Original articleEvent-related potentials of self-face recognition in children with pervasive developmental disorders
Introduction
Pervasive developmental disorders (PDD) are characterized by a unique behavior in communication. Persons with PDD often have difficulty reading facial expressions and deciphering their implied meaning. PDD may cause developmental deficits in theory of mind (ToM), mind-reading, and empathy underlying social interaction and communication skills [1], [2], [3], [4], [5]. They are probably related to face cognition, because in many cases the face information can help us understand others’ feelings and recognize the communication situation.
Recently, noninvasive neuroimaging techniques have found dysfunctions in the brain domain related to perception of the face, eye gaze, and facial expression in persons with PDD [6], [7], [8], [9], [10]. Some studies showed that face-structural analysis contributed to fusiform gyrus. Other studies showed that eye gaze, emotion, and person identity corresponded to the inferior frontal cortex (IFC), amygdala, limbic system, and superior temporal sulcus (STS) [11], [12]. These areas are partly referred as mirror neuron system (MNS), which is associated with execution and observation of actions by oneself and/or others [13], [14]. In other words, the MNS affects social cognition significantly [15], [16]. Hence, we hypothesized that self-awareness and familiarity of a face also correspond to the MNS because both processes mutually affect social skills and communicative abilities. Indeed, the areas IFC and STS showed strong activity during self-face cognition [7], [17], [18], [19], [20]. Such a neurophysiological approach would help to define the etiology of autistic disorders (ADs) in PDD and to improve poor social skills; however, such studies are rare.
Many studies have evaluated the developmental stages of cognitive function following visual and auditory perception using event-related potentials (ERPs) [9], [21], [22], [23]. This technique is advantageous for clinical application, because ERP can be measured noninvasively and repeatedly, even in children. Analysis of the P300 component is especially effective for checking developmental stage and symptom severity because this component influences discrimination ability of stimulus features i.e., frequency, size, shape, and familiarity [21]. In the present study, we measured P300 followed by the face-specific response N170, and compared among the responses to one’s own face, a familiar face and an unfamiliar face. This may be the first study based on neurological evidence to explore person identity nodes in face cognition in AD.
Section snippets
Subjects
The PDD group consisted of eight children (seven boys and one girl) with Asperger’s syndrome (AS) or high function autism (HFA) aged 10.8 ± 2.9 years, one of whom was left-handed (FIQ: 97 ± 12; VIQ: 102 ± 15; PIQ: 92 ± 11). The subjects were recruited from National Center Hospital of Neurology and Psychiatry (Kodaira, Japan), and their diagnosis was based on DSM-IV criteria (American Psychiatric Association, 1994) by two pediatric neurology specialists [24]. The subjects’ intelligence quotients were
Results
We checked that the subjects could correctly discriminate the stimulus images of each condition prior to the recordings. All subjects successfully pressed a key in response to target stimuli, and the accuracy was 96.4% in the PDD group, 98.8% in the Children group, and 99.8% in the Adult group. The RT was longer (P < 0.05) in the PDD (508.5 ± 63.8 ms) and Children (483.0 ± 96.4 ms) groups than in the Adult group (409.7 ± 58.9 ms).
For all subjects, the N170 component was observed in the occipito-temporal
Discussion
Self-awareness is often interpreted by two concepts; one concept is a feedback system to one’s own action through somatosensory, visual, and auditory processes. To pinch something, we usually control our fingers through vision and somatosensory information, while motor planning encodes expected sensory traces for actions. We continuously monitor both the efference copy by planned movements and the proprioceptor/exteroceptor from real movements; thus, the relationship may create self-body image
Acknowledgement
This study was supported by a Health and Labor Sciences Research Grant (H16-Kokoro-001) for Research on Psychiatric and Neurological Diseases and Mental Health from the Ministry of Health, Labor, and Welfare of Japan, JST “Brain science and Education” Type I, and a MEXT Grant-in-Aid for Young Scientists (B) (700324).
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