RIKEN neuroscientists have unveiled an extensive map of the marmoset brain, shedding light on how the prefrontal cortex connects with other cortical regions. This discovery holds promise for understanding and addressing neurological disorders related to the prefrontal cortex. Their groundbreaking research has been published in Neuron.
Much of our knowledge about the human brain stems from experiments on rats and mice. However, rodents lack a fully developed prefrontal cortex, the region behind our foreheads responsible for regulating thoughts, emotions, and actions. Research based on rodents might offer only a partial perspective on the human prefrontal cortex.
Akiya Watakabe from the RIKEN Center for Brain Science highlights the remarkable distinction of the human brain, particularly its large and highly specialized prefrontal cortex, a hub for higher brain functions, emotions, and thoughts.
Marmosets, as primates, bridge the gap between rodents and humans, boasting a more advanced prefrontal cortex. Yet, the intricacies of how the prefrontal cortex interacts with other brain areas have been largely unknown.
Watakabe, along with Henrik Skibbe and their team, has identified two types of connections—patchy and diffuse—that link the prefrontal cortex to the cortex and striatum. The patchy connections exhibit compact, column-like structures, while the diffuse connections spread widely across the cortex and striatum.
Watakabe explains, “The patchy one connects two points very strongly with each other, whereas the diffuse one connects to very large regions, but only very loosely. So we expect that the two connections have different functions.”
This discovery was made possible by injecting a viral tracer into over 40 locations and meticulously observing their pathways. It took seven years to gather and analyze this wealth of data.
This marks the first time such a comprehensive, detailed projection map has been created for primates. Watakabe remarks, “Whole-brain analysis at this high resolution hasn’t been done before for primates because it generates too much data.” Skibbe meticulously compiled and processed the data, utilizing deep learning to detect the tracer signal with precision.
The whole-brain map of prefrontal cortex projections in marmosets is now freely accessible on the Brain/MINDS data portal, representing a significant milestone in neuroscience research.