The authors utilized repetitive transcranial magnetic stimulation (rTMS) in 16 normal volunteers to investigate the role of the left dorsolateral prefrontal cortex (PFC) in analogic reasoning. rTMS over the left and right PFC, over the left motor cortex, and sham stimulation over the left PFC were administered during memory and analogic reasoning conditions. rTMS over the left PFC led to a significant reduction in response times only in the analogy condition without affecting accuracy. These results indicate that the left PFC is relevant for analogic reasoning and that rTMS applied to the PFC can speed up solution time.

Neurology 2001 Feb 27;56(4):526-8
Boroojerdi B, Phipps M, Kopylev L, Wharton CM, Cohen LG, Grafman J.
Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA.