I think therefore I am: Rest-related prefrontal cortex neural activity is involved in generating the sense of self.

The sense of self has always been a major focus in the psychophysical debate. It has been argued that this complex ongoing internal sense cannot be explained by any physical measure and therefore substantiates a mind-body differentiation. Recently, however, neuro-imaging studies have associated self-referential spontaneous thought, a core-element of the ongoing sense of self, with synchronous neural activations during rest in the medial prefrontal cortex (PFC), as well as the medial and lateral parietal cortices. By applying deep transcranial magnetic stimulation (TMS) over human PFC before rest, we disrupted activity in this neural circuitry thereby inducing reports of lowered self-awareness and strong feelings of dissociation. This effect was not found with standard or sham TMS, or when stimulation was followed by a task instead of rest. These findings demonstrate for the first time a critical, causal role of intact rest-related PFC activity patterns in enabling integrated, enduring, self-referential mental processing.

Positive effects of repetitive transcranial magnetic stimulation on attention in ADHD Subjects: a randomized controlled pilot study.

OBJECTIVES: Repetitive transcranial stimulation (rTMS) affects dopaminergic secretion in the prefrontal cortex. Attention deficit hyperactivity disorder (ADHD) had been suggested to involve dopaminergic prefrontal abnormalities. METHODS: In this crossover double-blind randomized, sham-controlled pilot study, patients diagnosed as having adult ADHD received either a single session of high-frequency rTMS directed to the right prefrontal cortex (real rTMS) or a single session of sham rTMS. RESULTS: A total of 13 patients (seven males, six females) who fulfilled the criteria for adult ADHD, according to DSM-IV criteria gave informed consent and were enrolled. There was a specific beneficial effect on attention 10 minutes after a real rTMS course. The post-real rTMS attention score improved significantly (M=3.56, SD=0.39) compared to the pre-real rTMS attention score (M=3.31, SD=0.5) [t(12)=2.235, P < 0.05]. TMS had no effect on measures of mood and anxiety. The sham rTMS had no effect whatsoever. CONCLUSIONS: Our findings should encourage future research on the possibility of amelioration of attention difficulties in patients suffering from ADHD by using high frequency rTMS directed to the right dorsolateral prefrontal cortex. (NIH registry NCT00825708).