Discoveries from an anatomy research lab at Des Moines University Medicine and Health Sciences provide valuable insights into differences in brain structure and function and contribute to a deeper understanding of the brain’s complexities across species and time.
DMU students, alumni, faculty and staff recently contributed to the publication of two manuscripts from the lab of Muhammad Spocter, Ph.D., director and professor of the university’s Master of Science in Anatomy program.
The first manuscript, “Gray matter volume and asymmetry in Broca’s and Wernicke’s area homologs in chimpanzees (Pan troglodytes) using a probabilistic region of interest approach,” published in NeuroImage, studies how the structure and organization of the parts of the brain linked to language differ within chimpanzees. These areas of the brain are challenging to compare between humans and other primates due to differences in their brain structure. Spocter, along with researchers from three other institutions, aimed to remedy this situation by creating maps of these brain areas in chimpanzees. The researchers used brain maps to measure differences in gray matter and how this differs between sexes and age groups. They found that female chimpanzees had more gray matter than male chimpanzees in a region known as Broca’s area, which is crucial for speech production. In humans, this sex difference contributes to better verbal fluency and language processing capabilities of females.
“The capacity for human speech and language is a fundamental attribute of our species but its emergence remains widely shrouded in mystery. Studies like ours working on present-day primates or human ancestors found in fossils help to fill in the missing pieces in our knowledge,” Spocter says.
The research team also found other characteristics that were shared between chimpanzees and humans, including that gray matter in these areas decreased with age and that the Broca’s area was strongly influenced by hereditary factors.
The second manuscript, “Predictive methods and probabilistic mapping of subcortical brain components in fossil Carnivora,” published in the Journal of Comparative Neurology, examines the relationship between the brain scaling of modern-day mammals and their ancestral fossil relatives. The team of researchers includes current DMU Doctor of Osteopathic Medicine students Rachna Sahasrabudhe, D.O.’25, Brandon Merritt, D.O.’27, Pallavi Mahesh, D.O.’25, Emily Baer, D.O.’27, M.S.A.’24 and Christelle Eliacin, D.O.’25. Also on the team of researchers are members of the Doctor of Osteopathic Medicine Class of 2024 Phuoc Nguyen, Susan La, Stefan Lilly, Jiyoon Song, Matthew Yee and Olivia Matz, and DMU faculty member Rachel Dunn, Ph.D.
“This study is the culmination of several years of work drawing upon two broad projects, one aimed at identifying differences in brain architecture between wild and domestic species and the other aimed at digitizing brain molds, also known as endocasts,” Spocter says.
The scientists used MRI scans on living dogs and cats as well as 3D laser scans on fossilized skulls to study how these animals evolved over 40 million years. By analyzing the relationship between the internal and external brain components, the researchers developed equations to estimate brain structures in extinct species.
“The approach we pioneered here shows that predicative methods, applied in a rather straightforward way, can help us visualize the size and spatial arrangement of brain structures that have been long lost to time,” Spocter says.
Their findings show that these equations could reliably predict the internal brain structures of modern carnivore animals from measurements of the external brain. Spocter’s team then applied these equations to fossils and combined it with probabilistic mapping to reconstruct the internal 3D anatomy of the brain in these extinct species. In extinct species, knowledge of the brain is limited by the features seen on the surface of these brain molds. The team of researchers overcame this challenge by virtually recreating the internal brain anatomy. This approach bridges the gap between modern neuroscience and paleontology, providing insights into brain evolution in ancient carnivores.
“Our research team at DMU continues to push the boundaries of neuroscience and anatomy. The publication of these two manuscripts highlights the contributions of our students, alumni and faculty in advancing our understanding of brain evolution, both in living and extinct species,” says Pravin Mishra, Ph.D., MBA, executive director of research at DMU. “It is truly inspiring to see how the innovative work coming out of our Master of Science in Anatomy program is contributing to the broader scientific community’s efforts to explore and map the complexities of the brain.”
