Emergence of novel functions in striatal low-threshold spike interneurons (Commentary on Gazan et al., 2019).

LTSIs selectively target distal dendrites of spiny projection neurons (SPNs, top). In this article by Gazan et al., the authors performed a selective ablation of LTSIs using Cre-dependent diphtheria toxin in SST-Cre mice, injected in the striatum. They demonstrate that the ablation of LTSIs (bottom) induced a decrease in the number of distal dendritic spines on SPNs associated with an increased intrinsic excitability of these cells. Behaviorally, this is associated with a potentiation of cocaine effect on locomotion. Whether these behavioral effects are the direct result of the loss of LTSIs or whether it involves rearrangements in glutamatergic (Glu) or dopaminergic (DA) synapses occurring normally on these dendritic spines remains to be explored. Commentary on Gazan A, Rial D, Schiffmann SN. Ablation of striatal somatostatin interneurons affects MSN morphology and electrophysiological properties, and increases cocaine induced hyperlocomotion in mice. Eur J Neurosci. 2020;51:1388-1402. https://doi.org/10.1111/ejn.14581.