Communication in the Brain

Understanding how the brain works depends on understanding how communication between neurons in different parts of the brain leads to behavior. Our research focuses on movements like looking, reaching, grasping and speaking. We ask how individual neurons and groups of neurons in the brain communicate with each other when we are thinking about moving.

Many areas of the brain are active when we are thinking about moving and they are connected into large-scale networks (Figure 1). Our view is that understanding these areas depends on understanding what they are saying to each other. How can we measure communication between brain regions? How does activity within a brain region depend on activity in another? Can we think of one area effectively exciting or inhibiting activity in another? Do areas gate activity in other areas? Which influences are direct and which involve many areas working in a network? How does behavior depend on communication between different brain regions? If we disrupt communication, can we predict changes in how people move? If we strengthen communication, can we improve what they will do?

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Figure 1 – Diffusion spectrum imaging of the macaque brain showing the┬áconnections that form large-scale networks. ┬áSchmahmann et al (2007)

Our work uses a combination of behavioral, physiological and mathematical methods. We examine how different signals, such as current sensory input, recent motor commands and prior experience, guide our movements. We perform experimental measurements and manipulations of neuronal activity across large-scale brain networks to see how brain processes lead to movements. Finally, we employ sophisticated mathematical tools to extract information and obtain inferences from our experimental measures.

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Figure 2 – The dorsal and ventral visual streams.

A great deal of our work examines the dorsal visual stream (Figure 2). This pathway is active when we are planning to move and converts visual inputs into plans for looking, reaching and grasping. In humans, we also study the dorsal stream which processes visual and auditory inputs into speech when we are thinking about talking (Figure 3). Substantial interplay exists between our work in systems neuroscience and our work in neural engineering that provides new ways to think about moving.