{
"papers": [
{
"n": null,
"doi": "10.1002/cne.23875",
"value": "two subtypes: PT-PNs and IT-PNs",
"method": "whole-cell patch + cluster analysis + retrograde tracing",
"metric": "Number of L5 Fezf2+ subtypes identified electrophysiologically",
"n_analyzed": null,
"ci_or_error": null,
"text_access": "abstract_only",
"n_definition": "patched Fezf2-GFP+ L5 neurons in M1",
"scope_region": "specific region (M1)",
"study_system": "mouse motor cortex L5, Fezf2-Gfp reporter",
"taxonomic_level": "fine type (Cre/reporter line × projection target)",
"scope_population": "subtype-Y only (Fezf2+ L5)",
"value_source_sentence": "Functional electrophysiology identified two distinct subtypes of Fezf2(+) neurons that resembled pyramidal tract projection neurons (PT-PNs) and intratelencephalic projection neurons (IT-PNs).",
"experimental_conditions": "in vitro slice, whole-cell patch + retrograde labeling"
},
{
"n": 3579,
"doi": "10.1016/j.cell.2019.09.023",
"value": "three top classes (IT, PT-like, CT) with laminar organization confirmed; additional projection type restricted to a transcriptomic IT subtype",
"method": "BARseq (RNA-barcoded projection mapping)",
"metric": "Projection classes confirmed in mouse auditory cortex via BARseq",
"n_analyzed": 3579,
"ci_or_error": null,
"text_access": "abstract_only",
"n_definition": "barcoded individual neurons with mapped projections",
"scope_region": "specific region (auditory cortex)",
"study_system": "mouse auditory cortex, BARseq",
"taxonomic_level": "broad category (IT/PT/CT)",
"scope_population": "all category-X (excitatory projection neurons)",
"value_source_sentence": "Mapping the projections to 11 areas of 3,579 neurons in mouse auditory cortex using BARseq confirmed the laminar organization of the three top classes (intratelencephalic [IT], pyramidal tract-like [PT-like], and corticothalamic [CT]) of projection neurons.",
"experimental_conditions": "in situ sequencing of projection barcodes"
},
{
"n": null,
"doi": "10.7554/eLife.97602",
"value": "L2/3 IT (Rasgrf2-dCre), L4 IT (Scnn1a-Cre), L5 IT, L5 PT, and L6 CT subclasses separately resolved",
"method": "light-sheet axon imaging + CNN-based segmentation",
"metric": "L5 projection sub-classes labeled by class-selective Cre lines",
"n_analyzed": null,
"ci_or_error": null,
"text_access": "abstract_only",
"n_definition": "axon-density quantification within CCF",
"scope_region": "specific region (whisker-related somatosensory cortex)",
"study_system": "mouse whisker-related S1/S2, multiple Cre lines",
"taxonomic_level": "fine type (Cre-line × projection class)",
"scope_population": "all category-X (excitatory projection neurons)",
"value_source_sentence": "Axonal density was analyzed for different classes of glutamatergic neurons using transgenic mouse lines selectively expressing Cre recombinase in layer 2/3 intratelencephalic projection neurons (Rasgrf2-dCre), layer 4 intratelencephalic projection neurons (Scnn1a-Cre), layer 5 intratelencephalic projection neurons (Tlx3-Cre), layer 5 pyramidal tract projection neurons (Sim1-Cre), layer 5 projection neurons (Rbp4-Cre), and layer 6 corticothalamic neurons (Ntsr1-Cre).",
"experimental_conditions": "Cre-dependent fluorescent labeling, light-sheet imaging, CCF registration"
},
{
"n": null,
"doi": "10.1523/JNEUROSCI.4023-14.2015",
"value": "strong CT↔CT and CT↔IT (L6 IT only); strikingly little CT↔PT excitatory connectivity",
"method": "CRACM + paired recording",
"metric": "Excitatory connectivity among IT/PT/CT classes in mouse M1",
