Abstract
The foundations of Neuropsychology lie in the fields of behavioral neuroscience, applied psychological evaluation, and behavioral neurological investigation. These areas have provided increasing sophistication about the nature of the relationship between changes in brain function and human behavior. Continuing developments in these fields will provide the foundation upon which our applied activities rest and from which they take their scientific validity. The use of neuropsychological evaluative tools as aids in understanding the consequences of subtle and, in many instances, not primarily neurological medical illnesses represents a threshold of investigation and clinical application. The sensitivity of clinical neuropsychological tools to disruptions in brain function, previously left unrecognized in individuals who have sustained neurological injury or illness, represents the second threshold issue. Yet another threshold issue is the use of neuropsychological investigation as a preventive tool and as an early warning signal for the appreciation of a broad range of risk factors encountered by individuals not typically thought of as potential patients for neuropsychologists. This article discusses the growing use of neuropsychological tools to understand the broader range of human behavioral difficulties and human medical consequences.