UC Berkeley

Theories of working memory and attention postulate that the prefrontal cortex (PFC) provides top-down signals to other brain regions in order to keep behaviorally relevant sensory information activated and to suppress competing task-irrelevant information. Although there are numerous studies that suggest the PFC is a source of top-down modulation of posterior brain regions, the vast majority of these studies offer only indirect evidence in support of this claim. Additionally, while this executive control is usually thought of as being beneficial to the task at hand, there is reason to believe that there are certain circumstances in which this control is deleterious to performance. Here we provide direct evidence using transcranial magnetic stimulation and neuroimaging that 1) the PFC is a source of top-down control of early visual regions and 2) interfering with PFC function can sometimes lead to paradoxical improvements in task performance.