Oddball Blocks Research Articles

Effects of Acoustic Context on the Perceptual Differences between Spatial Sound Stimuli

We studied the effects of the acoustic context on active and passive discrimination of moving sound signals. Different contexts were created by reversing the role of standard and deviant stimuli in the oddball blocks, while their acoustical features were kept the same. Three types of sounds were used as standard or deviant stimuli in different blocks: stationary midline noises and two (smooth and abrupt) moving sounds moving to the left or right of the midline. Auditory event-related potentials (ERPs) were recorded during passive listening (the sound stimulation ignored), and mismatch negativity potentials (MMNs) were obtained. Active discrimination of sound movements was measured by the hit rate (percent correct responses) and false alarm rate, as well as the reaction time. The influence of the stimulus context on active and passive discrimination of the moving sound stimuli was reflected in the phenomenon known as the effect of deviance direction. The hit rate and MMN amplitude were higher when the deviant moved faster than the standard. The MMN amplitude was more responsive to the velocity of sound stimuli than the hit rate and false alarm rate. The psychophysical measurements in the reversed contexts suggest that smooth and abrupt sound movements may belong to the same perceptual category (moving sounds), while the stationary stimuli form another perceptual category.

Hemispheric asymmetry of ERPs and MMNs evoked by slow, fast and abrupt auditory motion

The current MMN study investigates whether brain lateralization during automatic discrimination of sound stimuli moving at different velocities is consistent with one of the three models of asymmetry: the right-hemispheric dominance model, the contralateral dominance model, or the neglect model. Auditory event-related potentials (ERPs) were recorded for three patterns of sound motion produced by linear or abrupt changes of interaural time differences. The slow motion (450deg/s) was used as standard, and the fast motion (620deg/s) and the abrupt sound shift served as deviants in the oddball blocks. All stimuli had the same onset/offset spatial positions. We compared the effects of the recording side (left, right) and of the direction of sound displacement (ipsi- or contralateral with reference to the side of recording) on the ERPs and mismatch negativity (MMN). Our results indicated different patterns of asymmetry for the ERPs and MMN responses. The ERPs showed a velocity-independent right-hemispheric dominance that emerged at the descending limb of N1 wave (at around 120–160ms) and could be related to overall context of the preattentive spatial perception. The MMNs elicited in the left hemisphere (at around 230–270ms) exhibited a contralateral dominance, whereas the right-hemispheric MMNs were insensitive to the direction of sound displacement. These differences in contralaterality between MMN responses produced by the left and the right hemisphere favour the neglect model of the preattentive motion processing indexed by MMN.

Mismatch response (MMR) in neonates: Beyond refractoriness

In the adult auditory system, deviant detection and updating the representation of the environment is reflected by the event-related potential (ERP) component termed the mismatch negativity (MMN). MMN is elicited when a rare-pitch deviant stimulus is presented amongst frequent standard pitch stimuli. The same stimuli also elicit a similar discriminative ERP component in sleeping newborn infants (termed the mismatch response: MMR). Both the MMN and the MMR can be confounded by responses generated by differential refractoriness of frequency-selective neural populations. Employing a stimulus paradigm designed to minimize this confounding effect, newborns were presented with sequences of pure tones under two conditions: In the oddball block, rare deviant tones (500Hz; 10%) were delivered amongst frequent standards (700Hz; 90%). In the control block, a comparison tone (500Hz) was presented with the same probability as the deviant (10%) along with the four contextual tones (700Hz, 980Hz, 1372Hz, 1920.8Hz; 22.5% each). The significant difference found between the response elicited by the deviant and the comparison tone showed that the response elicited by the deviant in the oddball sequences cannot be fully explained by frequency-specific refractoriness of the neural generators. This shows that neonates process sounds in a context-dependent manner as well as strengthens the correspondence between the adult MMN and the infant MMR.

