This is our most detailed map of the brain’s memory centre
<p dir="ltr">Australian researchers have created the most detailed map we have of the hippocampus - the brain’s memory control centre - which could change the way we think about memory.</p>
<p dir="ltr">The hippocampus, a complex structure that looks like a seahorse, is located deep within the brain. It plays a vital role in forming memories and transferring memories from short-term to long-term storage, as well as in navigation, creating mental images, visual perception, decision making, and imagining fictitious or future experiences.</p>
<p dir="ltr">The team of scientists from the University of Sydney created the map using MRI scans from a database created for the Human Connectome Project, and used techniques they developed to follow connections from all different parts of the brain to the hippocampus.</p>
<p dir="ltr">“What we’ve done is take a much more detailed look at the white matter pathways, which are essentially the highways of communication between different areas of the brain,” said Dr Marshall Dalton, a Research Fellow in the School of Psychology.</p>
<p dir="ltr">“And we developed a new approach that allowed us to map how the hippocampus connects with the cortical mantle, the outer layer of the brain, but in a very detailed way.</p>
<p dir="ltr">“What we’ve created is a highly detailed map of white matter pathways connecting the hippocampus with the rest of the brain. It’s essentially a roadmap of brain regions that directly connect with the hippocampus and support its important role in memory formation.”</p>
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<p dir="ltr">Mapping the brain in this way has never been done before, due to technical limitations that only allowed connections between the hippocampus and other parts of the brain to be visualised in broad terms.</p>
<p dir="ltr"><img src="https://oversixtydev.blob.core.windows.net/media/2022/11/brain-diagram.jpg" alt="" width="1280" height="720" /></p>
<p dir="ltr"><em>The seahorse-shaped hippocampus is located deep within the brain, and now scientists have created a detailed map of the connections between it and the frontal cortex and amygdala. Image: Wikimedia</em></p>
<p dir="ltr">This scientific first has also come with some surprising discoveries that could change our understanding of human memory.</p>
<p dir="ltr">While they found that their results mostly aligned with previous studies on primate brains, the team found that the number of connections between the hippocampus and some brain areas differed from what they expected.</p>
<p dir="ltr">“We were surprised to find fewer connections between the hippocampus and frontal cortical areas, and more connections with early visual processing areas than we expected to see,” Dr Marshall said.</p>
<p dir="ltr">“Although, this makes sense considering the hippocampus plays an important role not only in memory but also imagination and our ability to construct mental images in our mind’s eye.”</p>
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<p dir="ltr">Although the differences in the number of connections could be a result of limitations of MRIs, they could also explain some of the differences between humans and our primate cousins, particularly when it comes to short-term memory.</p>
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<p dir="ltr">For example, chimpanzees have beaten humans at cognitive tasks that use game theory, a form of mathematics that relies on short-term memory, pattern recognition and rapid visual assessment.</p>
<p dir="ltr">“Although we have achieved this high-resolution mapping of the human hippocampus, the tract tracing method conducted on non-human primates – which can see down to the cellular level – is able to see more connections than can be discerned with an MRI,” mused Dr Dalton.</p>
<p dir="ltr">“Or it could be that the human hippocampus really does have a smaller number of connections with frontal areas than we expect, and greater connectivity with visual areas of the brain. As the neocortex expanded, perhaps humans evolved different patterns of connectivity to facilitate human-specific memory and visualisation functions which, in turn, may underpin human creativity.</p>
<p dir="ltr">“It’s a bit of a puzzle – we just don’t know. But we love puzzles and will keep investigating.”</p>
<p dir="ltr">The team published their findings in the journal <em><a href="https://doi.org/10.7554/eLife.76143" target="_blank" rel="noopener">Neuroscience</a></em>.</p>
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<p dir="ltr"><em>Image: Human Connectome Project</em></p>
