THE FIELD of NEUROSCIENCE IS VAST

with research going on at all levels, from single cells and the interactions of cells to the brain mechanisms enabling mental states. Understanding cells and their connectivity has been enhanced immeasurably with the introduction of molecular genetics techniques. Online neurophysiological recordings in behaving animals have revealed how to identify neural networks that are involved in how the brain makes decisions, the primary function of the brain. Finally, neuroimaging techniques have opened up ways to understand the brain during cognitive activity. Both activation studies and very recent studies on connectivity allow for the identification of specific networks that are active in mental states ranging from basic perception to empathy. The past century saw studies focused on individual cognitive states. In this century we’ll come to understand how the brain responds in a social context and how it makes judgments on intentions, moral responses, social comparisons, and a host of other mental states.


Michael S. Gazzaniga, DIRECTOR, CENTER FOR COGNITIVE NEUROSCIENCE, DARTMOUTH COLLEGE

I
n the last 25 years, the development of techniques to record the electrical activity of single nerve cells has been essential to our emerging understanding of how brains extract information from the world and transform and store this data. Neurons are the atoms of perception, memory, thought, and action. They communicate reliably, quickly, and over long distances with each other by means of binary pulses, spikes, or action potentials, traveling along thin wires, or axons. Today, by the grace of the electronics industry, the intrepid explorer of the brain can listen in to tens or even hundreds of neurons chatting away as the animal—or, on rare occasions, the human—moves about the environment, pulls a lever, or watches a picture on a monitor.
The next 25 years will see the birth of an inchoate neurotechnology industry. Our knowledge of the brain and its elements—membrane channels, synapses, axons, neurons, and the way neurons are organized into clusters, centers, and sheetlike maps—while far from complete, lets neuroscientists interfere with the injured or the diseased brain in a delicate and deliberate manner for therapeutic benefit. This could involve stem cell therapy to replace the neurons destroyed by the ravages of Parkinson’s disease, the implantation of a brain-machine interface into the cerebral cortex to read out the motor intention of a paralyzed patient and let a robotic arm carry out this intended action, or the silicon replacement of a retina impaired by macular degeneration. In the more distant future, many of these techniques will be used to enhance brain functions in healthy individuals. Why? Because they can do it.
Christof Koch, PROFESSOR OF COGNITIVE AND BEHAVIORAL BIOLOGY, CALTECH; AUTHOR OF THE QUEST FOR CONSCIOUSNESS: A NEUROBIOLOGICAL APPROACH (ROBERTS AND COMPANY, 2004)

The single greatest advance in neuroscience over the last 25 years is fMRI. With this tool, researchers have gained insights into how healthy brains work by observing, in real time, which parts of the brain light up during different perceptual, motor, and cognitive activities. Similarly, neurologists and psychiatrists have identified fMRI signatures of brain pathology that aid in the diagnosis and treatment of various disorders. In the next 25 years, the greatest advances will be made by integrating the twin disciplines of genomics and neuroscience. This fusion of the two will unravel mysteries about how the nervous system develops from a single fertilized egg, wires itself into a mature organism, then learns and adapts throughout life. By understanding these complex relationships, neurologists will ultimately be able to turn genes on and off to treat diseases such as Parkinson’s and Alzheimer’s and even reverse the damage and death of nerve cells due to aging.



Eric Haseltine, DIRECTOR OF RESEARCH, NATIONAL SECURITY AGENCY; DISCOVER NEUROQUEST COLUMNIST

T

he most important development in the last 25 years? No contest: the discovery of neurogenesis in adult animals. Until this discovery, made in the 1980s, every neuroscientist believed that the birth of new neurons was confined to early fetal development and the juvenile years. This dogma was flattened when biologists discovered that the brains of adult male canaries undergo considerable neural change as a function of seasonal variation in their song. New neurons are born in the song control areas, find their way to the relevant neural pathways, and then hook up so that new songs can be produced to lure willing female canaries. The finding set off a spate of parallel discoveries in rats, primates, and humans, with dramatic implications for how we think about neural plasticity and its potential role in rehabilitating individuals with acquired and inherited neural deficits, including patients with phantom limb pain, spinal cord injuries, and Parkinson’s disease. The most important development in the next 25 years? The capacity to understand the function of different neural pathways in sufficient detail to allow us to rewire existing circuits, transplant others, and shift imbalances in neurochemistry. With the birth of neural engineering, we will see the end of many devastating cases of brain abnormalities that cripple human life, including autism, depression, and schizophrenia. These advances will raise challenging ethical questions, a trademark of revolutionary science.


Marc D. Hauser, PROFESSOR OF PSYCHOLOGY, HARVARD UNIVERSITY; AUTHOR OF WILD MINDS (HOLT, 2000)

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