Multimodal Plasticity in Dorsal Striatum While Learning a Lateralized Navigation Task.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Synaptic Plasticity

Background:

• The dorsal striatum is crucial for cognitive and motor control.
• Skill learning involves a shift from attentive to habitual performance, engaging different dorsal striatal subregions (dorsomedial to dorsolateral).
• Neural mechanisms underlying these transitions remain incompletely understood.

Purpose of the Study:

• To investigate the neural mechanisms of cognitive and behavioral transitions during skill learning.
• To compare synaptic plasticity in dorsal striatal subregions and hemispheres relative to learned T-maze task performance.
• To examine changes in intrinsic excitability and neuronal morphology associated with learning stages.

Main Methods:

• Rats were trained on a directional T-maze task to transition from attentive to habitual performance.
• Bidirectional synaptic plasticity (long-term potentiation and long-term depression) was measured in striatal brain slices.
• Intrinsic excitability and dendritic morphology of medium spiny neurons were analyzed.
• Comparisons were made between early and late training stages, and between striatal subregions and hemispheres.

Main Results:

• Synaptic plasticity (LTP/LTD) is independently modulated by learning, dependent on striatal subregion, training stage, and hemisphere.
• Intrinsic excitability is enhanced in the dorsomedial striatum (contralateral hemisphere) during early training.
• Dendritic remodeling occurs after training, suggesting a novel form of pruning.
• Late training shows dampened population responses and changes in dorsolateral striatum plasticity.

Conclusions:

• Region- and hemisphere-specific changes in striatal synaptic, intrinsic, and morphological plasticity accompany T-maze learning stages.
• These plasticity changes likely contribute to the cognitive transition from attentive to habitual strategies.
• Dorsomedial striatum activity strengthens rewarded turns after brief training, while dorsolateral striatum activity suppresses unrewarded turns after extensive training.