Plasticity from muscle to brain

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Prog Neurobiol. 2006 Apr 26

Plasticity from muscle to brain.

Wolpaw JR, Carp JS.

Laboratory of Nervous System Disorders, Wadsworth Center, New York

State Department of Health and State University of New York, Albany,

NY 12201, USA.

Recognition that the entire central nervous system (CNS) is highly

plastic, and that it changes continually throughout life, is a

relatively new development. Until very recently, neuroscience has

been dominated by the belief that the nervous system is hardwired and

changes at only a few selected sites and by only a few mechanisms.

Thus, it is particularly remarkable that Sir Eccles, almost from

the start of his long career nearly 80 years ago, focused repeatedly

and productively on plasticity of many different kinds and in many

different locations.

He began with muscles, exploring their developmental plasticity and

the functional effects of the level of motor unit activity and of

cross-reinnervation. He moved into the spinal cord to study the

effects of axotomy on motoneuron properties and the immediate and

persistent functional effects of repetitive afferent stimulation. In

work that combined these two areas, Eccles explored the influences of

motoneurons and their muscle fibers on one another. He studied

extensively simple spinal reflexes, especially stretch reflexes,

exploring plasticity in these reflex pathways during development and

in response to experimental manipulations of activity and

innervation.

In subsequent decades, Eccles focused on plasticity at central

synapses in hippocampus, cerebellum, and neocortex. His endeavors

extended from the plasticity associated with CNS lesions to the

mechanisms responsible for the most complex and as yet mysterious

products of neuronal plasticity, the substrates underlying learning

and memory. At multiple levels, Eccles' work anticipated and helped

shape present-day hypotheses and experiments. He provided novel

observations that introduced new problems, and he produced insights

that continue to be the foundation of ongoing basic and clinical

research.

This article reviews Eccles' experimental and theoretical

contributions and their relationships to current endeavors and

concepts. It emphasizes aspects of his contributions that are less

well known at present and yet are directly relevant to contemporary

issues.