The delayed-conditional-discrimination task improves measurement of working memory in rats

Area of Science:

• Neuroscience
• Cognitive Psychology
• Animal Behavior

Background:

• Working memory (WM) models in rodents using Skinner boxes are often confounded by mediating behaviors during task delays.
• Traditional methods like delayed-matching-to-sample (DMTS) struggle to prevent these confounding factors.
• Existing solutions like true matching or supplementary tasks have proven insufficient in rats.

Purpose of the Study:

• To evaluate the effectiveness of different tasks in modeling rodent working memory.
• To identify a task that minimizes confounding behaviors for more accurate drug effect interpretation.
• To propose the delayed-conditional-discrimination (DCD) task as a preferred method for assessing WM in rats.

Main Methods:

• Comparison of delayed-matching-to-sample (DMTS) with and without modifications against the delayed-conditional-discrimination (DCD) task.
• Utilizing response similarity as a key feature to reduce mediating behaviors.
• Analyzing the impact of baseline performance and mediating behaviors on the interpretation of drug effects.

Main Results:

• Response similarity in the DCD task effectively reduces mediating behaviors, unlike other methods.
• The DCD task avoids high baseline performance levels often seen in other tasks.
• Delay-dependent drug effects can be artifactually induced by high baseline performance and mediating behaviors, complicating WM interpretations.

Conclusions:

• The DCD task is a more valid and reliable animal model for studying working memory in rats.
• Relying solely on delay-dependency to infer specific drug effects on WM is insufficient.
• The DCD task's design offers a clearer window into the neural mechanisms of working memory.