In 1932, the American psychologist Calvin S. Hall developed the open field test (OFT) for assessing the emotionality of animals.1 Since then, the OFT has undergone various modifications in step with modern technology, and its ability to evaluate the effects of drugs on animal behavior has had a significant impact in the fields of neuroscience and psychopharmacology.2 This article delves into the role of the locomotor activity test, a variation of the OFT, and explores its utility in understanding spatial perception and related neurological phenomena. It will discuss how studies have used locomotor activity technology and San Diego Instruments’ contribution in expanding the boundaries of scientific understanding.
The Locomotor Activity Test
Fundamentally, locomotor activity tests involve tracking an animal as it moves around an enclosed arena. These tests are commonly performed on rodents and capture ambulatory behavior by measuring metrics like speed, rest intervals, and distance traveled.3,4 Tracking is typically managed by either video-based or photobeam systems. Video tracking uses cameras sensitive to visible or infrared light to capture the subject’s movement, while photobeam setups employ infrared photoemitters and detectors to triangulate the animal’s location as it moves. Researchers may choose one method or use both for enhanced surveillance depending on experimental requirements.4
The collected data can be visualized through locomotor zone maps, which can be displayed as heat and density maps, to depict the subject’s travel path and time spent in specific sections. These locomotor zone maps provide invaluable insights into spatial perception and behavioral responses, advancing understanding of the subject’s locomotion and its interactions with the environment.4
Locomotor Activity Testing in Neuroscience and Psychopharmacology
The numerous facets of locomotor activity explain events occurring at the molecular level and the emergent properties of movement, motivation, and learning. For example, in a study aiming to understand the role of the D3 dopamine receptor in rodent locomotor behavior and its potential relevance to neuropsychiatric disease, the locomotor activity test enabled researchers to quantify the effects of D3 receptor agonists on mouse movement behavior. This helped establish that D3 receptor stimulation inhibits novelty-stimulated locomotion and provided conditions for in vivo administration of D3 receptor agonists.5
Locomotor activity tests have also been used to elucidate endogenous timing systems, downstream effects of genetic manipulation on locomotion, the impact and temporal importance of pharmacological substances on disease, and locomotor changes in neuropsychiatric conditions.6
Photobeam Tracking: The PAS-Home Cage and PAS-Open Field
San Diego Instruments (SDI) has pioneered cutting-edge technology in the field of locomotor activity testing, offering two systems that have revolutionized the way researchers study animal behavior – the Photobeam Activity System-Home Cage (PAS-HC) and the Photobeam Activity System (PAS)-Open Field.
The PAS-HC uses a 4×8 photobeam configuration to precisely capture and monitor the movement of mice or rats in their home cage environments. Real-time beam break reporting eliminates the need for specialized calibrators, ensuring accuracy in locomotor behavior measurement. In addition, the system’s sophisticated software enables comprehensive recording and analysis of diverse locomotor patterns, encompassing central peripheral activity, rearing, ambulation movements, and fine movements. The PAS-HC accommodates up to 48 test stations and can incorporate an optional rearing frame for up to 24 stations, providing flexibility and scalability.7
The PAS-Open Field provides researchers with a comprehensive toolkit for open field testing. It utilizes a 16×16 photobeam array to accurately track animal movement. The system’s advanced software enhances analysis by allowing pre-defined study parameters, automated test sessions, and real-time beam break displays. Notably, the PAS-Open Field can generate and utilize zone maps in both X and Y dimensions. This permits precise data analysis with customizable spatial divisions. The software further refines results by categorizing beam breaks into ambulations, fine movements, and rearing based on distance, enhancing result accuracy.8
A New Horizon in Locomotor Activity Testing
From its inception as the open field test to contemporary technologies like the PAS-HC and the PAS-Open Field, locomotor activity tests have catalyzed breakthroughs in neuroscience and psychopharmacology, revealing intricate links between genetic factors, environmental interactions, and drug effects on locomotion. Spearheading innovation, San Diego Instruments’ have empowered researchers to delve deeper into spatial perception, bridging the gap between behavior and neural mechanisms. As our understanding of locomotor activity expands, these tools continue to reshape our knowledge of how animals navigate their surroundings, forging a path towards enhanced therapeutic interventions and a deeper comprehension of the brain-body relationship.
References and Further Reading
- Hall CS. (1934). Emotional behavior in the rat. I. Defecation and urination as measures of individual differences in emotionality. Journal of Comparative Psychology. https://doi.org/10.1037/h0071444
- Choleris E, et al. (2001). A detailed ethological analysis of the mouse open field test: effects of diazepam, chlordiazepoxide and an extremely low frequency pulsed magnetic field. Neuroscience & Biobehavioral Reviews. https://doi.org/10.1016/S0149-7634(01)00011-2
- Belovicova K, et al. (2017). Animal tests for anxiety-like and depression-like behavior in rats. Interdisciplinary Toxicology. https://doi.org/10.1515/intox-2017-0006
- Behaviorcloud. (2019). [Webinar] Open Field Activity Tracking Webinar with BehaviorCloud & San Diego Instruments. Transcript available at: https://www.behaviorcloud.com/2019/07/17/Open-Field-Activity-Tracking-Webinar-with-BehaviorCloud-San-Diego-Instruments.html (Accessed on 08 August 2023).
- Pritchard LM, et al. (2003). 7-OH-DPAT and PD 128907 Selectively Activate the D3 Dopamine Receptor in a Novel Environment. Neuropsychopharmacology. https://doi.org/10.1038/sj.npp.1300018
- SD Instruments. What is the Locomotor Activity Test. Available at: https://sandiegoinstruments.com/what-is-the-locomotor-activity-test/ (Accessed on 09 August 2023).
- SD Instruments. Photobeam Activity System-Home Cage. Available at: https://sandiegoinstruments.com/product/pas-homecage/ (Accessed on 09 August 2023).
- SD Instruments. Photobeam Activity System-Open Field. Available at: https://sandiegoinstruments.com/product/pas-open-field/ (Accessed on 09 August 2023).