Response learning stimulates dendritic spine growth on dorsal striatal medium spiny neurons

Publication Year
2018

Type

Journal Article
Abstract

Increases in the number and/or the size of dendritic spines, sites of excitatory synapses, have been linked to different types of learning as well as synaptic plasticity in several brain regions, including the hippocampus, sensory cortex, motor cortex, and cerebellum. By contrast, a previous study reported that dorsal striatum-dependent maze learning has no effect on medium spiny neuron dendritic spines in the dorsal striatum. These findings might suggest brain region-specific differences in levels of plasticity as well as different cellular processes underlying different types of learning. No previous studies have investigated whether dendritic spine density changes may be localized to specific subpopulations of medium spiny neurons, nor have they examined dorsolateral striatum-dependent maze trained rats in comparison to an untrained maze-enriched control group. To address these questions further, we labeled medium spiny neurons with the lipophilic dye DiI and stained for the protein product of immediate early gene zif 268, an indirect marker of neuronal activation, in both trained and untrained maze groups. We found a small but significant increase in dendritic spine density on medium spiny neurons of the dorsolateral striatum after early intensive training, along with robust increases in the density of spines with mushroom morphology coincident with reductions in the density of spines with thin morphology. However, these results were not correlated with zif 268 expression. Our results suggest that short-term intensive training on a dorsolateral striatum-dependent learning paradigm induces rapid increases in dendritic spine density and maturation on medium spiny neurons of the dorsolateral striatum, an effect which may contribute to early acquisition of the learned response in maze training.

Journal
Neurobiology of Learning and Memory
Volume
155
Pages
50-59