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BackgroundPast research indicates that when younger adults are engaged in a visual working memory task, they are less distracted by novel auditory stimuli than when engaged in a visual task that does not require working memory. The current study aimed to determine whether working memory affords the same protection to older adults.MethodWe examined behavioral and EEG responses in 16 younger and 16 older adults to distractor sounds when the listeners performed two visual tasks; one that required working memory (W1) and the other that did not (W0). Auditory distractors were presented in an oddball paradigm, participants were exposed to either standard tones (600 Hz: 80%) or various novel environmental sounds (20%).ResultsIt was found that: 1) when presented with novel vs standard sounds, older adults had faster correct response times in the W1 visual task than in the W0 task, indicating that they were less distracted by the novel sound; there was no difference in error rates. Younger adults did not show a task effect for correct response times but made slightly more errors when a novel sound was presented in the W1 task compared to the W0 task. 2) In older adults (but not the younger adults), the amplitude of N1 was smaller in the W1 condition compared to the W0 condition. 3) The working memory manipulation had no effect on MMN amplitude in older adults. 4) For the W1 compared to W0 task, the amplitude of P3a was attenuated for the older adults but not for the younger adults.ConclusionsThese results suggest that during the working memory manipulation older adults were able to engage working memory to reduce the processing of task-irrelevant sounds.

Background Deficits in emotional prosody processing have been observed in bipolar disorder (BD). While recent neural studies have explored impaired processing of facial expressions, little is known about deficits in emotional speech processing, or the specific stages of processing at which they occur. This study examined if pre-attentive detection and attention to emotional speech is impaired in BD, relative to healthy individuals. Methods The EEG data was collected from 14 individuals with BD and 14 healthy control (HC) participants while the auditory stimuli was presented via a passive three-stimulus oddball sequence which included emotionally (neutral, happy, sad) spoken syllables and acoustically matched nonvocal tones. Event-related potentials (ERPs) were evaluated in terms of Mismatch Negativity (MMN) and P3a (event-related potentials signals). Results Individuals with BD showed normal MMN amplitude, but significantly delayed MMN latency and reduced P3a amplitude in response to the emotional syllables compared to HC. Limitations Small sample size, lack of control of psychopharmacological intervention and no inclusion of an affective prosody-labelling task. Conclusions The finding that changes in emotional speech prosody in the pre-attentive stages of processing (MMN) were unimpaired in individuals with BD; while automatic orientation towards emotionally salient speech (P3a) was reduced compared to HC, suggests that vocal emotional cues may not be recognised as salient by individuals with BD, resulting in fewer attentional resources allocation to further processing. This may lead to poorer integration of auditory emotional cues and other sensory information and negatively impact interpersonal and psychosocial functions.

Adolescence is a time of great change in the brain in terms of structure and function. It is possible to track the development of neural function across adolescence using auditory event-related potentials (ERPs). We measured passive auditory ERPs to pure tones and consonant–vowel (CV) syllables in 90 children and adolescents aged 10–18 years, as well as 10 adults. With one exception, the pattern of results were the same for tones and speech: Across adolescence, the P1 ERP peak decreased in size and latency, the N1 increased in size and decreased in latency, the P2 remained constant in size, and the N2 decreased in size but remained stable across adolescence. The exception was P2 latency, which increased for speech but remained stable for tones. Interesting step-like changes were observed for N1 latency for both tones and speech stimuli in 15- to 16-year-olds. These may stem from rapid hormonal changes that affect neurotransmitter activity of the ERP-generating neurons.

A recent meta-analysis emphasises that meditation can improve attention in healthy adults (Sedlmeier et al., 2012). The findings of a study by Cahn and Polich (2009) suggests that there is an effect of a meditative state on three event-related potential (ERP) brain markers of low-level auditory attention in expert meditators: the N1, the P2, and the P3a. The current study built on these findings by examining the trait and state effects of meditation on the passive auditory mismatch negativity (MMN), N1, and P2 ERPs. We found that the MMN was significantly larger in meditators than non-meditators regardless of whether they were meditating or not (a trait effect), and that the N1 was significantly attenuated during meditation in non-meditators but not meditators (an interaction between trait and state). These outcomes suggest that low-level attention is superior in long-term meditators in general. In contrast, low-level attention is reduced in non-meditators when they are asked to meditate for the first time, possibly due to cognitive overload.

