Research
The ultimate goals of the coordinated research programs being
carried out within the CCB are to understand the neural basis of
perception and cognition. The specific goals of current research are
to develop a novel unified theoretical and experimental approach to
decipher the natural language used by nerve cells to represent
information about the outside sensory world, and to apply that
approach toward the analysis of sensory processing and cognition in
several test systems.
A common focus across all research programs in the CCB is the study of
the manner in which information about the outside sensory world is
represented in nervous systems.
Within the last few years, biomedical researchers around the world
have mapped the human genome. We now have a blueprint of the genetic
information with which human beings are constructed. This knowledge is
expected to bring about a revolution in health care, and will have a
variety of larger societal implications. This revolution was enabled
by our understanding of the genetic code with which information is
represented in chromosomes. Unfortunately, neuroscience researchers do
not have an equivalent understanding of the neural code, i.e., the
language with which information is represented by the activity of
nerve cells in our own brains. Although the relationships between
sensory stimuli and the responses of nerve cells are understood at a
rudimentary level, we are still far from having a detailed
understanding of the neural code. That is, a neuroscientist cannot
decipher a nerve cell's activity pattern with a level of confidence
equivalent to that with which a molecular biologist can decipher a DNA
sequence.
As a consequence, neuroscientists are at a critical juncture in their
research. The development of unified theories for nervous system
function will require a more rigorous theoretical framework for
deciphering and interpreting activity patterns in nervous
systems. This will, in turn, require the development of technologies
for monitoring and modifying the activity of large ensembles of
neurons at multiple sites within nervous systems, so that those
theories can be tested, refined, and applied to the development of
effective new strategies for the diagnosis and treatment of perceptual
and cognitive disorders.
Although commercially-available data recording systems allow the
collection and storage of massive streams of neural activity patterns
at high rates, no systems provide the capability for deciphering the
'meaning' imbedded within the neural signals on a time scale that
enables interactive or prosthetic control. One major goal of our
research is to develop the means to record and decipher encoded
information rapidly enough that neural activity can be manipulated in
real time. In essence, we are developing hardware, software and
information-theoretic algorithms capable of 'reading and writing the
neural code' in real time, in a manner that allows controlled
manipulation of neurobiological data streams.
Over the last 10 years, the researchers that are now associated with
the CCB have independently developed several new theoretical and
experimental tools that, when integrated together, will enable a major
advancement toward the goals stated above. The first new tool is,
essentially, a novel analytical framework for deciphering the variety
of neural coding schemes used in different nervous systems. The second
tool is an advanced set of hardware devices enabling multi-unit
recording from extremely large ensembles of nerve cells. The third
tool is a neuroinformatics software system enabling the management and
analysis of the massive data sets generated by the experimental and
analytical tools.
The specific objectives of current research are a) to continue the
development and refinement of these tools, b) to integrate them as an
effective, comprehensive and practical research tool, and c) to
characterize three test preparations using this new integrated
framework. Ongoing experiments involve recording the activity patterns
from large groups of nerve cells during the presentation of complex
sensory stimuli to three biological test preparations: the visual
systems of macaque monkeys and cats, and the cercal sensory system of
the cricket. The cricket has proven to be a very valuable preparation,
in much the same way that a great deal of studies in genetics and
molecular biology are carried out on fruit flies.
One major research thrust in the CCB is focused on elucidating the
neuronal interactions among cortical areas that underlie and
contribute to visual perception and cognition. To this end, Dr. Gray
and his colleagues conduct experiments in macaque monkeys in which
neuronal activity is monitored at multiple cortical locations while
the animals perform specific perceptual and cognitive tasks. The goals
are to identify the neural correlates of inter-area interactions that
underlie these behaviors, and ultimately to understand the neuronal
mechanisms that mediate those interactions. This enterprise involves
the close cooperation of neuroscientists, engineers, computer
scientists and computational theorists. The long-term goal is to
develop an integrative theory of perceptual and cognitive function in
humans, the outcome of which may lead to advances in the diagnosis and
treatment of psychiatric disorders.
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Updated: 1/15/2008 |
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