产后与非产后抑郁症患者失配性负波的对比研究

目的探讨产后抑郁症与非产后抑郁症患者失配性负波（MMN）的差异,为产后抑郁症的预防提供参考指标。方法选择2011年4月一2012年12月解放军第三医院精神科收治的24例产后抑郁症患者（产后组）和25例非产后抑郁症患者（非产后组）为研究对象,并检测其事件相关电位MMN,将其与26名健康志愿者（对照组）的结果进行比较。结果①与对照组相比,产后组、非产后组blMN潜伏期均显著延迟（t=2．84,5．26;P〈0．05）,波幅均显著降低（t=4．16,4．19;P〈0．01）;②与产后组相比,非产后组MMN潜伏期显著延迟,差异有统计学意义（t=3．63,P〈0．05）;两组波幅差异均无统计学意义。结论产后与非产后抑郁症患者信息自动加工功能均受损,非产后抑郁患者受损程度大于产后抑郁患者。提示产后与非产后抑郁症患者大脑对外界信息的自动加工采用不同的机制。     

The Effects of Channel-Selective Attention on the Mismatch Negativity Wave Elicited by Deviant Tones

The mismatch negativity (MMN) is an event-related brain potential elicited by infrequent, physically deviant sounds in a sequence of repetitive auditory stimuli. Two dichotic listening experiments that were designed to optimize the selective focusing of attention provided a strong test of Näätänen's proposal that the MMN is unaffected by attention and reflects the operation of a strongly automatic mismatch detection system. In Experiment 1, tones were presented at intervals of 120-320 ms, and the deviant tones (intensity decrements) in both the attended and unattended ears elicited negative waves consistent in waveshape, latency, and distribution with previously described MMNs. In contrast to previous reports, however, the MMN elicited by the unattended-channel deviant was markedly reduced (peak amplitude of less than 1 μV) relative to the corresponding negative wave elicited by the attended-channel deviants (3–4 μV), as well as relative to previously reported MMNs (3–6 μV) elicited by comparable deviations in stimulus intensity. In Experiment 2, which employed interstimulus intervals of 65–205 ms, the unattended-channel MMN elicited by the deviant fainter tones was barely discernible, whereas the corresponding attended-channel negativity was again about 3-4 μV.
These findings call into question the assertion that the auditory mismatch detection process and the associated MMN wave are wholly independent of attentional influence. Rather, these data provide evidence that the processing of stimuli in unattended channels can be attenuated or gated at an early sensory level under conditions of highly focused auditory selective attention.     

Mismatch Negativity in Event-Related Potentials to Auditory Stimuli as a Function of Varying Interstimulus Interval

The mismatch negativity, isolated as a component of the event-related brain potential elicited by deviant auditory stimuli, was suggested by Näätänen (1984) as an indirect measure of the inferred neuronal representation of standard stimuli. The purpose of the present study was to determine the duration of the neuronal representation by varying the interstimulus intervals of 1, 6, and 10 seconds within experimental blocks. Mismatch negativities were found to be elicited by deviant stimuli (1500-Hz tones, sequential probability 10%) following standard stimuli (1000-Hz tones) with interstimulus intervals of 1, 6, and 10 s as well. The results suggest a duration of neuronal representation of at least 10 s. The within-block variation of interstimulus interval, the rather low temporal probability of deviants, and their large frequency deviance might explain the present results contradicting earlier findings that suggested a shorter duration of that neuronal representation.     

Mismatch Negativity Outside Strong Attentional Focus: A Commentary on Woldorff et al. (1991)

Several previous papers have suggested that the mismatch negativity (MMN), an event-related potential (ERP) component specific to stimulus change after repetition, is fully automatic, that is, not affected by attention. Woldorff, Hackley, and Hillyard (1991), however, report that the MMN elicited by an intensity decrement of a repeating stimulus is considerably attenuated when attention is strongly focused on other stimuli. The present commentary attributes most of this effect to attention effects on ERP components other than the MMN but also admits that some attentional reduction of the MMN component indeed occurred. This attenuation was interpreted by Woldorff et al. as indicating suppression of early sensory processing in unattended channels, but this is contraindicated by some very recent data from the present author's laboratory and elsewhere showing that the MMN to frequency change is not attenuated outside a strong attentional focus. Consequently, an alternative explanation is proposed for Woldorff et al.'s important finding.     

