What Are Rodents?

Rodents are an order of mammals (Rodentia) that includes rats, mice, guinea pigs, squirrels, and related species, comprising roughly 40 percent of all mammalian species by count. Within engineering and applied science, rodents occupy a central position as animal models in biomedical research, neuroscience, pharmacology, and the development of implantable and wearable sensing systems. Rats and mice in particular share sufficient physiological, genetic, and neurological similarity with humans to make them tractable subjects for hypothesis testing before clinical trials, and their relatively short reproductive cycles allow longitudinal studies within practical research timelines.

The scientific use of laboratory rodents expanded substantially in the twentieth century as genetic tools matured. Inbred strains, knockout mice, and transgenic models with specific genetic modifications allow researchers to isolate the contribution of individual genes to disease processes. Today, rodent models underpin a large fraction of peer-reviewed biomedical literature and serve as the primary preclinical safety screen for new drugs, medical devices, and neural interfaces.

Animal Models in Biomedical Research

Mice and rats are the most common subjects in preclinical pharmacology and toxicology studies. Regulatory guidelines from agencies such as the FDA and the European Medicines Agency require safety and tolerability data from at least one rodent species before human clinical trials can begin. Rodents in drug discovery are selected for their genetic tractability, reproducibility across laboratories, short generation times, and the availability of validated disease models spanning oncology, metabolic disorders, cardiovascular disease, and neurodegenerative conditions. Rats are often preferred over mice for behavioral pharmacology and central nervous system research because of their larger size, greater cognitive complexity, and superior surgical tolerability, which facilitates indwelling catheter implants and chronic electrode recordings.

Neural Recording and Brain-Computer Interfaces

Rodents serve as the primary in vivo testbed for electrophysiological recording technologies and implantable neural interfaces. Intracortical microelectrode arrays inserted into the rat or mouse cortex record single-unit action potentials and local field potentials, providing data on the neural correlates of motor planning, sensory processing, and learning. Neural correlates of behavior in freely behaving rodents using inertial sensors demonstrated that head-mounted accelerometers and gyroscopes can track locomotion and behavioral state without confining the animal, combining kinematic and electrophysiological data in naturalistic settings. Open-source wireless telemetry systems now transmit electrophysiological data from implanted electrodes without tethered cables, reducing movement artifacts and allowing study of complex social and spatial behaviors. These tools, validated first in rodents, inform the design of fully implanted human brain-computer interfaces.

Behavioral Studies and Computational Modeling

Rodent behavior provides a rich substrate for computational neuroscience. Standardized behavioral tasks, including the Morris water maze for spatial memory, fear conditioning protocols, and the elevated plus maze for anxiety assessment, yield quantitative behavioral metrics that can be correlated with neural recordings or pharmacological manipulations. Advances in deep learning have extended this further: a virtual rodent built from an artificial neural network actuates a biomechanically realistic rat model and was trained to imitate the movement kinematics of freely moving animals, enabling direct comparison between biological and artificial motor control. Computer vision tracking systems automate pose estimation and behavioral classification, replacing manual scoring with high-throughput quantitative analysis.

Applications

Rodent models have engineering and scientific applications across a range of domains, including:

• Preclinical safety and efficacy testing for pharmaceutical compounds and biologics
• Development and validation of implantable neural recording and stimulation devices
• Neuroscience research on learning, memory, and sensorimotor integration
• In vivo testing of biosensors, drug delivery systems, and biomaterials
• Behavioral phenotyping for genetic disease models and toxicological screening