Hemodynamic Differences in Children with Dichotic Listening Deficits: Preliminary Results from an fMRI Study during a Cued Listening Task

Abstract

Functional magnetic resonance images were acquired while children with and without dyslexia identified incongruous words embedded within fairy tale segments in a quasidichotic listening task. All children produced greater activation in the left hemisphere than in the right hemisphere during the binaural separation listening task. Children with dyslexia, who had a higher incidence of a dichotic left ear deficit from prescanning behavioral tests, produced fewer hits and more misses than control children while monitoring their left ears in the scanner. Control children produced stronger left hemispheric activation for ipsilateral left ear input than right hemispheric activation for ipsilateral right ear input, but ipsilateral activation patterns in children with dyslexia were symmetrical. Children with dyslexia who monitored their right ears first produced the lowest left hemispheric activation overall, suggesting that priming of the right ear may have inhibited the ability of children with a left ear deficit to adequately identify target words presented toward their left ears while in the scanner.

Sound localization and word discrimination in reverberant environment in children with developmental dyslexia

“…Sound localization process (important for word perception) has been few studied in school and social environments. Sound discrimination has been more studied, for example, Montcrieff et al carried-out observations of AD by means of fMRI in children with DD; they presented recordings of tales with discordant words and they observed that children with DD presented lower activation in left hemisphere, and a more symmetric inter-hemispheric activation 28 . Olivares-García et al data are in line with these conclusions, showing that AD requires a functional symmetry among cerebral hemispheres in children with DD 15 .…”

Abnormal Oscillatory Neural Coupling in Children with Language-Learning Problems and Auditory Processing Disorder

“…The integrative processing in ST and the effects of beta activity in dichotic temporal order judgments provide a plausible explanation for the deficits in dichotic listening skills often reported for children with LLP, including children with reading disorders. 37,38 In this way, deficits in temporal encoding networks might affect the detection of timing differences between dichotic stimuli resulting in insufficient gating of subsequent inputs. Of the 14 children with LLP tested for this study, we obtained behavioral results for 7 children, which included standard scores on the SCAN-C (Table 2), a clinical screening test for children with APD.…”

“…An explanation for these deficits may be an insufficient coupling and decoupling of task-related oscillatory networks resulting from an underlying interaural asymmetry in this population. 38,42,43 Beta activity during dichotic listening has been localized to bilateral auditory regions in ST. 29 It is possible that the separation of two beta COFs in the LLP group reveal a physiological signature of asymmetries between left and right auditory regions in ST. We note that such inferences should be taken with caution, as the stimuli in this study were not presented dichotically and did not require a behavioral response. Results from the present study can only point to a compromised alpha-beta network during early stages of auditory perception in children with LLP.…”

Dichotic listening deficits in amblyaudia are characterized by aberrant neural oscillations in auditory cortex

“…In a quasi-dichotic ERP study using speech stimuli, children with AMB were unable to process aberrant stimuli presented to their left ears with competing signals presented to their right ears (Jerger et al, 2002;Moncrieff et al, 2004). Similarly, early fMRI studies noted hemispheric deficiencies when children with AMB listened to dichotic stimuli compared to normal controls (Hashimoto et al, 2000;Moncrieff et al, 2008). Because dichotic listening places greater demands on attention, engaging more cognitive control to process information in the non-dominant ear, it typically results in greater activity in the left superior temporal gyrus, inferior frontal gyrus, and superior anterior cingulate (Hugdahl et al, 2003;Jäncke et al, 2001;Jäncke and Steinmetz, 2003).…”

“…Children with AMB have a range of difficulties in the domains of auditory (e.g., poor verbal working memory, speech comprehension (especially in noise), localization], cognitive [e.g., attention), linguistic (e.g., syntactic impairment), and social processing (e.g., poor adaptive and self-esteem skills) (Lamminen and Houlihan, 2015; Moncrieff et al, 2004; Popescu and Polley, 2010; Whitton and Polley, 2011). A unilateral deficit during dichotic listening tasks has long been attributed to callosal dysfunction (Musiek, 1983; Musiek and Weihing, 2011), though later studies have recognized that functional asymmetries along the auditory system might provide a basis for the disorder, possibly as low as the brainstem superior olivary complex (Hiscock and Kinsbourne, 2011; Moncrieff et al, 2008; Tollin, 2003). Otitis media, closed-head injuries, and co-morbid disabilities in early childhood may contribute to periods of auditory deprivation that are well known to produce structural and functional abnormalities in the brainstem (Clopton and Silverman, 1977; Coleman and O’Connor, 1979; Moore and Irvine, 1981; Popescu and Polley, 2010; Silverman and Clopton, 1977; Smith et al, 1983; Webster and Webster, 1979) that may lead to AMB.…”