Electrophysiological Indicators of the Age-Related Deterioration in the Sensitivity to Auditory Duration Deviance

The present study investigates age-related changes in duration discrimination in millisecond time domain. We tested young (N = 20, mean age = 24.5, SD = 2.97) and elderly (N = 20, mean age = 65.2, SD = 2.94) subjects using the mismatch negativity (MMN) paradigm. White-noise bursts of two different durations (50 and 10 ms) were presented in two oddball blocks. In one block (Increment Condition), the repetitive sequence of 10 ms standards was interspersed by occasional 50 ms deviants. In the Decrement Condition, the roles of the two stimuli were reversed. We analyzed the P1-N1 complex, MMN and P3a and found the effect of age for all these components. Moreover, the impact of stimulus presentation condition (increment/decrement) was observed for MMN and P3a. Our results confirmed the previous evidence for deteriorated duration discrimination in elderly people. Additionally, we found that this effect may be influenced by procedural factors.

Magnetic Source Localization of Early Visual Mismatch Response

Previous studies have reported a visual analogue of the auditory mismatch negativity (MMN) response that is based on sensory memory. The neural generators and attention dependence of the visual MMN (vMMN) still remain unclear. We used magnetoencephalography (MEG) and spatio-temporal source localization to determine the generators of the sensory-memory-based vMMN response to non-attended deviants. Ten participants were asked to discriminate between odd and even digits presented at the center of the visual field while grating patterns with different spatial frequencies were presented outside the focus of attention. vMMN was calculated as the difference between MEG responses to infrequent gratings in oddball blocks and the same gratings in equiprobable blocks. The peak latency of the vMMN response was between 100 and 160 ms. The neuromagnetic sources of the vMMN localized in the occipital cortex differed from the sources evoked by the equiprobable gratings and were stimulus-dependent. Our results suggest the existence of separate neural systems for pre-attentive memory-based detection of visual change and provide new evidence that the vMMN is feature-specific.

Repetition Suppression and Expectation Suppression Are Dissociable in Time in Early Auditory Evoked Fields

Repetition of a stimulus, as well as valid expectation that a stimulus will occur, both attenuate the neural response to it. These effects, repetition suppression and expectation suppression, are typically confounded in paradigms in which the nonrepeated stimulus is also relatively rare (e.g., in oddball blocks of mismatch negativity paradigms, or in repetition suppression paradigms with multiple repetitions before an alternation). However, recent hierarchical models of sensory processing inspire the hypothesis that the two might be separable in time, with repetition suppression occurring earlier, as a consequence of local transition probabilities, and suppression by expectation occurring later, as a consequence of learnt statistical regularities. Here we test this hypothesis in an auditory experiment by orthogonally manipulating stimulus repetition and stimulus expectation and, using magnetoencephalography, measuring the neural response over time in human subjects. We found that stimulus repetition (but not stimulus expectation) attenuates the early auditory response (40-60 ms), while stimulus expectation (but not stimulus repetition) attenuates the subsequent, intermediate stage of auditory processing (100-200 ms). These findings are well in line with hierarchical predictive coding models, which posit sequential stages of prediction error resolution, contingent on the level at which the hypothesis is generated.

Specific Neural Traces for Intonational Discourse Categories as Revealed by Human-evoked Potentials

The neural representation of segmental and tonal phonological distinctions has been shown by means of the MMN ERP, yet this is not the case for intonational discourse contrasts. In Catalan, a rising-falling intonational sequence can be perceived as a statement or as a counterexpectational question, depending exclusively on the size of the pitch range interval of the rising movement. We tested here, using the MMN, whether such categorical distinctions elicited distinct neurophysiological patterns of activity, supporting their specific neural representation. From a behavioral identification experiment, we set the boundary between the two categories and defined four stimuli across the continuum. Although the physical distance between each pair of stimuli was kept constant, the central pair represented an across-category contrast, whereas the other pairs represented within-category contrasts. These four auditory stimuli were contrasted by pairs in three different oddball blocks. The mean amplitude of the MMN was larger for the across-category contrast, suggesting that intonational contrasts in the target language can be encoded automatically in the auditory cortex. These results are in line with recent findings in other fields of linguistics, showing that, when a boundary between categories is crossed, the MMN response is not just larger but rather includes a separate subcomponent.

