It is a pleasure to present this year’s proceedings of
the M.R. Bauer Foundation Colloquium Series, Annual Scientific
Retreat, and Distinguished Guest Lecturer Series at Brandeis
University’s Volen National Center for Complex Systems.
Now in its eleventh year, the generous support of the
M.R. Bauer Foundation has enabled my colleagues and me
to bring neuroscientists carrying out some of the most
interesting work in the field to campus. These proceedings
reflect the outstanding lectures that were delivered,
but in addition the informal interactions that took place
during the speakers’ visits also served to enrich the
research and educational missions of the Volen Center.
At the core of the Volen Center’s mission is the mandate
to make known the results of its quickly advancing work
and to provide a forum for discussing them. I am especially
appreciative of the assistance of the M.R. Bauer Foundation,
which has facilitated this communication among our faculty
and students with so many of the leading practitioners
of neuroscience in the United States and throughout the
world.
The M.R. Bauer Colloquium Series hosted four speakers
in 2004-05. These talks focused on vision, stuttering,
and taste, and what these systems can tell us about brain
function. Dr. Yang Dan, an associate professor
of neurobiology at the University of California, Berkeley,
spoke about integrating our understanding of plasticity,
or adaptability, in the visual system at the synaptic,
circuit, and functional levels. How are changes that occur
in the synapse, for example, related to simultaneous changes
to the visual network? Scientists have studied extensively
how visual activities modify the connections between neurons
in this system or the overall system itself, but no one
has shown how these changes are related. Dr. Dan showed
how stimuli can induce changes in the visual system, mediated
by the relative timing of electrical inputs and outputs
of neurons. The complex patterns of this activity determine
the direction and magnitude of changes in the visual system.
Dr. Nancy Kanwisher, from MIT’s Department of Brain
and Cognitive Sciences, used functional magnetic resonance
imaging (fMRI) of the brain to show how humans recognize
the faces of people they know. Dr. Kanwisher is well known
for her pioneering work that identified regions of the
brain that play specialized roles in the perception of
faces, places, and objects. In her recent work, she examined
patients with macular degeneration, the central part of
whose retinas no longer send visual data to the cortex
in the brain for processing. She found the surprising
result that the visual cortex was still strongly activated
by peripheral stimuli from the retina. This work suggests
that large-scale reorganization of the brain and of visual
processing takes place in individuals with macular degeneration.
Dr. Kanwisher’s findings will likely prove very important
for any effort to develop new strategies for rehabilitating
patients with this widespread condition.
Dr. David Rosenfield, director of the Speech and
Language Center at the Baylor College of Medicine, spoke
about the neuroscience of stuttering. Using the zebra
finch as a model organism for study, Dr. Rosenfield focused
on the apparent anomaly that stutterers are fluent when
singing. Some one percent of the world’s adult population
suffers from stuttering. The disrupted speech typical
of stutterers is not random but rather likely reflects
a disturbance in auditory feedback. An improved understanding
of this disruption in speech motor output will contribute
to a better general understanding of language processing
in the brain. Dr. Steven Roper, from the University
of Miami School of Medicine’s Department of Physiology
and Biophysics, looked at signal processing in taste bud
cells in order to show that neurotransmitters play a role
in cell-to-cell communication. His findings may help to
resolve a controversy between scientists who study taste
at the molecular level and those who study it at the cellular
level. Dr. Roper has demonstrated that taste buds communicate
with each other through conventional transmitters such
as serotonin prior to signaling the brain.
The 2005 Volen Center Scientific Retreat took
place on April 25 at the Charles River Museum of Industry
in Waltham, Massachusetts. The event was attended by some
110 faculty, staff, and students, including visitors from
other institutions. We were pleased that Jeanette McCarthy,
Mayor of Waltham, was there to bring us her greetings.
Because of its locale, Dr. Daniel L. Perlman, assistant
professor of biology at Brandeis, was invited to speak
about the New England ecosystem as “another type of complex
system worth studying” in a talk entitled “A Brief Ecological
History of Boston’s Suburbs.” He emphasized the diversity
of the region in both space and time. Within a hundred
miles, there are three regions with very different geological
origins. New England has “never been as unchanging and
pristine as we once thought.” Returning to the meeting’s
focus on neuroscience, Dr. Susan Birren, associate
professor of biology and Volen Center, gave a talk entitled
“From Heart to Brain: Controlling Neuron Development and
Function.” It is well known that heartbeat is regulated
by the release of a neurotransmitter from neurons embedded
in cardiac tissue. Dr. Birren demonstrated that the same
neurotransmitter plays a role in regulating the balance
between excited and inhibited neurons in the forebrain.
