President's Pages in Princeton Alumni Weekly
Neuroscience: Exploring the Great Unknown
April 5, 2006
If I were beginning my scientific career today, I would choose to be a neuroscientist. Many of my former students have followed this path, and with good reason, for the brain is the most intricate, plastic, and therefore fascinating organ in the human body, defining us as individuals and as a species. This extraordinary three-pound mass of tissue, which even the most advanced computers cannot begin to rival, consists of some 100 billion neurons, each of which is connected with as many as a 100,000 others, creating the complex and evolving neural patterns and networks that make it possible for us to smell a flower (and register pleasure and not disgust), to remember (or forget) a name, to learn that two times two equals four, to reason or feel (and in what proportion), and to spend a third or so of our lives asleep. The scientific questions presented by the human brain are as numerous as they are intriguing, from the nature of consciousness, to the biological basis of decision-making, to the characterization of everything from higher order neural circuits to signaling molecules like dopamine. The answers we develop in the coming decades will help us all to understand ourselves more fully and find solutions to the neurological disorders that afflict some 50 million Americans each year.
Until comparatively recently, the complexity of the brain, a lack of non-invasive imaging techniques, and the limitations of traditional microscopy made it difficult for neuroscientists to form an integrated and dynamic picture of this organ. Nor were the computers of the time a match for the computational challenges, such as simulating large-scale neural networks, inherent in any systems-level study of the brain. Today, however, new technologies are providing a welcome complement to such tried and true techniques as recording the activity of single neurons or analyzing discrete slices of brain tissue. For example, functional magnetic resonance imaging (fMRI) provides a non-invasive means of gauging neural activity by detecting variations in blood oxygen levels in different areas of the brain, allowing neuroscientists to correlate these regions with particular cognitive functions or emotional responses in an alert human being. Another powerful tool—and a mouthful—is magnetoencephalography (MEG), which measures the magnetic fields emitted by neural currents and, unlike fMRI, can track extremely rapid changes in neural activity—down to the millisecond. In parallel with advances in human brain imaging, a second revolution is occurring in characterizing the microcircuitry of the brain in model organisms in biology such as the fruit fly, the mouse, and even the humble soil worm, C. elegans. Genetically encoded fluorescent proteins that change their glow with changes in neural activity can be expressed in specific brain circuits, and the detailed pattern of neural activity in these circuits can then be mapped with unprecedented speed and accuracy using highly sophisticated forms of optical microscopy. In all of these new areas of neural research, there is a growing recognition on the part of psychologists and biologists—and the life sciences in general—that a rigorous theoretical structure, anchored in quantitative models, is essential in any comprehensive study of the brain. The scale of this enterprise is simply too vast to depend on narrative descriptions alone.
Against this backdrop—and thanks to the leadership of Jonathan Cohen, the Eugene Higgins Professor of Psychology, and David Tank, the Henry L. Hillman Professor in Molecular Biology (who holds a joint appointment in physics)—Princeton is positioning itself to make a far-reaching contribution to the field of neuroscience. Last fall, following a careful review by a committee composed of distinguished scientists from other institutions, the Board of Trustees endorsed a proposal to create an Institute in Neuroscience that will coordinate and, over time, significantly expand our current curriculum and research programs. This initiative, to be co-directed by Professors Cohen and Tank, will give our University a significantly stronger voice in the rapidly expanding field of neuroscience and, more importantly, a distinctive one. Reflecting Princeton’s traditional theoretical and computational strengths, and accommodating the absence of a medical school, the institute is designed to integrate the work of theorists and experimentalists through new quantitative methods and an arsenal of cutting-edge technologies. It aims to do so in a way that treats the brain as a unified if complex whole, rather than as a multiplicity of parts, and in keeping with this holistic approach, it plans to incorporate the insights of a wide range of disciplines, from biology, psychology, and physics to mathematics, engineering, and economics. Rather than trying to do all things, the institute will focus, in the words of Professors Cohen and Tank, on “neural coding and the nature of distributed representations (relevant to perception and long-term memory)” and on “universal forms of circuit dynamics, such as persistent neural activity and integration (relevant to working memory, attention, and decision processes).”
The institute will draw on a rich pool of existing faculty who are already bridging disciplinary boundaries in their classrooms and labs, and it will identify junior and senior scholars who can strengthen these points of convergence while adding unique perspectives to the mix. In addition to fostering fundamental research, it will provide a new level of coherence and cohesion to our expanding undergraduate and graduate curricula in neuroscience. To forge a true community of scholars, with shared facilities and instruments, we plan to construct a state-of-the-art neuroscience center in close proximity to other scientific disciplines, allowing faculty and students to move between the institute and their home departments with ease. The questions with which the institute will grapple are among the most exciting in the scientific world today, and the creative collaborations, serendipitous discoveries, and intellectual advances that lie ahead will shape the face of neuroscience in this country and beyond. It is also safe to say that the implications of these strides for everything from ethics to medical science to economics will be profound, all of which is why I sometimes wish I were 18 again!