Earl Miller: 2012 Allen Institute for Brain Science Symposium

From physics to electrophysiology and imaging, Dr. Miller and his lab focus on broad and far-reaching approaches to neuroscience questions. This symposium talk focused on questions similarly posed by Sabine Kastner, namely the relationship between action potential timing and brain function. By recording neural activity in monkeys as they switch among two tasks, Miller found that over half of the recording sites in the network for one task also appear to participate in the network for the other task. This suggests that circuitry in the prefrontal cortex may overlap and that oscillations are the key to selecting appropriate networks for the task that needs to be performed. Miller showed that neural ensembles, or networks, in close proximity oscillate out of phase with one another to avoid being simultaneously activated. That is, the oscillations bind neural ensembles together and ensure that multiple ensembles don&interfere with one another. In fact this work responds to a question posed by Donoghue: how is one particular neural ensemble selected from large populations of highly connected neurons? The answer, posits Miller, is that they must have a key feature to support cognitive flexibility, allowing them to change from moment to moment just as thoughts change rapidly from moment to moment. This may in fact explain a fundamental point about consciousness, Miller suggests: only so many ensembles can fit in a single oscillation cycle, perhaps accounting for the limited...