Dorsolateral Prefrontal Cortex (DLPFC)
One part of the frontal lobe is worthy of our attention. The most recently evolved and last to develop in adulthood (age 20-24) is the Dorsolateral Prefrontal Cortex (DLPFC). This part of the brain does not receive sensory information from the eyes or the ears, and it does not send motor commands to the muscles. It is the Association cortex that bridges the input and output. This is the part of the brain involved with pausing and choosing actions (Fuster 1990), holding infomation in mind aka Working Memory, (Goldman-Rakic 2006) planning and action sequencing.
Injury or lack of development of this area causes problems with Working Memory, Sequencing, Flexibility, Self Control, Attention & Executive Function.
It is this part of the brain that is targeted for stimulation in rTMS.
By stimulating this area of the brain, depressive symptoms improve. This area was chosen because of the connections it makes with two deeper areas 1) Subgenual Cortex (BA25). Subgenual Cortex hyperactivity has been associated with depression (Mayberg et al., 1999, Drevets 1997). The subgenual region is strongly linked to the Ventral Striatum (Nucleus Accumbens) and orbitofrontal cortex (OFC). By stimulating DLPFC, Subgenual Cortex is inhibited which leads to mood improvement, return of interest and pleasure, better sleep and especially better concentration, memory and thinking.
This part of the brain has fascinated me for more than 20 years, when it was chosen as the target for rTMS stimulation treatment it felt very validating. Don't believe me? try these URLs, www.dorsolateral.com, www.DLPFC.com :-)