lateral fronto-orbital gyrus in 87%/90% (left/right), middle frontal gyrus in 60%/55%, superior frontal gyrus in 35%/20%, and posterior regions including middle occipital gyrus 65%/95%, lingual gyrus 80%/78%, superior parietal gyrus 35%/57%, and angular gyrus 10%/33%.
  • UF terminations also extended beyond the temporal pole: medial fronto-orbital gyrus, temporal pole, and superior temporal gyrus were present in 100% bilaterally; middle temporal gyrus in 98%/97%, inferior temporal gyrus in 88%/92%, and entorhinal gyrus in 77%/78%.
  • Stem volumes were larger on the right: IFOF left 82.5 ± 35.5 mm³ vs right 100.3 ± 47.0 mm³; UF left 74.0 ± 33.0 mm³ vs right 93.9 ± 33.1 mm³ (hemisphere effect F = 40.9, p < 0.0001).
  • Asymmetry analyses showed rightward lateralization of IFOF inferior frontal and middle/inferior occipital projections, leftward lateralization of medial fronto-orbital, cuneus, and lingual IFOF projections, and rightward lateralization of UF orbito-frontal and temporal branches.

Methods

  • Diffusion-weighted MRI in 60 healthy right-handed adults (30 female; mean age 30.1, range 20–53) from the BIL&GIN database, acquired on a 3T scanner with 21 non-collinear directions (b = 1000 s/mm²), 2 mm isotropic voxels.
  • Deterministic whole-brain tractography using FACT with 0.2 fractional anisotropy and 45° angle thresholds; IFOF and UF were extracted by manual stem-based virtual dissection using modified JHU template regions of interest.
  • Termination analysis used normalized termination density scores per cortical region, a false-positive-region threshold, Wilcoxon signed-rank tests with Bonferroni correction (p < 0.0018), and asymmetry indexes tested with Bonferroni-corrected ANOVAs.

Limitations

  • The paper states that the diffusion tensor model has limited ability to resolve crossing fibers, producing broken streamlines and likely underestimating terminations, especially for the longer IFOF; it also notes that template differences may contribute to discrepancies with prior studies.
  • Evident from the text: deterministic FACT tracking, manual stem delineation, and a healthy right-handed sample restrict generalizability; the study reports no clinical or behavioral outcomes.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3389/fnana.2016.00058

Cites

41 of 41 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

16 of 71 cited sources checked · 12 supported · 2 flagged · accuracy not yet measured

  • Premisecitation

    The inferior fronto-occipital (IFOF) and uncinate (UF) fasciculi are crucial for the ventral intra-hemispheric transfer of information between the frontal cortex and the occipital, temporal and parietal cortices.

    “Both inferior fronto-occipital (IFOF) and uncinate (UF) fasciculi are crucial for the ventral intra-hemispheric transfer of information between the frontal cortex and the occipital, temporal and parietal cortices”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Turken and Dronkers, 2011 source

      The Introduction describes the inferior occipito-frontal fasciculus as a pathway from frontal cortex to temporal, parietal, and occipital cortices. It describes the uncinate fasciculus more narrowly, as connecting the temporal pole with inferior frontal regions; the Results also associate it with the anterior superior temporal gyrus. These passages do not establish that both tracts are crucial for information transfer to all three posterior cortical regions. Page numbers are unavailable in our copy. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites Duffau, 2015 source
  • Findingcitation

    These proportions are consistent with those reported in Croxson et al. (2005) using probabilistic tractography.

    “These are consistent with the proportions reported in (Croxson et al., 2005) that used probabilistic tractography.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Croxson et al., 2005 source
  • Findingown data

    The stem-based virtual dissection results in more extensive IFOFs and UFs than current set-of-ROIs methods.

    “our stem-based virtual dissection results in more extensive IFOFs and UFs.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Catani and Thiebaut de Schotten, 2008 source
    • cites Zhang et al., 2010 source
  • Premisecitation

    Current tract segmentation approaches rely heavily on a priori knowledge, using set-of-ROIs strategies that place ROIs around known terminal areas or areas of passage.