Event-Related Potentials to Time-Deviant and Pitch-Deviant Tones

Twelve subjects were run in a paradigm designed to compare event-related brain potentials (ERPs) elicited by infrequent pitch-deviant and time-deviant tones under different attentional conditions. Tones with a pitch of 500 Hz or 1000 Hz were presented at regular interstimulus intervals of 800 ms. Changes in pitch or a shortening of interstimulus interval to 400 ms each occurred with 10% probability. Three different tasks (reading or reaction time to pitch or to timing deviances) were assigned on separate runs. N150 to deviant tones was not influenced by task. Its amplitude, peak latency, and frontally maximum distribution did not differ between pitch and timing deviance, but to pitch deviance it had an earlier onset. P350 amplitude to both types of deviant tones was larger than to standard tones when subjects pressed to time-deviant tones; only P350 to pitch-deviant tones was larger than to standards when subjects pressed to pitch-deviant tones. P350 latency was longer to timing deviance regardless of task. Our results support the view that negativities generated by mismatches in expected timing and pitch are qualitatively the same. ERP differences between these two types of deviance were probably due to differences in stimulus salience or discriminability.     

Mismatch negativity during objective and subjective sleepiness

The mismatch negativity (MMN) and P.3 of auditory event related potentials were studied during subjectively and objectively (physiologically) defined sleepiness under optimal stimulus conditions for MMN elicitation. The MMN and P3 were elicited by either small or large unattended auditory deviants presented to the left ear The participant's task was to defect either rare auditory targets presented to the right ear or rare changes in the light Hashes Eleven young adults served as participants in a nighttime experiment. The MMN declined especially at Fz and Cz bin not so markedly at the right mastoid as either subjective or objective alertness decreased The amplitude of P3 also decreased during sleepiness The attenuation of the MMN was paralleled by a decline in behavioral performance The results show that the MMN is attenuated by a decrease in alertness even before an actual sleep stale is reached.     

Mismatch negativity reflects numbers of tones of specific frequencies in humans

The human brain can automatically quantify objects and events. The mismatch negativity (MMN) of the event-related potential (ERP) was recently found to reflect one such ability in the auditory modality. The present study aimed to further validate the finding. ERPs were recorded in adult humans who passively listened to a series of 300-ms sequences of tones. The sequences occurred at 300-ms silent intervals. They comprised a total of six tones that each was either 440 or 660 Hz in frequency. MMN was found for a rare 4:2 ratio interspersed with a frequent 3:3 ratio between the tones of the different frequencies in a sequence, suggesting the ability of the human brain to preattentively discriminate numbers of sounds of specific frequencies at least at a 3:2 ratio.     

Mismatch Detection and the Latency of Temporal Judgments

Event-related potentials were recorded in two auditory tasks involving the discrimination of pitch or duration of binaurally presented tones. Frequently-presented nontarget tones, when compared to the same tones in a simple reaction time task, elicited two negative peaks, NA1 and NA2, followed by a positive peak, nontarget positivity. Infrequently-presented target tones, when compared to the nontargets, elicited mismatch negativity (MMN), followed by N2 and P3b. The peak latencies of NA1 and NA2 did not differ between the pitch and duration tasks, but the duration of NA1 and the peak latencies of mismatch negativity, N2, and P3b, as well as reaction time, increased in parallel for the duration task. It is proposed that the NA1-nontarget positivity sequence reflects the initiation, maintenance, and termination of an attention-modulated process, which is required for the performance of an auditory discrimination task, and that the MMN-N2-P3b sequence reflects a process elicited by infrequently-presented targets, which is the main determinant of reaction time under these testing conditions.     

