Mouse S1 developmental timeline of L5→L2/3 vs L4→L2/3 E synaptic recruitment; s…

{
  "n": null,
  "doi": "10.1038/s41467-024-55783-w",
  "claim": "Mouse S1 developmental timeline of L5→L2/3 vs L4→L2/3 E synaptic recruitment; supports developmental switch in dominant ascending E input.",
  "cite_key": "VargasOrtiz2025",
  "evidence": "Synchronous neuronal activity is a hallmark of the developing mouse primary somatosensory cortex. While the patterns of synchronous neuronal activity in cortical layer 2/3 have been well described, the source of the robust layer 2/3 activity is still unknown. Using a novel microprism preparation and in vivo 2-photon imaging in neonatal mice, we show that synchronous neuronal activity is organized in barrel columns across layers. Monosynaptic rabies tracing and slice electrophysiology experiments reveal that layer 2/3 pyramidal neurons receive significant layer 5 inputs during the first postnatal week, and silencing layer 5 synaptic outputs results in a significant reduction in spontaneous activity, abnormal sensory-evoked activity and disrupted layer 4-layer 2/3 connectivity. Our results demonstrate that translaminar layer 5-layer 2/3 connectivity plays an important role in synchronizing the developing barrel column to ensure the strengthening of layer 4-layer 2/3 connections, supporting the formation of the canonical cortical organization in barrel cortex.",
  "effect_size": null,
  "text_access": "fulltext",
  "study_system": "Translaminar synchronous neuronal activity is required for columnar synaptic strengthening in the mouse neocortex.",
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  "claim_source_sentence": "L2/3 pyramidal neurons are synchronized within the columnar SNA by L5 inputs at P7—rabies synaptic tracing and patch clamp recording indicate significant direct L5-L2/3 inputs in the 1PNW before the strengthening of L4-L2/3 inputs in the 3PNW.",
  "source_provenance_status": "ok",
  "replication_evidence_dois": [],
  "effect_size_source_sentence": null
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  "paper:paper-113803f405c0"
]

L2/3 pyramidal neurons are synchronized within the columnar SNA by L5 inputs at P7—rabies synaptic tracing and patch clamp recording indicate significant direct L5-L2/3 inputs in the 1PNW before the strengthening of L4-L2/3 inputs in the 3PNW.

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Synchronous neuronal activity is a hallmark of the developing mouse primary somatosensory cortex. While the patterns of synchronous neuronal activity in cortical layer 2/3 have been well described, the source of the robust layer 2/3 activity is still unknown. Using a novel microprism preparation and in vivo 2-photon imaging in neonatal mice, we show that synchronous neuronal activity is organized in barrel columns across layers. Monosynaptic rabies tracing and slice electrophysiology experiments reveal that layer 2/3 pyramidal neurons receive significant layer 5 inputs during the first postnatal week, and silencing layer 5 synaptic outputs results in a significant reduction in spontaneous activity, abnormal sensory-evoked activity and disrupted layer 4-layer 2/3 connectivity. Our results demonstrate that translaminar layer 5-layer 2/3 connectivity plays an important role in synchronizing the developing barrel column to ensure the strengthening of layer 4-layer 2/3 connections, supporting the formation of the canonical cortical organization in barrel cortex.