    “While current tract segmentation approaches rely heavily on a priori knowledge, using set-of-ROIs strategies that place the ROIs around their known terminal areas or areas of passage (Catani and Thiebaut de Schotten, 2008; Zhang et al., 2010)”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Catani and Thiebaut de Schotten, 2008 source
    • cites Zhang et al., 2010 source
  • Findingcitation

    Neither the superior temporal nor the middle temporal gyri were reported previously by Caverzasi et al. (2014).

    “Neither the superior temporal nor the middle temporal gyri were reported previously (Caverzasi et al., 2014).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Caverzasi et al., 2014 source
  • May combine two claims. 53
  • Classified as probably not a substantial claim. 12
  • The quote only partly states this claim. 4

  • May combine two claims.

    Interpretationreasoning

    Projections to the parietal lobe are systematically excluded using the method of Zhang et al. (2010) and are likely to be missed using the method of Catani and Thiebaut de Schotten (2008), as was the case in Sarubbo et al. (2013).

    “As shown Figure 8, projections to the parietal lobe are systematically excluded using the method of Zhang et al. (2010) and are likely to be missed using the method of Catani and Thiebaut de Schotten (2008) that use ROIs delineated around the frontal and occipital lobes, as was the case in Sarubbo et al. (2013).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Zhang et al. (2010) source

      The Results section (Comparison between the automated and manual methods; page not provided) says Zhang et al.’s automated method reconstructed superior longitudinal fasciculus projections to the parietal lobe. It was the manual comparison method, not Zhang et al.’s automated method, that lacked a posterior parietal–temporal segment. The paper does not establish the claim about the other named methods. (LLM, conf=0.90)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
    • cites Catani and Thiebaut de Schotten (2008) source
    • cites Sarubbo et al. (2013) source

  • May combine two claims.

    Premisecitation

    Projections to the nuclei of the amygdala reported in Ebeling and von Cramon (1992) refer to the entorhinal cortex and should not be mistaken for the amygdala proper.

    “Importantly, projections to the nuclei of the amygdala reported in Ebeling and von Cramon (1992) refers to the entorhinal cortex and should not be mistaken for the amygdala proper as is often done (Schmahmann and Pandya, 2006; Kim and Whalen, 2009).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Ebeling and von Cramon (1992) source
    • cites Schmahmann and Pandya, 2006 source
    • cites Kim and Whalen, 2009 source

      The Discussion (page unavailable) says the uncinate fasciculus interconnects the amygdala and orbitofrontal lobe, explicitly citing Ebeling and von Cramon (1992). It does not make the claimed distinction that those projections concern the entorhinal cortex rather than the amygdala proper; its statement points the other way. (LLM, conf=0.88)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S2 (checkable).

    Premisecitation

    Knowing the cortical terminations of the IFOF and UF is fundamental for understanding their role in mediating language semantics.

    “knowing their cortical terminations is fundamental for understanding their role in mediating language semantics”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Turken and Dronkers, 2011 source
    • cites Duffau, 2015 source

  • May combine two claims.

    Premisecitation

    Only one tractography study has examined the cortical terminations of the IFOF in a group of 20 subjects, confirming some of the more extensive projections described inconsistently in the literature, in particular within the parietal lobe.

    “only one tractography study has examined the cortical terminations of the IFOF in a group (20 subjects) confirming some of the more extensive projections described inconsistently thus far in the literature, in particular within the parietal lobe (Caverzasi et al., 2014).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Caverzasi et al., 2014 source

  • May combine two claims.

    Findingown data

    Superior parietal IFOF terminations were observed in the majority of subjects, consistent with Martino et al. (2010), and less frequently in the angular gyrus, in contrast to Caverzasi et al. (2014).

    “We observed superior parietal IFOF terminations in the majority of the subjects consistent with dissection [Martino et al. (2010) reported parietal connections in 9 out of 14 hemispheres], and less frequently in the angular gyrus in contrast to Caverzasi et al. (2014) who reported it in 100% of subjects.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Martino et al. (2010) source
    • cites Caverzasi et al. (2014) source

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

    Findingcitation

    The present results are consistent with the proportions reported in Croxson et al. (2005).

    “The present results are also consistent with the proportions reported in Croxson et al. (2005).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Croxson et al. (2005) source

  • May combine two claims.