Visual mismatch negativity elicited by facial expressions: new evidence from the equiprobable paradigm

BackgroundConverging evidence revealed that facial expressions are processed automatically. Recently, there is evidence that facial expressions might elicit the visual mismatch negativity (MMN), expression MMN (EMMN), reflecting that facial expression could be processed under non-attentional condition. In the present study, using a cross modality task we attempted to investigate whether there is a memory-comparison-based EMMN.Methods12 normal adults were instructed to simultaneously listen to a story and pay attention to a non-patterned white circle as a visual target interspersed among face stimuli. In the oddball block, the sad face was the deviant with a probability of 20% and the neutral face was the standard with a probability of 80%; in the control block, the identical sad face was presented with other four kinds of face stimuli with equal probability (20% for each). Electroencephalogram (EEG) was continuously recorded and ERPs (event-related potentials) in response to each kind of face stimuli were obtained. Oddball-EMMN in the oddball block was obtained by subtracting the ERPs elicited by the neutral faces (standard) from those by the sad faces (deviant), while controlled-EMMN was obtained by subtracting the ERPs elicited by the sad faces in the control block from those by the sad faces in the oddball block. Both EMMNs were measured and analyzed by ANOVAs (Analysis of Variance) with repeated measurements. sLORETA (standardized low-resolution brain electromagnetic tomography) was used to investigate the cortical generators of controlled-EMMN.ResultsBoth the oddball-EMMN in deviant-standard comparison and the controlled-EMMN in deviant-control comparison were observed at occipital-temporal regions with right hemisphere predominance. The oddball-EMMN was bigger and earlier than the controlled-EMMN because, besides the memory-based comparison, the former included a difference of refractoriness due to the distinction of presented probability between the deviant and standard face stimuli. The source analysis of controlled-EMMN indicated a current source primarily involved in posterior areas including superior temporal gyrus, postcentral gyrus, inferior parietal lobule as well as the insula.ConclusionsThe valid EMMN properly reflecting the memory-based comparison of facial expressions could be obtained, i.e., the controlled-EMMN.

Novelty Detection in the Human Auditory Brainstem

Auditory deviance detection has been associated with a human auditory-evoked potential (AEP), the mismatch negativity, generated in the auditory cortex 100-200 ms from sound change onset. Yet, single-unit recordings in animals suggest much earlier (∼20-40 ms), and anatomically lower (i.e., thalamus and midbrain) deviance detection. In humans, recordings of the scalp middle-latency AEPs have confirmed early (∼30-40 ms) deviance detection. However, involvement of the human auditory brainstem in deviance detection has not yet been demonstrated. Here we recorded the auditory brainstem frequency-following response (FFR) to consonant-vowel stimuli (/ba/, /wa/) in young adults, with stimuli arranged in oddball and reversed oddball blocks (deviant probability, p=0.2), allowing for the comparison of FFRs to the same physical stimuli presented in different contextual roles. Whereas no effect was observed for the /wa/ syllable, we found for the /ba/ syllable a reduction in the brainstem FFR to deviant stimuli compared with standard ones and to similar stimuli arranged in a control block, with five equiprobable, rarely occurring sounds. These findings demonstrate that the human auditory brainstem is able to encode regularities in the recent auditory past to detect novel events, and confirm the multiple anatomical and temporal scales of human deviance detection.

Electrophysiological Assessment of Auditory Stimulus-Specific Plasticity in Schizophrenia

Disrupted neuroplasticity may be an important aspect of the neural basis of schizophrenia. We used event-related brain potentials (ERPs) to assay neuroplasticity after auditory conditioning in chronic schizophrenia patients (SZ) and matched healthy control subjects (HC). Subjects (15 HC, 14 SZ) performed an auditory oddball task during electroencephalogram recording before and after auditory tetanic stimulation (Pre/Post Blocks). Each oddball block consisted of 1000-Hz and 1500-Hz standards and 400-Hz targets. During tetanic conditioning, 1000-Hz tones were presented at 11 Hz for 2.4 min. We analyzed the standard trials, comparing the ERPs evoked by the tetanized stimuli (1000 Hz tones: TS+) and untetanized stimuli (1500 Hz tones: TS-) in the Post Blocks with ERPs from the Pre Blocks (averaged into Baseline ERPs). In Post Block 1 in HC, TS+ tones evoked a negative shift (60-350 msec) at right temporal electrodes relative to Baseline. No pre-/post-tetanus effects were found in SZ. In Post Block 2 in HC, TS+ tones evoked a positive shift (200-300 msec) at bilateral frontal electrodes. In SZ, TS+ tones evoked a positive shift (100-400 msec) at right frontotemporal electrodes. No pre-/post-tetanus effects were found in either subject group for the TS- tones. The right temporal Post Block 1 and 2 effects were correlated in SZ, suggesting a trade-off in the expression of these effects. These results suggest that stimulus-specific auditory neuroplasticity is abnormal in schizophrenia. The electrophysiologic assessment of stimulus-specific plasticity may yield novel targets for drug treatment in schizophrenia.

