Increases of corticospinal excitability in self‐related processing

Abstract

Involvement of fronto-parietal structures within the right hemisphere in bodily self recognition has gained convergent support from behavioural, neuropsychological and neuroimaging studies. Increases in corticospinal excitability via transcranial magnetic stimulation (TMS) also testify to right hemisphere self-related processing. However, evidence for self-dependent modulations of motor excitability is limited to the processing of face-related information that, by definition, conveys someone's identity. Here we tested the hypothesis that vision of one's own hand, as compared with vision of somebody else's hand, would also engage specific self-hand processing in the right hemisphere. Healthy participants were submitted to a classic TMS paradigm to assess changes in corticospinal excitability of the right (Experiment 1) and left (Experiment 2) motor cortex, while viewing pictures of a (contralateral) still hand, which could either be their own (Self) or not (Other). As a control for body selectivity, subjects were also presented with pictures of a hand-related, but non-corporeal object, i.e. a mobile phone, which could similarly be their own or not. Results showed a selective right hemisphere increase in corticospinal excitability with self-hand and self-phone stimuli with respect to Other stimuli. Such a Self vs. Other modulation of primary motor cortex appeared at 600 ms and was maintained at 900 ms, but was not present at earlier timings (100 and 300 ms) and was completely absent following stimulation of the left hemisphere. A similar pattern observed for selfhand and self-phone stimuli suggests that owned hands and objects may undergo similar self-processing, possibly via a different cortical network from that responsible for self-face processing.

The Cognitive Ecology of the Internet

“…These showed 1) the subject's own hand, 2) the hand of another human subject, 3) the subject's own mobile phone, or 4) the mobile phone of another person. Interestingly, Salerno et al (2012) observed similar neurological responses when subjects were presented with images of both their own hands and their own mobile phones (i.e., self-related stimuli). However, these responses were distinct from those elicited by the images of 'other-related' stimuli (i.e., the hands or phones of other people).…”

“…However, these responses were distinct from those elicited by the images of 'other-related' stimuli (i.e., the hands or phones of other people). Although the psychological significance of these results is unclear at the present time, Salerno et al (2012) note that issues of bodily extension may be relevant to their findings. Interestingly, the effects observed by Salerno et al (2012) were specific to the right hemisphere of the brain.…”

“…Although the psychological significance of these results is unclear at the present time, Salerno et al (2012) note that issues of bodily extension may be relevant to their findings. Interestingly, the effects observed by Salerno et al (2012) were specific to the right hemisphere of the brain. This is consistent with neuropsychological research indicating that the right brain hemisphere is important to a sense of body ownership, with damage to the right hemisphere resulting in a form of 'disownership' of particular body parts (Aglioti et al, 1996;Vallar and Ronchi, 2009).…”

“…One further line of research that may be relevant to claims regarding the bodily incorporation of Internet-enabled devices comes from a study by Salerno et al (2012). Salerno et al (2012) sought to investigate the neural processing of self-and other-related stimuli using a trans-cranial magnetic stimulation technique.…”

“…Salerno et al (2012) sought to investigate the neural processing of self-and other-related stimuli using a trans-cranial magnetic stimulation technique. As part of their experimental protocol, human subjects were presented with four kinds of images.…”