    Findingown data

    Projections to the lingual gyrus were observed in almost all subjects, consistent with Caverzasi et al. (2014), but Martino et al. (2010) reported no projections to the lingual gyrus and considered them part of the optic radiations.

    “Projections to the lingual gyrus were observed in almost all subjects consistent with Caverzasi et al. (2014), however, Martino et al. (2010) reported no projections to the lingual gyrus and instead considered them as part of the optic radiations.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Caverzasi et al. (2014) source
    • cites Martino et al. (2010) source

  • May combine two claims.

    Findingown data

    The study confirmed frontal IFOF terminations within the inferior frontal and lateral and medial fronto-orbital gyri, and also in the superior and middle frontal gyri.

    “Our study first confirmed frontal IFOF terminations within the inferior frontal and lateral and medial fronto-orbital gyri corresponding to the conventional IFOF definition, but also in the superior and middle frontal gyri”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Sarubbo et al., 2013 source
    • cites Caverzasi et al., 2014 source

  • May combine two claims.

    Findingown data

    Projections to the cuneus were infrequent in the right hemisphere (15% vs. 38% in the left hemisphere), showing the opposite pattern of Caverzasi et al. (2014).

    “Projections to the cuneus were infrequent in the right hemisphere (present in 15 vs. 38% in the left hemisphere) showing the opposite pattern of Caverzasi et al. (2014)”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Caverzasi et al. (2014) source

  • May combine two claims.

    Interpretationcitation

    These discrepancies may be due to the existence of adjacent tracts, such as the amygdalo-temporo or amygdala-prefrontal pathways, which may have been sometimes misattributed to the UF.

    “These discrepancies may be due to the existence of adjacent tracts, such as the amygdalo-temporo or amygdala-prefrontal pathways (Klinger and Gloor, 1960; Kim and Whalen, 2009) which may have been sometimes misattributed to the UF.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Klinger and Gloor, 1960 source
    • cites Kim and Whalen, 2009 source

  • May combine two claims.

    Premisecitation

    Hemispheric asymmetry in the UF has been observed for both volume and diffusion metrics, but there are inconsistencies in the directionality of such asymmetry.

    “Hemispheric asymmetry in the UF has been observed for both volume and diffusion metrics but there are inconsistencies in the directionality of such asymmetry of the UF.”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites Highley et al., 2002 source
    • cites Park et al., 2004 source

      The Discussion (page unavailable) reports differing left–right patterns of uncinate fasciculus fractional anisotropy and concludes that its asymmetry remains controversial. It also cites a postmortem finding for cross-sectional area and fiber number, but does not report an uncinate fasciculus volume measurement; that specific part of the claim is not established by our copy. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites Thomas et al., 2015 source

  • The quote only partly states this claim.

    Findingown data

    Anteriorly, the IFOF has minor branches to the lateral fronto-orbital gyrus (NTDS 0.08 left, 0.10 right).

    “with minor branches projecting to the lateral (0.08 and 0.10)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The UF projected to the fusiform gyrus in 37% of left hemispheres and 43% of right hemispheres.

    “Projections to the fusiform gyrus were observed in the minority of subjects (37 and 43%)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Anteriorly, the IFOF terminates predominantly in the inferior frontal gyrus, with normalized termination density scores (NTDS) of 0.19 left and 0.26 right.

    “Anteriorly, the IFOF terminates predominantly in the inferior frontal gyrus (NTDS: 0.19 and 0.26 for the left and right, respectively henceforth)”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The UF projected to the lateral fronto-orbital gyrus in 88% of left hemispheres and 98% of right hemispheres.

    “almost always projected to the lateral fronto-orbital (88 and 98%)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The UF projected to the middle frontal gyrus in 12% of left hemispheres and 60% of right hemispheres.

    “Projections to the middle (12 and 60%)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The UF projected to the inferior temporal gyrus in 88% of left hemispheres and 92% of right hemispheres.

    “The UF also frequently projected to the inferior temporal gyrus (88 and 92%)”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data

    Posteriorly, the UF has minor branches in the inferior temporal gyrus (NTDS 0.04 bilaterally), fusiform gyrus (0.03 left, 0.05 right), and entorhinal gyrus (0.03 left, 0.05 right).

