Measuring executive function in sheep (Ovis aries) using visual stimuli in a semi-automated operant system.

Area of Science:

• Neuroscience
• Animal Cognition
• Behavioral Science

Background:

• Cognitive impairment is a hallmark of neurodegenerative diseases like Huntington's and Alzheimer's.
• The intra-dimensional (ID) extra-dimensional (ED) attentional set shift task assesses executive function but has lacked effective pre-clinical models.
• Sheep offer a promising model due to their executive task abilities and long lifespan for studying cognitive decline.

Purpose of the Study:

• To describe a novel methodology for testing sheep in the IDED task.
• To establish a clinically translatable pre-clinical model for executive function in neurodegenerative conditions.
• To adapt the IDED task for sheep using a semi-automated system with visual stimuli.

Main Methods:

• A semi-automated system was developed to present visual stimuli (colored letters) on computer screens.
• Twelve sheep (Ovis aries) were tested on the IDED task, involving discrimination and reversal learning across different stages.
• Performance was evaluated based on trials to criterion and errors made during each task phase.

Main Results:

• All sheep successfully learned to discriminate between colors and letters throughout the IDED task stages.
• Sheep required significantly more trials and made more errors during stimulus reversal, except for the ED shift.
• The new computer-based method demonstrated higher validity, flexibility, and throughput compared to previous maze-based approaches.

Conclusions:

• Sheep successfully performed the IDED attentional set shift task using a computer-based system.
• This methodology provides a quantifiable and clinically translatable measure of executive function in sheep.
• The study establishes a robust pre-clinical model for investigating cognitive decline in neurodegenerative diseases.