Functional dissociation between regularity encoding and deviance detection along the auditory hierarchy

Auditory deviance detection based on regularity encoding appears as one of the basic functional properties of the auditory system. It has traditionally been assessed with the mismatch negativity (MMN) long‐latency component of the auditory evoked potential (AEP). Recent studies have found earlier correlates of deviance detection based on regularity encoding. They occur in humans in the first 50 ms after sound onset, at the level of the middle‐latency response of the AEP, and parallel findings of stimulus‐specific adaptation observed in animal studies. However, the functional relationship between these different levels of regularity encoding and deviance detection along the auditory hierarchy has not yet been clarified. Here we addressed this issue by examining deviant‐related responses at different levels of the auditory hierarchy to stimulus changes varying in their degree of deviation regarding the spatial location of a repeated standard stimulus. Auditory stimuli were presented randomly from five loudspeakers at azimuthal angles of 0°, 12°, 24°, 36° and 48° during oddball and reversed‐oddball conditions. Middle‐latency responses and MMN were measured. Our results revealed that middle‐latency responses were sensitive to deviance but not the degree of deviation, whereas the MMN amplitude increased as a function of deviance magnitude. These findings indicated that acoustic regularity can be encoded at the level of the middle‐latency response but that it takes a higher step in the auditory hierarchy for deviance magnitude to be encoded, thus providing a functional dissociation between regularity encoding and deviance detection along the auditory hierarchy.     

Attention affects the organization of auditory input associated with the mismatch negativity system

The mismatch negativity (MMN), a component of event-related potentials (ERP), was used to investigate the effect of attention on auditory stream segregation. Subjects were presented with sequences of alternating high and low tones that occurred at a constant rate, which they ignored. When subjects ignored the stimuli, the three-tone standard and deviant sequences contained within the high- and low-pitched tones did not emerge and no MMNs were obtained. Subjects were then instructed to attend to the high-pitched tones of the stimulus sequences and detect the within-stream deviants. When subjects selectively attended the high-pitched tones, MMNs were obtained to the deviants within both the attended and unattended streams. These results indicate that attention can produce segregation such that the sequences of low- and high-pitched tones are available to the automatic deviance detection system that underlies the generation of the MMN. Selective attention can alter the organization of sensory input in the early stages of acoustic processing.     

Attention effects on auditory scene analysis in children

Auditory scene analysis begins in infancy, making it possible for the baby to distinguish its mother's voice from other noises in the environment. Despite the importance of this process for human behavior, the question of how perceptual sound organization develops during childhood is not well understood. The current study investigated the role of attention for perceiving sound streams in a group of school-aged children and young adults. We behaviorally determined the frequency separation at which a set of sounds was detected as one integrated or two separated streams and compared these measures with passively and actively obtained electrophysiological indices (mismatch negativity (MMN) and P3b) of the same sounds. In adults, there was a high degree of concordance between passive and active electrophysiological indices of stream segregation that matched with perception. In contrast, there was a large disparity in children. Active electrophysiological indices of streaming were concordant with behavioral measures of perception, whereas passive indices were not. In addition, children required larger frequency separations to perceive two streams compared to adults. Our results suggest that differences in stream segregation between children and adults reflect an under-development of basic auditory processing mechanisms, and indicate a developmental role of attention for shaping physiological responses that optimize processes engaged during passive audition.     

