Biology Reference
In-Depth Information
neuroprotection and regeneration of adult lesioned CNS neurons based on electrical
activity-dependent cell survival that may be applicable to various diseases of the CNS.
1. INTRODUCTION
Electrical activity plays an important role in promoting survival of
injured neurons in the nervous systems. Evidence from many studies of dif-
ferent parts of the nervous systems
in vivo
and
in vitro
support the idea that a
loss of electrical activity leads to neuronal death, and exogenous electrical
activity can enhance neuronal survival (
Corredor & Goldberg, 2009;
Goldberg, 2012; Goldberg & Barres, 2000; Linden, 1994; Mennerick &
Zorumski, 2000
). Much research has focused on the neurotrophic effects
that promote axonal regeneration, that is, neurite outgrowth, in different
neurons of the peripheral nervous system (PNS) and central nervous system
(CNS) during normal development and after injury.
Significant progress has been made in understanding the mechanism under-
lying the neuroprotective effects of electrical activity on various types of neurons
in vitro
and
in vivo
. There have also been significant advances in the past decade in
the development of neuroprostheses that can help restore sensory function and
communication that should aid humans with damage to the visual system. This
new branch of experimental neuroscience, called brain-machine interface
(BMI), offers the possibility of helping people with severe sensory andmotor dis-
abilities to interact better with the world and thus improve their quality of life.
Much attention has been focused on the relationship between the elec-
trical activity of neurons and neuroprotection. I will review recent studies
concerning the role of electrical activity of neurons on neuroprotection,
discuss the possible mechanisms for the neuroprotection, and introduce
the results of electrical stimulation treatments.
2. IMPORTANCE OF NEURONAL ACTIVITY DURING
NORMAL DEVELOPMENT
It is well accepted that programmed cell death (PCD) occurs during
normal development of the vertebrate nervous system. During the embryonic
development of the vertebrate nervous system, approximately one-half of all
neurons that are produced die by PCD. This appears to be a strategy of the
CNS to adapt neuronal populations to their innervation target size and speci-
ficity. This naturally occurring neuronal death has been documented for many
areas of both the central and PNSs of various species (
Oppenheim, 1991
).
According to the classic mechanism of neuronal survival during devel-
opment, neurons are dependent on target-derived neurotrophic factors. A
