Neck collar for restraining head and body movements in rats for behavioral task performance and simultaneous neural activity recording

Background: Head fixation has been one of the major methods in behavioral neurophysiology because it allows precision in stimulus application and behavioral assessment. Most neural recordings in awake monkeys have been obtained under head fixation, which is nowadays also being used in awake rodents. However, head fixation devices in rats often become unstable within several months, which increases risks for inflammation, infection, and necrosis of the bone and surrounding tissue. New method: In this study we developed a novel non-invasive "neck collar system" for restraining the head and body movements of behaving rats. Results: The attachment of the neck collar for 2-months did not affect the animals' health and welfare. Rats under neck-collar fixation could learn a behavioral task (standard delayed licking task) with the same efficiency as those under standard head fixation. They could also learn a more complicated task (delayed pro/anti-licking task) under neck-collar fixation and afterwards transfer their learning to the task under standard head fixation. Furthermore, we were able to record single-unit activity in rats under neck-collar fixation during the performance of the standard delayed licking task. Comparison with existing method(s): This system consists of economical materials and is easily constructed, and it enables head-restraint without surgery, thus eliminating the risk of inflammation or infection. Conclusions: We consider the neck-collar fixation developed in this study would be useful for restraining the head of a behaving rodent.