The prefrontal cortex maintains working memory information in the presence of distracting stimuli. It has long been thought that sustained activity in individual neurons or groups of neurons was responsible for maintaining information in the form of a persistent, stable code. This study shows that, upon the presentation of a distractor, information in the lateral prefrontal cortex was reorganized into a different pattern of activity to create a morphed stable code without losing information. In contrast, the code in the frontal eye fields persisted across different delay periods but exhibited substantial instability and information loss after the presentation of a distractor. Neurons with mixed-selective responses were necessary and sufficient for the morphing of code and it was observed that these neurons were more abundant in the lateral prefrontal cortex than the frontal eye fields. The authors suggest that mixed selectivity provides populations with code-morphing capability, a property that may underlie cognitive flexibility.
Parthasarathy A, Herikstad R, Bong JH, Medina FS, Libedinsky C, Yen SC: Mixed selectivity morphs population codes in prefrontal cortex. Nature Neuroscience 20(12): 1770-1779 (2017).