"n_analyzed": null,
"ci_or_error": null,
"text_access": "abstract_only",
"n_definition": "paired recordings + CRACM-defined inputs",
"scope_region": "specific region (forelimb M1)",
"study_system": "mouse forelimb M1, CT/IT/PT projection-defined neurons",
"taxonomic_level": "broad category (IT/PT/CT)",
"scope_population": "all category-X (projection-defined excitatory)",
"value_source_sentence": "Stimulating and recording from CT, intratelencephalic (IT), and pyramidal tract (PT) projection neurons, we found strong CT↔ CT and CT↔ IT connections; however, CT→IT connections were limited to IT neurons in layer 6, not 5B. There was strikingly little CT↔ PT excitatory connectivity.",
"experimental_conditions": "in vitro slice with Cre/retrograde targeting"
}
],
"audit_issues": [
{
"dimension": "scope_region",
"description": "Papers cover M1, mouse auditory cortex, whisker-related S1/S2 and forelimb M1; the IT/PT/CT framework is compared across regions rather than within one.",
"entries_affected": [
"10.1002/cne.23875",
"10.1016/j.cell.2019.09.023",
"10.7554/eLife.97602",
"10.1523/JNEUROSCI.4023-14.2015"
]
},
{
"dimension": "taxonomic_level",
"description": "Resolution differs: 'two Fezf2+ subtypes' (slice patch + clustering), 'three top classes' (BARseq), multiple Cre-line subclasses (light-sheet), and broad IT/PT/CT categories (paired patch). Counts of subtypes cannot be plotted as a single ordinal scale.",
"entries_affected": [
"10.1002/cne.23875",
"10.1016/j.cell.2019.09.023",
"10.7554/eLife.97602",
"10.1523/JNEUROSCI.4023-14.2015"
]
},
{
"dimension": "metric_definition",
"description": "Metrics are 'number of subtypes identified,' 'projection classes confirmed,' 'sub-classes labelled by Cre lines,' and 'qualitative excitatory-connectivity pattern' — they are not the same quantity.",
"entries_affected": [
"10.1002/cne.23875",
"10.1016/j.cell.2019.09.023",
"10.7554/eLife.97602",
"10.1523/JNEUROSCI.4023-14.2015"
]
}
],
"audit_verdict": "CAVEAT",
"comparison_id": "l5-projection-class-taxonomy-mouse",
"comparison_name": "Concordance of mouse L5 IT/PT projection-class taxonomy across genetic/transcriptomic vs paired-recording methods",
"comparison_type": "convergent evidence",
"what_it_reveals": "The IT/PT/CT taxonomy of mouse cortical excitatory projection neurons recurs across methodologically independent approaches — Cre-line + retrograde + electrophysiology, BARseq projection mapping, and CRACM paired recordings — but within-class heterogeneity (e.g., L6 IT vs L5B IT in CT-target specificity; Fezf2+ further split into PT-PN and IT-PN) means the same three-class label hides fine-scale subclasses that the chosen method resolves.",
"homogeneity_check": {
"caveats": [
"Cortical areas differ across rows (M1 motor, auditory, whisker-S1/S2) — the comparison is cross-area to show the IT/PT/CT framework recurs across regions.",
"Taxonomic resolution differs: BARseq and Fezf2 paper resolve subclasses, while the motor-cortex paired-recording paper uses broad IT/PT/CT categories."
],
"n_definition_uniform": "false",
"scope_region_uniform": "false",
"taxonomic_level_uniform": "false",
"scope_population_uniform": "true"
},
"suggested_plot_type": "grouped bar",
"mandatory_caption_caveats": [
"Rows span four cortical areas (M1, auditory, whisker-S1/S2, forelimb M1); the IT/PT/CT framework is compared across regions, not within one.",
"Taxonomic resolution differs across rows (broad IT/PT/CT vs. Cre-line- or transcriptomic-defined subclasses); subtype counts are not directly comparable."
]
}