Biomedical subjects

Erin A Hayes

Publications and source records attributed to Erin A Hayes.

4 recordsLinked to original sources

PubMed2005

Auditory training improves neural timing in the human brainstem.

The auditory brainstem response reflects neural encoding of the acoustic characteristic of a speech syllable with remarkable precision. Some children with learning impairments demonstrate abnormalities in this preconscious measure of neural encoding especially in background noise. This study investigated whether auditory training targeted to remediate perceptually-based learning problems would alter the neural brainstem encoding of the acoustic sound structure of speech in such children. Nine subjects, clinically diagnosed with a language-based learning problem (e.g., dyslexia), worked with auditory perceptual training software. Prior to beginning and within three months after completing the training program, brainstem responses to the syllable /da/ were recorded in quiet and background noise. Subjects underwent additional auditory neurophysiological, perceptual, and cognitive testing. Ten control subjects, who did not participate in any remediation program, underwent the same battery of tests at time intervals equivalent to the trained subjects. Transient and sustained (frequency-following response) components of the brainstem response were evaluated. The primary pathway afferent volley -- neural events occurring earlier than 11 ms after stimulus onset -- did not demonstrate plasticity. However, quiet-to-noise inter-response correlations of the sustained response ( approximately 11-50 ms) increased significantly in the trained children, reflecting improved stimulus encoding precision, whereas control subjects did not exhibit this change. Thus, auditory training can alter the preconscious neural encoding of complex sounds by improving neural synchrony in the auditory brainstem. Additionally, several measures of brainstem response timing were related to changes in cortical physiology, as well as perceptual, academic, and cognitive measures from pre- to post-training.

Attention↗

PubMed2004

Learning impaired children exhibit timing deficits and training-related improvements in auditory cortical responses to speech in noise.

The physiological mechanisms that contribute to abnormal encoding of speech in children with learning problems are yet to be well understood. Furthermore, speech perception problems appear to be particularly exacerbated by background noise in this population. This study compared speech-evoked cortical responses recorded in a noisy background to those recorded in quiet in normal children (NL) and children with learning problems (LP). Timing differences between responses recorded in quiet and in background noise were assessed by cross-correlating the responses with each other. Overall response magnitude was measured with root-mean-square (RMS) amplitude. Cross-correlation scores indicated that 23% of LP children exhibited cortical neural timing abnormalities such that their neurophysiological representation of speech sounds became distorted in the presence of background noise. The latency of the N2 response in noise was isolated as being the root of this distortion. RMS amplitudes in these children did not differ from NL children, indicating that this result was not due to a difference in response magnitude. LP children who participated in a commercial auditory training program and exhibited improved cortical timing also showed improvements in phonological perception. Consequently, auditory pathway timing deficits can be objectively observed in LP children, and auditory training can diminish these deficits.

Acoustic Stimulation↗

PubMed2003

Integration of heard and seen speech: a factor in learning disabilities in children.

Normal-learning children (NL) and children with learning disabilities (LD) reported their perceptions of unisensory (auditory or visual), concordant audiovisual (e.g. visual /apa/ and auditory /apa/) and conflicting (e.g. visual /aka/ and auditory /apa/) speech stimuli in quiet and noise (0 dB and -12 dB signal-to-noise ratio, SNR). In normal populations, watching such conflicting combinations typically changes auditory percepts ('McGurk effect'). NL and LD children identified unisensory auditory and congruent audiovisual stimuli similarly in all conditions. Despite being less accurate identifying unisensory visual stimuli, LD children were more likely than NL children to report hearing only the visual component of incongruent audiovisual stimuli at -12 dB SNR. Furthermore, LD children with brainstem timing deficits demonstrated a distinctive pattern of audiovisual perception. The results suggest that the perception of simultaneous auditory and visual speech differs between NL and LD children, perhaps reflecting variations in neural processing underlying multisensory integration.

Adolescent↗

PubMed2003

Neural plasticity following auditory training in children with learning problems.

OBJECTIVE: This study examined the plasticity of the central auditory pathway and accompanying cognitive changes in children with learning problems. METHODS: Children diagnosed with a learning disability and/or attention deficit disorder worked with commercial auditory processing training software for 8 weeks; control groups consisted of normal-learning and learning-impaired children who did not participate in any remedial programs. Auditory brainstem function was evaluated in response to click and speech stimuli in quiet; cortical responses to speech stimuli were obtained in quiet and noise. Academic achievement and cognitive abilities were assessed with standardized measures. RESULTS: Compared to controls, the trained group improved on measures of auditory processing and exhibited changes in cortical responses in quiet and in noise. In quiet, cortical responses reflected an accelerated maturational pattern; in background noise, cortical responses became more resistant to degradation. Brainstem responses did not change with training. CONCLUSIONS: Children with learning problems who practiced with auditory training software exhibited plasticity of neural encoding of speech sounds at the cortical, but not subcortical, level of the auditory pathway. This plasticity was accompanied by improvement in behavioral performance. SIGNIFICANCE: This study demonstrates that in learning-impaired children working with commercial auditory processing training programs affects both the perception and the cortical representation of sound.

Achievement↗