ERPs for infrequent omissions and inclusions of stimulus elements

A negative event-related potential (ERP) wave called mismatch negativity (MMN) is elicited by an infrequent deviant stimulus in a sequence of frequent standard stimuli. Omission of a stimulus in a sequence of stimuli, however, has been considered to elicit a negativity different from MMN. The present study addressed this issue by examining ERPs for infrequent omissions and inclusions of compound stimuli or their elements. Three kinds of stimuli were presented: a 1000-Hz sine wave tone (Sine), white noise with the 1000-Hz frequency sharply filtered out (Noise), and a composite of the pure tone and the filtered white noise (SiNoise). All stimuli had 50 ms duration and were presented with a regular interstimulus interval of 650 ms. Intensities were 75 dB SPL for the tone and noise stimuli and slightly higher for the composite stimulus. The three kinds of stimuli were presented on separate runs, either as the frequent stimulus or one of two infrequent stimuli, each with 10% probability. Infrequent omission of the large stimulus element (Sine deviant to SiNoise) tended to elicit later MMN than inclusion of the same element (SiNoise deviant to Sine). Omission of the small stimulus element (Noise deviant to SiNoise) elicited a smaller and later MMN than did inclusion of the same element (SiNoise deviant to Noise). These data suggest that MMNs are also elicited by partial stimulus omissions, although they seem to be more sensitive to other kinds of stimulus deviances.     

Distraction in a continuous-stimulation detection task

Event-related potential (ERP) correlates of distraction are usually investigated in the oddball paradigm following a discrete, trial-by-trial stimulation protocol. In this design, participants perform a discrimination task while oddball stimuli deviate in a task-irrelevant stimulus feature. In our experiment, participants detected gaps in a continuous tone while infrequent frequency glides served as distracting events.Glides preceding a gap by 150 ms delayed the response to the gap and elicited the ERP sequence of N1, probably MMN, P3a, and reorienting negativity, suggesting that these responses reflect distraction-related processes which are neither task- nor stimulation-specific.When participants watched a silent movie and the auditory stimulation was task-irrelevant, glides preceding a gap by 150 ms enhanced the amplitude of the gap-elicited N1. However, when the auditory stimulation was task-relevant, the gap-elicited N1 was attenuated. These results show that the glides drew attention away from the ongoing task, both from watching the silent movie and from detecting gaps.     

Source Generators of Mismatch Negativity to Multiple Deviant Stimulus Types

The purpose of the present study was to investigate auditory stimulus feature processing and how neural generators might differ among the mismatch negativity (MMN) responses to intensity, frequency, and duration deviant stimuli. Data collected from 72 electrodes in twelve adult female subjects were analyzed. For each subject, peak amplitude and latency values at Fz were compared among responses to the three deviant stimulus types presented in individual conditions with a probability of 0.10 and 0.30, and in the multiple deviant condition in which all three deviant types were presented (design based on Deacon et al. 1998). Further, equivalent current dipoles (ECD) for each deviant type, in each condition, and for each subject were calculated in three areas: right hemisphere, left hemisphere, and frontal. Peak amplitude and latency measured at Fz were consistent with previous findings by Deacon et al. (1998) and suggested parallel processing, perhaps by separate neural generators. However, ECD locations were not significantly different among the responses to the different deviant types. Further, the ECD magnitudes did not consistently reflect the differences in amplitude observed at the scalp among responses to the deviant types and conditions. The latter finding may indicate that the procedures were not sensitive enough to identify true differences among the generators. Alternatively, it was suggested that searching for separate neural generators at the cortical level may be too restrictive because the process may begin in subcortical areas, as indicated in animal models.     

