Table Of ContentNeuromethods 81
Peter V. Nguyen Editor
Multidisciplinary
Tools for
Investigating
Synaptic Plasticity
N
EUROMETHODS
Series Editor
Wolfgang Walz
University of Saskatchewan
Saskatoon, SK, Canada
For further volumes:
h ttp://www.springer.com/series/7657
Multidisciplinary Tools for
Investigating Synaptic Plasticity
Edited by
Peter V. Nguyen
Department of Physiology, School of Medicine, University of Alberta, Edmonton, AB, Canada
Editor
Peter V. Nguyen
Department of Physiology
School of Medicine
University of Alberta
Edmonton, AB , C anada
ISSN 0893-2336 ISSN 1940-6045 (electronic)
ISBN 978-1-62703-516-3 ISBN 978-1-62703-517-0 (eBook)
DOI 10.1007/978-1-62703-517-0
Springer New York Heidelberg Dordrecht London
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Preface to the Series
Under the guidance of its founders Alan Boulton and Glen Baker, the Neuromethods series
by Humana Press has been very successful since the fi rst volume appeared in 1985. In about
17 years, 37 volumes have been published. In 2006, Springer Science + Business Media
made a renewed commitment to this series. The new program will focus on methods that
are either unique to the nervous system and excitable cells or which need special consider-
ation to be applied to the neurosciences. The program will strike a balance between recent
and exciting developments like those concerning new animal models of disease, imaging, in
vivo methods, and more established techniques. These include immunocytochemistry and
electrophysiological technologies. New trainees in neurosciences still need a sound footing
in these older methods in order to apply a critical approach to their results. The careful
application of methods is probably the most important step in the process of scientifi c
inquiry. In the past, new methodologies led the way in developing new disciplines in the
biological and medical sciences. For example, Physiology emerged out of Anatomy in the
nineteenth century by harnessing new methods based on the newly discovered phenome-
non of electricity. Nowadays, the relationships between disciplines and methods are more
complex. Methods are now widely shared between disciplines and research areas. New
developments in electronic publishing also make it possible for scientists to download chap-
ters or protocols selectively within a very short time of encountering them. This new
approach has been taken into account in the design of individual volumes and chapters in
this series.
Wolfgang Walz
College of Medicine
Department of Psychiatry
University of Saskatchewan
Saskatoon, SK, Canada
v
Preface
Methods for Probing Synaptic Plasticity: Evolution and Revolution
Synapses in the nervous system are capable of a wide range of physiological and structural
modifi cations following both artifi cially imposed and naturally occurring regimens of
chemical and electrical activation. These alterations constitute “synaptic plasticity,” and
they are a central focus of modern neuroscience research. Investigations involving incisive
mechanistic dissection of various types of synaptic plasticity have revealed that they play key
roles in neural development, sensory information processing, cortical remapping following
brain injury, perception, and behavioral learning and memory. Conversely, disruptions of
synaptic plasticity may underlie neurological and behavioral disorders such as Alzheimer’s
disease, Fragile-X syndrome, autism spectrum disorder, and drug addiction. In short, syn-
aptic plasticity underlies the unique ability of the nervous system to adapt itself to cope with
internal and external challenges. Not surprisingly, research on the mechanisms of synaptic
plasticity holds considerable promise for increasing our understanding of brain function
and dysfunction. This research, like much of current neuroscience, embraces methodolo-
gies that are truly multidisciplinary. It is now d e rigueur to use multiple techniques, gleaned
from a seemingly disparate range of scientifi c disciplines, to address key questions in synap-
tic plasticity.
The substantial advances that we have witnessed in research on synaptic plasticity owe
much to technical achievements accomplished mostly in the second half of the twentieth
century. In my view, these accomplishments can be grouped under three categories. First,
the development of gel electrophoretic separation of proteins [1–2] and the creation of
genetically modifi ed (transgenic and knock-out) mice [3–8] have enabled the identifi cation
of functions for specifi c genes and proteins within identifi able brain regions and synaptic
circuits. Indeed, a very substantial portion of past and present research on synaptic plasticity
has focused on mapping out the intricate molecular signaling components that underlie
specifi c forms of activity-dependent synaptic plasticity, such as long-term potentiation
(LTP) and long-term depression (LTD). Second, the invention of confocal microscopy by
Marvin Minsky [9] led to the further development and emergence of more advanced opti-
cal imaging techniques, such as two-photon laser scanning microscopy [10], that can track
the spatial and temporal dynamics of chemical signaling within single dendritic spines and
glial processes in l iving brain tissue. Lastly, and from my own perspective as a cellular elec-
trophysiologist, the most critical technical achievement to have infl uenced the trajectory of
research on brain plasticity is the development of ex vivo brain slice preparations by Henry
McIlwain and his colleagues [11–12]. This innovation, coupled with the use of microelec-
trode technologies, enabled electrophysiological investigations of synaptic signaling in
semi-intact brain circuits that can be extracted from defi ned subregions of the mammalian
brain and kept alive ex vivo. Without brain slices, our knowledge of synaptic physiology
would have been greatly diminished. It should be noted that by themselves, these
vii
viii Preface
innovations were game-changing ones. They enabled neuroscientists to peer more deeply
into the intricate electrical and chemical machineries of the brain. When applied together,
these innovations, and their more refi ned descendants, collectively represent the state of the
art in the fi eld of synaptic plasticity. Overall, our steady progress in illuminating the myster-
ies of synaptic plasticity owes as much to revolutionary advances as it does to a gradual
evolution, or refi nement, of techniques.
