In Search of the Mind in the Brain

For a long time, the world's thinkers believed that mind and matter were two different things. René Descartes convincingly formulated this dualism as a separation between res extensa (the body) and res cogitans (the mind). This separation enabled early scientists to pursue their work undisturbed by the sensitivities of the church. Today, however, few researchers still assume that consciousness exists independently of a biological basis. The causal chain is reasonably conclusive: if certain areas of the brain fail, the person falls into a coma and is no longer conscious. Even in deep sleep – when large parts of the brain reduce their activity – consciousness does not occur.

However, knowing this does not help. Nor does it diminish the wonder of humanity: we still do not know how the brain manages to bring something as complex as us into being. Unanswered questions and pure fascination are leading some brain researchers today to tread philosophical paths. For the first time in human history, they – and their colleagues in the related sciences of psychology and philosophy – are now able to pursue the question of consciousness in a well-founded and empirical manner.

John C. Eccles ▸ John Eccles: Across the Gap, physician and philosopher, became Sir Eccles because (together with Alan Hodgkin and Andrew Huxley) he was awarded the Nobel Prize in 1963 for his work on the transmission of nerve impulses at the Synapse. Together with the philosopher Karl Popper – to whom scientific theory owes the principle of falsification – he was one of the last brain researchers to take a dualistic position. This fit well with Popper's dualism, the separation of the material world (“World 1”) from the spiritual (“World 2”). In their joint book The Self and Its Brain (1977), both presented the thesis that there is a region in the left Hemisphere of the brain that allows interaction between World 1 and World 2. Later in life, Eccles sought arguments in quantum mechanical processes – a trap that catches many thinkers as soon as they want to put the inexplicable on explainable footing.

Incidentally, one of the last great dualists today is the philosopher David Chalmers, an Australian like Eccles, who sees an easy and a hard problem when it comes to consciousness. The easy problem includes thinking, learning, and remembering – these are partially understood physiologically. The brain processes that occur, for example, when perceiving a red rose or when experiencing pain are also understood. But what the color red triggers subjectively in us, and how it feels to be in pain – we cannot yet explain that. This hard problem is taken very seriously by researchers who approach consciousness from a neuroscientific perspective.

Perhaps just as hard is a problem that can be illustrated by imagining that you are looking at the rose in question. There it stands before you, in all its red splendor, thorny and fragrant. As you look at it, your Visual system detects a wide variety of lines, which are further processed to form the shapes of the individual petals, and a little further back on the visual pathway, the visual impression of a rose is formed. Combined with the olfactory impression, this results in a complete picture, to which your Memory adds the name and the person to whom you want to give it as a marriage proposal. The question, however, is: How do all these individual processing stages ultimately come together again? How can what the sensory system breaks down be reassembled by perception? Anyone who has ever seen a diagram showing the connections between different areas of the brain – many labeled dots and a jumble of lines reminiscent of a ball of wool – can appreciate the problem.

In 1989, Wolf Singer – then director of the Max Planck Institute for Brain Research in Frankfurt – and his colleagues presented evidence that this connection between a wide variety of stimuli can be achieved through the synchronous discharge of nerve cells in the 40-hertz range. According to this model, shape, color, and scent come together to form the concept of a rose when all the neurons involved have coordinated their Oscillation behavior. This answers the question of how Perception can arise. But it does not answer the question of how it becomes conscious.

Now, with Gerald Edelman and Francis Crick, two Nobel Prize winners are entering the stage of consciousness research. The former has done groundbreaking work on the immune system, while the latter, together with John Watson, discovered the double helix structure of DNA. Neither of them were experts in neuroscience. And both entered into research collaborations with up-and-coming young scientists.

Edelman teamed up with Italian psychiatrist Giulio Tononi and developed an impressive systemic theory. Roughly simplified, it goes like this: Consider a group of neurons with a defined function as a functional cluster – for example, one for odor Perception. As other clusters for color and shape switch on and small clusters form larger clusters, an integrated process develops that can be scaled up arbitrarily in complexity toward consciousness. There, the perception of a rose arises – and becomes conscious.

