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Neurological Rehabilitation

Long-Term Somatosensory Map Plasticity in Non-Columnar Neurons Following Infra-Orbital Nerve Regeneration: Implications for Modeling Central Abnormal Sensations

Friday, October 24, 2025
8:00 AM - 9:15 AM MT
Location: Kiosk 10

    Poster Presenter(s)

  • Jang-Jier Tseng, MD (he/him/his)

    Attending Physiatrist
    Chang Gung Memorial Hospital, Linkou branch, Taiwan; New Taipei Municipal Tu Cheng Hospital (Built and Operated by Chang Gung Medical Foundation), Taiwan
    New Taipei City, Taiwan (Republic of China)

    • Co-Author(s)

  • YP

    Yu-Cheng Pei, MD, PhD

    Professor
    Chang Gung Memorial Hospital, Linkou Branch, Taiwan
    Taoyuan City, Taoyuan, Taiwan (Republic of China)

Disclosure(s):
Jang-Jier Tseng, MD: No financial relationships to disclose
Background and/or Objectives: Peripheral nerve reconstruction can lead to centrally mediated abnormal sensations, yet the time-course of cortical reorganization is unclear. We profiled long-term changes in layer-2/3 pyramidal (PYR) neurons of the barrel cortex (S1BF) after infra-orbital nerve (ION) reconstruction using chronic two-photon calcium imaging.

Design: Prospective longitudinal animal study.

Setting : In-vivo animal surgical suite and awake two-photon imaging laboratory.

Participants : Five adult GCaMP6 transgenic mice on a C57BL/6 background.

Interventions: Microsurgical transection and end-to-end repair of the left ION; no additional treatment.

Main Outcome Measures: (1) Proportion of whisker-responsive PYR neurons; (2) normalized response magnitude (ΔF/F); (3) best-whisker (BW) tuning sharpness (0–1); (4) tuning instability (% neurons whose BW changed, ΔBW).

Results: Whisker-evoked activity disappeared by week 1, reducing responsiveness from 91.1 % (baseline) to 26.7 % and depressing response magnitude (P < 0.01). Both indices recovered by week 10 (73.8 % responsive). BW tuning sharpness rose transiently at week 1 (Δ = +0.46, P = 0.007) and normalized by week 3. ΔBW affected ≤10 % of neurons during weeks 1–5 (except week 2, 20 %) but climbed to ~30 % during weeks 5–10, indicating increasing tuning instability as recovery advanced. Response magnitude did not predict ΔBW. A non-linear relationship emerged: neurons with either low ( < 0.5) or high (>0.5) sharpness retuned more often than mid-range cells.

Conclusions: ION reconstruction triggers an early silent phase with sharpened tuning, followed by progressive re-engagement of PYR neurons accompanied by growing map instability that persists to at least ten weeks. This two-photon model enables high-resolution tracking of cortical plasticity after peripheral nerve repair and provides a platform for evaluating rehabilitation or neuromodulatory strategies aimed at minimizing centrally mediated abnormal sensations.