MRI

has been the most important tool for neuroscience, both clinically and for research, for almost exactly 25 years. It has led to a clearer understanding of the anatomy of the brain and the nervous system. It has also allowed us to view abnormalities such as stroke, tumor, and infections much better, and then to compare the results of the pathology with the physical findings we observe in patients and laboratory animals. In addition, new fMRI techniques allow us to examine which parts of the brain are active. These techniques are powerful tools in determining how the brain works and how brain activity is altered when it is damaged. In the next 25 years, I believe the greatest advancement will come from molecular biology and gaining a better understanding of how the cells of the nervous system communicate chemically. This will lead to important improvements in our comprehension of brain and spinal cord function and to better treatments of conditions such as depression, schizophrenia, and chronic pain. We will also learn more about when nerve metabolism goes awry, which may lead to remarkable cures for many disorders, like Lou Gehrig’s disease, multiple sclerosis, and Alzheimer’s.
Todd Kuiken, DIRECTOR OF AMPUTEE PROGRAMS, REHABILITATION INSTITUTE OF CHICAGO

 

Every area of science has its big question. Most neuroscientists believe that the big one
about the brain is how it makes consciousness. For decades, though, consciousness was
viewed as taboo, mainly because it was too hard to approach scientifically. From the point
of view of scientific advancement, I believe this was actually a good thing because it allowed
a lot of progress to be made on more tractable problems, like how the brain mediates
vision, memory, or emotion. Here is a short list of some key discoveries: Most of what
the brain does, it does unconsciously; our perceptions are products of events occurring in
multiple independent processing streams; memory is formed and stored in parallel by a variety
of brain systems, each of which encodes a different kind of memory (sensory, motor,
cognitive, or emotional); at the molecular level, memory involves changes in synaptic
strength that are stabilized by specific molecules, which hold the key for the treatment of
memory disorders; certain mental and neurological disorders are due to the malfunction
of specific genes or sets of genes that might be controllable; and cells in certain areas of
the brain continue to be produced in adult brains, offering new hope for many forms of
brain repair. With better tools each year, neuroscientists have probed the workings of the
brain in greater and greater detail. But by digging deeper we have overlooked the big picture.
We know little, in other words, about how the brain works as a whole. To some, this
means we now need to study consciousness. But I believe that even if we solved the problem
of consciousness, we wouldn’t know the answer to an even bigger question about
the brain: How does it make the self? How does it make you who you are? That’s because
much of who you are is mediated unconsciously. Even if we never understand consciousness,
we can learn a lot about how the brain works by studying its unconscious aspects.
Joseph LeDoux, PROFESSOR OF NEURAL SCIENCE, NEW YORK UNIVERSITY; AUTHOR OF SYNAPTIC SELF: HOW OUR BRAINS BECOME WHO WE ARE (VIKING, 2002) AND THE EMOTIONAL BRAIN (SIMON & SCHUSTER, 1996)

T
he most important discovery in the last 25 years in systems neuroscience is the function of the dopamine neurons in the midbrain. These neurons fire at quite low rates of a few spikes per second, and they contact widely dispersed regions of the cerebral cortex and basal ganglia, with strong projections to the prefrontal cortex where actions are planned. Wolfram Schultz at Cambridge University showed that the neurons fire brief bursts of spikes when a monkey is rewarded, but after a while the response to the reward goes away and instead the neurons respond to sensory stimuli that predict that a reward will be received in the near future. This seminal observation gave rise to a new theory of how dopamine signals are used in the brain to plan actions based on the probability of obtaining rewards in the future, a theory that has served as the foundation for a new field called neuroeconomics. Looking to the next 25 years, I suspect the most important discoveries will be in the area of language, since for the first time in history we now have genetic and brain-imaging techniques to tackle language in humans. But what those discoveries will be is anyone’s guess.

Terrence Sejnowski, DIRECTOR, COMPUTATIONAL NEUROBIOLOGY LABORATORY, SALK INSTITUTE FOR BIOLOGICAL STUDIES


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