Auditory memory for backward masking signals in children with language impairment

Abstract

This study was designed to investigate early auditory memory and its possible contribution to an auditory processing deficit shown by some children with language impairment. Ten children with language impairment and 10 age-matched controls participated in a series of simultaneous and backward masking tasks. The same backward masking stimulus was then used to elicit a mismatch negativity response. In the behavioral conditions, children in the language impairment group had significantly higher (poorer) signal thresholds than their nonimpaired controls in backward masking, but their thresholds in simultaneous masking were not significantly different. In the mismatch-negativity conditions, latency was prolonged and the amplitude was diminished in the children with language impairment. Taken together, these psychoacoustic and electrophysiological data suggest that in a group of children with language impairment, underlying the nonsensory language disorder, there is a neurophysiological impairment in auditory memory for complex, nonlinguistic sounds.

Auditory Brainstem Correlates of Perceptual Timing Deficits

“…The backward masking findings reported here reinforce previous research, linking children with LPs with poor backward masking thresholds (Marler, Champlin, & Gillam, 2002;Wright et al, 1997).…”

“…Kujala et al suggested that backward masking interferes with sound perception at the level of the cortex at a preattentive level. Marler et al (2002) showed MMN latency delays and amplitude decreases in children with high backward masking thresholds. Additionally, they saw correlations between MMN and behavioral memory, and suggested impaired early memory mechanisms for complex sounds (Marler et al, 2002).…”

“…Accurate brainstem encoding of the onset of speech is essential for robust processing at the cortical level (Wible et al, 2005), normal patterns of hemispheric dominance (Abrams et al, 2006), as well as cortical sensitivity to acoustic change (Banai et al, 2005). Other studies have used electrophysiological measures in conjunction with backward masking tasks to understand temporal and memory processing in dyslexic adults and children (Kujala, Belitz, Tervaniemi, & Näätänen, 2003;Marler et al, 2002). Kujala et al (2003) found impaired cortical discrimination (mismatch negativity, MMN) of sound-order reversals in dyslexic adults when an additional sound followed the tone pairs, but not when the sound preceded the pairs.…”

Learning problems, delayed development, and puberty

“…These developmental trends are consistent with data from other investigations in which multiple masking conditions, sim- ilar to the present ones, were tested. Compared with same-age controls, thresholds were significantly higher (effect sizes are not available) in the backward but not the onset condition for Ϸ9.3-year-old children with specific language impairment (31) and in the backward but not the forward or delay conditions for Ϸ13-year-old children with dyslexia (29). Additionally, thresholds for a briefer tone than was used here tended to decrease with increasing age in backward, forward, and delay conditions in controls between 5 and 11 years old (32).…”

Neurophysiological indices of attention to speech in children with specific language impairment

“…However, results from several studies are consistent with the suggestion that attention to speech and/or auditory information may differ between SLI and TLD groups. Specifically, several studies have found later latency of N1 in, at least, a subset of Language Impaired (LI) children (Jirsa & Clontz, 1990;Neville, et al, 1993;Tonnquist-Uhlen, Borg, Persson & Spens, 1996), although this was not seen in other studies (e.g., Lincoln, et al, 1995;Marler, Champlin & Gillam, 2002). These differences in N1 latency could be due to reduced N1 negativity leading to the appearance of later N1 peak latency.…”