Musical scale properties are automatically processed in the human auditory cortex

While listening to music, we immediately detect ‘wrong’ tones that do not match our expectations based on the prior context. This study aimed to determine whether such expectations can occur preattentively, as indexed by event-related potentials (ERPs), and whether these are modulated by attentional processes. To this end, we recorded ERPs in nonmusicians while they were presented with unfamiliar melodies, containing either a pitch deviating from the equal-tempered chromatic scale (out-of-tune) or a pitch deviating from the diatonic scale (out-of-key). ERPs were recorded in a passive experiment in which subjects were distracted from the sounds and in an active experiment in which they were judging how incongruous each melody was. In both the experiments, pitch incongruities elicited an early frontal negativity that was not modulated by attentional focus. This early negativity, closely corresponding to the mismatch negativity (MMN) of the ERPs, was mainly originated in the auditory cortex and occurred in response to both pitch violations but with larger amplitude for the more salient out-of-tune pitch than the less salient out-of-key pitch. Attentional processes leading to the conscious access of musical scale information were indexed by the late parietal positivity (resembling the P600 of the ERPs) elicited in response to both incongruous pitches in the active experiment only. Our results indicate that the relational properties of the musical scale are quickly and automatically extracted by the auditory cortex even before the intervention of focused attention.     

Deviance detection is the dominant component of auditory contextual processing in the lateral superior temporal gyrus: A human ECoG study

Auditory contextual processing has been assumed to be based on a hierarchical structure consisting of the primary auditory cortex, superior temporal gyrus (STG), and frontal lobe. Recent invasive studies on mismatch negativity (MMN) have revealed functional segregation for auditory contextual processing such as neural adaptation in the primary auditory cortex and prediction in the frontal lobe. However, the role of the STG remains unclear. We obtained induced activity in the high gamma band as mismatch response (MMR), an electrocorticographic (ECoG) counterpart to scalp MMN, and the components of MMR by analyzing ECoG data from patients with refractory epilepsy in an auditory oddball task paradigm. We found that MMR localized mainly in the bilateral posterior STGs, and that deviance detection largely accounted for MMR. Furthermore, adaptation was identified in a limited number of electrodes on the superior temporal plane. Our findings reveal a mixed contribution of deviance detection and adaptation depending on location in the STG. Such spatial considerations could lead to further understanding of the pathophysiology of relevant psychiatric disorders.     

The mismatch negativity (MMN) in basic research of central auditory processing: A review

In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream.     

Simple and complex acoustic regularities are encoded at different levels of the auditory hierarchy

The detection of auditory stimuli that deviate from a simple or complex auditory regularity is reflected by the mismatch negativity component of the human auditory evoked potential. Moreover, simple deviants of an oddball paradigm modulate the preceding middle‐latency response of the auditory evoked potential. For the frequency oddball paradigms it has been shown that the Nb wave, at approximately 40 ms from stimulus onset, is enhanced in response to deviant compared with standard stimuli. In this study we tested whether the detection of auditory deviants in a (frequency‐location) feature‐conjunction paradigm is reflected by modulations of the Na, Pa or Nb wave of healthy human participants. In addition, a frequency oddball paradigm was applied to directly contrast the results of a simple and a complex invariance. Feature‐conjunction deviants did not elicit any modulations of the tested middle‐latency waves. Deviants of the frequency oddball paradigm, by contrast, elicited an enhancement of the Nb wave, confirming the outcome of precedent studies. In both conditions a significant mismatch negativity component was elicited, which showed larger amplitudes and shorter latencies in the oddball condition than in the feature‐conjunction condition. These findings corroborate the idea that simple auditory regularities are encoded upstream of those of more complex auditory features and are in line with the idea of a hierarchically working auditory novelty system.     

Long-term auditory processing outcomes in early implanted young adults with cochlear implants: The mismatch negativity vs. P300 response

ObjectiveLong-term outcomes of early implanted, young adult cochlear implant (CI) users remain variable. We measured auditory discrimination by means of event-related potentials in this population to examine whether variability at the level of cortical auditory processing helps to explain speech abilities.MethodsUsing an auditory oddball paradigm, the P300 and Mismatch Negativity (MMN) were measured in 8 young adult CI users and 14 normal-hearing peers. We related P300 amplitude and latency to clinical speech perception scores in quiet and to duration of deafness.ResultsAll individuals showed P300 responses. The MMN response was less robust in both groups. There was no evidence for differences in P300 responses between CI users and controls. P300 amplitude was associated with speech perception scores (r = 0.70, p = .05) and duration of deafness (r = −0.83, p = .009).ConclusionsEarly CI implantation yields good auditory processing outcomes at young adult age and, in contrast to MMN, the P300 provides a robust measure for auditory processing on an individual level.SignificanceAt the cortical level, early implanted, long-term CI users have good auditory discrimination, leaving variability in implantation outcomes unexplained. This group provides unique insight into the long-term neurophysiological underpinnings of early implantation.     

