Visual information is processed by multiple brain systems. These systems connect what we see, hear and feel with what we want to do and they do so according the kind of movement we are making (see Figure 1. One system is active when we are thinking about moving the eyes (red; saccade), and another system for moving the arm (green; reach). In the human brain, there are similar circuits that let us listen and speak (see Speech).
We are interested in how neurons in different regions of the brain work together to control our behavior. Coordination is an exceptional feature of natural behavior. Eye movements guide reaching movements of the arm and grasping movements of the hand. Since the brain systems for moving each have a different behavioral output, coordination provides an opportunity to investigate how communication guides behavior. In particular, we can ask, How does coordination depend on communication between different regions of the brain? Our recent work indicates that the neurons in the eye movement and arm movement systems of posterior parietal cortex, (known as area LIP and PRR) are communicating with each other in order to coordinate when we move the eyes with the arm. Interestingly, posterior parietal neurons appear to use temporal patterns of activity, called neuronal coherence, to communicate with other groups of neurons.