在单一模式和双模式刺激下gamma节律与ERP的同步效应

探讨视觉单一刺激、听觉单一刺激和视听双模式刺激的情况下,诱发脑电中的gamma节律的活动与刺激和ERP成分的同步效应。利用小波变换提取EEG诱发电位中的gamma节律成分,并用Gabor变换对其进行时频分析,结果发现gamma节律的活动不仅与外源性的刺激信号有关,而且与ERP的内源性成分(如N2b、P300)也具有明显的同步关系。同时,通过gamma节律在视听交叉模式下的活动规律也体现了人脑在多感觉模式下感觉的交叉与综合。根据在听力信号刺激后100~200ms左右出现的gamma活动增强,认为gamma波活动可能与大脑对声音信号的感知有关。     

ERP correlates of pre-attentive processing of Cantonese lexical tones: The effects of pitch contour and pitch height

The pre-attentive processing of Cantonese tones was studied with an auditory passive oddball paradigm. Event-related potentials to standard and deviant auditory stimuli were recorded as participants watched a silent movie attentively. The standards and deviants differed in either pitch level or pitch contour. Mismatch negativity (MMN) and P3a were elicited by all types of deviant tones, suggesting that lexical tone was processed pre-attentively. In addition, the size and latency of MMN were sensitive to the size of pitch level change, while the latency of P3a captured the presence of pitch contour change. These results indicate that pitch contour and pitch height are two important dimensions in sensory processing of lexical tones.     

ERP correlates of online monitoring of auditory feedback during vocalization

When speakers hear the fundamental frequency (F0) of their voice altered, they shift their F0 in the direction opposite the perturbation. The current study used ERPs to examine sensory processing of short feedback perturbations during an ongoing utterance. In one session, participants produced a vowel at an F0 of their own choosing. In another session, participants matched the F0 of a cue voice. An F0 perturbation of 0, 25, 50, 100, or 200 cents was introduced for 100 ms. A mismatch negativity (MMN) was observed. Differences between sessions were only found for 200-cent perturbations. Reduced compensation when speakers experienced the 200-cent perturbations suggests that this larger perturbation was perceived as externally generated. The presence of an MMN, and no earlier (N100) response suggests that the underlying sensory process used to identify and compensate for errors in mid-utterance may differ from feedback monitoring at utterance onset.     

Mismatch negativity in dichotic listening: Evidence for interhemispheric differences and multiple generators

The characteristics of mismatch negativity (MMN) elicited by dichotic stimulation were examined using frequency-deviant stimuli presented to the right, to the left, or to both sides. The experiment was run twice, once using earphones and once using loudspeakers in free field. With both modes of stimulation, deviants presented in the left, right, or both ears, or tones that were switched between ears, elicited comparable MMNs, with a peak latency of about 180 ms. With earphones, the amplitude of the MMN was bigger at the frontal-lateral right hemisphere sites than at the homologous left-hemisphere sites for all deviance conditions. Scalp current density analysis revealed that deviance in the right side elicited bilaterally equivalent frontal current sinks and a trend towards stronger contralateral current sources at the mastoid sites. In contrast, left side deviance elicited frontal sinks and temporal current sources stronger over the right hemiscalp. These results are compatible with the multiple-generator model of MMN. The attention-related role of the MMN is discussed, suggesting comparable attention mechanisms for vision and audition.     

The processing of sound duration after left hemisphere stroke: Event-related potential and behavioral evidence

The ability of left-hemisphere stroke patients ( n = 8) and healthy control subjects ( n = 8) to process sounds preattentively and attentively was studied by recording auditory event-related potentials (ERPs) and behavioral responses. For the right-ear stimulation, the mismatch negativity (MMN) was significantly smaller in the patients than control subjects over both hemispheres. For the left-ear stimuli, the MMN was significantly smaller in the patient group than in the control group over the left hemisphere, whereas no group differences were obtained over the right hemisphere. In addition, the N1 amplitude was reduced bilaterally for the right-ear stimulation (with the reduction being larger over the left hemisphere), whereas no significant effects on the N1 amplitude were found for the left-ear stimulation. Behaviorally, the patients detected significantly fewer deviant tones than did the control subjects irrespective of the stimulated ear. The present results thus suggest that the long-latency ERPs can be used to probe such auditory processing deficits that are difficult to define with behavioral measures. Especially by recording MMN to monaural stimuli, the discrimination accuracy can be separately determined for the left and right temporal lobes.     