Finding the right control: The mismatch negativity under investigation

ObjectiveWhen investigating auditory perceptual regularity processing, mismatch negativity (MMN) is commonly used. MMN is computed as a difference signal between the event-related potentials (ERPs) elicited by repeated standard tones and rarely occurring deviant tones. This procedure leads to an underestimation of the N1 component elicited by standards compared to the N1 to deviants which might affect the MMN. Consequently, a random control design was previously introduced. This design, however, overestimates the N1 to the deviant. Here, we developed a new paradigm that avoids previous drawbacks. MethodsWe designed a regular cascadic sequence as a control to the deviant. ERPs were measured while presenting conventional oddball blocks (standards, deviants), random control blocks and a cascadic control block. ResultsMMN was observed in each difference signal. Regarding the N1, standards elicited smallest amplitudes. The N1 for the deviant and the cascadic control was comparable. The largest N1 was elicited by the random control. ConclusionStandards underestimate N1 refractoriness effects in the responses to deviants, while random control tones overestimate. Cascadic control tones, however, provide a reasonable estimation for the N1. SignificanceThe new cascadic control design is suitable to investigate auditory perceptual regularity processes while controlling for N1 refractoriness effects.

Frequency following responses to speech sounds in a passive oddball paradigm

Event Abstract Back to Event Frequency following responses to speech sounds in a passive oddball paradigm Lavinia Slabu1*, Sabine Grimm1 and Carles Escera1 1 University of Barcelona, Spain Auditory evoked potential (AEP) studies indicate that infrequent deviant sounds reliably elicit a negative potential approximately 100-300 ms after the stimulus onset called mismatch negativity response, associated with change detection. Recent results from animal studies (Malmierca et al., 2009) suggest that cognitive AEPs in humans might be preceded by earlier novelty-related activity. The goal of the current study is to investigate the effect of auditory deviance detection on the brainstem frequency following response (FFR) for speech syllables. Five different consonant-vowel syllables were presented monaurally to the right ear. The stimuli differed in the duration of the transition of the first and second formants of the syllable, 20, 35, 50, 65, and 80 ms. The stimuli were perceived either as /ba/ or as a soft to a strong /wa/. Three blocked conditions were presented: an oddball block with a deviant /wa/1 probability of p = .2; a reverse oddball block; and a control block in which the five stimuli were presented randomly (p = .2). FFR were recorded from 18 participants at Cz using left earlobe as reference. 8192-points Fourier analyses were applied on the individual FFR in the time window 20-85 ms after syllable onset and the mean spectral amplitude was calculated for 10 Hz wide bins surrounding the F0 (100 Hz) and the subsequent three harmonics, H2, H3, H4. The amplitudes of the H2 (F2,34 = 5.312, p = .017) and H4 (F2,34 = 6.172, p = .010) for the /ba/ syllable were significant smaller for the deviant stimulus than for the responses elicited both to the standard and to the control stimuli. The results of the present study confirm that the human brainstem encodes acoustic regularities and reveal that auditory deviance detection can take place in human auditory brainstem. Funding: Supported by PSI2009-08063 grant; Consolider-Ingenio2010 Program (CDS2007-00012) of the Spanish Ministry of Science and Innovation, 2009SGR11 grant Keywords: auditory evoked potential, Perception Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Neurophysiology of Sensation and Perception Citation: Slabu L, Grimm S and Escera C (2011). Frequency following responses to speech sounds in a passive oddball paradigm. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00333 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Lavinia Slabu, University of Barcelona, Barcelona, Spain, lslabu@yahoo.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Lavinia Slabu Sabine Grimm Carles Escera Google Lavinia Slabu Sabine Grimm Carles Escera Google Scholar Lavinia Slabu Sabine Grimm Carles Escera PubMed Lavinia Slabu Sabine Grimm Carles Escera Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Preattentive Phonotactic Processing as Indexed by the Mismatch Negativity

