Nat Commun , May 2022

Selective plasticity of callosal neurons in the adult contralesional cortex following murine traumatic brain injury


Laura Empl, Alexandra Chovsepian, Maryam Chahin, Wing Yin Vanessa Kan, Julie Fourneau , Valérie Van Steenbergen , Sanofer Weidinger, Maite Marcantoni, Alexander Ghanem, Peter Bradley, Karl Klaus Conzelmann, Ruiyao Cai, Alireza Ghasemigharagoz, Ali Ertürk, Ingrid Wagner, Mario Kreutzfeldt, Doron Merkler, Sabine Liebscher, Florence M Bareyre

Traumatic brain injury (TBI) results in deficits that are often followed by recovery. The contralesional cortex can contribute to this process but how distinct contralesional neurons and circuits respond to injury remains to be determined. To unravel adaptations in the contralesional cortex, we used chronic in vivo two-photon imaging. We observed a general decrease in spine density with concomitant changes in spine dynamics over time. With retrograde co-labeling techniques, we showed that callosal neurons are uniquely affected by and responsive to TBI. To elucidate circuit connectivity, we used monosynaptic rabies tracing, clearing techniques and histology. We demonstrate that contralesional callosal neurons adapt their input circuitry by strengthening ipsilateral connections from pre-connected areas. Finally, functional in vivo two-photon imaging demonstrates that the restoration of pre-synaptic circuitry parallels the restoration of callosal activity patterns. Taken together our study thus delineates how callosal neurons structurally and functionally adapt following a contralateral murine TBI.

 

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