Lesion-induced and training-induced brain reorganization.

Abstract

INTRODUCTION:

A stroke may modulate motor cortex excitability. We examined if distinct ischemic brain lesions are associated with a specific pattern of excitability changes. We also investigated the effects of a rehabilitative therapy on motor excitability.

METHODS:

In stroke patients, the consequences of a) a lesion in the central somatosensory system, b) a cerebellar lesion and c) a two week period of Constraint-induced movement therapy (CIMT), on motor cortex excitability were studied. Transcranial magnetic stimulation techniques and functional magnetic resonance imaging (fMRI) were employed.

RESULTS:

Patients with a lesion in the primary somatosensory cortex or in the ventroposterolateral nucleus of the thalamus had a decreased intracortical inhibition on the affected side. Patients with lesions in the territory of the superior cerebellar artery had a loss of intracortical facilitation and an increase of intracortical inhibition. Patients with cortical lesions undergoing CIMT had a loss of intracortical inhibition prior to therapy. After CIMT, changes of ICI were stronger in the lesioned than in the non-lesioned hemisphere but could result either in an increase of ICI or a reduction of ICI. In three patients fMRI results showed that cortical activation was less post CIMT as compared to pre-treatment activation. In parallel, ICI was reduced after treatment.

CONCLUSIONS:

Our results suggest that, physiologically, central somatosensory influence on the motor cortex is inhibitory. In contrast, the cerebellum normally exerts a facilitatory influence on the motor cortex. CIMT induces changes of intracortical excitability mainly in the affected hemisphere.

• Authors: J Liepert, F Hamzei, C Weiller
• Journal: Restorative neurology and neuroscience (Restor Neurol Neurosci) Vol. 22 Issue 3-5 Pg. 269-77 ( 2004) ISSN: 0922-6028 [Print] Netherlands
• PMID: 15502271 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Review)

Topics

• Brain (pathology, physiology)
• Humans
• Neuronal Plasticity (physiology)
• Recovery of Function (physiology)
• Stroke (pathology)
• Stroke Rehabilitation