Barbara Knowlton, Ph.D.
Department of Psychology
University of California, Los Angeles
March 28, 2011
Habit Learning in Humans and Animal Models
Will Durant (1885–1981) wrote that, "We are what we repeatedly do. Excellence, then, is not an act, but a habit." The essence of this statement is implicitly represented in the work of many modern day neuroscientists. In her presentation, Dr. Knowlton described work showing that habit memories have very unique properties with respect to other types of memory, and that the formation of these memories can be localized to a particular structure in the brain.
Over the last several decades, neuroscientists have learned that the brain does not treat memories, in the broadest sense, as a single format. Rather, our brains produce different types of memories that are acquired, coded and stored in different manners. For example, the way we remember the names of our friends and family is rather distinct from how we remember to drive a car or ride a bicycle. Our capacity to remember names and events is referred to as declarative memory, while our ability to ride a bicycle has been classified as a procedural memory. Furthermore, the division between procedural and declarative memories is not merely categorical, it is supported by the evidence that impairing or removing different parts of the brain may affect declarative but not procedural memory, and vice versa. These compartmental differences between types of memory raise interesting questions about how we store information about the world. The Knowlton lab is interested in a particular type of memory known as habit learning.
During the course of her presentation, Dr. Knowlton argued that much of our ongoing behavior is based on habits that allow us to use our attentional resources for other tasks. Habits, as we all know, are learned, and so must be stored somewhere in the brain. The key to understanding this process lies in converging data from humans and animal models indicating that habits depend on a brain structure known as the striatum. Dr. Knowlton discussed the notion that habit memories have distinct behavioral properties. Her results suggested that learning under distraction is likely to result in habit memories that are less flexible than memories learned under full attention. On the other hand, patients with disorders of striatum, including Parkinson's disease, may have difficulty with habit learning, and thus must effortfully and consciously retrieve information that would otherwise be retrieved automatically as a habit.