Understanding the relationship between brain and behavior has been an important, but at the same time complex, phenomenon in the field of neuropsychology. Studying the effects of brain functions on human behavior requires working with methods that allow us to analyze different aspects of mental functions. This article therefore addresses one of the ways to assess brain function in human and non-human animals; the lesion method (in Banich, 2004). The basic concept of the lesion method is to determine a correlation between a lesion in a certain region of the brain and the behaviors that occur. The lesion method strategy therefore involves ablation or destruction of a part of the brain in order to understand the functional nature of that specific part of the brain and its effects on behavior (in Carlson, 2006). A lesion refers to the structural change or damage of brain tissues that can be directly related to a certain aspect of mental function, thus leading to a decline in brain functioning. The existence of injuries in humans can occur in many different ways, such as strokes, tumors, traumatic brain injuries, accidents, etc. And it is these patients who have provided us with valuable information about the effects of brain injury on human behavior and the nature of brain injury. neurologically intact individuals (in Carlson, 2006). Overall, research agrees that different aspects of behavior are mediated by distinctive parts of the brain; a concept called localization of function (in Banich, 2004). Since the brain is made up of various components, each of which provides support for different mental processes, the principle of localization of function implies that some regions of the brain are limited to specific locations (in Banich, 2004)....... half of the paper .. .... has contributed to our understanding of the brain not only by allowing us to uncover the nature of lesion deficits in brain-damaged patients, but also by allowing us to study brain function in neurologically intact individuals. Intact individuals have also contributed to our understanding of the different neuroanatomical structures of the brain and how mental processes work. Works Cited Banich MT (2004). Cognitive neuroscience and neuropsychology (2nd ed.). Boston: Houghton Mifflin CO. Boddy., J. (1978). Brain systems and psychological concepts. Sutton Surrey. By John Wiley & Sons, Ltd.Carlson. Navy (2006). Fundamentals of behavioral neuroscience. (8th ed.). Allyn and Bacon. Pearson Education, Inc. Passer, M., Smith, R., Holt, N., Bremner, A., Sutherland, E., & Vliek, M. (2009). Psychology; Science of mind and behavior. (European edition). New York.