An extremely detailed circuitry diagram of the human brain exposes the wide variety of various connections. Credit: Human Connectome Project
Australian scientists have created the most in-depth map ever of the communication links in between the hippocampus, the brains memory control center, and the rest of the brain, potentially transforming our understanding of human memory.
” We were amazed to find fewer connections in between the hippocampus and frontal cortical locations, and more connections with early visual processing areas than we anticipated to see,” said Dr. Marshall Dalton, a Research Fellow in the School of Psychology at the University of Sydney. “Although, this makes good sense thinking about the hippocampus plays an essential function not only in memory however likewise creativity and our capability to build psychological images in our minds eye.”
Located within the brain, the hippocampus is a complex structure that looks like a seahorse. It is necessary for the brain and plays an important role in memory development along with the transfer of memories from short-term to long-term storage. In addition to these functions, the hippocampus likewise plays a function in navigation, the ability to picture fictitious or future experiences, the production of psychological imagery, and even in visual understanding and decision-making.
Located within the brain, the hippocampus is a complex structure that looks like a seahorse. Technical restrictions intrinsic to previous MRI investigations of the human hippocampus meant it was just possible to picture its connections in really broad terms. And that hasnt been done before in a living human brain,” stated Dr. Dalton.
They may, for example, aid describe why some of our primate cousins– specifically chimpanzees– are better at some memory jobs than people, particularly those relying on short-term memory. Chimpanzees have bested human beings at cognitive jobs involving a kind of mathematics understood as video game theory, which relies on short-term memory, pattern recognition, and fast visual evaluation.
Graphic showing the mapping process of the hippocampus carried out by the University of Sydney group. Credit: Marshall Dalton/ University of Sydney
To produce their map, the team– led by Dr. Dalton and consisting of Dr. Arkiev DSouza, Dr. Jinglei Lv, and Professor Fernando Calamante from the University of Sydneys Brain and Mind Centre– counted on MRI scans from a neuroimaging database created for the Human Connectome Project (HCP), a research consortium led by the U.S. National Institutes of Health.
They processed the existing HCP information using tailored methods that they established. This permitted them to follow the connections from all corners of the brain to their termination points in the hippocampus– something that had actually never ever been achieved before in the human brain.
Most in-depth map to date
” What weve done is take a much more in-depth look at the white matter pathways, which are basically the highways of communication between different areas of the brain,” said Dr Dalton. “And we developed a brand-new method that permitted us to map how the hippocampus gets in touch with the cortical mantle, the external layer of the brain, however in a very in-depth way.
” What weve created is a highly detailed map of white matter pathways linking the hippocampus with the remainder of the brain. Its basically a roadmap of brain regions that directly link with the hippocampus and support its essential function in memory development.”
High-resolution image of the electrical wiring diagram of a human brain revealing connections to the hippocampus. Credit: Marshall Dalton/ University of Sydney
Technical restrictions inherent to previous MRI investigations of the human hippocampus meant it was only possible to picture its connections in really broad terms. “But we have now developed a tailored technique that allows us to verify where within the hippocampus various cortical areas are linking. And that hasnt been done before in a living human brain,” said Dr. Dalton.
Unanticipated results
The group was thrilled their outcomes mostly lined up with information from previous research studies overseas over the past couple of decades, which had actually depended on post-mortem studies of primate brains. However, the University of Sydney team found that the number of connections in between the hippocampus and some brain areas was either much lower (when it comes to frontal cortical areas) or greater (when it comes to visual processing areas) than anticipated.
This might suggest that although some paths were saved as human beings evolved, human brains may also have developed special patterns of connectivity various from other primates. Additional research is required to tease this apart in more information.
A mass of white matter tracts in the human brain. Credit: USC Stevens Neuroimaging and Informatics Institute
These differences in connection may simply be a constraint of the MRI method– or it could be real. They may, for instance, help explain why a few of our primate cousins– specifically chimpanzees– are much better at some memory jobs than humans, especially those relying on short-term memory. Chimpanzees have actually bested humans at cognitive jobs involving a kind of mathematics called video game theory, which depends on short-term memory, pattern recognition, and fast visual evaluation.
” Although we have actually accomplished this high-resolution mapping of the human hippocampus, the tract-tracing technique conducted on non-human primates– which can see down to the cellular level– has the ability to see more connections than can be recognized with an MRI,” mused Dr. Dalton.
” Or it might be that the human hippocampus really does have a smaller number of connections with frontal locations than we expect, and higher connectivity with visual areas of the brain. As the neocortex broadened, maybe human beings progressed different patterns of connection to assist in human-specific memory and visualization functions which, in turn, may underpin human creativity.
” Its a bit of a puzzle– we just do not understand. We enjoy puzzles and will keep investigating.”
Reference: “New insights into physiological connection along the anterior– posterior axis of the human hippocampus utilizing in vivo quantitative fibre tracking” by Marshall A. Dalton, Arkiev DSouza, Jinglei Lv, Fernando Calamante, 8 November 2022, eLife.DOI: 10.7554/ eLife.76143.
The study was moneyed by the National Health and Medical Research Council and the Australian Research Council..