Self-specific processing in the default network: a single-pulse TMS study
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In examining neural processing specific to the self, primarily by contrasting self-related stimuli with non-self-related stimuli (i.e., self vs. other), neuroimaging studies have activated a consistent set of regions, including medial prefrontal cortex (MPFC), precuneus, and right and left inferior parietal cortex. However, criticism has arisen that this network may not be specific to self-related processing, but instead reflects a more general aspect of cortical processing. For example, it is almost identical to the active network of the resting state, the “default” mode, when the subject is free to think about anything at all. We tested the self-specificity of this network by using transcranial magnetic stimulation (TMS) to briefly disrupt local cortical processing while subjects rated adjectives as like or unlike themselves or their best friend. Healthy volunteers show a self-reference effect (SRE) in this task, in which performance with self-related items is superior to that with other-related items. As individual adjectives appeared on a monitor, single-pulse TMS was applied at five different times relative to stimulus onset (SOA: stimulus onset asynchrony) ranging from 0 to 480 ms. In 18 subjects, TMS to left parietal cortex suppressed the SRE from 160 to 480 ms. SRE suppression occurred at later SOA with TMS to the right parietal cortex. In contrast, no effects were seen with TMS to MPFC. Together with our previous work, these results provide evidence for a self-specific processing system in which midline and lateral inferior parietal cortices, as elements of the default network, play a role in ongoing self-awareness.
KeywordsTMS Self Parietal cortex Default network
Dr. Lisanby has received research support, for topics not presented here, from Magstim Company, Neuronetics, Cyberonics, and ANS. Columbia University has applied for a patent for novel TMS technology developed in Dr. Lisanby’s Laboratory, for work unrelated to the topic presented here.
- Anderson NH (1968) Likableness ratings of 555 personality-trait words. J Pers Soc Psychol 9:272–279Google Scholar
- Deng Z-D, Peterchev AV, Lisanby SH (2008) Coil design considerations for deep-brain transcranial magnetic stimulation (dTMS). In: Conference Proceedings of IEEE Engineering in Medicine and Biology Society, pp 5675–5679Google Scholar
- Deng Z-D, Lisanby SH, Peterchev AV (2009) Effect of anatomical variability on neural stimulation strength and focality in electroconvulsive therapy (ECT) and magnetic seizure therapy (MST). In: Conference Proceedings of IEEE Engineering in Medicine and Biology Society, pp 682–688Google Scholar
- Gardiner JM (2001) Episodic memory and autonoetic consciousness: a first person approach. Philos Trans R Soc Lond B Biol Sci 356:1351Google Scholar
- Homan RW, Herman J, Purdy P (1987) Cerebral location of international 10–20 system electrode placement. Electroencephalogr Clin Neurophysiol 66:376–382Google Scholar
- Luber B, Peterchev A, Nguyen T, Sporn A, Lisanby SH (2007a) Application of TMS in psychophysiological studies. In: Cacioppo JT, Tassinary LG, Berntson GG (eds) Handbook of psychophysiology, 3rd edn. Cambridge University Press, New YorkGoogle Scholar
- Raichle ME, MacLeod AM, Snyder AZ, Powers WJ, Shulman GL (2001) A default mode of brain function. Proc Natl Acad Sci USA 98:676–682Google Scholar
- Rossini PM, Rossi S (2007) Transcranial magnetic stimulation: diagnostic, therapeutic, and research potential. Neurology 68:484–488Google Scholar
- Ruby P, Legrand D (2008) Neuro imaging the self? In: Haggard P, Rosetti Y, Kawato M (eds) Sensorimotor foundations of higher cognition. Attention and performance XXII. Oxford University Press, LondonGoogle Scholar