The effect of aging on auditory components of event-related brain potentials

OBJECTIVE: To describe auditory perceptual, pre-attentive, attention-related and cognitive processes along lifespan in normal people by a simple auditory oddball paradigm easily usable in clinical practice. METHODS: ERPs were recorded in 72 normal subjects. Four blocks of tones were delivered (20% rare 2,000 Hz and 80% frequent 1,000 Hz). In the former two blocks, subjects performed a concomitant distracting visual search task (distracted condition); in the latter two blocks, they had to attend the occurrence of the rare tones (active condition). Latency and amplitude of ERPs were analyzed according to age, gender, educational level and repetition. RESULTS: N100 amplitude was greater in active than in distracted condition. MMN amplitude decreased with age. N2b and P300 latencies increased with age, while their amplitudes decreased. Females produced greater P300 than males. In the elderly, P300 latency was found to be longer in the second block than in the first one. CONCLUSIONS: N100 and MMN were found to be less affected by age than N2b and P300. When repeated, P300 showed increased latency in elderly subjects. SIGNIFICANCE: The protocol detected the higher influence of aging on late cognitive processes than on the perceptual and pre-attentive ones. Age-adjusted normative data were produced.     

Direct evidence for differential roles of temporal and frontal components of auditory change detection

Automatic change detection is a fundamental capacity of the human brain. In audition, this capacity is indexed by the mismatch negativity (MMN) event-related potential, which is putatively supported by a network consisting of superior temporal and frontal nodes. The aim of this study was to elucidate the roles of these nodes within the neural network of change detection. We used a dichotic paradigm in which subjects (N=14) attended targets defined by either pitch or spatial location in one auditory stream while the MMN was measured in response to unattended deviants of pitch and spatial location in the other stream. The frontal and temporal components of the MMN were examined using current source density (CSD) measurements. Competition for processing resources nearly eliminated the temporal CSD mismatch response, in a highly feature-specific manner: the response to spatial location deviants was reduced when the target dimension was spatial location but not when it was pitch, whereas the reverse occurred for pitch deviants. In contrast, the frontal CSD mismatch response was neither affected by competition nor by general attention demands. Thus, within the network of change detection, the temporal generators are specifically associated with processing feature-specific information, whereas the role of the frontal generators remains unclear. Moreover, the results are inconsistent with a serial model in which the frontal generator is contingent on activation of the temporal generator.     

Encoding of nested levels of acoustic regularity in hierarchically organized areas of the human auditory cortex

Our auditory system is able to encode acoustic regularity of growing levels of complexity to model and predict incoming events. Recent evidence suggests that early indices of deviance detection in the time range of the middle‐latency responses (MLR) precede the mismatch negativity (MMN), a well‐established error response associated with deviance detection. While studies suggest that only the MMN, but not early deviance‐related MLR, underlie complex regularity levels, it is not clear whether these two mechanisms interplay during scene analysis by encoding nested levels of acoustic regularity, and whether neuronal sources underlying local and global deviations are hierarchically organized. We registered magnetoencephalographic evoked fields to rapidly presented four‐tone local sequences containing a frequency change. Temporally integrated local events, in turn, defined global regularities, which were infrequently violated by a tone repetition. A global magnetic mismatch negativity (MMNm) was obtained at 140–220 ms when breaking the global regularity, but no deviance‐related effects were shown in early latencies. Conversely, Nbm (45–55 ms) and Pbm (60–75 ms) deflections of the MLR, and an earlier MMNm response at 120–160 ms, responded to local violations. Distinct neuronal generators in the auditory cortex underlay the processing of local and global regularity violations, suggesting that nested levels of complexity of auditory object representations are represented in separated cortical areas. Our results suggest that the different processing stages and anatomical areas involved in the encoding of auditory representations, and the subsequent detection of its violations, are hierarchically organized in the human auditory cortex. Hum Brain Mapp 35:5701–5716, 2014. © 2014 Wiley Periodicals, Inc.     

