Beyond Movement: Exploring the Difference between Motor Function and Coordination

Although often used in a interchangeable manner, “motor function" and "motor coordination” have a subtle difference.

While “motor function" refers to general motor performance including strength, and in general the ability to execute purposeful movements, "motor coordination” is a slightly more specific concept even more tightly related to measure the harmonious functioning on the muscles and limbs to produce smooth and efficient movements.

For this reason the tools used for the two aspects are different. The RotaRod is the classic device for motor coordination, while the Grip Strength Meter and the Horizontal Treadmill are the devices of election for motor function.

The Rota-Rod

Motor coordination is a complex process and involves several areas of the brain about which the RotaRod can provide insights: from the cerebellum, to the basal ganglia, the motor cortex and several others. In the early days specific lesions to these areas would precede the RotaRod task. Nowadays, it is more common to use molecular or chemical tools but the goal is the same: investigating the basic mechanisms and the opportunities in terms of treatments for disease like:

• Parkinson's Disease
• Ataxia
• Huntington's Disease
• Traumatic Brain Injury (TBI)
• Spinal Cord Injury
• Multiple Sclerosis (MS)
• Amyotrophic Lateral Sclerosis (ALS)
• Drug-Induced Motor Impairments
• Genetic Disorders
• Aging-Related Motor Decline

Following you can find and interesting article in which the RotaRod is used to evaluate motor coordination in Parkinson’s disease, one of the most common neurodegenerative disorders of aging: https://www.sciencedirect.com/science/article/abs/pii/S0304394022004682

The Grip Strength meter

Grip strength meters are used to assess the neuromuscular function, strength, and coordination of the animals' forelimbs. The procedure involves training the rodents to grip a force-sensitive apparatus, typically a grid or a bar, and measuring the force applied during the grip.

The data collected from grip strength meters in rodent studies contribute to a better understanding of motor function, disease mechanisms, and potential treatments in preclinical research. The most common applications are:

• ALS
• Parkinsons
• Spinal cord injury
• Muscular distrophy
• Arthritis
• Peripheral neuropathy
• Stroke
• Aging
• Traumatic Brain Injury

These are just a few examples, and grip strength assessments can be adapted to study a wide range of diseases and conditions affecting motor function in rodents.

Following you can find and interesting article in which the Grip Strength Meter from Ugo Basile was used to find new therapeutic target in stroke related inflammation: https://link.springer.com/article/10.1186/s12974-024-03026-6

Horizontal Treadmills

The horizontal treadmill is strictly related to studies in which is necessary to control and standardize exercise conditions, facilitating the investigation of various physiological and pathological aspects related to exercise, health, and disease. It provides a versatile tool for exploring the impact of physical activity on different organ systems and overall well-being in rodent models.

Treadmills are commonly used in rodent studies for various purposes, primarily to assess physical fitness, endurance, locomotor function, and to induce specific conditions for research purposes. Here are some key applications of treadmills in rodent studies:

• Exercise and physical fitness assessment
• Cardiovascular research
• Metabolic studies
• Obesity and diabetes
• Neuromuscular research

Treadmills provide the motivation to run to rodents via an electric shock or air puffs.

Following we propose an interesting paper that describes typical example of the Treadmill device to perform an exhaustion test: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10716216/

Conclusion

In summary, while each device serves a specific purpose, their commonalities lie in their contribution to the assessment of motor function and physical performance in rodent studies. Researchers often integrate multiple tools in a comprehensive experimental approach to gain a thorough understanding of the effects of genetic modifications, diseases, or interventions on motor function and coordination in rodents.

Beyond the specificity of their use they share commonalities:

• Versatility: can be adapted for use in a wide range of experimental paradigms and research questions.
• Standardization: consistency in measurements and facilitating the comparison of results across different studies or between groups of animals.
• Neurological and Muscular Assessments: Each device can be employed to assess the impact of neurological or muscular conditions on motor function. For example, they are used in studies related to neurodegenerative diseases, muscle disorders, or the effects of drug interventions.
• Preclinical Disease Models: utilized in preclinical disease models to evaluate the progression and severity of motor deficits associated with conditions such as Parkinson's disease, muscular dystrophy, or spinal cord injury.
• Longitudinal Studies: employed in longitudinal studies to monitor changes in motor function over time, providing insights into disease progression, recovery, or the effectiveness of interventions.