Adaptive brain rewiring after brain injury via adult neurogenesis

The adult mammalian brain possesses limited regenerative abilities but retains the capacity for functional reorganization after experiencing various stimuli, such as injury or disease. While localized plasticity at injury sites has been observed, the broader consequences of a focal injury and the underlying biological processes remain unclear.

To investigate this, researchers conducted a comprehensive, unbiased examination of neuronal activity at the single-cell level following a targeted injury to the primary visual cortex (V1) in mice. The findings revealed that olfactory processing areas exhibited unexpected remote activation following the V1 injury. Additionally, the study demonstrated that V1 injury encouraged the integration of adult-born neurons into the olfactory bulb (OB) and intensified cortical feedback onto these bulbar circuits.

Utilizing high-density multielectrode array recordings alongside two-photon calcium imaging, the researchers observed circuit-level functional enhancements characterized by heightened synchrony and refined tuning among principal output neurons in the OB. These improvements in circuit function were accompanied by enhanced performance in odor-guided tasks.

Notably, motor cortex lesions did not provoke comparable cellular or behavioral responses, indicating that distal adaptation only occurs when injury is accompanied by heightened olfactory demands. The study concludes that the adult brain can mobilize alternative sensory circuits, distant from the initial lesion, to undergo adaptive, functionally relevant reorganization.

Moreover, it implicates adult neurogenesis as a crucial mechanism enabling this phenomenon. The discovery underscores a previously unrecognized degree of remote plasticity and highlights the novel role of adult neurogenesis in sensory compensation following focal brain injury.