In this essay a few relevant aspects of the neural and behavioral development of the brain in the human and in the rat are reviewed and related to the consequences of lesions in the central and peripheral nervous system at early and later age. Movements initially are generated by local circuits in the spinal cord and without the involvement of descending projections. After birth, both in humans and in rats it seems that the devlopment of postural control is the limiting factor for several motor behaviors to mature. Strong indications exist that the cerebellum is significantly involved in this control. Lesions in the CNS at early stages interfere with fundamental processes of neural development, such as the establishment of fiber connections and cell death patterns. Consequently, the functional effects are strongly dependent on the stage of development. The young and undisturbed CNS, on the other hand, has a much greater capacity than the adult nervous system for compensating abnormal reinnervation in the peripheral nervous system. Animal experiments indicated that the cerebellar cortex might play an important part in this compensation. This possibility should be investigated further as it might offer important perspectives for treatment in the human.

Albert  Gramsbergen

Normal and Abnormal Development of Motor Behavior:Lessons From Experiments in Rats

Neurorehabilitation is increasingly taking account of scientific findings. Research areas directing stroke rehabilitation are neurophysiology; adaptability to use and activity; biomechanics; skill learning; and exercise science (task, context specificity). Understanding impairments and adaptations enables a reappraisal of interventions—for example,changes in motor control resulting from impairments (decreased descending inputs, reduced motor unit synchronization), secondary soft tissue changes (muscle length and stiffness changes) are adaptations to lesion and disuse. Changes in interventions include increasing emphasis on active exercise and task-specific training, active and passive methods of preserving muscle extensibility. Training has the potential to drive brain reorganization and to optimize functional performance. Research drives the development of training programs, and therapists are relying less on one-to-one, hands-on service delivery, making use of circuit training and group exercise and of technological advances (interactive computerized systems, treadmills) which increase time spent in active practice, Emphasis is on skill training, stressing cognitive engagement and practice, aiming to
increase strength, control, skill, endurance, fitness, and social readjustment. Rehabilitation services remain slow to make the changes necessary to upgrade environments, attitudes, and rehabilitation methodologies to those shown to be more scientifically rational and for which there is evidence of effectiveness.

Roberta B. Shepherd

Exercise and Training to Optimize Functional Motor
Performance in Stroke: Driving Neural Reorganization?

Mijna  Hadders-Algra

Albert   Gramsbergen

Discussion on Possibilities for Therapeutic Interventionin Children and Adults with Motor Disorders

Our knowledge of components of the humanmotor system has been growing steadily, but ourunderstanding of its integration into a system islagging behind. It is suggested that a combinationof measurements of forces and movements of themotor system in a functionally meaningfulenvironment in conjunction with computersimulations of the motor system may help us inunderstanding motor system properties. Neurotraumacan be seen as a natural deviation, withrecovery as a slow path to yet another deviantstate of the motor system. In that form they maybe useful in explaining the close interactionbetween form and function of the human motorsystem.

E.  Otten

The Motor System: The Whole and its Parts

Patients with an upper motor neurone syndrome (CP) suffer from many disabling primary symptoms: spasms, weakness, and loss of dexterity. These primary &#08216;neurogenic&#08217; symptoms often lead to secondary disabilities, muscle contractures, and tertiary effects, bone deformations. A common symptom of CP is hypertonia, with. the consequence that the involved muscles remain in an excessively shortened length for most of the time. As a normal reaction of the muscle tissue, the number of sarcomeres is reduced and the muscle fibers shorten permanently: a contracture develops. A possible second type of contracture is that normal muscle lengthening along with bone growth is affected. Current treatments for the secondary effects include (1) reduction of muscle force, (2)lengthening of the muscle fibers by serial plaster casts, and (3)surgical lengthening of tendons or aponeurosis. The choice of treatment depends on the cause of the functional deficit. Bone tissue also adapts itself to abnormal forces, especially in the growth period. The hypertonias or contractures of CP so may give rise to bone malformations that interfere with function (e.g. femur endorotation) or may reduce the action of muscles by changing the lever arm (e.g. ankle varus). Although prevention should always be preferred, a timely surgical intervention cannot always be avoided. The differences in treatment for the various groups require and justify an extensive laboratory investigation, including EMG recordings in gait, measurement of passive elastic properties, and long-term observation of the hypertonia.

