Differential auditory experiences of children with hearing-loss who receive cochlear implants (CIs) may influence the integration of lexical and conceptual information. Here we measured event-related potentials during a word-picture priming task in CI-using children (n = 29, mean age = 81 months) and typically-hearing children (n = 19, mean age = 75 months) while they viewed audiovisual-word primes and picture targets that were semantically congruent or incongruent. In both groups, semantic relatedness modulated ERP amplitude 300-500ms after picture onset, signifying an N400 semantic effect. Critically, the CI-using children's responses to unrelated pairs were significantly more negative than hearing children's responses. Group differences were mirrored in an earlier 150-275ms time window associated with a P2 response. The present findings suggest attentional and/or strategic differences impact semantic processing and contribute to the N400 differences observed between groups.

Background

A neurobiological-based classification of attention-deficit/hyperactivity disorder (ADHD) subtypes has thus far remained elusive. The aim of this study was to use oscillatory changes in the electroencephalogram (EEG) related to informative cue processing, motor preparation, and top-down control to investigate neurophysiological differences between typically developing (TD) adolescents, and those diagnosed with predominantly inattentive (IA) or combined (CB) (associated with symptoms of inattention as well as impulsivity/hyperactivity) subtypes of ADHD.

Methods

The EEG was recorded from 57 rigorously screened adolescents (12 to 17 years of age; 23 TD, 17 IA, and 17 CB), while they performed a cued flanker task. We examined the oscillatory changes in theta (3-5 Hz), alpha (8-12 Hz), and beta (22-25 Hz) EEG bands after cues that informed participants with which hand they would subsequently be required to respond.

Results

Relative to TD adolescents, the IA group showed significantly less postcue alpha suppression, suggesting diminished processing of the cue in the visual cortex, whereas the CB group showed significantly less beta suppression at the electrode contralateral to the cued response hand, suggesting poor motor planning. Finally, both ADHD subtypes showed weak functional connectivity between frontal theta and posterior alpha, suggesting common top-down control impairment.

Conclusions

We found both distinct and common task-related neurophysiological impairments in ADHD subtypes. Our results suggest that task-induced changes in EEG oscillations provide an objective measure, which in conjunction with other sources of information might help distinguish between ADHD subtypes and therefore aid in diagnoses and evaluation of treatment.

Deaf children who receive a cochlear implant early in life and engage in intensive oral/aural therapy often make great strides in spoken language acquisition. However, despite clinicians' best efforts, there is a great deal of variability in language outcomes. One concern is that cortical regions which normally support auditory processing may become reorganized for visual function, leaving fewer available resources for auditory language acquisition. The conditions under which these changes occur are not well understood, but we may begin investigating this phenomenon by looking for interactions between auditory and visual evoked cortical potentials in deaf children. If children with abnormal auditory responses show increased sensitivity to visual stimuli, this may indicate the presence of maladaptive cortical plasticity. We recorded evoked potentials, using both auditory and visual paradigms, from 25 typical hearing children and 26 deaf children (ages 2-8 years) with cochlear implants. An auditory oddball paradigm was used (85% /ba/ syllables vs. 15% frequency modulated tone sweeps) to elicit an auditory P1 component. Visual evoked potentials (VEPs) were recorded during presentation of an intermittent peripheral radial checkerboard while children watched a silent cartoon, eliciting a P1-N1 response. We observed reduced auditory P1 amplitudes and a lack of latency shift associated with normative aging in our deaf sample. We also observed shorter latencies in N1 VEPs to visual stimulus offset in deaf participants. While these data demonstrate cortical changes associated with auditory deprivation, we did not find evidence for a relationship between cortical auditory evoked potentials and the VEPs. This is consistent with descriptions of intra-modal plasticity within visual systems of deaf children, but do not provide evidence for cross-modal plasticity. In addition, we note that sign language experience had no effect on deaf children's early auditory and visual ERP responses.

Purpose

This research examined the expression of cortical auditory evoked potentials in a cohort of children who received cochlear implants (CIs) for treatment of congenital deafness (n = 28) and typically hearing controls (n = 28).

Method

We make use of a novel electroencephalography paradigm that permits the assessment of auditory responses to ambiently presented speech and evaluates the contributions of concurrent visual stimulation on this activity.

Results

Our findings show group differences in the expression of auditory sensory and perceptual event-related potential components occurring in 80- to 200-ms and 200- to 300-ms time windows, with reductions in amplitude and a greater latency difference for CI-using children. Relative to typically hearing children, current source density analysis showed muted responses to concurrent visual stimulation in CI-using children, suggesting less cortical specialization and/or reduced responsiveness to auditory information that limits the detection of the interaction between sensory systems.

Conclusion

These findings indicate that even in the face of early interventions, CI-using children may exhibit disruptions in the development of auditory and multisensory processing.