Hemispheric lateralization for early auditory processing of lexical tones: Dependence on pitch level and pitch contour

In Mandarin Chinese, a tonal language, pitch level and pitch contour are two dimensions of lexical tones according to their acoustic features (i.e., pitch patterns). A change in pitch level features a step change whereas that in pitch contour features a continuous variation in voice pitch. Currently, relatively little is known about the hemispheric lateralization for the processing of each dimension. To address this issue, we made whole-head electrical recordings of mismatch negativity in native Chinese speakers in response to the contrast of Chinese lexical tones in each dimension. We found that pre-attentive auditory processing of pitch level was obviously lateralized to the right hemisphere whereas there is a tendency for that of pitch contour to be lateralized to the left. We also found that the brain responded faster to pitch level than to pitch contour at a pre-attentive stage. These results indicate that the hemispheric lateralization for early auditory processing of lexical tones depends on the pitch level and pitch contour, and suggest an underlying inter-hemispheric interactive mechanism for the processing.     

Comorbidity in ADHD-children: effects of coexisting conduct disorder or tic disorder on event-related brain potentials in an auditory selective-attention task

In children with attention-deficit hyperactivity disorder (ADHD) some deficits in auditory information processing seem to exist. Further, comorbidity of ADHD with conduct disorder (CD) and tic disorder (Tic) is quite common but not yet fully understood. Thus, we investigated the effects of these two disturbances, when combined with ADHD, on electrophysiological correlates of auditory information processing. An auditory selective-attention task was used, and temporal as well as frontal lobe sensitive event-related electrical brain activity indicators like mismatch negativity (MMN) and negative difference wave (Nd), as well as P300 were registered in four groups of children (healthy controls, ADHD-only, and combined ADHD + CD as well as ADHD + Tic; total number 42). Performance measures showed that ADHD + CD had a higher impact on errors and reaction times than ADHD + Tic. The MMN effect indicated that all ADHD groups showed lower MMN amplitudes compared to normals, but only the group with ADHD + CD suffered from a significant deficiency in automatic auditory information processing. Nd and P300 amplitudes showed no significant group differences. It may be assumed that neurodynamic sufficiency in ADHD-only and ADHD + Tic children seems to be similarly impaired while there might be a greater deficit in ADHD + CD.

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Received: 10 May 1999 / Accepted: 3 January 2000     

Electrophysiological index of acoustic temporal regularity violation in the middle latency range

Objective

Acoustic violations in temporal regularity have been traditionally indexed by mismatch negativity (MMN). However, recent studies have demonstrated that humans can detect auditory changes in physical sound features, such as frequency, location and intensity, in the first 50 ms after sound onset. Our aim was to examine if temporal regularity violations could be detected in the middle latency range.

Methods

We used an oddball paradigm with 290 ms as standard stimulus onset asynchrony (SOA) and 200 ms as deviant SOA. We also employed a control paradigm that comprised of seven SOAs including 200 and 290 ms, in order to control for differences due to refractoriness.

Results

In the middle latency range, temporal regularity violations led to enhanced Pa and Nb responses, which behaved differently to the corresponding SOAs in the control condition. In the long latency range, temporal regularity violations led to similar behaviours in both oddball and control paradigms.

Conclusions

These findings suggest that with a fast presentation rate, human brains are capable to detect temporal regularity violations in the middle latency range.

