Parietal cortex and representation of the mental Self Hans C.Lou*t+,Bruce Luber*,Michael Crupain*,Julian P.Keenans,Markus Nowak',Troels W.Kjaert Harold A.Sackeim*,and Sarah H.Lisanby* Magnetic Brain Stimulation Laboratory,Department of Biological Psychiatry.New York State Psychiatric Institute,and Department of Psychiatry,Columbia Neurpimaging Laboratory.Department of Psychology.Montclair State University,219 Dickson.Upper Montcar.Ngen Denmark:and Cognitive Edited by Michael I.Posner,University of Oregon,Eugene,OR,and approved March 11,2004(received for review January 8,2004) For a coherent and meaningful life,conscious self-representation is a simple non-memory-loaded condition with identical input and mandatory.Such explicit"autonoetic consciousness"is thought to output as a control. emerge by retrieval of memory of personally experienced events Finally,not only may episodic memory retrieval and,hence, ("episodic memory").During episodic retrieval,functional imaging autonoetic consciousness be accompanied by activation in the studies consistently show differential activity in medial prefrontal medial parietal region,but this region could also be essential for and medial parietal cortices.With positron-emission tomography the task.To test this third hypothesis,we use transcranial we here show that these medial regions are functionally connected magnetic stimulation (TMS)(5)to transiently disrupt normal and interact with lateral regions that are activated according to the neural activity in the medial parietal region to see whether such degree of self-reference.During retrieval of previous judgments of disruption would affect the task. Oneself,Best Friend,and the Danish Queen,activation increased in the left lateral temporal cortex and decreased in the right inferio Subjects and Methods parietal region with decreasing self-reference.Functionally.the CBF.Thirteen right-handed participants of Danish nationality (7 former region was preferentially connected to medial prefrontal females;age range,20-38 yr,median age of 27 yr)first rated a cortex,the latter to medial parietal.The medial parietal region series of 75 personality trait adjectives as to how well they applied may,then,be conceived of as a nodal structure in self-represen- to themselves.or.in separate series.their best friend or the tation,functionally connected to both the right parietal and the Danish Queen,translated into Danish from ref.6.The rating was medial prefrontal cortices.To determine whether medial parietal done on a six-point scale to ensure adequate encoding (7).The cortex in this network is essential for episodic memory retrieval adjectives were allocated to the series randomly,to achieve with self-representation,we used transcranial magnetic stimula- counterbalance for likeability,and were shown sequentially on a tion over the region to transiently disturb neuronal circuitry.There monitor.Scanning took place =5 min later while the series of was a decrease in the efficiency of retrieval of previous judgment adjectives was shown again,one at a time.The subjects should of mental Self compared with retrieval of judgment of Other with have recalled whether each adjective had initially been charac- transcranial magnetic stimulation at a latency of 160 ms,confirm- terized as fitting the person or not.Accuracy was stressed,speed ing the hypothesis.This network is strikingly similar to the network was not.The results were reported on a keyboard with a of the resting conscious state,suggesting that self-monitoring is a two-point scale by using the right index finger (2).Two scans core function in resting consciousness. were carried out for each of the three conditions for each participant.In addition,a control scan was done during presen-