    “with minor branches in the inferior temporal (0.04 bilaterally), fusiform (0.03 and 0.05) and entorhinal (0.03 and 0.05) gyri”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The IFOF projected to the angular gyrus in 10% of left hemispheres and 33% of right hemispheres.

    “Projection to the cuneus (38 and 15%), fusiform gyrus (12 and 32%) and angular gyrus (10 and 33%) were observed in the minority of subjects.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Findingown data

    The mean Euclidean distance between the right IFOF and UF stem centers of mass was 10.5 ± 2.1 mm, significantly different from 0 (p < 0.0001).

    “The mean Euclidean distances between the left IFOF and UF stem centers of mass were 9.4 ± 2.7 mm and for the right IFOF and UF stems was 10.5 ± 2.1 mm, both being significantly different from 0 (Student’s t-test, p < 0.0001).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.

  • May combine two claims.

    Findingown data

    The IFOF projected to the middle temporal gyrus in 33% of left hemispheres and 52% of right hemispheres.

    “The IFOF also terminated in the inferior occipital gyrus (30 and 77%), in the temporal lobe in the superior (73 and 45%) and middle (33 and 52%) temporal gyri, and in the parietal lobe in the superior parietal gyrus (35 and 57%).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Findingown data

    The IFOF projected to the fusiform gyrus in 12% of left hemispheres and 32% of right hemispheres.

    “Projection to the cuneus (38 and 15%), fusiform gyrus (12 and 32%) and angular gyrus (10 and 33%) were observed in the minority of subjects.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • The quote only partly states this claim.

    Findingown data

    Posteriorly, the UF projects in a graded manner with the largest portion in the temporal pole (NTDS 0.25 left, 0.47 right).

    “Posteriorly, the UF projects in a graded manner with the largest portion in the temporal pole (0.25 and 0.47)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The UF projected to the rectus gyrus in 83% of left hemispheres and 93% of right hemispheres.

    “and rectus (83 and 93%) gyri”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The IFOF projected to the middle occipital gyrus in 65% of left hemispheres and 95% of right hemispheres.

    “The most frequent posterior termination regions were the middle occipital gyrus (65 and 95%) and lingual gyrus (80 and 78%).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Findingown data

    Posteriorly, the IFOF has minor branches in the superior parietal gyrus (NTDS 0.05 left, 0.07 right) and angular gyrus (0.06 left, 0.03 right).

    “in the superior parietal (0.05 and 0.07) and angular (0.06 and 0.03,) gyri”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data

    For the UF, anterior projections are most predominant in the medial fronto-orbital gyrus (NTDS 0.10 left, 0.31 right).

    “For the UF, the anterior projections are most predominant in the medial fronto-orbital gyrus (0.10 and 0.31)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The IFOF projected to the middle frontal gyrus in 60% of left hemispheres and 55% of right hemispheres.

    “Anteriorly, the IFOF always projected to the inferior frontal gyrus (present in all subjects, bilaterally), almost always projected to the lateral fronto-orbital gyrus (87 and 90% for the left and right hemispheres, respectively henceforth) and less frequently projected to the medial fronto-orbital gyrus (63 and 32%) and middle frontal gyrus (60 and 55%).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Findingown data

    The UF terminated in the middle temporal gyrus in 98% of left hemispheres and 97% of right hemispheres.

    “almost always in the middle temporal gyrus (98 and 97%)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The IFOF projected to the lingual gyrus in 80% of left hemispheres and 78% of right hemispheres.

    “The most frequent posterior termination regions were the middle occipital gyrus (65 and 95%) and lingual gyrus (80 and 78%).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Findingown data

    The UF projected to the inferior frontal gyrus in 37% of left hemispheres and 35% of right hemispheres.

    “and inferior (37 and 35%) frontal gyri”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The IFOF projected to the cuneus in 38% of left hemispheres and 15% of right hemispheres.

    “Projection to the cuneus (38 and 15%), fusiform gyrus (12 and 32%) and angular gyrus (10 and 33%) were observed in the minority of subjects.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Findingown data

    The UF projected to the entorhinal gyrus in 77% of left hemispheres and 78% of right hemispheres.

    “and entorhinal gyrus (77 and 78%)”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The IFOF projected to the superior frontal gyrus in 35% of left hemispheres and 20% of right hemispheres.

