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May 9, 2002 The human brain is still the most mysterious organ: speaker



German neurologist Wolf Singer

by Sylvain Comeau

Science still does not understand very much about the human brain, and maybe some of the limitations to that understanding lie in the brain itself. German neurologist Wolf Singer said in a recent Concordia lecture that unconscious impulses run much of the show in our minds, to the point where even freedom of choice comes into question.

Singer, director of the Max-Planck Institute for Brain Research, in Frankfurt, explained that the brain works through interacting neurons, which form different assemblies depending on the task at hand. But while everyone’s brain works that way, that does not mean that everyone will come to the same conclusion about the world. Quite the contrary.

“We have ample evidence that the brain is a highly idiosyncratic system. It is hard to say whether it really tells us what it should — if it is telling us what the world is really like.”

In other words, interpretations, conclusions and answers that come through to the individual from the barrage of sensory data plus the interplay with our fevered thoughts can produce a view of the world which is not necessarily on speaking terms with reality. Or, as Singer says, “perception is filtered by the first-person perspective.”

“There are many areas of the brain which talk to each other all the time,” he said, a very impressive and complex system, but also “very autistic.”

In an interview following his lecture, Singer explained that his view is not jaundiced but quite realistic.

“Evolved brains — complex brains of higher mammals, with a developed cerebral cortex — have a lot of knowledge of the world, partly inborn and partly through learning. They can use this knowledge to deliberate, formulate expectancies and hypotheses, and develop predictive models of the world, which they then match with input.

“What is actually perceived is the result of a comparative operation between these self-generated hypotheses and the actual input. So it’s an interpretation.”

That system’s first-person filter twists the interpretation in any number of ways.

“It’s autistic because it’s so self-referential. It spends a lot of time with its own preoccupations; [the brain’s] knowledge base is so huge that it can get away without taking in much input from outside while it is busy constructing models of the world. To the individual, the answers the brain comes up with appear to be the only way to interpret the world.”

But why is the interpretation so compelling to the individual, even when one’s view of the world may seem nonsensical to others?

”Maybe because we only become conscious of solutions, not of the way we came up with them. Without examining the thought processes that led us that way, we are not conscious of other possibilities, nor of how we might have gone wrong. Only when we talk to others do we discover other interpretations which could be valid.”

Singer feels that current understanding of how the brain works does not leave any room for free will.

“I think the issue of free will is an all-or-nothing question. Either we have it or we don’t. I think we can’t have just a little bit of free will. If what we do is the result of the neuronal interactions in our brain, including our thoughts, decision-making processes and values, then there can’t be another entity on top of this which makes choices which are then executed by neurons.”

Singer says that if there is a free-will mechanism in this system, science has yet to discover it. “If our understanding of neurobiology is valid and complete, there can be no free will. If there is free will, there must be something in addition that none of us has ever come across.

“There are processes that underlie decision-making, but again, these are neuronal processes. For example, a winner-take-all mechanism, in which there is a competition between two neuronal states, one wins, so that action A takes place rather than action B. The reason that A or B wins is that there was a bias in the likelihood that one of the two will make it. This process is not governed by free will.”

As for human consciousness, that may be over-rated. Singer says that the unconscious mind is far more active.

“The large majority of the processes in the brain remain unconscious. The consciousness platform is so limited with respect to the capacity of contents it can keep at the same time.

“We constantly have to select, through attention mechanisms, what we will have in your conscious mind, so most of the processes influencing behaviour are not present in consciousness, but still influence what you do. That is why explanations people provide for their behaviour are often unconvincing.”

Singer’s lecture on April 10 was presented by the Science College.