Behavioral assessment after spinal cord contusion has long focused on open field locomotion using modifications of a rating scale developed by Tarlov and Klinger (1954). However, on-going modifications by several groups have made interlaboratory comparison of locomotor outcome measures difficult. The purpose of the present study was to develop an efficient, expanded, and unambiguous locomotor rating scale to standardize locomotor outcome measures across laboratories. Adult rats (n = 85) were contused at T7–9 cord level with an electromagnetic or weight drop device. Locomotor behavior was evaluated before injury, on the first or second postoperative day, and then for up to 10 weeks. Scoring categories and attributes were identified, operationally defined, and ranked based on the observed sequence of locomotor recovery patterns. These categories formed the Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale. The data indicate that the BBB scale is a valid and predictive measure of locomotor reco...

A Sensitive and Reliable Locomotor Rating Scale for Open Field Testing in Rats

The prevalence and cost of chronic pain is a major physical and mental health care problem in the United States today. As a result, there has been a recent explosion of research on chronic pain, with significant advances in better understanding its etiology, assessment, and treatment. The purpose of the present article is to provide a review of the most noteworthy developments in the field. The biopsychosocial model is now widely accepted as the most heuristic approach to chronic pain. With this model in mind, a review of the basic neuroscience processes of pain (the bio part of biopsychosocial), as well as the psychosocial factors, is presented. This spans research on how psychological and social factors can interact with brain processes to influence health and illness as well as on the development of new technologies, such as brain imaging, that provide new insights into brain-pain mechanisms.

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The Biopsychosocial Approach to Chronic Pain: Scientific Advances and Future Directions

Degeneration and regeneration of the nervous system

http://yael-nissan.weebly.com/uploads/5/2/9/2/5292348/the_introduction_to_pain_an_integrative_review_-_millan.pdf

The induction of pain: an integrative review

Graded Histological and Locomotor Outcomes after Spinal Cord Contusion Using the NYU Weight-Drop Device versus Transection

The hypothesis that collateral sprouting might be correlated with recovery of function was tested by a combination of behavioral and anatomical studies. Partial hemisections, sparing the dorsal columns, were made between T12 and L1 of cat spinal cord. Initially, all reflex and locomotor hindlimb activity was depressed ipsilaterally. During two postoperative weeks behavioral and electromyographic responses increased in response to intrinsic reflex elicitation but not to descending or crossed reflex elicitation. Marked improvement in use of the limb occurred as intrinsic reflex activity increased and became, in some cases, hyperactive. The status then remained stable for ten months. Since intrinsic reflexes are mediated by ipsilateral dorsal roots, the intraspinal distribution of L5 or L6 dorsal roots was determined by degeneration methods ten months after hemisection or by quantitative radioautography 20 days after hemisection. By both methods, the dorsal root distribution was found to be asymmetrical in the spinal gray. It was greater on the experimental side and the distribution was altered, having a greater distribution medially in Rexed's lamina VI and laterally in lamina VII. These anatomical changes are considered as signs of collateral sprouting from dorsal roots in response to degeneration of descending tracts on the same side. Dorsal root distribution to dorsal horn (laminae I–IV), motor nuclei, and nucleus gracilis is symmetrical. Regions of increased and of expanded dorsal root input can be correlated with electrophysiologically determined location of interneurons in the path of cutaneous reflexes and of stretch reflex facilitation. Behavioral and anatomical changes were selective; intrinsic reflexes recovered or became hyperactive and ipsilateral dorsal roots showed evidence of collateral sprouting during the recovery period, although a causal relationship between the two cannot be proven, by the present experiments.

Restitution of function and collateral sprouting in the cat spinal cord: the partially hemisected animal

Unilateral hindlimb deafferentation is followed initially by generalized loss of all reflex and useful function. As useful movement returns, certain descending reflexes recover and become hyperactive: crossed reflexes do not. Recovery of movement and reflex hyperactivity are then abolished by subsequent destruction of the ipsilateral descending systems. Although there is no sprouting from contralateral dorsal roots, bilateral degeneration of descending systems is asymmetrical, being greater in density and distribution on the previously deafferented side. Collateral sprouting to certain spinal laminae apparently took place during the recovery period from the same source which mediated reflex hyperactivity; the ipsilateral descending systems. A substantial descending projection to Clarke's nucleus was found only on the experimental side, however, suggesting that a central feedback system replaced the abolished peripheral feedback. If functional, this might subserve recovery of the ability to maintain a limb position.



Chronically deafferented cats which are then transected show, for the first time, hyperreflexia of crossed responses, which develops gradually during the first week post-transection. It may be related to sprouting of contralateral dorsal roots for contralateral ganglion injection with 3H-proline gives a larger than normal ipsilateral distribution of grain density over the commissural nuclei.



It is suggested that recovery and hyperactivity of reflex responses underlie the recovery of useful movement and that reflex recovery may be related to collateral sprouting. It is also suggested that both the reflex and the anatomical response to a given lesion is restricted to only one of the remaining systems and is therefore a specific rather than a generalized response.

Restitution of function and collateral sprouting in the cat spinal cord: the deafferented animal.

The recovery of postural reflexes and locomotion following low thoracic hemisection in adult cats involves compensation by undamaged primary afferent pathways

Spinal cord damage in neonatal cats has different effects on different spinal pathways. Corticospinal projections exhibit anatomical plasticity, forming an aberrant pathway that bypasses the lesion. In contrast, brainstem-spinal pathways undergo massive retrograde degeneration. Neither of these responses occurs in adult cats. Sparing of motor function is found in cats operated on as neonates but not in cats operated on as adults, and appears to depend on the plasticity of the corticospinal tract.

https://science.sciencemag.org/content/sci/217/4559/553.full.pdf

Anatomical plasticity and sparing of function after spinal cord damage in neonatal cats

The effects of the gamma-aminobutyric acid (GABA) antagonist bicuculline (BCC) on hindlimb motor performance was examined in mature spinal cats with spinal cord transections made either on the day of birth or at approximately two weeks postpartum and in chronic adult cats with spinal transections made in adulthood. In those adult operates, whose pre-drug performance was poor compared to neonatal operates, treadmill locomotion and weight support were improved dramatically by BCC administration. In neonatal operates (examined as adults), BCC administration increased the force of extension to abnormal levels and this increase appeared to disrupt locomotion. Immunocytochemical localization of GABA's synthetic enzyme, glutamic acid decarboxylase (GAD) within the spinal cords of these animals revealed an abnormal distribution of GAD reaction product only in newborn operates. The behavioral results indicate that the full extent of recovery in adult operates is prevented by inhibitory influences and this may contribute to the comparatively superior performance of neonatal operates i.e., the infant lesion effect. The anatomical results suggest that one requirement for the normal development of some intrinsic spinal circuitry is transneuronal regulation mediated by the maturation of descending systems.

Michael E. Goldberger

Papers

Restitution of function and collateral sprouting in the cat spinal cord: the partially hemisected animal

Restitution of function and collateral sprouting in the cat spinal cord: the deafferented animal.

The recovery of postural reflexes and locomotion following low thoracic hemisection in adult cats involves compensation by undamaged primary afferent pathways

Anatomical plasticity and sparing of function after spinal cord damage in neonatal cats

The development and recovery of motor function in spinal cats. II. Pharmacological enhancement of recovery.