rTMS to the right inferior parietal lobule disrupts self–other discrimination

Abstract

Self-other discrimination is fundamental to social interaction, however, little is known about the neural systems underlying this ability. In a previous functional magnetic resonance imaging study, we demonstrated that a right fronto-parietal network is activated during viewing of self-faces as compared with the faces of familiar others. Here we used image-guided repetitive transcranial magnetic stimulation (rTMS) to create a 'virtual lesion' over the parietal component of this network to test whether this region is necessary for discriminating self-faces from other familiar faces. The current results indeed show that 1 Hz rTMS to the right inferior parietal lobule (IPL) selectively disrupts performance on a self-other discrimination task. Applying 1 Hz rTMS to the left IPL had no effect. It appears that activity in the right IPL is essential to the task, thus providing for the first time evidence for a causal relation between a human brain area and this high-level cognitive capacity.

Transcranial alternating current stimulation to the inferior parietal lobe decreases mu suppression to egocentric, but not allocentric hand movements

“…These results provide direct evidence that the IPL is essential in self-other differentiation (Spence et al, 1997;Blanke et al, 2002;Uddin et al, 2006) as -suppression during observation of hands movements significantly decreased subsequent to IPL-stimulation. In addition, our results support a neurophysiological advantage for self-related stimuli (Jackson, Meltzoff, & Decety, 2006;Maeda, Kleiner-Fisman, & Pascual-Leone, 2002) as subsequent to IPL-stimulation, -suppression only decreased for the egocentric hands movements.…”

“…Thus, the IPL's role in self-other differentiation may be to recognize self-related stimuli. It is possible that the modulation of IPL activity could impact perception of hands movements from both egocentric and allocentric perspectives given that interfering with IPL has been shown to selectively disrupt performance on self-other discrimination (Uddin et al, 2006). This possibility should be more directly tested in the future.…”

“…Neuroimaging studies investigating the neural basis of self-recognition and self-other differentiation have consistently pointed to the involvement of the inferior parietal lobule (IPL) and the inferior frontal gyrus (IFG) Decety et al, 2002;Farrer & Frith, 2002;Farrer et al, 2003;Kaplan et al, 2008;Ruby & Decety, 2001;Uddin et al, 2006). However, neuropsychological literature suggests that the pivotal role is rather played by the IPL.…”

“…Additionally, disruptive brain stimulation to areas within the IPL (right angular gyrus and temporo-parietal junction) results in the out-of-body phenomenon (Blanke et al, 2002;Blanke et al, 2005) and impaired performance on a self-other discrimination task (Uddin et al, 2006). Self-other relations have frequently been studied by means of perspectives or viewpoints (e.g.…”

“…Two alternative hypotheses were made: 1) if IPL is specifically attuned to self-related stimuli (e.g. Kaplan et al, 2008;Uddin et al, 2006) then we expect tACS to selectively reduce -suppression during observation of egocentric (but not allocentric) movements; 2) if IPL is reactive to both self-and other-related stimuli alike (e.g. Spence et al, 1997;Goldenberg & Karnath, 2006) then we predict reduced -suppression following IPL stimulation regardless of perspective.…”