Processing of an obligatory phonotactic restriction outside the focus of the participants' attention was investigated by means of ERPs using (reversed) experimental oddball blocks. Dorsal fricative assimilation (DFA) is a phonotactic constraint in German grammar that is violated in *[epsilonx] but not in [open ox], [epsilonintegral], and [open ointegral]. These stimulus sequences engage the auditory deviance detection mechanism as reflected by the MMN component of the ERP. In Experiment 1 (n = 16), stimuli were contrasted pairwise such that they shared the initial vowel but differed with regard to the fricative. Phonotactically ill-formed deviants elicited stronger MMN responses than well-formed deviants that differed acoustically in the same way from the standard stimulation but did not contain a phonotactic violation. In Experiment 2 (n = 16), stimuli were contrasted such that they differed with regard to the vowel but shared the fricative. MMN was elicited by the vowel change. An additional, later MMN response was observed for the phonotactically ill-formed syllable only. This MMN cannot be attributed to any phonetic or segmental difference between standard and deviant. These findings suggest that implicit phonotactic knowledge is activated and applied in preattentive speech processing.

The P300 signal is monotonically modulated by target saliency level irrespective of the visual feature domain

Abstract Purpose Event related responses to infrequent and task‐relevant stimuli often include an attentional peak, the P300 component. This component is typically regarded as independent from the sensory modality, with amplitude depending on target occurrence probability. In this study, we investigated whether the P300 signal could similarly be modulated by the degree of perceptual difference across visual target properties. Methods We used an oddball block design with texture and colour as perceptual category features and a frequency ratio of 1:16. EEG/ERP responses were recorded from 68 channels in 9 healthy participants, matched for age and educational level. For the colour condition, 3 targets with increasing steps of categorical deviation in perceived redness from the standard stimulus were used. Concerning the texture segmentation condition, 3 targets with increasing spatial phase difference were chosen. Colour target patches were presented against a reference background of a standard additive primary red patch, and texture patches against a standard grating one with no phase segregation contrast. Results Repeated measure analysis results suggest a significant modulation of P300 amplitude target levels in midline central and parietal channels for both conditions. Significant Spearman correlations (positive with amplitude and negative with latency) support this order effect between target perceptual level and the P300 response. Conclusion We conclude that the amplitude and latency of the P300 response is monotonically modulated by saliency levels of distinct target categories.

A neurophysiological correlate of animal novelty neurons recorded from the human scalp?