Do N1/MMN,P3a,and RON form a strongly coupled chain reflecting the three stages of auditory distraction?

Distraction triggered by unexpected events is generally described in a serial model comprising (1) automatic detection of unexpected task-irrelevant events, (2) orienting towards the event, and (3) recovery from distraction. Processes taking place at the three stages are assumed to be reflected by the N1 and mismatch negativity (MMN); the P3a; and the reorienting negativity (RON) event-related potentials (ERPs), respectively. We investigated whether the processes indexed by these components form a strongly coupled chain, each co-varying with the preceding one. To this end, micro-sequence analysis of the ERPs elicited by unpredictable pitch-changes was conducted in an auditory duration discrimination task. Results indicated that the processes indexed by the above-mentioned ERPs are not strongly coupled. Pair-wise dissociations were found between the ERPs reflecting each processing stage: P3a can be elicited without concurrent N1-increase or MMN elicitation and without subsequent elicitation of the RON. Possible interpretations of P3a and RON are discussed.     

Mismatch negativity to auditory stimulus change recorded directly from the human temporal cortex

Mismatch negativity (MMN) is an event-related potential (ERP) component elicited by any discernible change in a repetitive sound even in the absence of attention. Previous studies have established that MMN is generated by change detection in a process comparing the deviant sensory input with the neural memory trace encoding the physical features of the repetitive sound. In the present study, we recorded MMNs to tonal frequency changes directly from the human temporal cortex of patients with electrodes implanted in the brain for diagnosis and therapy. The intracranially recorded MMN was found to be attention independent and modality specific. It was confined to a rather small area in temporal cortex, which was different from the structures where attention-dependent N2 and P3 responses to the frequency change could be recorded.     

音乐速度变化感知的失匹配负波

感知速度变化对音乐认知具有重要意义。本研究采用5个鼓点音构成标准等间距序列,再通过调整序列第3个刺激间隔(IOI)的长度引入局部速度扰动(IOI缩短:加速;IOI延长:减速)。从行为实验及被动听觉脑电实验入手,记录被试主动检测三种典型序列速度(快速:IOI=300 ms;中速:IOI=600 ms;慢速:IOI=900 ms)下的局部IOI扰动的行为响应,及自动感知中速序列(IOI=600 ms)局部IOI扰动的脑电响应。行为数据显示:中速的响应精度显著大于快速和慢速;加速与减速的辨别力指数在快速和慢速下均有显著差异,而在中速下无显著差异。脑电数据显示:在额中区电极Fz处,加速的失匹配负波(MMN)比减速的幅度更大、潜伏期更早。实验结果表明,中速序列的局部速度扰动对MMN的影响显著不同;即使在行为无偏差的中等序列速度下,大脑对局部速度扰动的感知加工还是有差异的。     

Music-induced mood modulates the strength of emotional negativity bias: an ERP study

The present study investigated the effect of music-elicited moods on the subsequent affective processing through a music-primed valence categorization task. Event-related potentials were recorded for positive and negative emotional pictures that were primed by happy or sad music excerpts. The reaction time data revealed longer reaction times (RTs) for pictures following negative versus positive music pieces, irrespective of the valence of the picture. Additionally, positive pictures elicited faster response latencies than negative pictures, irrespective of the valence of the musical prime. Moreover, the main effect of picture valence, and the music by picture valence interaction effect were both significant for P2 amplitudes and for the averaged amplitudes at 500-700ms interval. Negative pictures elicited smaller P2 amplitudes than positive pictures, and the amplitude differences between negative and positive pictures were larger with negative musical primes than with positive musical primes. Similarly, compared to positive pictures, negative pictures elicited more negative deflections during the 500-700ms interval across prime types. The amplitude differences between negative and positive pictures were again larger under negative versus positive music primes at this interval. Therefore, the present study observed a clear emotional negativity bias during either prime condition, and extended the previous findings by showing increased strength of the negative bias under negative mood primes. This suggests that the neural sensitivity of the brain to negative stimuli varies with individuals' mood states, and this bias is particularly intensified by negative mood states.