scholarly journals Cortical Processing of Binaural Cues as Shown by EEG Responses to Random-Chord Stereograms

Author(s):  
Henri Pöntynen ◽  
Nelli Salminen

AbstractSpatial hearing facilitates the perceptual organization of complex soundscapes into accurate mental representations of sound sources in the environment. Yet, the role of binaural cues in auditory scene analysis (ASA) has received relatively little attention in recent neuroscientific studies employing novel, spectro-temporally complex stimuli. This may be because a stimulation paradigm that provides binaurally derived grouping cues of sufficient spectro-temporal complexity has not yet been established for neuroscientific ASA experiments. Random-chord stereograms (RCS) are a class of auditory stimuli that exploit spectro-temporal variations in the interaural envelope correlation of noise-like sounds with interaurally coherent fine structure; they evoke salient auditory percepts that emerge only under binaural listening. Here, our aim was to assess the usability of the RCS paradigm for indexing binaural processing in the human brain. To this end, we recorded EEG responses to RCS stimuli from 12 normal-hearing subjects. The stimuli consisted of an initial 3-s noise segment with interaurally uncorrelated envelopes, followed by another 3-s segment, where envelope correlation was modulated periodically according to the RCS paradigm. Modulations were applied either across the entire stimulus bandwidth (wideband stimuli) or in temporally shifting frequency bands (ripple stimulus). Event-related potentials and inter-trial phase coherence analyses of the EEG responses showed that the introduction of the 3- or 5-Hz wideband modulations produced a prominent change-onset complex and ongoing synchronized responses to the RCS modulations. In contrast, the ripple stimulus elicited a change-onset response but no response to ongoing RCS modulation. Frequency-domain analyses revealed increased spectral power at the fundamental frequency and the first harmonic of wideband RCS modulations. RCS stimulation yields robust EEG measures of binaurally driven auditory reorganization and has potential to provide a flexible stimulation paradigm suitable for isolating binaural effects in ASA experiments.

2006 ◽  
Vol 18 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Joel S. Snyder ◽  
Claude Alain ◽  
Terence W. Picton

A general assumption underlying auditory scene analysis is that the initial grouping of acoustic elements is independent of attention. The effects of attention on auditory stream segregation were investigated by recording event-related potentials (ERPs) while participants either attended to sound stimuli and indicated whether they heard one or two streams or watched a muted movie. The stimuli were pure-tone ABA-patterns that repeated for 10.8 sec with a stimulus onset asynchrony between A and B tones of 100 msec in which the A tone was fixed at 500 Hz, the B tone could be 500, 625, 750, or 1000 Hz, and was a silence. In both listening conditions, an enhancement of the auditory-evoked response (P1-N1-P2 and N1c) to the B tone varied with f and correlated with perception of streaming. The ERP from 150 to 250 msec after the beginning of the repeating ABA-patterns became more positive during the course of the trial and was diminished when participants ignored the tones, consistent with behavioral studies indicating that streaming takes several seconds to build up. The N1c enhancement and the buildup over time were larger at right than left temporal electrodes, suggesting a right-hemisphere dominance for stream segregation. Sources in Heschl's gyrus accounted for the ERP modulations related to f-based segregation and buildup. These findings provide evidence for two cortical mechanisms of streaming: automatic segregation of sounds and attention-dependent buildup process that integrates successive tones within streams over several seconds.


2013 ◽  
Vol 479-480 ◽  
pp. 480-485
Author(s):  
Ming Chung Ho ◽  
Chin Fei Huang ◽  
Chia Yi Chou ◽  
Ming Chi Lu ◽  
Chen Hsieh ◽  
...  

Brain dynamics is an important issue in understanding child development. However, very little research of the event-related responses has been used to explore changes during childhood. The aim of this study was to investigate mature changes in spatiotemporal organization of brain dynamics. We hypothesized that oscillatory event-related brain activity were affected by age-related changes. The sample include three age groups, namely 7 years (N = 18), 11 years (N = 18), and adults (N = 18). The event-related spectral power (ERPSP), and inter-trial phase locking (ITPL) of the event-related potentials (ERPs) were obtained from the time-frequency analysis of the auditory oddball task. Results revealed that: (a) decreased theta power, but alpha power increased with age; (b) the values of ITPL in the theta and alpha bands increased with age. These suggest that ERPSP, and ITPL provide useful indicators of cognitive maturation processes in children aged 7 and 11 years.


2005 ◽  
Vol 17 (5) ◽  
pp. 811-818 ◽  
Author(s):  
Claude Alain ◽  
Karen Reinke ◽  
Yu He ◽  
Chenghua Wang ◽  
Nancy Lobaugh

The discrimination of concurrent sounds is paramount to speech perception. During social gatherings, listeners must extract information from a composite acoustic wave, which sums multiple individual voices that are simultaneously active. The observers' ability to identify two simultaneously presented vowels improves with increasing separation between the fundamental frequencies (f0) of the two vowels. Event-related potentials to stimuli presented during attend and ignore conditions revealed activity between 130 and 170 msec after sound onset that reflected the f0 differences between the two vowels. Another, more posterior and right-lateralized, negative wave maximal at 250 msec, and a central-parietal slow negativity were observed only during vowel identification and may index stimulus categorization. This sequence of neural events supports a multistage model of auditory scene analysis in which the spectral pattern of each vowel constituent is automatically extracted and then matched against representations of those vowels in working memory.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Niels A Kloosterman ◽  
Julian Q Kosciessa ◽  
Ulman Lindenberger ◽  
Johannes Jacobus Fahrenfort ◽  
Douglas D Garrett

