Neuropil variation in the frontal, motor, and visual cortex of the beaver (Castor canadensis) and domestic rat (Rattus rattus domesticus)
Description
Beavers are a remarkable example of a species with the ability to shape and impact their environment, ultimately creating cascading influences on the broader ecology. Although beavers have been the subject of several ecological studies, their comparative neurobiology has not been studied extensively, and several questions remain concerning the neuroanatomical basis of their seemingly complex behavior and how this might differ from that of other rodent species. Here, we undertook a preliminary survey of the neuropil space in the frontal, motor, and visual cortex of two North American beavers (Castor canadensis) and one rat (Rattus rattus) to see how these two species might differ from one another in the amount of neuropil space, an established proxy for cortical connectivity. To address this question, we used Cresyl violet-stained sections through the frontal, motor, and occipital lobes, then surveyed the neuropil space using a design-based stereological sampling approach followed by image capture. Rendered image stacks were then subjected to a trained machine learning model, which helped to isolate and quantify the neuropil space. Our results revealed the existence of marked differences in mean neuropil space between the two species, with beavers having larger neuropil space (i.e., connectivity) in the frontal and occipital lobe than that observed in the rat. In conclusion, these results indicate evidence of anatomical and species differences in the structural arrangement of the beaver brain, which likely underlie differences in rodent behavior.
Citation Information
Van, Helen DO and Spocter, Muhammad A., "Neuropil variation in the frontal, motor, and visual cortex of the beaver (Castor canadensis) and domestic rat (Rattus rattus domesticus)" (2026). Office of Research DMU Research Symposium. 111.
https://digitalcommons.dmu.edu/researchsymposium/2025rs/2025abstracts/111
Neuropil variation in the frontal, motor, and visual cortex of the beaver (Castor canadensis) and domestic rat (Rattus rattus domesticus)
Beavers are a remarkable example of a species with the ability to shape and impact their environment, ultimately creating cascading influences on the broader ecology. Although beavers have been the subject of several ecological studies, their comparative neurobiology has not been studied extensively, and several questions remain concerning the neuroanatomical basis of their seemingly complex behavior and how this might differ from that of other rodent species. Here, we undertook a preliminary survey of the neuropil space in the frontal, motor, and visual cortex of two North American beavers (Castor canadensis) and one rat (Rattus rattus) to see how these two species might differ from one another in the amount of neuropil space, an established proxy for cortical connectivity. To address this question, we used Cresyl violet-stained sections through the frontal, motor, and occipital lobes, then surveyed the neuropil space using a design-based stereological sampling approach followed by image capture. Rendered image stacks were then subjected to a trained machine learning model, which helped to isolate and quantify the neuropil space. Our results revealed the existence of marked differences in mean neuropil space between the two species, with beavers having larger neuropil space (i.e., connectivity) in the frontal and occipital lobe than that observed in the rat. In conclusion, these results indicate evidence of anatomical and species differences in the structural arrangement of the beaver brain, which likely underlie differences in rodent behavior.