Significance

Together with previous studies that found early change detection responses, the current study emphasises that the human brain can encode simple regularity violation as early as approximately 50 ms post-stimulus onset.     

The effect of early auditory deprivation on the age-dependent expression pattern of NR2B mRNA in rat auditory cortex

NMDA receptors have been well shown to be involved in neuronal plasticity. In order to understand the role of NR2B subtype NMDA receptors in auditory function development, the present study investigated the effect of early auditory deprivation on the expression of NR2B mRNA in rat auditory cortex (AC) during postnatal development. For normal rats, the NR2B mRNA expression was highest at birth (postnatal day 1 [P1]) and declined rapidly to low level during adulthood. However, during the critical period of rat auditory development (two to three weeks after birth), there was a transient NR2B expression peak on postnatal day 21 (P21). For the auditory-deprived rats, the general declining trend of NR2B mRNA expression from birth to adult was similar to that observed in the normal group, whereas the expression level from P15 to P27 was significantly lower than normal and the transient peak on P21 disappeared. In both groups, the distribution pattern of NR2B mRNA-positive neurons was also examined in various layers and dorsal, medial and ventral subdistricts of AC. There is no significant effect on the spatial expression of the NR2B mRNA in the AC between normal and deprived group. Our results indicated that the early auditory deprivation decreased the expression levels of NR2B mRNA in AC during the critical period of rat auditory development, suggesting that NR2B plays an important role in the developmental plasticity of auditory function in rats.     

Lasting first impressions: a conservative bias in automatic filters of the acoustic environment

Even in the unattended auditory environment, what we learn first appears resistant to re-evaluation based on experience. Mismatch negativity (MMN) is an auditory event-related potential elicited to rare deviation from automatically generated predictions about the sound environment. MMN amplitude is thought to reflect the potential importance of a sound for further processing. This study was designed to explore the degree to which past experience with a sound can alter automatic attributions about that sound's importance. MMN was elicited to rare (p = .125) physical “deviants” amongst a sequence of highly probable (p = .875) “standard” sounds. Sound identity alternated across blocks within the sequence (i.e., the former deviant became the new standard and the former standard the new deviant). The time period over which a standard remained the more probable tone was varied over Fast (0.8 min), Medium (1.6 min) and Slow (2.4 min) change conditions. Given that local within-block probabilities remained constant across conditions, any change in MMN size was considered a reflection of more rostral brain regions enabling a longer time scale (across-block) representation of event-probability extraction. Larger MMNs were expected to deviations in blocks with longer standard-stability. Although a significant increase in MMN amplitude was observed with increased rule stability, MMN amplitude was heavily dependent on the initial sequence structure. A “primacy bias” was observed such that prolonged stability produced large increases in the MMN to deviations from the first established standard but substantially smaller MMN to this first standard as a later deviant. The primacy effect in these data implies that the automatic filtering of sound relevance is biased toward a confirmation of initial expectations. Initial experience therefore altered the perceived salience of subsequent events.     

Transcranial direct current stimulation of prefrontal cortex: An auditory event-related potential and proton magnetic resonance spectroscopy study

Transcranial direct current stimulation (tDCS) is a non-invasive intervention altering neural plasticity by modulating neuronal excitability of pre- and postsynaptic neuron populations, which has been shown to improve depression symptoms and cognition. We investigated the effects of a single session of 20 min of 2 mA left-prefrontal anodal versus sham stimulation on auditory event-related potentials (ERPs) in 11 male and 5 female healthy subjects (mean age of 28.6 [SD 6.2] years) by employing a randomized single-blind crossover design. Stimulation effects on cortical glutamate (Glu) and glutamine (Glx) levels were subsequently measured in 12 of the 16 healthy subjects in a 3 T proton magnetic resonance spectroscopy scan. tDCS was associated with a significant increase of N1 amplitudes while smaller P3b amplitudes correlated with higher cortical Glu and Glx levels in the stimulated brain area when performing an auditory go/no-go discrimination task. tDCS did not change mismatch negativity, nor task performance or cortical Glu/Glx levels which, together with N1 amplitudes, depended on stimulation order (“sham” versus “active”). Increased N1 amplitudes are consistent with higher levels of cortical excitability following prefrontal anodal tDCS. The failure to replicate Glu/Glx changes with tDCS may have been masked by between-session carry-over effects while ceiling effects may have masked tDCS effects on task performance.     

