Would you be happy in a job where every single deliberate and conscious action you made had to be previously approved by your boss? Thankfully, in this scenario, the only one you must answer to is within your brain. The prefrontal cortex (PFC) has long been thought of as the executive control center of goal-directed behavior, and like how a world leader needs to be prepared and able to quickly change strategies as demands and circumstances change within their nation, your PFC facilitates and executes behavior in a fluid, information-sensitive manner.

Research unveiling the mystery of how these executive processes occur have been largely aided by technological advances in neurosurgery. For example, scientists can now implant recording devices directly onto, and sometimes through, the brain surface of patients treated for neurological disorders (e.g. epilepsy), unveiling a wealth of data that is collected as the patient is awake and performing various tasks. More importantly, these intracranial recordings (electrocorticography; ECoG) are highly precise in their spatial and temporal resolution, providing an arguably better idea of brain function compared to other prominent imaging techniques, such as the less temporally precise functional magnetic resonance imaging method. In ECoG, tiny electrodes record local field potentials (LFPs), which serve as a proxy for the summed electric current flowing from a collection of neurons.

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Intracranial electrode grid for electrocorticography (ECoG) [Wikipedia Commons]

How decision making occurs has begun to be looked at an elevated level compared to single neuron activity; while the individual activation of single brain cells can be highly associated with cognitive phenomena, their spiking and excitability properties can be better thought of as being a consequence sustained activation or interactions at the population level. For instance, human intracranial data filtered to look at high-frequency (70-200 Hz) activity revealed that the PFC became active only when unpredicted deviants (e.g. errors) were detected in an auditory attention task. At Robert Knight’s cognitive neuroscience research laboratory at the University of California, Berkeley, it has recently been proposed that such oscillatory dynamics at the network level reflect “activity-silent” encoding of rules relevant to the task at hand. For example, while active processing by the brain’s executive control center has been thought of as increase in neuronal spiking or high frequency activity, cognitive phenomena, such as prediction error detection, has been observed to arise without changes in individual spiking activity. This “activity silent” encoding is thought to reflect endogenous oscillatory activity that may underlie how PFC guides behavior.

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“Different contexts could be embedded in distinct spatiotemporal configurations of the same network” [Randolph & Knight, 2016]

Come check out Dr. Knight’s talk, titled “Insights into human cognition from intracranial recording”, on Tuesday, April 4th, at 4 P.M. in the CNCB Marilyn Farquhar Seminar Room.

Christian Cazares is a first-year neuroscience graduate student rotating in the Chalasani Lab. He can be reached at @fleabrained and www.chriscaz.com

Randolph F. H. and Knight R. T. (2016) Oscillatory Dynamics of Prefrontal Cognitive Control Trends in Cognitive Sciences, Volume 20 , Issue 12 , 916 – 930

Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436.

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