Half a Brain is Enough: The Story of Nico
Antonio M. Battro
Cambridge Uni. Press
134 pp.; $23

Listening in the Silence, Seeing in the Dark: Reconstructing Life after Brain Injury Ruthann Knechel Johansen
Univ. Of California Press
246 pp.; $24.95

Most of us experience our "self" as a stable property of our psyche, an identity that links our past to our present and can be projected into the future. It belongs to us, it is us—distinctive, inviolable, and enduring. Those who have experienced brain injury, malformation, or disease have learned otherwise. Their often agonizing journeys have revealed that the "self" can be shattered, captionered beyond recognition, and—sometimes—reconstructed. These experiences have profound implications for our understanding of the nature of the self.

The observation that the self appears to be vulnerable to material injury or pathology challenges those who view the self as an immaterial entity enduring through time, experience, and beyond death. Some conclude that the self is simply the subjective manifestation of the organization and activities of the brain, and has no reality beyond this complex biological system. Others believe that the self is something richer and multidimensional, emerging from the relationships and interactions of a body-brain with the physical and social worlds.

These books tell the stories of two boys: Erik, 15, and Nico, five. Erik was a normal, intelligent boy until he suffered severe and extensive brain trauma in a car accident. At the time—1985—his prognosis was poor: even if he recovered from the initial coma, he was not expected to function as a fully self-aware, relational, and independent person.

Nico was born with some left-side paralysis. At two he began to experience epileptic seizures, originating in his malformed right cerebral hemisphere, and soon they were so frequent, severe, and unresponsive to medication that they interfered significantly with normal activity and development. Doctors and parents agreed on radical neurosurgery, disconnecting his right cerebral cortex from the rest of the brain. The identity and development of both boys were significantly captionered by these widespread and profound changes in brain structure and function.

Antonio Battro is a physician and cognitive psychologist who worked closely with Nico from age five. He shares Nico's story to illustrate how the neural architecture underlying our cognitive abilities can be reorganized or profoundly captionered with no apparent detriment. Battro has expertise in diverse fields including medicine, perception, Piagetian cognitive psychology, philosophy, education, and computer science.

They frame his exploration of the neural mechanisms of cognition and how computers can facilitate cognitive and perceptual development when these mechanisms are damaged. While cautious about generalizing, his passion to understand the flexibility and limitations of the brain, and to develop methods to actively mediate the relationship between brain and environment, provide inspiration and hope to those whose brains have been wounded.

Unfortunately, Battro's book is not very accessible to readers without a strong background in neuroscience and cognitive development. The presence of a brief glossary will be insufficient to guide most readers through the high-level concepts and occasionally convoluted arguments. The benefits of this book will be more indirect, as its insights may influence professionals attempting to facilitate healing and cultivate the potential of those with brain trauma or developmental delays.

Nico's story shows that, at least under certain circumstances, "there is no such thing as half reasoning with half a brain." Despite more than three and a half years with a malfunctioning right hemisphere, often debilitated by seizures, and currently using half the usual amount of cortical tissue, Nico demonstrates completely normal reasoning and emotion, and advanced language skills. His only symptoms are some motor and visual impairment on his left side. Remarkable! If one can function quite normally with half a brain, then what is the other half for?

Battro concludes that the remaining neural tissue has become reorganized and is used more efficiently, but he provides no direct evidence for this neural reorganization, only inference from performance. Nico's cognitive development has been facilitated through carefully designed interactions with computers, suggesting that computers can provide a kind of prosthesis for the missing neural circuitry, plus a framework through which functionally useful neural reorganization can be stimulated. Thus, while the brain is a necessary component in the development, experience and expression of aspects of the self, it functions as a flexible architecture that is shaped at least in part by experience.