Effects of Presentation Rate and Attention on Auditory Discrimination: A Comparison of Long-Latency Auditory Evoked Potentials in School-Aged Children and Adults.

Decoding human speech requires both perception and integration of brief, successive auditory stimuli that enter the central nervous system as well as the allocation of attention to language-relevant signals. This study assesses the role of attention on processing rapid transient stimuli in adults and children. Cortical responses (EEG/ERPs), specifically mismatch negativity (MMN) responses, to paired tones (standard 100-100 Hz; deviant 100-300 Hz) separated by a 300, 70 or 10 ms silent gap (ISI) were recorded under Ignore and Attend conditions in 21 adults and 23 children (6-11 years old). In adults, an attention-related enhancement was found for all rate conditions and laterality effects (L>R) were observed. In children, 2 auditory discrimination-related peaks were identified from the difference wave (deviant-standard): an early peak (eMMN) at about 100-300 ms indexing sensory processing, and a later peak (LDN), at about 400-600 ms, thought to reflect reorientation to the deviant stimuli or "second-look" processing. Results revealed differing patterns of activation and attention modulation for the eMMN in children as compared to the MMN in adults: The eMMN had a more frontal topography as compared to adults and attention played a significantly greater role in childrens' rate processing. The pattern of findings for the LDN was consistent with hypothesized mechanisms related to further processing of complex stimuli. The differences between eMMN and LDN observed here support the premise that separate cognitive processes and mechanisms underlie these ERP peaks. These findings are the first to show that the eMMN and LDN differ under different temporal and attentional conditions, and that a more complete understanding of children's responses to rapid successive auditory stimulation requires an examination of both peaks

Adult <i>Ignore</i> grand averaged topographic maps.

<p>Whole-head topographies for grand average waveforms for the <i>Ignore</i> condition at Fc₃ (Ch 17) and Fc₄ (Ch 54) for 300ms (top), 70ms (middle) and 10ms (bottom) ISI’s are shown. Negativity up, positivity down. The standard wave is shown in blue, deviant in red, and difference (deviant-standard) in green. Vertical bars on the baseline indicate the onset of the tones. Tone 1 and tone 2 are paired stimuli.</p

Child <i>Attend</i> grand averaged topographic maps.

<p>Whole-head topographies for grand average waveforms for the <i>Attend</i> condition at Fc₃ (Ch 17) and Fc₄ (Ch 54) for 300ms (top), 70ms (middle) and 10ms (bottom) ISI’s are shown. Negativity up, positivity down. The standard wave is shown in blue, deviant in red, and difference (deviant-standard) in green. Vertical bars on the baseline indicate the onset of the tones. Tone 1 and tone 2 are paired stimuli.</p

Adult <i>Ignore</i> Condition.

<p>Grand average ERP’s of the adults for the <i>Ignore</i> condition at Fc₃ (Ch.17) and Fc₄ (Ch.54) for 300ms (top), 70ms (middle) and 10ms (bottom) ISI’s are shown. Response to the standard stimuli (blue line), the deviant stimuli (red line) and the difference condition (standard- deviant; green line) are plotted. Vertical pink bars on the baseline indicate the onset of the tones. Tone 1 and tone 2 are paired stimuli. Negative voltages are plotted up, positive voltages are plotted down.</p

Adult <i>Attend</i> Condition.

<p>Grand average ERP’s of the adults for the <i>Attend</i> condition at Fc₃ (Ch 17) and Fc₄ (Ch 54) for 300ms (top), 70ms (middle) and 10ms (bottom) ISI’s are shown. Response to the standard stimuli (blue line), the deviant stimuli (red line) and the difference condition (standard- deviant; green line) are plotted. Vertical pink bars on the baseline indicate the onset of the tones. Tone 1 and tone 2 are paired stimuli. Negative voltages are plotted up, positive voltages are plotted down.</p

Children <i>Attend</i> Condition.

<p>Grand average ERP’s of children for the <i>Attend</i> condition at Fc₃ (Ch. 17) and Fc₄ (Ch. 54) for 300ms (top), 70ms (middle) and 10ms (bottom) ISI’s are shown. Response to the standard stimuli (blue line), the deviant stimuli (red line) and the difference condition (standard- deviant; green line) are plotted. Vertical pink bars on the baseline indicate the onset of the tones. Tone 1 and tone 2 are paired stimuli. Negative voltages are plotted up, positive voltages are plotted down.</p

Adult <i>Attend</i> grand averaged topographic maps.

<p>Whole-head topographies for grand average waveforms for the <i>Attend</i> condition at Fc₃ (Ch 17) and Fc₄ (Ch 54) for 300ms (top), 70ms (middle) and 10ms (bottom) ISI’s are shown. Negativity up, positivity down. The standard wave is shown in blue, deviant in red, and difference (deviant-standard) in green. (deviant-standard) in green. Vertical bars on the baseline indicate the onset of the tones. Tone 1 and tone 2 are paired stimuli.</p

Children <i>Ignore</i> Condition.

<p>Grand average ERP’s of children for the <i>Ignore</i> condition at Fc₃ (Ch 17) and Fc₄ (Ch 54) for 300ms (top), 70ms (middle) and 10ms (bottom) ISI’s are shown. Response to the standard stimuli (blue line), the deviant stimuli (red line) and the difference condition (standard- deviant; green line) are plotted. Vertical pink bars on the baseline indicate the onset of the tones. Tone 1 and tone 2 are paired stimuli. Negative voltages are plotted up, positive voltages are plotted down.</p

Means and Standard Deviations of the Late Difference Negativity (LDN) Amplitude (mV) in the <i>Ignore</i> and <i>Attend</i> condition for Children.

<p>Means and Standard Deviations of the Late Difference Negativity (LDN) Amplitude (mV) in the <i>Ignore</i> and <i>Attend</i> condition for Children.</p