A new 3-D map illuminates the ‘little brain’ within the heart
Nerve cells in the organ are poorly understood
Nerve cells (yellow) that make up a heart’s “brain” cluster around the top of this reconstructed rat heart, near where blood vessels enter and exit the organ. Other colors show the contours of distinct heart areas, such as the left atrium (green), right atrium (teal), left ventricle (blue) and right ventricle (purple).
The heart has its own “brain.” Now, scientists have drawn a detailed map of this little brain, called the intracardiac nervous system, in rat hearts.
The heart’s big boss is the brain, but nerve cells in the heart have a say, too. These neurons are thought to play a crucial role in heart health, helping to fine-tune heart rhythms and perhaps protecting people against certain kinds of heart disease.
But so far, this local control system hasn’t been mapped in great detail.
To make their map, systems biologist James Schwaber at Thomas Jefferson University in Philadelphia and colleagues imaged male and female rat hearts with a method called knife-edge scanning microscopy, creating detailed pictures of heart anatomy. Those images could then be built into a 3-D model of the heart. The scientists also plucked out individual neurons and measured the amount of gene activity within each cell.
These measurements helped sort the heart’s neurons into discrete groups. Most of these neuron clusters dot the top of the heart, where blood vessels come in and out. Some of these clusters spread down the back of the heart, and were particularly abundant on the left side. With this new view of the individual clusters, scientists can begin to study whether these groups have distinct jobs.
The comprehensive, 3-D map of the heart’s little brain could ultimately lead to targeted therapies that could treat or prevent heart diseases, the authors write online May 26 in iScience.
Using mathematics in a novel way in neuroscience, the Blue Brain Project shows that the brain operates on many dimensions, not just the three dimensions that we are accustomed to.
For most people, it is a stretch of the imagination to understand the world in four dimensions but a new study has discovered structures in the brain with up to eleven dimensions – ground-breaking work that is beginning to reveal the brain’s deepest architectural secrets.
Using algebraic topology in a way that it has never been used before in neuroscience, a team from the Blue Brain Project has uncovered a universe of multi-dimensional geometrical structures and spaces within the networks of the brain.
The research, published today in Frontiers in Computational Neuroscience, shows that these structures arise when a group of neurons forms a clique: each neuron connects to every other neuron in the group in a very specific way that generates a precise geometric object. The more neurons there are in a clique, the higher the dimension of the geometric object.
Topology in neuroscience: The image attempts to illustrate something that can not be imaged – a universe of multi-dimensional structures and spaces. On the left is a digital copy of a part of the neocortex, the most evolved part of the brain. On the right are shapes of different sizes and geometries in an attempt to represent structures ranging from 1D to 7D and beyond. The “black-hole” in the middle is used to symbolise a complex x of multi-dimensional spaces, or cavities. Courtesy of the Blue Brain Project
“We found a world that we had never imagined,” says neuroscientist Henry Markram, director of Blue Brain Project and professor at the EPFL in Lausanne, Switzerland, and co-founder and Editor-in-Chief of Frontiers, “there are tens of millions of these objects even in a small speck of the brain, up through seven dimensions. In some networks, we even found structures with up to eleven dimensions.”
Markram suggests this may explain why it has been so hard to understand the brain. “The mathematics usually applied to study networks cannot detect the high-dimensional structures and spaces that we now see clearly.”
If 4D worlds stretch our imagination, worlds with 5, 6 or more dimensions are too complex for most of us to comprehend. This is where algebraic topology comes in: a branch of mathematics that can describe systems with any number of dimensions. The mathematicians who brought algebraic topology to the study of brain networks in the Blue Brain Project were Kathryn Hess from EPFL and Ran Levi from Aberdeen University.
“Algebraic topology is like a telescope and microscope at the same time. It can zoom into networks to find hidden structures – the trees in the forest – and see the empty spaces – the clearings – all at the same time,” explains Hess.
In 2015, Blue Brain published the first digital copy of a piece of the neocortex — the most evolved part of the brain and the seat of our sensations, actions, and consciousness. In this latest research, using algebraic topology, multiple tests were performed on the virtual brain tissue to show that the multi-dimensional brain structures discovered could never be produced by chance. Experiments were then performed on real brain tissue in the Blue Brain’s wet lab in Lausanne confirming that the earlier discoveries in the virtual tissue are biologically relevant and also suggesting that the brain constantly rewires during development to build a network with as many high-dimensional structures as possible.
