The human brain is quite complicated, although it appears to look simple. Its structure and functions are so intricate and interesting that it can even convince a person who hates biology, like me, to fall in love with it. Believe it or not, but as you read this, a large number of electrical signals are firing up inside your brain to help you do so. The irony is that the brain is so important, that even for you to feel bored studying about the brain, it has to function properly to make that possible. Isn’t this compelling yet scary at the same time?
Let’s look into some of the more complicated aspects of this brain. We all know that the brain is the commander of our central nervous system, which controls the actions of the various parts of our body. It is made up of around ninety billion neurons, one hundred and fifty trillion synapses, and has three major parts: the cerebrum, cerebellum, and brainstem. Here is an image of the human brain that we all might have seen in our biology textbooks.
But this twentieth-century image of the brain was not enough for scientists to truly understand how it works. They were not able to answer the questions like, “Why does one person like blue and the other like pink?” with the information they had at the time. Doctors also needed more data about the working of the brain, to treat neurological and psychiatric diseases. This led them to try examining the brain on a deeper level- that of neurons. As they went deeper, they discovered that these neurons were similar to wires in a circuit, connecting the various parts of the brain and that these connections were unique to each person. They realized that by mapping these connections, they could find answers to most of their questions. They then began mapping these neural connections and called them mappings connectomes. Eventually, the study of these connectomes developed into a branch of neuroscience known as “Connectomics”.
But it isn’t easy to map out all the connections of an active human brain. This is why in 2010, the National Institute of Health (NIH) started a project called The Human Connectome Project (HCP) to develop better neuroimaging methods and map these connections on both a macro and micro level. Macro-level connectomes concentrate on mapping the neural connections between two parts of the brain while performing a function i.e. it maps the functional connectivity of the brain. Micro-level connectomes concentrate on mapping every neuron or dendrite in a particular region i.e. it maps the structural connectivity of the brain. The image below explains these terms more explicitly.
The NIH announced that the project would be split between two consortia. The first consortium consisted of Washington University, Oxford University, and the University Of Minnesota, which work with the mapping of connectomes at a macro level. For the first two years, they were developing the non- invasive neuroimaging techniques such as functional MRI (fMRI), Magnetoencephalography (MEG), Electroencephalography (EEG), and others. Using these advanced imaging techniques, this consortium managed to succeed substantially in mapping functional connectivity. Here is a recorded fMRI image of the brain activity of one of the consortium's subjects for one second. The red and yellow areas represent the active regions and the green areas represent the dormant regions at that particular moment.
Before going to the next consortium, I would like to reiterate that these functional connections are like the wires that connect the various parts of the brain and these connections are made up of several neurons, whose mapping comes under the micro connectome that the second consortium of Harvard-UCLA works with. Various techniques like diffusion MRI and Brainbow are being employed to map each neuron in the brain. Here are the images of all the neurons present in a very small piece of the brain using the Brainbow method. Here, each colour represents a neuron:
The project is still ongoing but it seems like there’s a long road ahead before they can achieve the ultimate goal of this ambitious project. This is because it takes a lot of resources like money, labour, and advanced technology to make it possible. It actually took a hundred days for the scientists to even produce a single image on an infinitesimally small piece of a brain, with all of the neurons present in it. At the current rate, it will surely take more than a lifetime before we can produce a complete picture of a whole brain, with every single one of its neurons. But in the future, it could even be one of us who finds an easier way to map these connectomes. Once we make the breakthrough, we will be able to open the gateway to a whole new world within all of us, and it undoubtedly has the potential to change our perception about the world around us.