what is brain lesions
1 Brain lesions (lesions on the brain) refers to any type of abnormal tissue in or on brain tissue.  Major types of brain lesions are traumatic, infectious, malignant, benign, vascular, genetic, immune, plaques, brain cell death or malfunction, and ionizing radiation.
Humans with brain lesions are often the subjects of research with the goal of establishing the function of the area where their lesion occurred. A drawback to the use of human subjects is the difficulty in finding subjects who have a lesion to the area which the researcher wishes to study.