My primary goal in editing this book was to assemble chapter contributions that would
highlight techniques and strategies used in probing the cellular and molecular mechanisms
of synaptic plasticity in the nervous systems of vertebrate and invertebrate species. A reduc-
tionist approach is evident throughout this section, as it has proven to be a very incisive,
and productive, approach for elucidating detailed mechanisms of synaptic plasticity that are
pertinent for dissecting higher brain functions [13]. The chapters should serve as “primers”
for introducing new trainees, and perhaps even seasoned investigators, to specifi c tech-
niques that may be unfamiliar to them but which they may wish to adopt to pursue novel
questions in the laboratory.
This book is divided into three sections. The fi rst deals with biochemical and genetic
strategies for studying synaptic plasticity and behavior. Thorsten Buch and his colleagues
describe conditional gene targeting in mice, a widely used approach for probing both syn-
aptic and cognitive plasticity. Then Hélène Marie describes viral-directed recombinant pro-
tein expression as a means of exploring the functions of specifi c genes in mammalian nervous
systems. Wayne Sossin and his colleagues then present an approach that uses exogenous
protein expression in the much “simpler” nervous system of a marine snail, A plysia califor-
nica , to probe protein function in a well-defi ned neural circuit underlying behavioral learn-
ing. The last chapter of this fi rst section looks ahead to later chapters in this book. Charles
Hoeffer and his colleagues present an amalgamation of brain slice electrophysiology and gel
electrophoretic strategies in their exploration of the roles of the cell’s translational (protein
synthesis) machinery in regulating synaptic plasticity in the mouse hippocampus. Overall,
the contributions of the fi rst section underscore the strategies that can be used to probe the
roles of s pecifi c genes and proteins in synaptic plasticity.
The second section of the book addresses issues pertaining to neural development and
synaptogenesis. The billions of connections between neurons that need to be correctly
confi gured to make up the adult nervous system pose a formidable challenge for neuro-
physiologists interested in elucidating the factors and “rules” that govern neural develop-
ment. One preparation that can be used to track synaptogenesis in vivo, while mitigating
much of the diffi culties associated with recording and imaging synaptic connections in vivo
in developing mammalian nervous systems, is the zebrafi sh embryo. Declan Ali and his col-
leagues describe their strategies for exploring the emergence of functional glutamatergic
synapses in zebrafi sh embryos. In mammals, adult neurogenesis is evident in discrete brain
subregions, such as the dentate gyrus of the hippocampus. Tracking the birth and develop-
ment of new neurons and new synapses in this region has been challenging. Shira Rosenzweig
and Martin Wojtowicz describe their quantitative immunohistochemical methods for detec-
tion of endogenous markers in immature adult-born neurons. Their approach may be used
to index variations in dendritic growth and complexity among immature neurons.
Collectively, these two chapters underscore the notion that our grasp of synaptic formation
in the mature adult nervous system depends critically on the ability to track developmental
processes that initiate, refi ne, and consolidate synaptic connections.
In the fi nal section of this book, six chapters cover a wide breadth of cellular electro-
physiological and optical methods for addressing a diverse array of experimental issues. All
Preface ix
use brain slice preparations. In the fi rst chapter, Tom O’Dell and Erin Gray describe the
hippocampal CA1 slice preparation, and highlight the potent utility of this slice for micro-
electrode- and biochemically-driven investigations of glutamate receptor signaling during
synaptic plasticity. Then Richard Morris and Roger Redondo present their modifi cations of
hippocampal slice maintenance techniques to show how viable recordings of LTP can be
accomplished many hours after slice preparation. They present their fi ndings in the context
of exploring synaptic and behavioral “tagging,” processes believed to contribute to some
forms of associative learning in rodents. Richard Robitaille and Aude Panatier then present
cellular loading and optical imaging approaches for probing calcium signaling in astrocytes
within hippocampal slices. When combined with patch-clamp recording, these techniques
provide a very fi nely resolved window on synaptic transactions occurring between neurons
and glial processes in a slice preparation. Melanie Woodin’s chapter focuses on probing
inhibitory synaptic transmission, an often-neglected area that is overshadowed by research
on excitatory synapses. A chapter by Qi Yuan and her colleagues is presented to highlight
the use of in vivo imaging in a simplifi ed mammalian slice preparation, containing olfactory
circuitry, that can be used to probe electrophysiological correlates of olfactory learning in
young rat pups. There may now be a rebuttal against those who claim that invertebrates
have a monopoly on “simple” nervous systems! Lastly, a chapter by Gregory Funk and
Nicholas Mellen describes a rat hindbrain slice preparation that can be used to explore sig-
naling in neural circuits directly relevant for generating respiratory rhythms. It has the
potential for revealing forms of synaptic plasticity that may importantly modify respiratory
rhythm generation under various physiological and pathological conditions. These six
chapters highlight the evolving state of potent research strategies that are centered on the
use of brain slice preparations.
I would like to thank the series editor, Wolfgang Walz, for his patience and guidance
during this project; Patrick Marton and the editorial staff at Springer, New York, for their
patience and professionalism; Stephanie Del Alba for creating the cover art; and all of the
chapter contributors for their diligence and enthusiasm in preparing their contributions for
this book.
Edmonton, AB, Canada Peter V. Nguyen
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