Thalamic-cortical-striatal circuitry subserves working memory during delayed responding on a radial arm maze

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Behavioral Neuroscience

Background:

• The medial dorsal nuclei of the thalamus (MDNt), prefrontal cortex, and ventral striatum form a circuit potentially involved in working memory.
• Understanding the functional interactions within this circuit is key to elucidating working memory mechanisms.

Purpose of the Study:

• To investigate the functional interactions between the MDNt, prefrontal cortex, and ventral striatum in rats performing spatial working memory tasks.
• To determine the role of serial information transmission within this circuit for guiding search behavior.

Main Methods:

• Transient inactivation of the MDNt using lidocaine in rats performing delayed and non-delayed radial-arm maze tasks.
• Asymmetrical lidocaine injections to disconnect the MDNt, prefrontal cortex, and nucleus accumbens, assessing effects on task performance.

Main Results:

• MDNt inactivation selectively impaired performance on the delayed spatial task, not the non-delayed task.
• Disconnection between the MDNt and prefrontal cortex, and between the prefrontal cortex and nucleus accumbens, disrupted foraging in the delayed task.
• Disconnection between the MDNt and nucleus accumbens had no significant effect.

Conclusions:

• Serial information processing among the MDNt, prefrontal cortex, and nucleus accumbens is essential for trial-unique, short-term spatial memory guiding search behavior.
• These findings support a distributed neural network model for executive functions in working memory.