    “Projections to the superior frontal gyrus were observed in the minority of subjects (35 and 20%).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Findingown data

    The mean Euclidean distance between the left IFOF and UF stem centers of mass was 9.4 ± 2.7 mm, significantly different from 0 (p < 0.0001).

    “The mean Euclidean distances between the left IFOF and UF stem centers of mass were 9.4 ± 2.7 mm and for the right IFOF and UF stems was 10.5 ± 2.1 mm, both being significantly different from 0 (Student’s t-test, p < 0.0001).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.

  • May combine two claims.

    Findingown data

    Posteriorly, the IFOF has minor branches in the middle temporal gyrus (NTDS 0.05 left, 0.04 right) and fusiform gyrus (0.05 left, 0.03 right).

    “in the middle temporal (0.05 and 0.04) and fusiform (0.05 and 0.03) gyri”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The study observed a rightward lateralization of projections to the lateral frontal and occipital areas (inferior frontal, middle and inferior occipital gyri), and a leftward lateralization of projections to medial frontal and occipital areas (superior frontal, medial fronto-orbital, cuneus and lingual gyri).

    “We observed a rightward lateralization of projections to the lateral frontal and occipital areas (inferior frontal, middle and inferior occipital gyri), and a leftward lateralization of projections to medial frontal and occipital areas (superior frontal, medial fronto-orbital, cuneus and lingual gyri) (Figure 7).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The IFOF's primary branch is the inferior frontal subcomponent, followed by the orbito-frontal subcomponent, with about equal density across the superior frontal and middle frontal subcomponents.

    “We showed that the IFOF’s primary branch is clearly the inferior frontal subcomponent followed by the orbito-frontal subcomponent, with about equal density across the superior frontal and middle frontal subcomponents.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The study confirmed anterior UF terminations mainly within the medial and lateral orbito-frontal areas, and minor branches in the middle and inferior frontal and rectus gyri.

    “We confirmed anterior UF terminations mainly within the medial and lateral orbito-frontal areas, and minor branches in the middle and inferior frontal and rectus gyri consistent with dissection and tractography studies”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Klinger and Gloor, 1960 source
    • cites Ebeling and von Cramon, 1992 source
    • cites Thiebaut de Schotten et al., 2012 source

  • May combine two claims.

    Findingcitation

    In the temporal lobe, the IFOF projects to the superior and middle temporal gyri and to a lesser extent to the fusiform gyrus, confirming dissection studies.

    “In the temporal lobe, the IFOF projects to the superior and middle temporal gyri and to a lesser extent to the fusiform gyrus, confirming dissection studies (Crosby et al., 1962; Martino et al., 2010).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Crosby et al., 1962

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

    • cites Martino et al., 2010 source

  • May combine two claims.

    Findingown data

    The stem-based virtual dissection allowed reproduction of consensus findings regarding IFOF and UF tract projections and provided clear evidence for more extensive projections beyond their conventional definitions.

    “Nonetheless, thanks to the stem-based virtual dissection our approach allowed us to: (1) reproduce the consensus findings regarding IFOF and UF tract projections, and (2) provide clear evidence for more extensive projections beyond their conventional definitions”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    This premature stopping is especially noticeable for the IFOF, which presents the longest streamlines with the highest chance to cross other tracts.

    “This is especially noticeable for the IFOF, which presents the longest streamlines with the highest chance to cross other tracts.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The study did not observe any projection to the cingulate gyrus or to the amygdala.

    “We did not observe any projection to the cingulate gyrus, neither to the amygdala”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Dejerine and Dejerine-Klumpke, 1895

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

    • cites Ebeling and von Cramon, 1992 source
    • cites Klinger and Gloor, 1960 source

  • May combine two claims.

    Findingcitation

    Projections to the inferior occipital gyrus were observed, twice less in the left than in the right hemisphere, though reported in all subjects in a dissection study (Martino et al., 2010).

    “Projections to the inferior occipital gyrus were observed, twice less in the left than in the right hemisphere, though it was reported in all subjects in a dissection study (Martino et al., 2010).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Martino et al., 2010 source

  • May combine two claims.

    Findingown data

    The IFOF projects mainly to the occipital lobe (especially middle occipital and lingual gyri, with minor projections to inferior occipital gyrus and cuneus), with minor projections to the temporal lobe (superior and middle temporal and fusiform gyri) and parietal lobe (superior parietal and angular gyri).

