The paper is a synthesis of the results from a number of human functional imaging studies. It provides a perspective on the human results that is difficult to see in individual studies. From this perspective emerges evidence for up to eight different motor and premotor areas in the human brain. Thus, it is a useful guide for relating activations observed in human functional imaging studies to the motor areas of the non-human primate brain. The broad scope of the analysis and the usefulness of the framework presented probably contributed to the number of citations that our manuscript received.

  Does it describe a new discovery or a new methodology that's useful to others?

While the methodology is not new, the framework provided by our meta-analysis may be useful for the localization of activations observed in any human functional imaging study.

  Could you summarize the significance of your paper in layman's terms?

New technology allows us to view the human brain in action and to image cognitive processes. Techniques like functional magnetic resonance imaging and positron emission tomography are widely used to generate activation maps of the brain that reflect neuronal activity going on during a task or mental process. Still, our understanding of these maps is constrained by a lack of knowledge of the anatomical organization of the human brain. It is known that the brains of non-human primates contain multiple motor, premotor, and executive areas. These areas are well defined in monkeys. Where they are located in the human brain is far less clear. By using our knowledge of the organization of the monkey brain to interpret maps of activations across many human imaging studies, we identified several distinct fields in the human brain that are involved in specific aspects of motor control. We propose that activations associated with different aspects of movement planning, execution, and control correspond to distinct functional areas that are equivalent to those of non-human primates. Our analysis thus provides a framework for interpreting the results of functional imaging studies in humans and helps to clarify the organization of the motor areas in the human.

  How did you become involved in this research?

A central question in our research is the respective role of each of the multiple motor and premotor areas of the frontal lobe for the generation and control of voluntary movement. We study this in the monkey by a combination of anatomical and physiological techniques. Functional imaging is valuable in measuring the activity of all areas simultaneously. However, it became clear that human imaging studies were a jumble because of the poor knowledge of the organization of the motor and premotor areas in humans. We used our knowledge of this organization in monkeys to make sense of activation maps and, hopefully, lay the groundwork for understanding the functional organization of the motor areas in the human brain.

Nathalie Picard, Ph.D.
Research Assistant Professor
Department of Neurobiology
University of Pittsburgh School of Medicine
Pittsburgh, PA, USA