showed an increase for 20-Hz response to the same driving frequencies. Several studies have reported that patients with schizophrenia showed a decreased 40-Hz response to both 20- and 40-Hz stimulation compared with healthy subjects, whereas Vierling-Claassen et al. Because ASSR is prominent at rates near 40 Hz 14 according to almost all studies examining 40-Hz ASSR, 1- 8 ASSR at 40 Hz was measured.ĪSSR at 20 Hz was measured in addition to at 40 Hz because of findings related to patients with schizophrenia. The children were younger than those of previous studies 4, 6- 8, 11- 13 (Table 1), and a narrow age range was chosen for this study to avoid the variation with age shown previously. The aim of the present study was to investigate the ASSR at 40 Hz and 20 Hz in TD children and children with ASD aged 5–7 years. These findings emphasize the importance of age when investigating the brains of children with ASD. In a previous study using graph theory, enhanced and reduced small-worldness, representing the efficiency of information processing, were observed in ASD children (aged 40–70 months). 9 reported hypo- and hyper-connectivity as being partially attributable to the age of the participants examined and hypothesized that in children with ASD, there is an abnormal developmental pattern that shifts from intrinsic hyper-connectivity to hypo-connectivity during the pubertal period. 8 found that both groups showed weak 40-Hz ASSR gamma power, with no group difference between the groups. 5, 7 In a study of typically developing (TD) children and children with ASD aged 7–14 years, Edgar et al. The detection of ASSR patterns could potentially help with this identification however, few studies have investigated ASSR patterns in children with ASD. 6 It is essential that autistic tendencies in children are identified as early as possible so that appropriate care and education can be given. 7 Age-related changes in the strength of the magnetic 40-Hz ASSR from 5 to 52 years have also been reported. 7 In contrast, the evoked power and phase-locking factor for the 20-Hz stimulation had flat or decreasing profiles from the age of 8 to 16 years. 6 In particular, the 40-Hz evoked power and phase-locking factor have been observed to increase monotonically in children between the ages of 8 and 16 years, and then to decrease to the age of 20–22 years. It has been reported that ASSR signals are relatively small during childhood and that they increase as the child grows older. 1 It has been used as an index of the ability for gamma band frequency generation in local cortical networks in mental disorders, including schizophrenia, 2 bipolar disorder, 3 and autism spectrum disorder (ASD). The 40-Hz stimulus produces the strongest steady state response, but the exact mechanism is not fully understood. The auditory steady-state response (ASSR) can be elicited by periodic stimuli and evoked in the primary auditory cortex. Left-side 40-Hz ASSR was associated with intelligence score in both groups. No difference in ASSR was observed between the children with ASD and the TD children, although the right-side 40-Hz ASSR increased with age only in the TD children. Right-dominant ASSR was successfully detected in young TD children and children with ASD. The Kaufmann Assessment Battery for Children score was correlated with the left-side 40-Hz ASSR in both groups.
In the TD children, the right-side 40-Hz ASSR was correlated with age. Consistent with previous findings, right dominance of the 40-Hz ASSR was observed in both groups. Responses to 20 Hz and 40 Hz were clearly detected in both groups with no significant difference identified. Using a custom-made magnetoencephalography device, we measured ASSR at 20 Hz and 40 Hz, compared the results between groups, and evaluated the association with intellectual function as measured by Kaufmann Assessment Battery for Children. The participants were 23 children with ASD and 32 TD children aged 5–7 years. This study investigated the ASSR at 20 Hz and 40 Hz in typically developing (TD) children and children with ASD aged 5–7 years. The auditory steady-state response (ASSR) provides a passive, non-invasive technique for assessing neural synchrony at specific response frequencies in many mental disorders, including autism spectrum disorder (ASD), but few studies have investigated its use in young children. The early detection of autistic tendencies in children is essential for providing proper care and education.
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