    “In terms of posterior density distribution, we showed that the IFOF projects mainly to the occipital lobe (especially the middle occipital and lingual gyri, with minor projections to the inferior occipital gyrus and cuneus), with minor projections to the temporal lobe (superior and middle temporal and fusiform gyri) as well as to the parietal lobe (superior parietal and angular gyri)”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Posteriorly, the study observed occipital projections to the middle and inferior occipital gyri, as well as additional terminations in the occipital (cuneus and lingual gyrus), temporal (superior and middle temporal gyri, fusiform gyrus), and parietal (superior parietal and angular gyri) cortices.

    “Posteriorly, we observed occipital projections to the middle and inferior occipital gyri also consistent with the conventional definition of the IFOF, as well as additional terminations in the occipital (cuneus and lingual gyrus), temporal (superior and middle temporal gyri, fusiform gyrus) and parietal (superior parietal and angular gyri) cortices.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    By delineating anatomically both IFOF and UF stems, the study minimized constraints on tract terminations and observed far more extensive projections than their conventional definitions.

    “By delineating anatomically both IFOF and UF stems, we minimized the constraints on the tract terminations and observed far more extensive projections than their conventional definitions (Figure 1B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Post-mortem dissection studies confirmed the conventional definition of the respective tracts but also revealed termination territories beyond those previously described, suggesting more expansive definitions are needed.

    “While these dissection studies confirmed the conventional definition of the respective tracts, they also revealed termination territories in more detail and beyond those previously described, suggesting more expansive definitions are needed.”
    Quote in the paperSubstantial claim

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

    Premisenone given

    The anatomical description of the UF has remained stable, connecting fronto-orbital cortices with the temporo-polar cortex.

    “While the anatomical description of the UF has remained stable (connecting fronto-orbital cortices with the temporo-polar cortex)”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    The consensus on the UF is that it connects, along with the fronto-orbital and temporo-polar cortices, ventral temporal areas.

    “The consensus on the UF is that it connects, along with the fronto-orbital and temporo-polar cortices, ventral temporal areas (Ebeling and von Cramon, 1992; Catani and Thiebaut de Schotten, 2008).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Ebeling and von Cramon, 1992 source
    • cites Catani and Thiebaut de Schotten, 2008 source

  • Classified as probably not a substantial claim.

    Premisecitation

    The consensus is that the IFOF connects the ventral occipital cortex with the inferior frontal and fronto-orbital cortices.

    “the IFOF connects the ventral occipital cortex with the inferior frontal and fronto-orbital cortices”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Dejerine and Dejerine-Klumpke, 1895

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

    • cites Catani and Thiebaut de Schotten, 2008 source
    • cites Martino et al., 2010 source

  • May combine two claims.

    Premisecitation

    The IFOF and UF are clearly distinct at the level of the stem and can be separated by a notable cleavage line.

    “However, they are clearly distinct at the level of the stem and can be separated by a notable cleavage line (Curran, 1909; Kier et al., 2004; Martino et al., 2010; Sarubbo et al., 2013).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Curran, 1909 source
    • cites Kier et al., 2004
    • cites Martino et al., 2010 source

  • May combine two claims.

    Interpretationown data

    In both tracts, the termination territories were more extensive than their conventional definitions, within the middle and superior frontal, superior parietal and angular gyri for the IFOF and the middle frontal gyrus and superior, middle and inferior temporal gyri beyond the temporal pole for the UF.

    “In both tracts, we consistently observed more extensive termination territories than their conventional definitions, within the middle and superior frontal, superior parietal and angular gyri for the IFOF and the middle frontal gyrus and superior, middle and inferior temporal gyri beyond the temporal pole for the UF.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.
    • Rests on an assumption: The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

  • May combine two claims.

    Study design and conductown data

    The mean Euclidean distances between the stems drawn by the two operators were 1.7 ± 0.8 mm and 1.9 ± 0.8 mm for the left and right IFOF stems and 1.4 ± 1.1 mm and 1.4 ± 0.9 mm for the left and right UF stems, distances below the 2-mm voxel resolution.