When the researchers presented the virtual brain tissue with a stimulus, cliques of progressively higher dimensions assembled momentarily to enclose high-dimensional holes, that the researchers refer to as cavities. “The appearance of high-dimensional cavities when the brain is processing information means that the neurons in the network react to stimuli in an extremely organized manner,” says Levi. “It is as if the brain reacts to a stimulus by building then razing a tower of multi-dimensional blocks, starting with rods (1D), then planks (2D), then cubes (3D), and then more complex geometries with 4D, 5D, etc. The progression of activity through the brain resembles a multi-dimensional sandcastle that materializes out of the sand and then disintegrates.”
The big question these researchers are asking now is whether the intricacy of tasks we can perform depends on the complexity of the multi-dimensional “sandcastles” the brain can build. Neuroscience has also been struggling to find where the brain stores its memories. “They may be ‘hiding’ in high-dimensional cavities,” Markram speculates.
Citation: Reimann MW, Nolte M, Scolamiero M, Turner K, Perin R, Chindemi G, Dłotko P, Levi R, Hess K and Markram H (2017) Cliques of Neurons Bound into Cavities Provide a Missing Link between Structure and Function. Front. Comput. Neurosci. 11:48. doi: 10.3389/fncom.2017.00048
This research was funded by: ETH Domain for the Blue Brain Project (BBP) and the Laboratory of Neural Microcircuitry (LNMC); The Blue Brain Project’s IBM BlueGene/Q system, BlueBrain IV, funded by ETH Board and hosted at the Swiss National Supercomputing Center (CSCS); NCCR Synapsy grant of the Swiss National Science Foundation; GUDHI project, supported by an Advanced Investigator Grant of the European Research Council and hosted by INRIA.
You may recall that yesterday I blogged about an allegedly successful experiment in the “freezing”, or at least, “extreme cooling” of a human being, and his or her successful “reanimation.” The key to the allegedly successful experiment was, you might also recall, the removal of the patient’s blood and its replacement by an “ice-cold saline solution.” And I speculated that the whole procedure, since it was performed with the consent of the government, might have had as a hidden goal to discover what happened to that individual’s consciousness while undergoing the “procedure.” We may now also wonder if, indeed, the removal of the individual’s blood was part of my hypothesized “consciousness experiment”; was the individual’s own blood even restored to him or her? Or was it someone else’s?
We don’t know, because there was scanty information provided about the whole alleged success; we were told only that its performer, Dr. Samuel Tisherman, promises to deliver a paper on the whole thing in 2020.
But in that respect, there’s another odd story that was spotted by M.C., who is due a big thank you for sending it along:
Now, this is not exactly new; I have in fact blogged about the unusual nature of this “heart-brain” idea before; neurons are not confined merely to the brain, but appear in the heart as well. There was, however, something that caught my eye in this article, and I rather suspect it’s what caught M.C.’s eye as well and compelled M.C. to send the article along; you’ll note that the article enumerates various cases of individuals who have received heart transplants, and whose behavior suddenly changes to embrace habits and behaviors associated with the donor of the heart. While the article does not mention them, similar experiences have been recorded for other types of organ transplants. One wonders if a similar phenomenon can be associated with blood transplants.
But in any case, what caught my attention in this article was this statement:
Neurologist Dr. Andrew Armour from Montreal in Canada discovered a sophisticated collection of neurons in the heart organised into a small but complex nervous system. The heart’s nervous system contains around 40,000 neurons called sensory neurites that communicate with the brain. Dr. Armour called it “the Little Brain in the Heart”. It has been known for many years that memory is a distributive process. You can’t localize memory to a neuron or a group of neurons in the brain. The memory itself is distributed throughout the neural system. So why do we draw a line at the brain? (Emphasis added)
This idea of distributed memory sounds a bit like a hologram, and the article quickly proceeds to try to avoid the unpleasant aspects of that by quickly trying to tie it all to good-old-fashioned-and-purely-materialistic speculations:
Other medical experts offer different explanations, but all agree that it is not so much mystical as it is science, and a science that needs further exploration.Professor Pr Paul Pearsall and Pr Gary Schwarz got together.
Professor Gary Schwartz says that “Feedback mechanisms are involved in learning. When we talk, for example, about how the brain learns, we talk about what we call neural networks in the brain. It turns out that the way a neural network works is that the output of the neurons feeds back into the input of the neurons. And this process goes over and over again. So long as the feedback is present the neurons will learn. If you cut the feedback, there is no learning in the neurons.”
The Mind is Not Just in the Brain
Dr. Candace Pert, a pharmacologist at Georgetown University believes that the mind is not just in the brain, but also exists throughout the body. This school of thought could explain such strange transplant experiences. “The mind and body communicate with each other through chemicals known as peptides. These peptides are found in the brain as well as in the stomach, in muscles and in all of our major organs. I believe that memory can be accessed anywhere in the peptide/receptor network. For instance, a memory associated with food may be linked to the pancreas or liver and such associations can be transplanted from one person to another”.