A. L. Hof

Changes in Muscles and Tendons Due to Neural Motor Disorders:Implications for Therapeutic Intervention

Parkinson's disease is one of the most
frequent neurodegenerative brain diseases. Its
time course is slow and is characterized by
progressive loss of dopaminergic and other
brainstem neurons resulting in malfunctioning of
the cerebral neuronal systems responsible for
motor functions. The clinical signs are slowness
of movement, muscle rigidity and rest-tremor
amongst other features. The cause of the disease
is unknown, but recently involvement of genetic
factors is being researched. Positron emission
tomography (PET) allows in vivo determination
of striatai dopaminergic activity. This has
increased our insight in the pathophysiology of
the disease and permits direct study of disease
progression at a biochemical level and equally to
monitor whether potential neuroprotective interventions
are indeed effective. Thus far no drug
has emerged but promising substances are
currently being studied.

K. L. Leenders

W. H. Oertel

Parkinson's Disease: Clinical Signs and Symptoms,
Neural Mechanisms, Positron Emission Tomography,
and Therapeutic Interventions

Following central motor lesions, two forms
of adaptation can be observed which lead to
improved mobility: (1) the development of spastic
muscle tone, and (2) the activation of spinal
locomotor centers induced by specific treadmill
training. Tension development during spastic
gait is different from that during normal gait
and appears to be independent of exaggerated
monosynaptic stretch reflexes. Exaggerated
stretch reflexes are associated with an absence
or reduction of functionally essential polysynaptic
reflexes. When supraspinal control of spinal
reflexes is impaired, the inhibition of monosynaptic
reflexes is missing in addition to a
reduced facilitation of polysynaptic reflexes.
Therefore, overall leg muscle activity becomes
reduced and less well modulated in patients with
spasticity. Electrophysiologicai and histological
studies have shown that a transformation of
motor units takes place following central motor
lesions with the consequence that regulation of
muscle tone is achieved at a lower level of
neuronal organization which in turn enables the
patient to walk. Based on observations of the
locomotor capacity of the spinal cat, recent
studies have indicated that spinal locomotor
centers can be activated and trained in patients
with complete or incomplete paraplegia when
the body is partially unloaded. However, the
level of electromyographic activity in the
gastrocnemius (the main antigravity muscle
during gait) is considerably lower in the patients
compared to healthy subjects. During the course
of a daily locomotor training program, the
amplitude of gastrocnemius, electromyographic
activity increases significantly during the stance
phase, while inappropriate tibialis anterior
activation decreases. Patients with incomplete
paraplegia benefit from such training programs
such that their walking ability on a stationary
surface improves. The pathophysiology and
functional significance of spastic muscle tone and
the effects of treadmill training on the locomotor
pattern underlying new attempts to improve the
mobility of patients with paraplegia are reviewed.

V. Dietz

Spinal Cord Lesion: Effects of and Perspectives for Treatment

This article stresses the plasticity of theadult sensorimotor cortex in response tovarious injuries or environmental changes. Thedominant role of sensory input is discussed. Anumber of studies are presented that show howinput may lead to learning and change. Learningis discussed in relation to recovery. It is shownhow concepts from the field of motor controland learning may be used for improving neurologicalrehabilitation. Specific attention is givento the variability of input, the meaningfulnessof input, and the role of the learning context.The learning context and the applicationcontext should have essential characteristics incommon, otherwise transfer of learning will benon-optimal. It is argued that learning landscapesare necessary in order to treat patientsin such a way that he learned skills aretransferable to situations outside the hospital.

