چه کسی آشناتر از من است؟خود، دیگری و آشنایی در اسکیزوفرنی

Background Familiarity disorders (FDs) critically impact social cognition in persons with schizophrenia. FDs can affect both relationships with people familiar to the patient and the patient's relationship with himself, in the case of a self-disorder. Skin conductance response (SCR) studies have shown that familiar and unknown faces elicit the same emotional response in persons with schizophrenia with FD. Moreover, in control subjects, one's own face and familiar faces have been shown to activate strongly overlapping neural networks, suggesting common processing. The aim of the present study was to determine whether the mechanisms involved in processing one's own and familiar faces are similarly impaired in persons with schizophrenia, suggesting a link between them. Method Twenty-eight persons with schizophrenia were compared with twenty control subjects. Three face conditions were used: specific familiar, self and unknown. The task was to indicate the gender of the faces presented randomly on a screen during SCR recording. Face recognition was evaluated afterwards. Results Control subjects exhibited similar SCRs for the familiar and self-conditions, which were higher than the responses elicited by the unknown condition, whereas persons with schizophrenia exhibited no significant differences between the three conditions. Conclusion Persons with schizophrenia have a core defect of both self and familiarity that is emphasised by the lack of an increased SCR upon presentation with either self or familiar stimuli. Familiarity with specific familiar faces and one's own face may be driven by the same mechanism. This perturbation may predispose persons with schizophrenia to delusions and, in particular, to general familiarity disorder. Abbreviations SCR, skin conductance response; FD, familiarity disorders; μS, microsiemens

Since the early 20th century, familiarity disorders (FD) have been described as a failure of affective judgement (Capgras and Reboul-Lachaux, 1923) capable of strongly impacting social interactions. More recently, the literature on schizophrenia has provided evidence for a defect in the feeling of familiarity in front of familiar individuals, despite preserved recognition (Ellis et al., 1997 and Hirstein and Ramachandran, 1997). Indeed, by using the skin conductance response (SCR) as a somatic indication of emotional arousal, these studies highlighted a lack of emotion elicited by familiar faces in persons with schizophrenia with FD, even though the patients were able to process visual facial features and to recognise their own and familiar faces (Joshua and Rossell, 2009). FD has been described as both a self-centred expression of delusion, in which patients do not express a feeling of familiarity in front of their own face, or as subjective double syndrome, in which they recognise a physical double of themselves in strangers (Luauté and Bidault, 1994 and Luauté, 2009). Despite the growing literature suggesting that schizophrenia is essentially a self-disease (for a review see Nelson et al., 2013a and Nelson et al., 2014b), only a few studies have focused on the ability to recognise one's own face compared with familiar faces in schizophrenia (or in schizotypy), and the studies performed did not reach a clear consensus. Indeed, although some of these studies suggest a general deficit in self-awareness unrelated to familiarity (Kircher et al., 2007, Lee et al., 2007 and Yun et al., 2014), others support a general impairment in familiarity including the familiarity of the self, instead of deficits in self-awareness alone (Irani et al., 2006, Caharel et al., 2007 and Zhang et al., 2012). In addition, these studies have potential biases. First, an explicit judgement of the self or familiarity was required (Caharel et al., 2007, Kircher et al., 2007 and Zhang et al., 2012). This implies conscious processes that could not be involved in familiarity, which is described as a relatively fast and automatic process (Yonelinas and Jacoby, 1994). Second, famous rather than specific familiar (e.g., relatives or friends) faces were used (Lee et al., 2007, Zhang et al., 2012 and Yun et al., 2014). This is an important psychopathological point because famous or widely known individuals do not induce FD in persons with schizophrenia (Capgras and Reboul-Lachaux, 1923). Moreover, different forms of declarative memory have been shown to be involved depending on the stimulus type. Specific familiarity, including familiarity with self, involves episodic or autobiographical memories, whereas famous individuals recruit semantic memories (Gillihan and Farah, 2005). Finally, the neural circuitry involved in the processing of one's own face and familiar faces strongly overlaps (mainly in the temporo-parietal junction), highlighting the link between them, whilst the processing of a famous face recruits different cortical regions (Qin and Northoff, 2011). In the present study, we characterised the affective processing involved in both self and familiarity disorders in persons with schizophrenia using SCR recordings in an implicit task on specific familiar (including self) and unknown faces. Under the assumption that in face recognition, the self will be recognised as familiar, it was expected that persons with schizophrenia would exhibit the same lack of emotional arousal in front of themselves as when facing specific familiar individuals.