Cortical plasticity induced by transplantation of embryonic somatostatin or parvalbumin interneurons

GABAergic inhibition has been shown to play an important role in the opening of critical periods of brain plasticity. We recently have shown that transplantation of GABAergic precursors from the embryonic medial ganglionic eminence (MGE), the source of neocortical parvalbumin- (PV⁺) and somatostatin-expressing (SST⁺) interneurons, can induce a new period of ocular dominance plasticity (ODP) after the endogenous period has closed. Among the diverse subtypes of GABAergic interneurons PV⁺ cells have been thought to play the crucial role in ODP. Here we have used MGE transplantation carrying a conditional allele of diphtheria toxin alpha subunit and cell-specific expression of Cre recombinase to deplete PV⁺ or SST⁺ interneurons selectively and to investigate the contributions of each of these types of interneurons to ODP. As expected, robust plasticity was observed in transplants containing PV⁺ cells but in which the majority of SST⁺ interneurons were depleted. Surprisingly, transplants in which the majority of PV⁺ cells were depleted induced plasticity as effectively as those containing PV⁺ cells. In contrast, depleting both cell types blocked induction of plasticity. These findings reveal that PV⁺ cells do not play an exclusive role in ODP; SST⁺ interneurons also can drive cortical plasticity and contribute to the reshaping of neural networks. The ability of both PV⁺ and SST⁺ interneurons to induce de novo cortical plasticity could help develop new therapeutic approaches for brain repair.