Now I’m all for feedback loops as I’ve talked about them in all sorts of contexts. And for that matter, the idea of the heart being part of a kind of “distributed brain” also appeals to me; for one thing, octopuses appear to have this type of structure to their nine brains. But more importantly, I’ve always been an advocate of the more ancient idea that human reason is not mere ratiocination, but incorporates and includes what the ancients would have called the passions, a deeper word than “emotions.” So it appeals to me for this reason as well.
But it’s that “distributed memory” idea and its “holographic” overtones that really appeals, for lurking deeply within that idea is the idea that memory is not local, existing or concentrated in this or that area of the brain, or the body. It rather as if what is implied by that idea is the opposite: that the body exists within a memory, and is imprinted with it like a psychotronic object. If it’s distributed, and non-local, then perhaps it’s also an indicator that the body, in order to be a body, is integrated at the quantum level, by quantum tunneling, perhaps, and that memory may be a function of this somehow. Whatever one makes of my speculations here, I strongly suspect that this idea of distributed memory means that those old Cartesian dualisms and epiphenomena are, like all over-simplified dualisms, going to go the way of the dodo bird, and that the relationship between the tangible physical body and the immaterial intangible world of things like memory are going to turn out to be far more complex than we imagined, and that those “feedback loops” between the two are the key.
The multi-dimensional universe hiding inside your head
A model from the Blue Brain Project describes the brain as being made up of ‘multi-dimensional’ geometrical structures and spaces
stockdevil / iStock
A fabric of complex structures in our brain could be the key to understanding how the organ works, according to a new study. It could even provide an answer to mysteries like where our memories are stored.
The human brain is one of the most complex structures in nature, and we are still a long way from fully understanding how it works. Now, a group of researchers from the Blue Brain Project is bringing us closer to this goal using complex computer models.
Its latest model describes the brain as being made up of ‘multi-dimensional’ geometrical structures and spaces.
“We found a world that we had never imagined,” said neuroscientist Henry Markram, director of Blue Brain Project and professor at the EPFL in Lausanne, Switzerland.
“There are tens of millions of these objects even in a small speck of the brain, up through seven dimensions. In some networks, we even found structures with up to eleven dimensions.”
The structures form when a group of neurons – cells that transmit signals in the brain – forms something called a clique. Each neuron connects to every other neuron in the group in a specific way, to form a new object.
The more neurons there are in a clique, the higher the ‘dimension’ of the object.
It is important to understand these structures do not exist in more than three dimensions in space. Only the mathematics used to describe them uses more than three dimensions.
“Outside of physics, high-dimensional spaces are frequently used to describe complex data structures or conditions of systems, for instance, the state of a dynamical system in state space,” professor Cees van Leeuwen, from KU Leuven, Belgium and reviewer of the paper, told WIRED.
“The space is simply the union of all the degrees of freedom the system has, and its state describes the values these degrees of freedom are actually assuming.”
“When you take a complex network like the brain, you try to associate some familiar objects with it so that you can try to understand what it does,” Ran Levi from Aberdeen University, who worked on the paper, told WIRED. “Without it, all you see is a mess of ‘trees’ i.e. neurons firing at what appears to be random patterns.
“What we did is we took the complex structure of the brain network and mapped it to this universe. thus picking up very precisely defined high dimensional objects that give us a key to understanding structure and function.”
The team used a mathematical branch called algebraic topology to model these structures within a virtual brain, generated using a computer. Experiments were then carried out on real brain tissue, to test the results.
When the researchers added a stimulus into the virtual brain tissue, cliques of progressively higher dimensions assembled. In between these cliques were holes, or cavities.
“The appearance of high-dimensional cavities when the brain is processing information means that the neurons in the network react to stimuli in an extremely organised manner,” said Levi.
“It is as if the brain reacts to a stimulus by building then razing a tower of multi-dimensional blocks, starting with rods (1D), then planks (2D), then cubes (3D), and then more complex geometries with 4D, 5D, etc. The progression of activity through the brain resembles a multi-dimensional sandcastle that materialises out of the sand and then disintegrates.”
The next step will be to see what practical role these structures play in the brain. For example, neuroscience has also been struggling to find where the brain stores its memories, and the holes could be a solution.
“They may be ‘hiding’ in high-dimensional cavities,” Markram speculates.
The research is published in Frontiers in Computational Neuroscience.
