The Human Brain Project is born

It has been ten years since the European Union launched an ambitious and highly funded project to understand the human brain in depth, and in particular to decipher how the brain creates consciousness. According to a 2012 report to the European Commission, the hope is that “We can gain fundamental insights into what it means to be human.”[1]

The idea was based on a proposal put forward by Spaniard Rafael Yuste, professor at Columbia University, and George Church, of Harvard University, at a meeting of neuroscientists and nanoscientists held in England in 2011: to map the activity of the entire human brain at the level of individual neurons and detail how they form circuits.[2] Two years earlier, in a TED talk, Henry Markram presented his vision of mathematically simulating the brain’s 86 billion neurons and 100 trillion synapses on a supercomputer. “We can do it within 10 years,” he promised the audience, suggesting that such a mathematical model might even be capable of creating consciousness.[3]

Markram, backed by his as yet unfinished work of simulating a tiny fragment of mouse brain (a set of about 100,000 neurons) at the Swiss Federal Institute of Technology in Lausanne (EPFL), was chosen to lead the European Union’s star project, which was called HBP, the acronym for the “Human Brain Project”.

Conceived as the flagship of the European Commission’s (EC) Future and Emerging Technologies program, the project involved scientists from more than 100 institutions in 24 countries and more than €1 billion in funding over 10 years from the EC and Member States. HBP was created with a view to producing a computer simulation of the human brain, parallel to other objectives in the field of neuroscience, such as the unified understanding of the brain, from genes to behavior, as well as other medicine- and computer science-related objectives.

Expectations are lowered

HBP was criticized from the start for being too ambitious, considering the number of neurons and connections in the human brain and their variation between people and even within the same individual throughout life. This was already evident at the 2011 meeting, at which Yuste and Church proposed their ambitious idea. In an article published in Scientific American[4] in 2013, Partha Mitra, a professor at Cold Spring Harbor Laboratory, argued that it would not be enough to record all the spikes of all the neurons in the brain, since for the data to make sense, one would have to simultaneously record all external stimuli and all aspects of behavior; this would lead to a “comprehensive” measurement exercise that would extend ad infinitum. In the same article, he reasoned that we should understand the brain at a macroscopic level before attempting to decode the meaning of the activity of individual neurons. Criticism intensified once the project was underway, arguing that it was focusing too much on information and communication technologies and not enough on real brains. An open letter signed by 800 scientists called for a change of scientific approach and a new management structure. The project was redirected to providing new computational research infrastructure to help neuroscientists store, process and analyze large amounts of data and to develop 3D brain atlases and simulation software.[5]

The project ends

Last March, the final summit meeting of the project took place.[6] Although it brought together 700 researchers from 27 countries, it did not celebrate the discovery of how the brain creates consciousness, nor did it propose such a task for the next decade. We lack knowledge of how brain structure, chemical substances, and connectivity interact to produce our thoughts and behaviors. However, if we avoid comparison with the euphoria that pervaded the early steps of the project, we can admit that significant progress has been achieved in partial and different aspects. HBP’s own organization stands out as one of the enduring contributions of the EBRAINS research infrastructure project, which provides open access to advanced technologies, tools, data and services for brain-related research. And in a paper authored by neuroscientists from the University of Cambridge and the Jülich Research Center, the authors positively assess that the fact that the project “has made substantial discoveries and innovation, relevant for tackling clinical disorders, as well as technological advances.”[7]

A research effort that has been global

Parallel to the European HBP proposal, in 2013, President Barack Obama presented the BRAIN initiative (Brain Research through Advancing Innovative Neurotechnologies) as “the next great American project”,[8] with the idea that neuroscience had already acquired a level at which “we can imagine a global understanding of the brain in action, encompassing molecules, cells, circuits, systems and behavior”.[9] The project, which concludes in 2025, was presented with funding of the same order as the European project, although it will eventually reach a much higher figure. Nevertheless, recognizing the limits of what is possible, the project already evolved at its origin into something more pragmatic, focusing on the development of different technologies to analyze the brain.

The impetus given by the EU and the US to research to better understand the human brain led to the incorporation into this current research of countries such as Japan, Australia, Canada, China, South Korea and Israel, and so we can talk of a global research effort.

Difficulties in understanding brain dynamics remain

Despite this great research effort in recent years, we are still far from understanding the fundamental aspects of the brain. Its complexity may be comparable to that of the universe. It acts entirely by electromagnetic phenomena from the level of the atoms upwards. Moreover, it has 86 billion neurons, a figure of the same order as the number of stars in the Milky Way. If we look at the synapses – the connections between neurons – the figures start to become incomprehensible. The number of synapses in the human brain is estimated to be over 100 trillion, each containing different molecules and different molecular switches. By function, each synapse would be equivalent to a set of one thousand transistors. Furthermore, not all neurons are the same; we don’t even know how many different types of neurons we have, and nor are the synapses all the same[10]. Added to this is the massive criss-crossing of its trillions of wires and connections at all scales and physical layers. Given this complexity, it is easy to understand that the goal of modeling the entire brain is, for now, unattainable. The power of our computers is far from being able to do that work. It has been calculated[11] that simulating a whole human brain at cellular resolution would require up to ~4×1029 TFLOPS,[12] while the Frontier supercomputer, the largest computing infrastructure at the moment, has a peak performance of ~1.1×106 TFLOPS.

Understanding the brain, however, necessarily involves answering the question: “How does the brain create consciousness?” And even if the goal of modeling the brain by reproducing the functioning of all its circuits were achieved, the question of understanding the causal links between structure and brain function would remain open, just as copying computer hardware, atom by atom, would tell us little about the complex software running on it.

