Archives

  • 2018-07
  • 2018-10
  • 2018-11
  • 2019-04
  • 2019-05
  • 2019-06
  • 2019-07
  • 2019-08
  • 2019-09
  • 2019-10
  • 2019-11
  • 2019-12
  • 2020-01
  • 2020-02
  • 2020-03
  • 2020-04
  • 2020-05
  • 2020-06
  • 2020-07
  • 2020-08
  • 2020-09
  • 2020-10
  • 2020-11
  • 2020-12
  • 2021-01
  • 2021-02
  • 2021-03
  • 2021-04
  • 2021-05
  • 2021-06
  • 2021-07
  • 2021-08
  • 2021-09
  • 2021-10
  • 2021-11
  • 2021-12
  • 2022-01
  • 2022-02
  • 2022-03
  • 2022-04
  • 2022-05
  • 2022-06
  • 2022-07
  • 2022-08
  • 2022-09
  • 2022-10
  • 2022-11
  • 2022-12
  • 2023-01
  • 2023-02
  • 2023-03
  • 2023-04
  • 2023-05
  • 2023-06
  • 2023-07
  • 2023-08
  • 2023-09
  • 2023-10
  • 2023-11
  • 2023-12
  • 2024-01
  • 2024-02
  • 2024-03
  • 2024-04

    • At the age of years all

    2018-11-07

    At the age of 5 years, all three groups exhibited more negative responses to the deviant stimuli in the 335–535ms interval, and there was no group difference in the LDN mean amplitude. This suggests that the lexical tone perception abilities of late-talking children continue to develop with age, growing closer to the ability level of the TLD group. Nevertheless, we observed less mature MMRs in LTs in the change of topography. The results showed a site-by-group interaction in the 185–335ms and 335–535ms intervals. The differences between the frontal and central MMRs (i.e., Fz–Cz, F4–C4) were negative in the two time intervals for the TLD group. In the two late-talking groups, the MMRs were more positive than those of the TLD group at the frontal sites in the mid and right channels in the 185–335ms and 335–535ms intervals. Studies using the MMN paradigm to investigate the categorical perception of Mandarin lexical tone in native Chinese adults reported that across-category deviants elicited higher MMN than within-category deviants in the left frontal site (Xi et al., 2010), but children with dyslexia did not show this pattern (Zhang et al., 2012). Furthermore, when infants’ neural responses to Finnish consonant-vowel syllables were tested, the pp1 responses to/ga/at approximately 600ms in at-risk newborns had a slower polarity shift from the major positive peak toward the later negative deflection; this pattern was the clearest at the right hemisphere (Guttorm et al., 2001). A subsequent longitudinal study showed that children who exhibit at-risk processing patterns at birth achieve lower receptive language skill scores between the ages of 2.5 and 5 years and have lower word/nonword reading accuracy and fluency measures in the first grade than children who exhibit normative responses do (Guttorm et al., 2005). Corresponding to the previous study, the rightward site differences in our study indicated that LTs still possess a less sophisticated speech perception ability at 5 years of age. Grossheinrich et al., (2010) compared MMN responses to frequency change in pure tones (1000Hz vs. 1200Hz) under two interstimulus (ISI) conditions to investigate whether a reduced duration of auditory sensory memory is found in late talking children. Their results showed that MMN mean amplitude was reduced only for the ISI of 2000ms in former late talking children both with and without persistent language deficits. Comparing the results of Grossheinrich et al. (2010) and our study, while their LT participants exhibit a MMN comparable to those of controls for shorter ISI conditions (500ms), our results demonstrated the group differences in MMR amplitude at 3 years old and topographic distribution at 5 years old. One of the reasons for the discrepancy might be resulted by the participants’ age (4 years and 7 months); the other possibility would be that LTs only have deficits in discriminating speech stimuli and have preserved ability to discriminate nonspeech (pure tone) frequency changes. Future studies directly compare MMRs to speech and nonspeech stimuli would clarify this issue. Several studies have suggested that the MMR elicited in infants is predictive of later language outcomes (Leppänen et al., 2002; van Leeuwen et al., 2006; van Zuijen et al., 2013). Our correlation analysis extended the predictive role of MMRs to later language outcome measures in the preschool period. The mean MMR amplitude at 3 years of age in the frontocentral channels were significantly correlated with vocabulary, syntax, and overall language performance on standardized tests at 6 years. Comparing with previous behavioral studies, MacRoy-Higgins et al. (2013) examined the causal relationship between phonology and lexical acquisition in 24-month-old children who either were LTs or had TLD. The toddlers were taught 12 novel words differing in phonotactic probability (high vs. low) by using focused stimulation procedures over the course of 10 training sessions. After the training sessions, a preferential-looking paradigm was used to test word retention through comprehension, production, and toddlers’ ability to detect mispronunciations of the newly learned words. The results showed that LTs did not differentiate between words containing high and those containing low phonotactic probability. The authors concluded that the underlying impairment in late-talking toddlers could be an early inability to detect regularities in the phonological system of the language that they are exposed to, which in turn inhibits their ability to store the phonological forms required to acquire lexical items. The correlation results in our study confirmed that the sophisticated speech discrimination ability at the early age might not only be a supporting mechanism for establishing stable phonological representation but also be essential for language development in children with late expressive language.