ERP Evidence of a Dichotic Left-Ear Deficit in Some Dyslexic Children

Abstract

Children with and without behavioral dichotic left-ear deficits participated in an event-related potential study with quasidichotic presentations of familiar fairy tale segments. Electrical activity was recorded from the scalp while the children listened for semantically and/or syntactically anomalous words from either the right side or the left side while competing segments of the fairy tale were simultaneously presented from the opposite side. Latencies and amplitudes were averaged for each target condition within the group with dichotic left-ear deficits (LED) and the group with normal dichotic listening performance (WNL). Individual global field power waveforms and topographic brain maps were generated for the average response in each of the two listening conditions, target right and target left. Cross-correlations were performed on the grand averaged global field power waveforms to measure the degree of synchrony between target right and target left responses in both groups. Integration functions were performed to compare the accumulated sum of voltages during target (right and left) and control (right and left) conditions. WNL children produced typical ERP responses to the target words in both target right and target left conditions. Responses from LED children were at delayed latencies in the target left condition and were at reduced amplitudes in both target conditions. Topographic brain maps revealed more lateralized scalp distributions and greater activation of frontal regions in LED children in the target left condition. Cross-correlational and integration function results demonstrated interaural asymmetries in responses from the LED children. Overall results suggest that slowed neural conduction times, poor interhemispheric transfer of neural activity, and a failure to suppress competing information arriving at the right ear may be involved in poor left-sided processing in children with behavioral left-ear dichotic deficits.

Auditory processing tests for Spanish-speaking adults: An initial study

“…From the first studies of Bocca et al (1954) using filtered speech to assess subjects with temporal lobe tumour, and those of Kimura (1961) using dichotic stimulation to assess subjects with cerebral lesions, to recent studies using electrophysiological measurements to assess AP (Moncrieff et al, 2004), this area has been of interest to audiologists. AP has been explored in many groups of subjects, such as in persons with Alzheimer's disease (Iliadou & Kaprinis, 2003;Strouse et al, 1995), presbycusis (Frisina & Frisina, 1997), dyslexia (Hugdahl et al, 1998;Sapir et al, 2002;Schulte-Korne et al, 1998), specific language impairment (Tallal et al, 1985), brainstem and cortical lesions (Baran et al, 2004;Musiek, 1983), organic solvent exposure (Varney et al, 1998), and epilepsy (Ortiz et al, 2002).…”

Divided-Attention and Directed-Attention Listening Modes in Children with Dichotic Deficits: An Event-Related Potential Study

“…T he degree and direction of interaural asymmetry on dichotic listening (DL) tests, or, in some cases, the lack thereof, has received considerable interest in research examining a wide spectrum of clinical disorders, ranging from dyslexia and attention-deficit disorder to schizophrenia and epilepsy. In the particular case of children suspected of having an auditory processing disorder (APD), there is cause to suggest that discrepancies between the right-and left-ear performance scores, generally in the form of a left-ear deficit (LED), may be one sign characterizing the disorder (Morton and Siegel, 1991;Lamm and Epstein, 1994;Moncrieff and Musiek, 2002;Moncrieff et al, 2004). Studies using auditory event-related potentials (ERPs) to explore interaural asymmetry in these children have obtained similar results (Jerger et al, 2002;Moncrieff et al, 2004).…”

“…In the particular case of children suspected of having an auditory processing disorder (APD), there is cause to suggest that discrepancies between the right-and left-ear performance scores, generally in the form of a left-ear deficit (LED), may be one sign characterizing the disorder (Morton and Siegel, 1991;Lamm and Epstein, 1994;Moncrieff and Musiek, 2002;Moncrieff et al, 2004). Studies using auditory event-related potentials (ERPs) to explore interaural asymmetry in these children have obtained similar results (Jerger et al, 2002;Moncrieff et al, 2004). Given the profile of the test outcome and what is known about the maturation and role of the corpus callosum in mediating interhemispheric communication, it has been hypothesized that the LED may arise from a disruption in the interhemispheric transfer of auditory information (Musiek et al, 1984;Jerger et al, 1986;Musiek et al, 1988).…”

A Brief Overview of Amblyaudia

“…The deficits in speech comprehension also impact reading fluency and comprehension through a chain of reactions. The misperception of verbal phonemes leads to a poor semantic database, which then makes reading comprehension more tedious, decreases reading fluency, and increases the likelihood of dyslexia [8] [24].…”

“…Children who experience temporary hearing loss, most commonly from ear infections, are at an increased risk of developing amblyaudia [5] [6]. Characteristics of amblyaudia include speech comprehension difficulties, reading difficulties, information processing deficits, poor verbal working memory, poor adaptive skills, and inattention [7] [8].…”