The Brazilian-born neurophysiologist Miguel Nicolelis performed experiments in
which a brain was connected to a machine so that the brain's activity
directed the machine's movement.
The book is both a chronicle of the way those experiments came to be, a
history of modern neurophysiology, and a personal meditation on both small
and big things of a scientist's life.
Nicolelis' brain-machine interfaces are the descendants of a long dynasty of neurophysiological discoveries. The book contains a detailed timeline of achievements over the decades in understanding how the brain works. In 1969 the Spanish neurophysiologist Jose Delgado implanted devices in the brain of a monkey and then sent signals in response to the brain's activity, thus creating the first bidirectional brain-machine-brain interface. He also speculated that brain implants could some day be used to to control minds. That's probably the closest forerunner of Nicolelis' research. In 2002 John Chapin, Nicolelis' own mentor, had already debuted his "roborats", rats whose brains were fed electrical signals via a remote computer to guide their movements. Also in 2002 Nicolelis and his coworkers achieved the feat of making a monkey's brain control a robot's arm. That extended the monkey's brain in three directions: it expanded the distance at which that brain could operate (because the robot was physically outside the monkey's body), it increased the strength of the force it could generate (because the robot was stronger than the monkey's body), and it reduced the time for a thought to translate into a movement (because the robot reacted faster than the body itself). In 2008 the team made the monkey control a remote robot (in fact, located in another continent) and control it to cause bipedal locomotion. This further extended the distance, the strength and the speed of which the monkey's brain was capable. Finally, they implemented a bidirectional brain-machine-brain interface within the same individual brain; but the next step will be to mediate communications between two brains forcing them to collaborate towards the realization of a given goal.
Nicolelis spends quite a bit of time grounding his experiments into a theory of the brain that views the neural group (a population of interconnected neurons) as the elementary unit of thought rather than the single neuron. A stimulus has an effect on a neural group: a population of "tuned" neurons is the unit that detects, stores and responds to information. This is a view that he contrasts with the reductionist approach to dig deeper and deeper into smaller and smaller constituents to explain the functioning of the whole. I am not sure that he proves his point (i suspect that we still need a reductionist approach to understand where consciousness and free will come from), but there is certainly general consensus that cognitive functions (the various aspects of "thought") are distributed over a large population of neurons, a fact that makes the brain very fault-tolerant. These neural groups perform massively parallel information processing that results in accurate movements. The individual neuron may participate in more than one neural group, and its spiking may have different "meanings" in the various groups. And, viceversa, a particular outcome may be generated by a variety of different neural activities. For example, there are multiple ways that a brain can encode a memory. Neurons can interact even with distant neurons because the substance enveloping them is highly conductive of electrical signals. This facilitates the creation of countless feedforward and feedback connections, and not only among neighboring neurons. Nicolelis therefore is lukewarm at the idea that the cortex is divided into functionally specialized areas. This broad connectionist view also implies that the brain's working cannot be reduced to a computational algorithm: the human brain is noncomputable.
Nicolelis also emphasizes that the brain is not a passive tool waiting to react to stimuli from the environment but an active information-seeker. And there is vast consensus among biologists that this is true for all forms of life. Nicolelis believes that this active process generates a "brain's point of view" about what is going on in the world and in the body. This nonstop process de facto provides a live simulation of the world, and therefore a set of expectations that in turn determine what the brain seeks for and what the brain will "understand". Hence the brain is three machines in one: a tool to maintain homeostasis in the body (basically, to keep us alive); a simulator to continuously update a model of the world; and an agent to continuously seek information in the environment.
Another interesting finding came from the analysis of brain activity, a finding first presented by Atsushi Iriki ("Coding of modified body schema during tool use by macaque postcentral neurons", 1996). Brains seem to incorporate the tools that the body is using not only in their model of the world but in their very model of the body itself. Tools are represented by the brain as seamless extensions of the body. These "extensions" contributing to one's sense of self would then include clothes, kitchenware, bicycles, cars, digital devices... and even family, friends and acquaintances. (Nicolelis does not seem to make the next logical step: perhaps it is not that tools are represented as limbs or organs by the brain but that limbs and organs are represented by the brain just like tools: from the viewpoint of a brain they are all "tools" that help the brain survive, explore the environment, manipulate the environment, fuel itself and reproduce).
Generally speaking, the brain is a very plastic device: it adapts all the time, and it is not only the cortex that is capable of changing (during adult life) but also the subcortical structures.
On the other hand, i am not sure what to make to the many "principles" that Nicolelis spells out to summarize his conclusions. For example: "The receptive field of an individual neuron and the maps embedded in brain regions are defined by the asynchronous spatiotemporal convergence of multiple ascending, local and descending influences provided by a myriad of other neurons."
Nicolelis envisions a brain-centered future in which one's brain would do everything simply by thinking, without having to rely on body movements and not even on language; in which machines will obey orders received wirelessly from the brain of the master; in which people will be able to communicate remotely with each other without any need to pick up a phone or type an email; in which people will be able to experience the surface of a distant planet while comfortably sitting in a living room's armchair; and in which one would be able to access the thoughts of their dead forefathers and relive vividly their most intimate experiences.
A few detours feel redundant (although it is refreshing to have someone waste my time with tales of football instead of obscure sports like baseball and what is improperly called "football" in the USA like books published in the USA often do); and the language is often too technical even for those trained in cognitive science. But the conclusions of each chapter capture the imagination and are certainly worth the effort to read through the difficult parts.
TM, ®, Copyright © 2011 Piero Scaruffi