Limits...
Late, not early mismatch responses to changes in frequency are reduced or deviant in children with dyslexia: an event-related potential study.

Halliday LF, Barry JG, Hardiman MJ, Bishop DV - J Neurodev Disord (2014)

Bottom Line: However, findings have been inconsistent, both for behavioural and electrophysiological measures.Conventional analyses revealed no significant differences between groups in the size of the MMN to either large or small frequency deviants.Rather, deficits in late-stage auditory processing appear to be a feature of this population.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Psychology and Language Sciences, University College London, 2 Wakefield Street, London WC1N 1PF, UK ; Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK.

ABSTRACT

Background: Developmental disorders of oral and written language have been linked to deficits in the processing of auditory information. However, findings have been inconsistent, both for behavioural and electrophysiological measures.

Methods: In this study, we examined event-related potentials (ERPs) in 20 6- to 14-year-old children with developmental dyslexia and 20 age-matched controls, divided into younger (6-11 years, n = 10) and older (11-14 years, n = 10) age bands. We focused on early (mismatch negativity; MMN) and late (late discriminative negativity; LDN) conventional mismatch responses and associated measures derived from time-frequency analysis (inter-trial coherence and event-related spectral perturbation). Responses were elicited using an auditory oddball task, whereby a stream of 1000-Hz standards was interspersed with rare large (1,200 Hz) and small (1,030 Hz) frequency deviants.

Results: Conventional analyses revealed no significant differences between groups in the size of the MMN to either large or small frequency deviants. However, the younger age band of children with dyslexia showed an enhanced inter-trial coherence in the theta frequency band over the time window corresponding to the MMN to small deviants. By contrast, these same children showed a reduced-amplitude LDN for the small deviants relative to their age-matched controls, whilst the older children with dyslexia showed a shorter and less intense period of event-related desynchronization over this time window.

Conclusions: Initial detection and discrimination of auditory frequency change appears normal or even enhanced in children with dyslexia. Rather, deficits in late-stage auditory processing appear to be a feature of this population.

No MeSH data available.


Related in: MedlinePlus

Average mismatch responses from first principal component by DYS status and age band. Dummy difference files are shown in grey, large deviants in red, and small deviants in blue. Regions where t test value is < -1.96 are shown as bars of same colour below the plot.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4126817&req=5

Figure 3: Average mismatch responses from first principal component by DYS status and age band. Dummy difference files are shown in grey, large deviants in red, and small deviants in blue. Regions where t test value is < -1.96 are shown as bars of same colour below the plot.

Mentions: The difference waveforms for each subgroup are shown in Figure 3. One-sample t tests were conducted at each time point to identify regions where the averaged difference waveform for all participants fell significantly below zero. T values < -1.96 are shown below the waveforms in Figure 3. In order to give an indication of how much amplitude is to be expected by chance, dummy waveforms were created by subtracting the average for standards from each standard-before-deviant. These show the likelihood of obtaining spurious differences as a result of conducting multiple comparisons across time points that are not independent of one another. As illustrated in Figure 3, both the younger and the older DYS groups showed a short period of enhanced negativity occurring around 200 ms post-stimulus onset (i.e. during the time window corresponding to the MMN) for large deviants only. The same pattern was not reliably seen in the TD group. For the LDN time window (350–550 ms), the DYS group showed a significant difference wave, although this was significant for large deviants only in the younger DYS group and for small deviants only in the older DYS group. The opposite pattern was seen in the TD group (i.e. a significant difference wave occurred during the LDN time window to small deviants for the younger TD group and to large deviants for the older TD group).


Late, not early mismatch responses to changes in frequency are reduced or deviant in children with dyslexia: an event-related potential study.

Halliday LF, Barry JG, Hardiman MJ, Bishop DV - J Neurodev Disord (2014)

Average mismatch responses from first principal component by DYS status and age band. Dummy difference files are shown in grey, large deviants in red, and small deviants in blue. Regions where t test value is < -1.96 are shown as bars of same colour below the plot.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4126817&req=5

Figure 3: Average mismatch responses from first principal component by DYS status and age band. Dummy difference files are shown in grey, large deviants in red, and small deviants in blue. Regions where t test value is < -1.96 are shown as bars of same colour below the plot.
Mentions: The difference waveforms for each subgroup are shown in Figure 3. One-sample t tests were conducted at each time point to identify regions where the averaged difference waveform for all participants fell significantly below zero. T values < -1.96 are shown below the waveforms in Figure 3. In order to give an indication of how much amplitude is to be expected by chance, dummy waveforms were created by subtracting the average for standards from each standard-before-deviant. These show the likelihood of obtaining spurious differences as a result of conducting multiple comparisons across time points that are not independent of one another. As illustrated in Figure 3, both the younger and the older DYS groups showed a short period of enhanced negativity occurring around 200 ms post-stimulus onset (i.e. during the time window corresponding to the MMN) for large deviants only. The same pattern was not reliably seen in the TD group. For the LDN time window (350–550 ms), the DYS group showed a significant difference wave, although this was significant for large deviants only in the younger DYS group and for small deviants only in the older DYS group. The opposite pattern was seen in the TD group (i.e. a significant difference wave occurred during the LDN time window to small deviants for the younger TD group and to large deviants for the older TD group).

Bottom Line: However, findings have been inconsistent, both for behavioural and electrophysiological measures.Conventional analyses revealed no significant differences between groups in the size of the MMN to either large or small frequency deviants.Rather, deficits in late-stage auditory processing appear to be a feature of this population.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Psychology and Language Sciences, University College London, 2 Wakefield Street, London WC1N 1PF, UK ; Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK.

ABSTRACT

Background: Developmental disorders of oral and written language have been linked to deficits in the processing of auditory information. However, findings have been inconsistent, both for behavioural and electrophysiological measures.

Methods: In this study, we examined event-related potentials (ERPs) in 20 6- to 14-year-old children with developmental dyslexia and 20 age-matched controls, divided into younger (6-11 years, n = 10) and older (11-14 years, n = 10) age bands. We focused on early (mismatch negativity; MMN) and late (late discriminative negativity; LDN) conventional mismatch responses and associated measures derived from time-frequency analysis (inter-trial coherence and event-related spectral perturbation). Responses were elicited using an auditory oddball task, whereby a stream of 1000-Hz standards was interspersed with rare large (1,200 Hz) and small (1,030 Hz) frequency deviants.

Results: Conventional analyses revealed no significant differences between groups in the size of the MMN to either large or small frequency deviants. However, the younger age band of children with dyslexia showed an enhanced inter-trial coherence in the theta frequency band over the time window corresponding to the MMN to small deviants. By contrast, these same children showed a reduced-amplitude LDN for the small deviants relative to their age-matched controls, whilst the older children with dyslexia showed a shorter and less intense period of event-related desynchronization over this time window.

Conclusions: Initial detection and discrimination of auditory frequency change appears normal or even enhanced in children with dyslexia. Rather, deficits in late-stage auditory processing appear to be a feature of this population.

No MeSH data available.


Related in: MedlinePlus