重复经颅磁刺激对精神分裂症患者事件相关电位的影响

目的:探讨重复经颅磁刺激(rTMS)对精神分裂症患者失匹配负波(MMN)及P300的影响。方法:应用美国脑电生理仪器,对78例精神分裂症患者在rTMS治疗前后进行P300和MMN检测,观察rTMS治疗前后P300和MMN的变化。结果:与正常组比较,精神分裂症组MMN潜伏期延迟,和波幅降低(P0.05或P0.01),P300中的靶波幅P3降低(P0.05)。患者组经过25次rTMS治疗后MMN波幅及P300靶波幅P3明显提高(P0.05或P0.01)。结论:rTMS治疗可以提高精神分裂症患者事件相关电位的MMN及P3波幅。     

Early processing of pitch in the human auditory system

Middle‐latency auditory evoked potentials, indicating early cortical processing, elicited by pitch changes and repetitions in pure tones and by complex tones with a missing‐fundamental pitch were recorded in healthy adults ignoring the sounds while watching a silenced movie. Both for the pure and for the missing‐fundamental tones, the Nb middle‐latency response was larger for pitch changes (tones preceded by tones of different pitch) than for pitch repetitions (tones preceded by tones of the same pitch). This Nb enhancement was observed even for missing‐fundamental tones preceded by repeated tones that had a different missing‐fundamental pitch but included all harmonics of the subsequent tone with another missing‐fundamental pitch. This finding rules out the possibility that the Nb enhancement in response to a change in missing‐fundamental pitch was simply attributable to the activity of auditory cortex neurons responding specifically to the harmonics of missing‐fundamental tones. The Nb effect presumably indicates pitch processing at or near the primary auditory cortex, and it was followed by a change‐related enhancement of the N1 response, presumably generated in the secondary auditory cortex. This N1 enhancement might have been caused by a mismatch negativity response overlapping with the N1 response. Processing of missing‐fundamental pitch was also reflected by the distribution of Nb responses. Tones with a higher missing‐fundamental pitch elicited more frontally dominant Nb responses than tones with a lower missing‐fundamental pitch. This effect of pitch, not seen for the pure tones, might indicate that the exact location of the Nb generator source in the auditory cortex depends on the missing‐fundamental pitch of the eliciting tone.     

The effect of measurement error on the test–retest reliability of repeated mismatch negativity measurements

Objective

The aim was to study how the measurement error affects the repeatability of mismatch negativity (MMN) measurements.

Methods

Event-related potentials (ERPs) to changes in sound frequency, location, intensity, duration, and composition were recorded five times during 1–3 weeks from 13 healthy adults using a multi-feature MMN paradigm. The accumulation of MMN was modeled empirically with respect to measurement error, and repeatability was estimated at 0.6–3.5-μV error levels. The analysis was made for the results in the single deviant conditions and their pattern (auditory discrimination profile).

Results

At the single-subject level, the measurement error significantly affected the repeatability until it went below 9–17% of MMN peak amplitude. At the group level, the threshold was higher. Peak amplitude was generally the most repeatable parameter. Latency was superior when the error was moderate or small (<2–3 μV).

Conclusions

The measurement error affects the repeatability of MMN. In single-subject studies, it should not be neglected if it exceeds 10% of the MMN amplitude. The application of the auditory discrimination profile is recommended for future applications.

Significance

The study provided quantitative results to support the discussion on improving the repeatability of the MMN measurements. They are expected to apply conditionally to other ERP measurements, too.