Halligan & Wade_22

A theory of cognitive rehabilitation should specify how change from a damaged state of cognitive processing can be modified into a normal, or more functional, state of cognitive processing. Such a theory should incorporate what is known about the cognitive representations and processes underlying normal cognition, how these are affected by brain damage, and how learning or modification of cognitive processing occurs. It is therefore argued that development of a useful theory of cognitive rehabilitation will require integrating advances from cognitive neuropsychology, experimental psychology, computational neuroscience, and molecular biology of the brain, as well as empirical evidence from various branches of rehabilitation. It is likely that such a theory will specify how behavioral rehabilitation strategies can be augmented by pharmacological agents. Rehabilitation of cognitive impairments is among the most challenging and rewarding endeavors of clinician-scientists. Hence, it is no wonder that seemingly everyone wants to ‘get in on the act.’ In the past two decades, cognitive rehabilitation has been the focus of investigators and therapists in a wide range of disciplines: speech-language pathology, occupational therapy, clinical psychology, neuropsychology, experimental psychology, neurology, neuroscience, linguistics, education, neuroimaging, computationalism, and others. This cross interaction has been productive. For example, many speech language pathologists treating aphasia or other cognitive impairments caused by focal brain damage have found it useful to consider cognitive neuropsychological models of the cognitive processes underlying the task to be treated (see Chapey 2001; Coltheart, Chapter Brunsdon and Nickess, Chapter 2 this volume; Hillis 2002; Riddoch and Humphreys 1994a; Seron and DeLoche 1989, for examples). Several authors have argued that these models provide an essential first step to rehabilitation, in terms of identifying the components of each task that are impaired, and the components that are spared, allowing the clinician to capitalize on the spared components and to focus treatment or facilitation on the damaged components (Beeson and Rapczak 2002; Hillis 1993, 1994, 1998; Riddoch and Humphreys 1994b; Wilson and Patterson 1990). The focus of this chapter concerns the next step: How do we move beyond the demonstrated success in determining ‘what to treat’ to the critical issues of ‘when, how, and how much to treat’? We (Caramazza and Hillis 1993; see also Hillis 1993, 1998) have previously argued that the questions of when, how, and how much to treat cannot be answered on the basis of cognitive neuropsychological models. Such models have been developed to represent a theory of the normal cognitive processes that must be engaged in order to perform a task (e.g., reading a word). They are Halligan & Wade_22 13/12/2004 6:32 PM Page 271