Consciousness is all that we experience, it is the knowledge we have of ourselves and of what surrounds us, it is the feeling and emotion that is produced through perception and thought. Neuroscience has provided evidence that neurons are fundamental to consciousness; that, somehow, the connectivity of neurons computes the features of our experience.[13] But the problem of consciousness is radically unlike any other scientific problem and the reason for this is that consciousness is unobservable. In view of this, the best that scientists can do is to correlate unobservable experiences with observable processes such as, for example, scanning a person’s brain and relating it to their experience at that time.[14] But that does not lead us to understand the mechanism of how a physical system such as the brain has experiences.

There is not a single accepted theory about how the brain works and this leads to a huge drift in the way research should be conducted. And, although it is not a new idea, a growing number of neuroscientists and physicists think that quantum theory could explain the relationship between the mind and the brain. These theories consider the mind connected to the brain, but maintaining a separation between the two. Quantum physical laws seem to agree with certain characteristics of the mind-brain relationship. Thus, for example, the principles of quantum physics allow energy to be extracted from the quantum vacuum on condition that it can be recovered at the same time, and this would allow us to respond to the fact that a mental phenomenon, which has no source of energy, gives rise to a phenomenon that depends on energy. The principle according to which elementary particles are both waves and particles also allows us to regard the mental workspace to be non-material, but in relation to the brain, entertains a non-dual wave-particle relationship according to quantum physical principles. Danko Georgiev alludes to the plethora of models based on the nanoscale organization of the neurons in which mental states can affect the brain through quantum effects.[15] Additionally, a team of researchers has observed possible entanglement in the brain, which could indicate that some of our brain activity, and perhaps even consciousness, operates on a quantum level.[16] If these assumptions are correct, we have to add the difficulty in understanding the corresponding quantum phenomena to the difficulty posed by the physical complexity of the brain.

We still don’t know how to reach the goal

We continue to consider the human brain as the most complex object we know and the one that raises the most questions in the fields of both science and philosophy.

What we can do to understand the brain and how its functioning relates to the mind, is to focus on small issues, albeit using increasingly detailed data, hoping that perhaps it will be possible to successfully address the broader question of the mind-brain mechanisms if the cumulative results of these neuroscientific studies are combined with the complementary approaches of physics and philosophy. At present, however, these small steps are not leading to an understanding of the basics. More than 2500 new articles have been written in the field of the HBP alone,[17] and it must be assumed that each of them has contributed a certain increase in knowledge, which allows us to climb a new step on the ladder of understanding the brain. But after having climbed these thousands of steps, not only have we not reached the top of the ladder, but we haven’t even glimpsed how far our global understanding of the brain in action could go.

We find ourselves in the same situation as described in British newspaper The Economist before the development of the major projects discussed herein. In 2006, in an article entitled “I think, therefore I am, I think”, subtitled “Consciousness awaits its Einstein”, it analyzed how to discover the emergence of consciousness: “The truth, unsatisfactory though it is, is that no one really knows. Nor does anyone know where the next breakthrough will come from.” And it ventured: “[…] perhaps a bored, unregarded clerk will come to the rescue with an insight that dominates 21st-century thinking in the way that relativity dominated the 20th.” “After all, it was by sitting and thinking about some paradoxical results in physics that Albert Einstein was able to break out of the mental mould of classical physics and invent the non-commonsensical but scientifically successful theory of relativity.[18]

Manuel Ribes

Bioethics Observatory – Institute of Life Sciences

Catholic University of Valencia


[1] The Human Brain Project, April 2012

[2] Emily Mullin, How big science failed to unlock the mysteries of the human brain – MIT Technology Review, 25 August 2021

[3] Stefan Theil, Why the Human Brain Project Went Wrong – and How to Fix ItScientific American, 1 October 2015

[4] Partha Mitra, What’s Wrong with the Brain Activity Map ProposalScientific American, 5 March 2013

[5] Emily Mullin, How big science failed to unlock the mysteries of the human brain MIT Technology Review, 25 August 2021

[6] Final Human Brain Project Summit closes with a vision for the future of digital brain research Human Brain Project 31 March 2023

[7] Barbara J Sahakian, Christelle Langley, Katrin Amunts The Human Brain Project: six achievements of Europe’s largest neuroscience programThe Conversation, 11 October 2021

[8] Barack Obama, Remarks by the President on the BRAIN Initiative and American Innovation – Office of the White House Press Secretary, 2 April 2013

[9] BRAIN 2025: A Scientific Vision – National Institutes of Health, 5 June, 2014

[10] Rachel Tompa, Why is the human brain so difficult to understand? We asked 4 neuroscientists – Allen Institute, 21 April 2022

[11] Egidio D’Angelo – Viktor Jirsa, The quest for multiscale brain modelingTrends in Neuroscience, 26 July 2022 DOI: 10.1016/j.tins.2022.06.007

[12] TFLOPS, short for TeraFLOPS, is a direct mathematical measure of a computer’s performance

[13] Kitchener PD and Hales CG (2022), What Neuroscientists Think, and Don’t Think, About Consciousness. Front.Hum.Neurosci.16:767612. doi: 10.3389/fnhum.2022.767612

[14] Philip Goff, Science as we know it can’t explain consciousness – but a revolution is coming – The Conversation, 1 November 2019

[15] Danko Georgiev, A linkage of mind and brain: Sir John Eccles and modern dualistic interactionism  Biomedical Reviews 2011; 22: 81- 84

[16] Elizabeth Fernandez, Brain experiment suggests that consciousness relies on quantum entanglement Big Think November 22, 2022

[17] Roberto Inchingolo et al., HUMAN BRAIN PROJECT A closer look at scientific advances, March 2023

[18]  I think, therefore I am, I thinkThe Economist, 23 December 2006


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