Mediodorsal Thalamic Input to Striatum Contributes to Early Action Learning

Area of Science:

• Neuroscience
• Behavioral Neuroscience

Background:

• Action control relies on corticothalamo-basal ganglia circuits for learning and updating action contingencies.
• The mediodorsal thalamus (MD) is implicated in volitional control via prefrontal cortex interactions, but its role in striatal projections is unclear.

Purpose of the Study:

• To investigate the contribution of mediodorsal thalamus (MD) projections to the dorsal medial striatum (DMS) in volitional action control.
• To elucidate the role of MD→DMS pathways in the acquisition and adaptation of action contingencies.

Main Methods:

• Utilized a mouse model to study volitional action control in both sexes.
• Recorded calcium activity in MD terminals within the DMS during novel action contingency acquisition and adaptation.
• Functionally attenuated MD→DMS activity to assess its necessity for behavioral control.

Main Results:

• MD terminal calcium activity in the DMS (MD→DMS) encoded action information during initial learning of a novel action contingency, decreasing with experience.
• MD→DMS activity was essential for learning and utilizing contingency control over actions.
• Attenuation of MD→DMS activity impaired exploration, promoted repetitive actions, and prevented adaptation to changing action contingencies.

Conclusions:

• MD projections into the striatum are vital for the plasticity underlying initial action strategy learning.
• These MD→DMS pathways contribute significantly to volitional action control, supporting the acquisition of adaptive behaviors in response to changing environmental contingencies.