Striatum in stimulus-response learning via feedback and in decision making

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Cognitive deficits are a key feature of Parkinson's disease.
• The striatum, particularly the dorsal striatum, plays a role in cognitive functions affected by Parkinson's disease.
• Previous research often conflates learning and decision-making processes in the striatum.

Purpose of the Study:

• To differentiate the roles of the dorsal and ventral striatum in learning and decision-making.
• To investigate the neural mechanisms underlying stimulus-response association and decision enactment.
• To clarify the striatum's function in cognitive processes relevant to Parkinson's disease.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to monitor brain activity in healthy young adults.
• Participants underwent a two-session learning task involving associating images with responses using feedback.
• Session 2 involved response selection without feedback to isolate decision enactment.

Main Results:

• Dorsal striatum activation was associated with response selection and decision enactment, not feedback-based learning.
• Ventral striatum activity was preferentially observed during feedback, particularly early in the learning phase.
• Dorsal striatum activity increased as associations were learned and was present in the feedback-absent session.

Conclusions:

• The ventral striatum mediates the learning of stimulus-response associations through feedback.
• The dorsal striatum is crucial for decision-making and enacting learned responses.
• These findings distinguish the functional roles within the striatum, offering insights into Parkinson's disease cognitive impairments.