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Directors Letter
Leslie Gonzalez Rothi
Program Director, VA RR&D
Brain Rehabilitation Research Center A century of pessimism about the potential for neurorehabilitation
began with Cajal’s description made over 100 years ago,
of the synapse in the central nervous system (CNS). His view that
there was little potential for changes (plasticity) to synaptic
connections after puberty effectively became dictum for much of
the 20 th century with few challenges from neuroscientists, and
acceptance by clinicians that, following CNS injury in adulthood
recovery was limited to what nature could provide.
Rehabilitation efforts have historically been focused primarily upon helping survivors
compensate for their disabilities. To the extent that neurorehabilitation efforts strove to
reconstitute function, the strategies employed were based upon pragmatic or theoretical
considerations that bore little if any relationship to neural processes. These restitutive
efforts have been viewed with significant skepticism by those outside the field of speech-language
pathology. However, the last 25 years have seen several parallel lines of physiologic investigation
that recently have come together in gradual confluence and are now poised to have a profound impact
on the clinical practice of neurorehabilitation.
As a result of these recently emerging discoveries, neurorehabilitation is undergoing a
dramatic paradigm shift that weds the rapidly expanding basic science of neural plasticity to
applied approaches including behavior and pharmacological restitutive or substitutive treatments.
While the wedding of basic science to clinical application in neurorehabilitation is a
significant paradigm shift for all of us in rehabilitation (speech-language pathologists,
audiologists, physical therapists, occupational therapists, etc.), neuroscience now provides
plausibility and even optimism to the possibility of reconstituting damaged neural functions,
and it generates hypotheses that motivate specific clinical therapeutic experiments.
We now know that rehabilitation after brain injury depends upon two proesses: (1) the
endogenous responses of neural tissue (reactive plasticity), which include reactive neurogenesis,
neural migration, axonal sprouting and extension to target structures, and synaptogenesis; and
(2) the replacement of knowledge lost due to injury through experience-based, behavioral
inter-ventions. The study of these processes at the confluence of basic and applied sciences
in neurorehabilitation has provided the motive for “experienced dependent learning
methods” such as constraint-induced movement therapy (CIMT) for paresis following stroke
(Taub et al., 1990). Although there has certainly been controversy about the specifics of
CIMT – in particular whether this particular form of therapy warrants wide application
at this point (Siegert et al., 2004) – the principles have found wider applicability such
as that found in “body weight supported treadmill therapy” for gait impairment
following spinal cord injury (Behrman & Harkema, 2000), for one example.
The focus of these approaches is on the “replacement of knowledge” through the act
of doing the desired behavior. Additionally, the idea is to do it intensively and avoid behaviors
that serve to compensate for or are in lieu of the desired behavior. A promising avenue for
extending these principles for “experience (or use; or activity) dependent learning”
beyond exclusively applying them to motor dysfunctions has been described by Pulvermuller and
colleagues (2001) in their study of a method of rehabilitation for chronic forms of aphasia.
These investigators reported that individuals with chronic, stable aphasia benefited
(statistically as well as clinically) from language treatment designed to include attributes
of CIMT (forced-use delivered in high doses over a relatively short period of time).
Our research here at the Veterans Affairs Rehabilitation and Research Development
(VA RR&D) Brain Rehabilitation Research Center emphasizes the application of
experienced-dependent learning principles compatible with neural processes of recovery to
chronic motor or cognitive dysfunctions resulting from neurologic disease or injury, including
several studies specific to aphasia. These include a pilot study led by Lynn Maher (Houston VAMC
and Baylor College of Medicine) and funded by the VA RR&D Service in which we attempted to
expand and formalize a method referred to as Constraint Induced Language Therapy, begin to
control for confounding variables, and study varying treatment intensities.
Additional studies are ongoing at our Center that study further aspects of “
experience-dependent” learning principles as applied to language, including
one led by Diane Kendall (Gainesville VAMC and University of Florida)
that focuses on phonological processes in which she uses an adapted version of the
LIPS program (Lindamood et al., 1997). Another, led by Maher, is studying errorless
learning ap-plications in a treatment targeted at the sentence level, and two by Anastasia
Raymer (Old Dominion University) and Bruce Crosson (Gainesville VAMC and University
of Florida) focus on treatment targeted at deficits at the lexical level. All the
studies look at aspects of experience – dependent learning
principles as applied to language rehabilitation. We are expanding
our focus to other aspects of communication including a project
led by Jay Rosenbek and Ken Heilman (University of Florida and Gainesville VAMC) focused
on refinements of a treatment for aspects of aprosodia.
All of these studies will serve collectively to tell us the story on the value of experiences
in informing a recovering nervous system.
(Published in the ASHA Leader, December
14, 2004, p 29-30 and a version of this appeared in the VA RR&D Center Grant application.)
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