Dr. Jordan Pollack, associate professor of computer
science and Volen Center, spoke about “Recent Progress
in Coevolutionary Learning.” Dr. Pollack has designed
robots that use evolution as a means for open-ended self-organization
(described during the 2001 Retreat). However, the system
works only if fitness is seen as relative to other individuals
rather than as absolute. Co-evolutionary learning fails
when teachers and students become locked into collusive
mediocrity—easy questions make both “successful,” but
the students don’t learn anything. With the proper motivational
structure built in, based on seeing other players as dimensions
of the system rather than as competitors, agents can create
continuous progress. Dr. Daniel Oprian, the Louis
and Bessie Rosenfield Professor of Biochemistry and Volen
Center, talked about his work on congenital night blindness
in “Mutation of Rhodopsin in Health, Disease, and Sabbatical
Leave.” Closing fifteen years of work, Oprian determined
that one of the two explanations for the mutations causing
CNB was not viable. A sabbatical spent with Prof. Gebhard
Schertler at the Laboratory for Molecular Biology in Cambridge,
England, was useful in obtaining structures from crystals
of the dark and active states of rhodopsin, a protein
that is notoriously difficult to crystallize. Dr. John
Lisman, professor of biology and Volen Center, also
spoke about the culmination of many years of research
in his talk entitled “CaMKII as a Synaptic Memory Molecule:
The Final Key Experiments Fall into Place.” Building on
the work of many other laboratories that strongly suggests
this protein (calcium/calmodulindependent kinase II) is
the key element in creating memory, Lisman has recently
shown that this chemical switch consisting of fifteen
to twenty molecules can remain stable for a century. Using
an inhibitor to turn off this switch and reset memory
at the synapse, Lisman provided further evidence that
this protein in fact is responsible for memory. While
each speaker at the Retreat addressed a different kind
of complex system, ranging in scale from the molecular
(memory) to the global (ecosystems) and artificial (robotics),
the talks underscored the progress that has been made
in some of the major unsolved problems in neuroscience.
Now completing its seventh year, the M.R. Bauer Distinguished
Guest Lecturer Series brought Dr. Hollis Cline
to the annual retreat as its keynote speaker. Dr. Cline
is the Charles and Marie Robertson Professor of Neurobiology
and Associate Director for Research at the Cold Spring
Harbor Laboratory on Long Island, New York. Using the
tadpole as a model organism, she studies the retinal projection
to the optic tectum, the structure in the midbrain associated
with vision. She is especially interested in how connections
are made in the early development of the brain. Her work
has shown a surprising result—as growth occurs, neurons
continually add new branches, but they also retract many
branches in a “trial and error” process. Professor Cline
is well 5 known for having conducted one of the first
experiments to visualize the axon, the fiber that conducts
impulses away from a neuron, in a living brain. Her highly
original work in looking at various forms of plasticity
in the brain has helped to change the static picture of
dendrites and synapses previously held by many neuroscientists.
There are many ways that sensory activity affects the
development of neural circuits, including their growth
rate, excitability, and map formation, among others. Professor
Cline’s talk, entitled “Multiple Activity Dependent Mechanisms
Control Visual System Development in Xenopus [the
tadpole],” focused on a few experiments that looked closely
at neurons’ growth rate and ability to form synapses,
the connections among neurons where memories form and
take hold. In early development, there is a large increase
in transmissions to receptors at the synapse, which stabilizes
them and allows them to function despite larger shifts
in electrical activity. Cline has been able to see the
entire dendritic arbor, the tree-like branches that extend
from the neuron to connect with other neurons, and the
axon. What controls the development of the arbor, which
becomes more complex over the first several days of the
tadpole’s life? The dendritic arbor is important because
its complexity, developed in a series of branchings and
retractions, will determine the number of inputs or connections
from other cells. Professor Cline believes that visual
activity itself regulates this process. Does synaptic
input promote arbor development or do larger arbors permit
the creation of new synapses? Because the growth of dendrites
is concurrent with the maturation of the synapse, Professor
Cline tried to sort out the mechanism that is driving
this process. Her experiments showed that synaptic transmissions,
which channel sensory inputs, regulate the growth of arbors.
Professor Cline also wanted to know whether synaptic contacts
regulate axon development— the “output” side of the story.
Using tags to see proteins at the presynaptic vesicles,
she showed that strong synapses stabilize retracting branches.
Branches tend to pull back until they reach a strong synapse,
suggesting that synapses strengthened by activity stabilize
the axon branch on which they reside. The Retreat audience
was particularly impressed by Professor Cline’s visual
evidence, a series of photographs of living neurons showing
growth or retraction.
For more than a decade, the M.R. Bauer Foundation Colloquium
and Scientific Retreat have helped to spur exchanges among
neuroscientists that have advanced the study of the brain,
learning, and memory. Likewise, the M.R. Bauer Distinguished
Guest Lecture Series, which for seven years has brought
some of the field’s most honored scientists to campus,
has greatly benefited our faculty and students. This booklet
conveys, in brief abstracts, some of the most exciting
work taking place in neuroscience today and demonstrates
the diversity of approaches and problems that fall under
this broad field. My colleagues and I are delighted to
express our sincere gratitude to the M.R. Bauer Foundation
for its continuing, generous support that has made these
programs possible—and that has fostered the intense conversations
that help to advance our work in solving these problems.
Arthur Wingfield, D.Phil.
Nancy Lurie Marks Professor of Neuroscience and Director,
Volen National Center for Complex Systems