Adolescents experience significant changes in various physiological and psychological domains due to changes in their brain’s structure and function. A lot is known about structural changes in the brain across adolescence. However, less research has investigated changes in brain function during this period. In this study, we tracked the maturation of the auditory mismatch negativity (MMN) and P3a brain responses – both posited as neural indices of auditory discrimination – in 90 adolescents aged 10–18 years. We found that P3a mean amplitude and latency decreased significantly across adolescence, but there was no reliable change in the MMN. These results suggest that neural processes associated with passive auditory processing continue to develop well into adolescence.

Objective To determine if an audible movie soundtrack has a degrading effect on the auditory P1, N1, P2, N2, or mismatch negativity (MMN) event-related potentials (ERPs) in children, adolescents, or adults. Methods The auditory ERPs of 36 children, 32 young adolescents, 19 older adolescents, and 10 adults were measured while they watched a movie in two conditions: with an audible soundtrack and with a silent soundtrack. Results In children and adolescents, the audible movie soundtrack had a significant impact on amplitude, latency or split-half reliability of the N1, P2, N2, and MMN ERPs. The audible soundtrack had minimal impact on the auditory ERPs of adults. Conclusions These findings challenge previous claims that an audible soundtrack does not degrade the auditory ERPs of children. Further, the reliability of the MMN is poorer than P1, N1, P2, and N2 peaks in both sound-off and sound-on conditions. Significance Researchers should be cautious about using an audible movie soundtrack when measuring auditory ERPs in younger listeners.

Background. Auditory event-related potentials (ERPs) have proved useful in investigating the role of auditory processing in cognitive disorders such as developmental dyslexia, specific language impairment (SLI), attention deficit hyperactivity disorder (ADHD), schizophrenia, and autism. However, laboratory recordings of auditory ERPs can be lengthy, uncomfortable, or threatening for some participants – particularly children. Recently, a commercial gaming electroencephalography (EEG) system has been developed that is portable, inexpensive, and easy to set up. In this study we tested if auditory ERPs measured using a gaming EEG system (Emotiv EPOC®, www.emotiv.com) were equivalent to those measured by a widely-used, laboratory-based, research EEG system (Neuroscan). Methods. We simultaneously recorded EEGs with the research and gaming EEG systems, whilst presenting 21 adults with 566 standard (1000 Hz) and 100 deviant (1200 Hz) tones under passive (non-attended) and active (attended) conditions. The onset of each tone was marked in the EEGs using a parallel port pulse (Neuroscan) or a stimulus-generated electrical pulse injected into the O1 and O2 channels (Emotiv EPOC®). These markers were used to calculate research and gaming EEG system late auditory ERPs (P1, N1, P2, N2, and P3 peaks) and the mismatch negativity (MMN) in active and passive listening conditions for each participant. Results. Analyses were restricted to frontal sites as these are most commonly reported in auditory ERP research. Intra-class correlations (ICCs) indicated that the morphology of the research and gaming EEG system late auditory ERP waveforms were similar across all participants, but that the research and gaming EEG system MMN waveforms were only similar for participants with non-noisy MMN waveforms (N = 11 out of 21). Peak amplitude and latency measures revealed no significant differences between the size or the timing of the auditory P1, N1, P2, N2, P3, and MMN peaks. Conclusions. Our findings suggest that the gaming EEG system may prove a valid alternative to laboratory ERP systems for recording reliable late auditory ERPs (P1, N1, P2, N2, and the P3) over the frontal cortices. In the future, the gaming EEG system may also prove useful for measuring less reliable ERPs, such as the MMN, if the reliability of such ERPs can be boosted to the same level as late auditory ERPs.