    “The mean Euclidean distances between the stems drawn by the two operators was 1.7 ± 0.8 mm and 1.9 ± 0.8 mm for the left and right IFOF stems and was 1.4 ± 1.1 mm and 1.4 ± 0.9 for the left and right UF stems, distances below the 2-mm voxel resolution at which our stems were drawn.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductown data

    The delineation of the stems was consistent between operators both in terms of volumes and mean centers of mass.

    “The delineation of the stems was consistent between operators both in terms of volumes and mean centers of mass (Table 1).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductown data

    The mean volume differences between operators were between 6 and 9 mm3 for left and right IFOF stems and between 7 and 8 mm3 for left and right UF stems, and were not significant (all p > 0.05).

    “The mean differences of volume between operators were between 6 and 9 mm3 for left and right IFOF stems and between 7 and 8 mm3 for left and right UF stems, which corresponds approximately to a difference of one voxel (8 mm3) and was not significant between operators (all Student’s t-tests, p > 0.05).”
    Quote in the paperSubstantial claim

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

    Interpretationreasoning

    These differences may be due in part to the difference in templates used to register the terminations (Freesurfer Desikan-Kyliany atlas vs. JHU atlas).

    “These differences may be due in part to the difference in templates used to register the terminations (they used the Freesurfer Desikan-Kyliany atlas whereas we used the JHU atlas).”
    Quote in the paperNot a substantial claim

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

    Interpretationown data

    The prominence of the inferior frontal and orbito-frontal terminations may explain why these regions are consistently observed in the literature.

    “The prominence of the inferior frontal and orbito-frontal terminations may explain why these regions are consistently observed in the literature.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationreasoning

    This may also be due to technical limitations arising from the tractography method since it is farther and may require tracking through areas of crossings.

    “This may also be due to technical limitations arising from the tractography method since it is farther and may require tracking through areas of crossings.”
    Quote in the paperNot a substantial claim

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

    Interpretationreasoning

    The superior frontal streamline densities may be underrepresented given the limitations of the tractography method.

    “It could also be that the superior frontal streamlines densities may be underrepresented given the limitations of the tractography method mentioned above.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The large variability observed in the frequency of projections among subjects in these areas is likely due to such limitations, and thus their densities may also be underrepresented.

    “Moreover the large variability observed in the frequency of projections among subjects in these areas are likely to be due to such limitations and thus their densities may also be underrepresented.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Areas of intersecting, overlapping, or bordering pathways greatly affect the tracking process and cause it to stop, producing broken streamlines.

    “Thus areas of intersecting/overlapping/bordering pathways will greatly affect the tracking process and cause it to stop, producing broken streamlines.”
    Quote in the paperSubstantial claim

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

    Interpretationreasoning

    This may be due to possible crossings with other prominent tracts (inferior longitudinal, vertical occipital fasciculi) in the occipital lobe, especially for the left hemisphere.

    “This may be due to possible crossings with other prominent tracts (inferior longitudinal, vertical occipital fasciculi) in the occipital lobe, especially for the left hemisphere.”
    Quote in the paperNot a substantial claim

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

    Interpretationcitation

    The medial occipital cortex (cuneus and lingual gyrus) is not often cited as a termination territory of the IFOF, possibly due to a lack of anatomical specificity in earlier descriptions, with its first mention appearing late in the literature.

    “The medial occipital cortex (cuneus and lingual gyrus) are not often cited as a termination territory of the IFOF possibly be due to a lack of anatomical specificity in some of the earlier descriptions of the tract, with its first mention appearing late in the literature (Crosby et al., 1962).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Crosby et al., 1962

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

  • May combine two claims.

    Interpretationown data

    The hook-shaped pattern of these posterior temporal streamlines looks more like UF than IFOF streamlines, which led the authors to consider them as belonging to the UF.

    “Note that the hook-shaped pattern of these posterior temporal streamlines looks more like UF than IFOF streamlines, which led us to consider them as belonging to the UF.”
    Quote in the paperSubstantial claim

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

    Interpretationnone given

    The quantitative information available through diffusion imaging provides not only tract-specific but branch-specific measures of the tracts, providing better specificity that can be correlated with behavioral measures or patient populations.

