Mark M. Churchland
The Logic of Brain Function
The brain is not only a remarkable computational organ, capable of feats that stymie the best computers and robots; it is the generator of our thoughts and actions. Yet the field of neuroscience has principally asked how the brain transforms inputs into outputs. This approach has led to foundational, Nobel-prize winning work. Yet the brain is clearly more than a glorified input-output device. The neural networks within it do not just respond reflexively to external stimuli, they also generate their own activity. In doing so they produce thoughts, plans, decisions and actions. A central goal of my laboratory is to understand the mechanisms and logic that allow the brain to generate meaningful internal activity. How does a neural circuit plan and decide? How does it generate movement? To address these questions, we use tasks that require ours subjects to decide upon a course of action, plan that movement, and then generate the neural activity to produce that movement. While the task is being performed, we record the activity of large populations of neurons in parts of the brain that are active during decision-making, movement preparation, and movement generation. We use mathematical analysis and modeling techniques to try and decipher how, at a mechanistic level, the neural circuitry functions to allow the subject to succeed at the task. This work is expected to shed light on some of the most important neural capacities that define who we are. Our work is also informs the development of neural-prosthetic devices, which allow paralyzed patients to directly drive external devices using their own internally generated neural activity.