Theo  Mulder

Jacqueline  Hochstenbach

Adaptability and Flexibility of the Human Motor System:Implications for Neurological Rehabilitation

The Neuronal Group Selection Theory (NGST) could offer new insights into the mechanisms directing motor disorders, such as cerebral palsy and developmental coordination disorder. According to NGST, normal motor development is characterized by two phases of variability. Variation is not at random but determined by criteria set by genetic information. Development starts with the phase of primary variability,during which variation in motor behavior is not geared to external conditions. At function-specific ages secondary variability starts, during which motor performance can be adapted to specific situations. In both forms, of variability, selection on the basis of afferent information plays a significant role. From the NGST point of view, children with pre- or perinatally acquired brain damage, such as children with cerebral palsy and part of the children with developmental coordination disorder, suffer from stereotyped motor behavior, produced by a limited repertoire or primary (sub)cortical neuronal networks. These children also have roblems in selecting the most efficient neuronal activity, due to deficits in the processing of sensory information. Therefore, NGST suggests that intervention in these children at early age should aim at an enlargement of the primary neuronal networks. With increasing age, the emphasis of intervention could shift to the provision of ample opportunities for active practice, which might form a compensation for the impaired selection.

Early Brain Damage and the Development of Motor Behaviorin Children: Clues for Therapeutic Intervention&#63;

The movement disorder of cerebral palsy (CP) is expressed in a variety of ways and to varying degrees in each individual. The condition has become more complex over the last 20 years with the increasing survival of children born at less than 28 to 30 weeks gestationai age. Impairments present in children with CP as a direct result of the brain injury or occurring indirectly to compensate for underlying problems include abnormal muscle tone; weakness and lack of fitness; limited variety of muscle synergies; contracture and altered biomechanics, the net result being limited functional ability. Other contributors to the motor disorder include sensory, cognitive and perceptual impairments. In recent years understanding of the motor problem has increased, but less is known about effects of therapy. Evidence suggests that therapy can improve functional possibilities for children with cerebral palsy but is inconclusive as to which approach might be most beneficial. The therapist requires an understanding of the interaction of all systems, cognitive/perceptual, motor, musculoskeletal, sensory and behavioral, in the context of the development and plasticity of the CNS. It is necessary to understand the limitations of the damaged immature nervous system, but important to optimize the child&#0039;s functional possibilities.

Margaret J. Mayston

People With Cerebral Palsy:Effects of and Perspectives for Therapy

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Neural Plasticity is an interdisciplinary journal dedicated to the publication of articles related to all aspects of neural plasticity, with special emphasis on its functional significance as reflected in behavior and in psychopathology.

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Chief Editor, Professor Baudry, is currently University Professor at Western University of Health Sciences in Pomona, CA. His research focuses on understanding the molecular/cellular mechanisms of learning and memory and neurodegeneration.

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Neural Plasticity

This Issue is now open for submissions.
Papers are published upon acceptance, regardless of the Special Issue publication date.

Neural Plasticity

Therapeutic Intervention in Motor Disorder

Therapeutic Intervention in Motor Disorder

Articles

Normal and Abnormal Development of Motor Behavior: Lessons From Experiments in Rats

Exercise and Training to Optimize Functional Motor Performance in Stroke: Driving Neural Reorganization?

Discussion on Possibilities for Therapeutic Intervention in Children and Adults with Motor Disorders

The Motor System: The Whole and its Parts

Changes in Muscles and Tendons Due to Neural Motor Disorders: Implications for Therapeutic Intervention

Parkinson's Disease: Clinical Signs and Symptoms, Neural Mechanisms, Positron Emission Tomography, and Therapeutic Interventions

Spinal Cord Lesion: Effects of and Perspectives for Treatment

Adaptability and Flexibility of the Human Motor System: Implications for Neurological Rehabilitation

Early Brain Damage and the Development of Motor Behavior in Children: Clues for Therapeutic Intervention?

People With Cerebral Palsy: Effects of and Perspectives for Therapy