    “In addition, the quantitative information available through diffusion imaging provides not only tract-specific but branch-specific measures of the tracts providing better specificity that can be correlated with behavioral measures or patient populations.”
    Quote in the paperSubstantial claim
66 of 66

  • The paper relies on this without support.

    The stem of a tract is the point of passage where all fibers pass through, and extracting streamlines passing through the stem yields the complete tract.

    “we adopted the approach of neuroanatomists who first locate the stem, which is the point of passage where all fibers pass through, as an anatomical reference to identify the tract.”

  • The paper relies on this without support.

    The precentral and superior parietal gyri contain no true terminations of IFOF and UF, respectively, and can serve as false positive regions for thresholding.

    “The precentral and superior parietal gyri were chosen as the regions containing false positives (FP_REG) for the IFOF and UF, respectively.”

  • The paper relies on this without support.

    The posterior projections of the IFOF pass through the inferior longitudinal fasciculus within the temporal lobe to reach the middle occipital gyrus.

    “Similarly the posterior projections of the IFOF need to pass through the inferior longitudinal fasciculus within the temporal lobe in order to reach the middle occipital gyrus.”
3 of 3

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • UF termination densities exceed their stated normalization total

    Major

    The reported right-hemisphere UF densities for the six posterior regions sum to 1.11. A score defined by dividing each region's count by the total number of left and right UF streamlines cannot sum to more than 1 across right-hemisphere regions alone.

  • Cuneus comparison calls the same hemispheric pattern opposite

    Minor

    The paper reports more subjects with cuneus projections on the left than the right, then calls this the opposite of another study that it also describes as finding more subjects on the left than the right.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 5

  1. Burdach, Vom Baue und Leben des Gehirns und Rückenmark., 1819
  2. Dejerine, 1895, Anatomie des Centres Nerveux. Tome 1.
  3. Reil, 1809, Die Sylvische Grube oder das Thal, das gestreifte grobe hirnganglium, dessen kapsel und die seitentheile des grobn gehirns., Arch. Physiol., 9, 195
  4. Trolard, 1906, Le faisceau longitudinal inférieur du cerveau., Rev. Neurol., 14, 440
  5. Wang, 2007, Diffusion toolkit: a software package for diffusion imaging data processing and tractography, Proceedings of the International Society for Magnetic Resonance in Medicine

Cited by

Sorted by citations

Related

Authors
Hau, J., Sarubbo, S., Perchey, G., Crivello, F., Zago, L., Mellet, E., Jobard, G., Joliot, M., Mazoyer, B. M., Tzourio-Mazoyer, N., & Petit, L.
Affiliations
  • Centre National de la Recherche Scientifique (FR)
  • Ospedale Santa Chiara (IT)
Corresponding author
Petit, Laurent
ORCID
Venue
Frontiers in Neuroanatomy
Publisher
Frontiers Media SA
Published
2016-05-24
Volume
10
Pages
58-58
ISSN
1662-5129 (ISSN-L)
DOI
10.3389/fnana.2016.00058
PMC
PMC4877506
OpenAlex
W2401804202
Semantic Scholar
f35b01547d5fb73b199505278b89977ed455f872
Cited by
142
References
41
Citations by year
2026: 4 · 2025: 12 · 2024: 11 · 2023: 9 · 2022: 16 · 2021: 25 · 2020: 20 · 2019: 13 · 2018: 15 · 2017: 15 · 2016: 2
FWCI
11.82
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Frontiers in Neuroanatomy (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Institutional Research Information System (Università degli Studi di Trento) (submittedVersion, cc-by)
  • Europe PMC (PubMed Central) (submittedVersion, cc-by)
  • PubMed Central (submittedVersion, cc-by)
  • HAL (Le Centre pour la Communication Scientifique Directe) (submittedVersion, cc-by)
Funders
Agence Nationale de la Recherche (10-LABX-57, ANR-10LABX-57, ANR-10, ANR-10-LABX)
Topics
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced Neuroimaging Techniques and Applications
  • Health Sciences › Medicine › Anatomy › Medical and Biological Sciences
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Functional Brain Connectivity Studies
Keywords
inferior fronto-occipital fasciculus, uncinate fasciculus, association tracts, hemispheric lateralization, white matter tracts, diffusion tractography

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-18.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-18.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

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