Introduction

Patients who survive focal brain injury for example stroke, undergo complete or more commonly partial recovery of function (Twitchell, 1951). The management of patients with incomplete recovery draws on specific rehabilitation interventions aimed at assisting adaptation to impairment. However there is a growing interest in designing therapeutic strategies to promote cerebral reorganisation as a way of reducing rather than compensating for impairment. This interest stems largely from experiments in animal models, which have unequivocally demonstrated post-lesional changes in cerebral organisation related to recovery. In addition, it is clear that focal cortical damage in adult brains renders widespread surviving cortical regions more able to change structure and function in response to afferent signals in a way normally only seen in the developing brain (Schallert et al., 2000; Bury and Jones, 2002) (see Chapter 14 of Volume I, pp. 21-28 for a more extensive discussion of these changes). Activity-driven changes in these regions may be enhanced by experiential (Nudo et al., 1996) or pharmacological (Feeney, 1997) context, and correlate with functional recovery. These findings are clearly very exciting for clinicians. It has been suggested that similar injury-induced changes occur in the human brain, and that their manipulation will provide a means of promoting functional recovery in patients with focal brain damage. One crucial aspect of developing such strategies involves building an empirical understanding of how the brain responds to injury and how such changes may be manipulated in a way that promotes functional recovery. The investigation of cerebral reorganisation after focal brain injury in humans is less well advanced than similar work in animal models. There are clearly greater limitations in studying the human brain, but functional imaging, a technique that allows measurement of task-related brain activation, provides an opportunity to do so. Furthermore, one must consider that the findings from animals apply almost exclusively to cortical damage, whereas much of the work in humans to date has been performed in patients with deep subcortical infarcts. Nevertheless, both approaches have yielded important results from which a clearer picture of functional cerebral reorganisation is beginning to emerge.

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