Adopting particular decision biases allows organisms to tailor their choices to environmental demands. For example, a liberal response strategy pays off when target detection is crucial, whereas a conservative strategy is optimal for avoiding false alarms. Using conventional time-frequency analysis of human electroencephalographic (EEG) activity, we previously showed that bias setting entails adjustment of evidence accumulation in sensory regions (Kloosterman et al., 2019), but the presumed prefrontal signature of a conservative-to-liberal bias shift has remained elusive. Here, we show that a liberal bias shift is reflected in a more unconstrained neural regime (boosted entropy) in frontal regions that is suited to the detection of unpredictable events. Overall EEG variation, spectral power and event-related potentials could not explain this relationship, highlighting that moment-to-moment neural variability uniquely tracks bias shifts. Neural variability modulation through prefrontal cortex appears instrumental for permitting an organism to adapt its biases to environmental demands.


2021 ◽  
Vol 15 ◽  
Author(s):  
Colin Conrad ◽  
Aaron Newman

Mind wandering can inhibit learning in multimedia classrooms, such as when watching online lectures. One explanation for this effect is that periods of mind wandering cause learners’ attention to be redirected from the learning material toward task-unrelated thoughts. The present study explored the relationship between mind wandering and online education using electroencephalography (EEG). Participants were asked to attend to a 75 minute educational video lecture, while task-irrelevant auditory tones played at random intervals. The tones were of two distinct pitches, with one occurring frequently (80%) and the other infrequently (20%). Participants were prompted at pseudo-random intervals during the lecture to report their degree of experienced mind wandering. EEG spectral power and event-related potentials (ERP) were compared between states of high and low degrees of self-reported mind wandering. Participants also performed pre/post quizzes based on the lecture material. Results revealed significantly higher delta, theta and alpha band activity during mind wandering, as well as a decreased P2 ERP amplitude. Further, learning scores (improvement on quizzes pre to post) were lower among participants who reported higher degrees of mind wandering throughout the video. The results are consistent with a view that mind wandering during e-learning is characterized by a shift in attention away from the external world and toward internal thoughts, which may be a cause of reduced learning.


2012 ◽  
pp. S119-S127 ◽  
Author(s):  
J. LANGROVÁ ◽  
J. KREMLÁČEK ◽  
M. KUBA ◽  
Z. KUBOVÁ ◽  
J. SZANYI

Gender is presumed to be one of the factors causing interindividual variability in the brain’s electrophysiological parameters. Our aim was to characterize the role of gender in visual evoked potentials (VEPs), event-related potentials (ERPs), visual mismatch negativity (vMMN) and the spectral characteristics of the EEG. We examined 42 healthy volunteers (21 women and 21 men, aged 20-29 years). We measured VEPs in response to pattern-reversal and motion-onset stimulation, ERPs in an oddball paradigm and vMMN in response to a combination of motion directions presented in the visual periphery. P100 peak latency for 40’ reversal VEPs was significantly shorter in women than in men as determined using a non-parametric Wilcoxon signed-rank test. In addition, women showed higher relative EEG spectral power in the alpha band (p=0.023) and lower power in the theta band (p=0.004). Our results in this small but homogeneous group of subjects confirm previously reported gender influences on pattern-reversal VEPs and the EEG frequency spectrum. Gender should be taken into consideration in establishing norms on these measures. We found no statistically significant differences between women and men for any of the other stimuli presented.


Cephalalgia ◽  
2020 ◽  
pp. 033310242095150
Author(s):  
Adrià Vilà-Balló ◽  
Angela Marti-Marca ◽  
Marta Torres-Ferrús ◽  
Alicia Alpuente ◽  
Victor José Gallardo ◽  
...  

Background The characteristics of the hypersensitivity to auditory stimuli during the interictal period in episodic migraine are discussed. The combined use of event-related potentials, time-frequency power and phase-synchronization can provide relevant information about the time-course of sensory-attentional processing in migraine and its underlying mechanisms. Objective The aim of this nested case-control study was to examine these processes in young, female, episodic migraine patients interictally and compare them to controls using an active auditory oddball task. Method We recorded, using 20 channels, the electrophysiological brain activity of 21 women with episodic migraine without aura and 21 healthy matched controls without family history of migraine, during a novelty oddball paradigm. We collected sociodemographic and clinical data as well as scores related to disability, quality of life, anxiety and depression. We calculated behavioural measures including reaction times, hit rates and false alarms. Spectral power and phase-synchronization of oscillatory activity as well as event-related potentials were obtained for standard stimuli. For target and novel stimuli, event-related potentials were acquired. Results There were no significant differences at the behavioural level. In migraine patients, we found an increased phase-synchronization at the theta frequency range and a higher N1 response to standard trials. No differences were observed in spectral power. No evidence for a lack of habituation in any of the measures was seen between migraine patients and controls. The Reorienting Negativity was reduced in migraine patients as compared to controls on novel but not on target trials. Conclusion Our findings suggest that migraine patients process stimuli as more salient, seem to allocate more of their attentional resources to their surrounding environment, and have less available resources to reorient attention back to the main task.


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