Who is speaking? Implicit and explicit self and other voice recognition.

In the domain of self-recognition, voice is a critical feature for self/other distinction. The aim of this study was to explore if people have an implicit and/or explicit knowledge of their voice. A group of healthy participants were submitted to an implicit and an explicit self-voice recognition task. They listened to pairs of pre-recorded auditory stimuli (words or pseudowords) pronounced by themselves, by a familiar or an unfamiliar person. Afterwards, in the "Implicit task" participants had to judge whether the pair of stimuli were pronounced by same or different speakers; in the "Explicit task" they had to identify if one of the stimuli was or not their own voice. Results showed a difference between Implicit and Explicit tasks since participants were more accurate in implicit than explicit self voice-recognition. Moreover, in the Implicit task, participants had the same level of accuracy when they had to judge stimuli pronounced with self or others' voice, whereas when an explicit voice-recognition was required, they were less accurate with self than with others' voice.

Increases of corticospinal excitability in self-related processing.

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 self-hand 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.

Scared by you: modulation of bodily-self by emotional body-postures in autism.

OBJECTIVE: Bodily self-recognition is one aspect of our ability to distinguish between self and others and is central to effective socialization. Here we explored the influence of emotional body postures on bodily self-processing in typically developing (TD) as well as in high-functioning ASD children. METHOD: Subjects' bodies were photographed while expressing endogenously- (self-generated, Experiment 1) or exogenously-driven body emotions (imitated upon request, Experiment 2). Postures conveying positive (happiness), negative (fearful) and neutral valences were used. These pictures served as stimuli in a visual matching-to-sample task with self and others' body-images. RESULTS: A similar self-versus-others advantage was found in TD and in ASD children, since participants were faster with stimuli representing their own than others' body. This "self-advantage" was modulated by self-expressed emotional body postures being present with pictures of happy and neutral, but not fearful body images. This modulation was stronger when emotional postures were endogenously rather than exogenously driven. Moreover, faster responses were observed for others' fearful rather than happy or neutral body images in both groups. CONCLUSIONS: The bodily self-advantage is a low-level function present in typically developing (TD) and in high-functioning ASD children. Body postures, especially when they are endogenously generated, modulate the self and others' body processing. The advantage for processing others' fearful, comparing to others' happy and neutral, body postures may have played a crucial evolutionary role for species survival.

Visual processing of moving and static self body-parts.

Humans' ability to recognize static images of self body-parts can be lost following a lesion of the right hemisphere [Frassinetti, F., Maini, M., Romualdi, S., Galante, E., & Avanzi, S. (2008). Is it mine? Hemispheric asymmetries in corporeal self-recognition. Journal of Cognitive Neuroscience, 20, 1507-1516]. Here we investigated whether the visual information provided by the movement of self body-parts may be separately processed by right brain-damaged (RBD) patients and constitute a valuable cue to reduce their deficit in self body-parts processing. To pursue these aims, neurological healthy subjects and RBD patients were submitted to a matching-task of a pair of subsequent visual stimuli, in two conditions. In the dynamic condition, participants were shown movies of moving body-parts (hand, foot, arm and leg); in the static condition, participants were shown still images of the same body-parts. In each condition, on half of the trials at least one stimulus in the pair was from the participant's own body ('Self' condition), whereas on the remaining half of the trials both stimuli were from another person ('Other' condition). Results showed that in healthy participants the self-advantage was present when processing both static and dynamic body-parts, but it was more important in the latter condition. In RBD patients, however, the self-advantage was absent in the static, but present in the dynamic body-parts condition. These findings suggest that visual information from self body-parts in motion may be processed independently in patients with impaired static self-processing, thus pointing to a modular organization of the mechanisms responsible for the self/other distinction.