Two other factors are important: First, there is a kind of Darwinian selection between the individual clusters. If we no longer look at the red rose, but at the yellow carnation, the “red” cluster no longer has a chance and falls out of perception. The second factor solves the problem that neurons tick on a faster timeline than our consciousness. In order to remain active and permanently integrate the activity of widely separated brain areas, the information must be fed back into the system again and again – a “reentry” that allows neural activity to be synchronized in the first place.

If we take a step back and look at the various clusters and their interactions, we see that, according to Edelman and Tononi, consciousness is a dynamic system. Numerous other researchers share this view. Incidentally, this is why it makes no sense to accuse Wolf Singer of simple determinism, i.e., the simple predictability of behavior. The neural determinism that Singer advocates refers to precisely such highly dynamic systems and is therefore chaotic: if we knew all the initial conditions of the system, we could actually predict its future. But there are far too many influences.

In contrast to their almost mathematical colleagues Edelman and Tononi, Francis Crick and Christof Koch took a very practical approach to the search for the so-called neural correlates of consciousness (NCC). Applied to the rose, this means that when we look at it, certain neurons in our brain are active and enable us to become aware of the rose. To quote Koch: “There must be an explicit correspondence between a mental event and its neural correlates.”

Crick suspected that the actual seat of consciousness was the claustrum, a flat sheet of neurons between the Basal ganglia and the Cortex. Its neurons have some special features, and its connections are so complex that Crick and Koch believed it played the role of a conductor in the brain. But that was some time ago, and it's probably not that simple.

Giulio Tononi, in particular, takes a completely different and very theoretical approach: calculating the degree of consciousness in every conceivable entity. Tononi explains the concept here in the ▸ video about Phi – it's actually not that simple, but it fascinates the field of consciousness researchers.

Returning to the brain, consciousness also needs a workplace. Dutch cognitive scientist Bernhard Baars has been pursuing this idea since 1986, calling it the global workspace. ▸ What is consciousness? It is where we find what is currently active in the mind and subjectively experienced. In the case of the rose in our hand, this might include a warning about thorns and the hope of finding a vase, but in any case, it includes whatever is needed to do justice to the interpersonal situation at hand.

There are clear parallels here with working memory – the seven plus/minus two pieces of information that we can hold in our heads at any one time. But there are differences: although the content of working Memory is influenced by unconscious factors, we are always aware of it. So aware, in fact, that some researchers even equate working memory with consciousness. Baars' global workspace, on the other hand, also has room for unconscious information, thus circumventing the problem that consciousness itself only deals with a fraction of the available data.

Stanislas Dehaene – well known for his work on writing and reading –, Jean-Pierre Changeux, and colleagues have studied the global workspace in a neural context for many years and developed a three-stage computer model in 2006: Level 1 maps the activity of individual neurons, Level 2 maps various connections between the thalamus and Cortex. The thalamus is considered the gateway to consciousness because it transmits information to the cortex, and only there can this information become conscious. Level 3 represents a network of distant structures that exchange information in a constant process of feedback and feedforward. In this way, the Dehaene-Changeux model attempts to reproduce higher cognitive functions and, indeed, consciousness. In practical trials, it has proven to be trainable – and even helpful, for example, in the study of inattentional blindness.

But such successes are rare. Consciousness research using neuroscientific methods is therefore a popular target for neuro-bashing, which is always in vogue from time to time. Brain research is too limited in its search for consciousness, not only in its methods but also – at least according to some critics – in its conceptual approaches. The argument is compelling, because so far, neuroscientists have not really made much progress in their search for consciousness in the brain. However, it overlooks the time factor – and is somewhat reminiscent of a statement made by a former director of the New York Patent Office in 1899: “Everything that can be invented has already been invented.” As we know, this statement was impressively refuted.

It can therefore be assumed that brain researchers will still discover a great deal. When it comes to consciousness, however, it may take a little longer.

Further reading

• Edelman, Gerald M. and Tononi, Giulio: A Universe Of Consciousness: How Matter Becomes Imagination. 2000.
• Koch, Christof: The Quest for Consciousness: A Neurobiological Approach. 2004.
• Libet, Benjamin: Mind Time: The Temporal Factor in Consciousness. Frankfurt 2005.

First published on August 29, 2013
Last updated on December 16, 2025