Event Abstract Back to Event A neurophysiological correlate of animal novelty neurons recorded from the human scalp? Sabine Grimm1*, L. Slabu1, J. Costa-Faidella1 and Carles Escera1 1 Department of Psychiatry and Clinical Psychobiology, Faculty of Psychology, University of Barcelona , Spain Novelty detection is a crucial property of the auditory system which subserves an efficient representation of the acoustic input and allows at the same time for prompt adaptive behavior to potentially relevant new stimuli. In human studies, novelty detection is linked to the occurrence of the mismatch negativity (MMN) – a component of the scalp potential evoked by rare sounds. Recently, its underlying neural mechanisms have been presumed in the responsiveness of so-called novelty neurons found in animal studies whose discharge habituates with stimulus repetition but is restored with small changes in the stimulus properties. Being found at early latencies and on multiple stages of the auditory pathway, these probability-sensitive neural responses are thought to precede and probably induce the activity measured as the scalp MMN rather than being its direct neural correspondent. To further investigate the link between animal and human findings, the present study is looking for correlates of the early animal novelty responses in the human scalp potential. Therefore, we measured in 20 human subjects long-latency (LAEP) and middle-latency auditory evoked potentials (MAEP) to frequency deviants (p=0.2) in two ranges (800 Hz, 3730 Hz) in an oddball paradigm. Deviants were compared to physically identical stimuli presented with high probability in a reversed oddball block (standard) and in a block intermixing randomly five equally low probable tones of different frequencies (control). 960 trials were delivered for each condition with an inter-stimulus interval of 297 ms, and EEG was recorded with special settings (sampling rate: 2500 Hz; online-filter: 0.1 to 500 Hz), which allowed for the extraction of latencies and amplitudes of the MAEP components Na, Pa, Nb, and the MMN component of the LAEP in different offline analyses. In both frequency ranges we obtained a clear MMN with somewhat smaller amplitudes for the “true” MMN from the deviant-control comparison. More interestingly, already in the range of MAEP, the Nb component peaking at about 40-42 ms was enhanced for deviants compared to standards (repeated measures contrast: F(1,19)=9.98, p=0.005) and controls (repeated measures contrast: F(1,19)=6.57, p=0.019) in both frequency ranges. This response indexes an early process of novelty detection preceding the well-studied higher-order cognitive detection index. The finding strongly supports the idea of a multi-stage comparison processes serving auditory novelty detection and might be discussed as a human correlate of novelty neurons’ activity. Conference: MMN 09 Fifth Conference on Mismatch Negativity (MMN) and its Clinical and Scientific Applications, Budapest, Hungary, 4 Apr - 7 Apr, 2009. Presentation Type: Oral Presentation Topic: Abstracts Citation: Grimm S, Slabu L, Costa-Faidella J and Escera C (2009). A neurophysiological correlate of animal novelty neurons recorded from the human scalp?. Conference Abstract: MMN 09 Fifth Conference on Mismatch Negativity (MMN) and its Clinical and Scientific Applications. doi: 10.3389/conf.neuro.09.2009.05.082 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Mar 2009; Published Online: 25 Mar 2009. * Correspondence: Sabine Grimm, Department of Psychiatry and Clinical Psychobiology, Faculty of Psychology, University of Barcelona, Barcelona, Spain, sabine.grimm@uni-leipzig.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Sabine Grimm L. Slabu J. Costa-Faidella Carles Escera Google Sabine Grimm L. Slabu J. Costa-Faidella Carles Escera Google Scholar Sabine Grimm L. Slabu J. Costa-Faidella Carles Escera PubMed Sabine Grimm L. Slabu J. Costa-Faidella Carles Escera Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Auditory pre-attentive processing of Chinese tones

Chinese tones are considered important in Chinese discrimination. However, the relevant reports on auditory central mechanisms concerning Chinese tones are limited. In this study, mismatch negativity (MMN), one of the event related potentials (ERP), was used to investigate pre-attentive processing of Chinese tones, and the differences between the function of oddball MMN and that of control MMN are discussed. Ten subjects (six men and four women) with normal hearing participated in the study. A sequence was presented to these subjects through a loudspeaker, the sequence included four blocks, a control block and three oddball blocks. The control block was made up of five components (one pure tone and four Chinese tones) with equiprobability. The oddball blocks were made up of two components, one was a standard stimulus (tone 1) and the other was a deviant stimulus (tone 2 or tone 3 or tone 4). Electroencephalogram (EEG) data were recorded when the sequence was presented and MMNs were obtained from the analysis of the EEG data. Two kinds of MMNs were obtained, oddball MMN and control MMN. Oddball MMN was obtained by subtracting the ERP elicited by standard stimulation (tone 1) from that elicited by deviant stimulation (tone 2 or tone 3 or tone 4) in the oddball block; control MMN was obtained by subtracting the ERP elicited by the tone in control block, which was the same tone as the deviant stimulation in the oddball block, from the ERP elicited by deviant stimulation (tone 2 or tone 3 or tone 4) in the oddball block. There were two negative waves in oddball MMN, one appeared around 150 ms (oddball MMN 1), the other around 300 ms (oddball MMN 2). Only one negative wave appeared around 300 ms in control MMN, which was corresponding to the oddball MMN 2. We performed the statistical analyses in each paradigm for latencies and amplitudes for oddball MMN 2 in discriminating the three Chinese tones and reported no significant differences. But the latencies and amplitudes for control MMN in discriminating the three tones all were significantly different. There are evident waveforms for oddball and control MMN obtained in normal hearing persons, indicating that the change of Chinese tones could be detected in the pre-attentive stage. Because control MMN can eliminate reflects for physical characteristics of sound, it is the genuine memory-based pre-attentive processing. Since control MMN can reflect the differences of Chinese tones processing better than oddball MMN, it is more sensitive in evaluating pre-attentive processing in Chinese tones discrimination.

