Abstract
Understanding the nature and form of prefrontal cortex representations that support flexible behavior is an important open problem in cognitive neuroscience. In humans, multi-voxel pattern analysis (MVPA) of fMRI BOLD measurements has emerged as an important approach for studying neural representations. An implicit, untested assumption underlying many MVPA studies is that the base rate of decoding information encoded in neuronal activity from BOLD activity patterns, is invariant across brain regions. Here we test this assumption by estimating these base rates from a meta-analysis of published MVPA studies. We show that this assumption is violated for the prefrontal cortex, which shows a significantly lower base rate for decoding than visual sensory cortex. Our results have implications for the design and interpretation of MVPA studies of prefrontal cortex, and raise important questions about its functional organization.