Mismatch negativity to frequency changes: no evidence from human event-related brain potentials for categorical speech processing of complex tones resembling vowel formant structure

Based on a memory-comparison process, changes in the pitch of repetitive sounds are pre-attentively detected, reflected by the mismatch negativity (MMN) event-related brain potential. In the present investigation of categorical speech perception, complex tones were used that consisted of vowel-defining F1 and F2 formant information while not being perceived as speech. MMN was obtained in oddball blocks. The auditory system tracks two simultaneous changes in formant frequencies of 50 Hz while also abstracting from three levels of intensity variation. Lower frequency deviants elicited larger MMN. No effects of language-categorical processing were observed.

Mismatch negativity to frequency changes: no evidence from human event-related brain potentials for categorical speech processing of complex tones resembling vowel formant structure

Based on a memory-comparison process, changes in the pitch of repetitive sounds are pre-attentively detected, reflected by the mismatch negativity (MMN) event-related brain potential. In the present investigation of categorical speech perception, complex tones were used that consisted of vowel-defining F1 and F2 formant information while not being perceived as speech. MMN was obtained in oddball blocks. The auditory system tracks two simultaneous changes in formant frequencies of 50 Hz while also abstracting from three levels of intensity variation. Lower frequency deviants elicited larger MMN. No effects of language-categorical processing were observed.

Preattentive Memory-Based Comparison of Sound Intensity

Changes in the intensity of repeated, ignored sounds elicit the mismatch negativity (MMN) brain response which reflects preattentive detection of the change. It is generally assumed that the MMN in response to intensity changes reflects a memory-based comparison mechanism rather than being due to differential states of refractoriness of intensity-specific cortical neurons. In the present study, an experimental protocol consisting of 4 oddball blocks and 1 control block was used in order to separate memory-comparison-related effects from refractoriness-related ones. This design allowed an assessment of intensity MMN using physically identical stimuli with equal probability of occurrence in separate blocks, while avoiding contamination by refractoriness. Results were consistent with an MMN in response to intensity change that reflects genuine memory-based comparison.

On the validity of interblock averaging of P300 in clinical settings

The reduction of long-latency auditory ERPs amplitude, including P300, to repeated stimuli has been well documented in the literature on habituation. The effect of block repetition on auditory ERPs recorded for clinical purposes, where interblock intervals are commonly longer than those employed in habituation studies, was studied in a sample of 38 adults submitted to two blocks of a counting oddball paradigm. Four different experimental conditions were considered, differing in target probability, delivery or not of a previous passive oddball tone sequence, and the performance or not of other oddball tasks requiring more complex discriminative responses between the two blocks. Results showed that: (1) N1 amplitude to the frequent non-target stimuli decreased in the second block under all the conditions; (2) when the two blocks were consecutive (separated by 2–3 min), P300 amplitudes were unaffected by block repetition, this whatever the probability of the target (25% vs. 10%) and whether or not a passive oddball sequence preceded the two active blocks; (3) P300 amplitude was only affected by stimulus repetition in those subjects who performed more complex cognitive tasks between the first and second blocks and; (4) latency values were unaffected by repetition. It is hypothesised that the N1 amplitude decline may be caused by a decrease in alertness or arousal level produced by stimuli repetition. Reduction in P3 amplitude only appeared when more difficult tasks had to be done between the two oddball blocks and may reflect a decrease in the amount of attentional resources allocated to the second block, due either to fatigue or over training. The practice of using a grand average of several repetitions of the oddball paradigm, as recommended for the clinical use of long-latency ERPs, seems to be adequate provided that long interblock intervals are used and that the subject is not engaged in tasks requiring a high mental workload between the trial blocks.