Personality and the effects of acute alcohol intake. A contingent negative variation study in healthy subjects

This study investigates the relationship between blood alcohol concentrations (BACs) and contingent negative variation (CNV). Fourteen healthy subjects were divided on the basis of their personality profiles--the Minnesota Multiphasic Personality Inventory (Hs+Hy+D/3)--into a high score (HS) and low score (LS) subgroup. The CNV was recorded using a choice-reaction time (RT) task. CNV recording was performed in two conditions: inter-stimulus intervals (ISIs) of 1500 ms and 2500 ms at three different BACs (0.3, 0.5 and 0.8 g/L) after acute alcohol administration. At the high BAC (0.8 g/L), both subgroups showed a reduced CNV amplitude area and a longer RT (p<.05) in both ISI conditions. No effects either on the CNV or on the RT were observed at the low BAC (0.3 g/L). At the intermediate BAC (0.5 g/L), the HS subgroup displayed an increased CNV amplitude (p<.05), not accompanied by a significantly longer RT (short ISI condition), and a reduced late CNV (p<.05) with a longer RT (p<.05) (long ISI condition). In the LS group, only a longer RT was observed in the long ISI condition. CNV modifications point to an individual, apparently personality-related, threshold of sensitivity to different alcohol levels.

The error-related negativity as a state and trait measure: Motivation, personality, and ERPs in response to errors

This study examines changes in the error-related negativity (ERN/Ne) related to motivational incentives and personality traits. ERPs were gathered while adults completed a four-choice letter task during four motivational conditions. Monetary incentives for finger and hand accuracy were altered across motivation conditions to either be equal or favor one type of accuracy over the other in a 3:1 ratio. Larger ERN/Ne amplitudes were predicted with increased incentives, with personality moderating this effect. Results were as expected: Individuals higher on conscientiousness displayed smaller motivation-related changes in the ERN/Ne. Similarly, those low on neuroticism had smaller effects, with the effect of Conscientiousness absent after accounting for Neuroticism. These results emphasize an emotional/evaluative function for the ERN/Ne, and suggest that the ability to selectively invest in error monitoring is moderated by underlying personality.

The sequential processing of visual feature conjunction mismatches in the human brain

To clarify the brain mechanism for multifeature stimulus comparison, subjects matched the features of two serial visual stimuli in pairs. Stimulus pairs were of four categories: C-S-, color same, shape same (match); C-S+, color same, shape different (shape mismatch); C+S-, color different, shape same (color mismatch); C+S+, color different, shape different (conjunction mismatches). Subjects matched the stimuli in three different sessions according to different attention tasks: attending to color (Ac), attending to shape (As), or attending to both color and shape (Acs). A negative one-peak brain potential, N270, was elicited in all the mismatch conditions with amplitude enhanced in the task-relevant mismatch. Negative potential with two peaks, N270 and N400, appeared when attending to the conjunction mismatches concurrently. The two serial negativities in response to attended feature conjunctions might reflect the temporal different stages for processing conjunction mismatches or conflicts.

Event-related potentials associated with sound discrimination versus novelty detection in children

In children, deviant sounds in an oddball paradigm elicit a mismatch negativity (MMN) indexing discrimination of sound change and late difference negativity (LDN) with unknown functional significance. Salient sounds elicit an ERP index if orienting, P3a, and a late negative component, Nc. We compared children's responses elicited by moderate sound changes and novel sounds to examine the relationships between MMN and LDN, and LDN and Nc. Two components of the Nc, the Nc1 and Nc2, were identified. The scalp topography of LDN differed from those of the MMN and Nc1. Children's early P3a appeared mature but late P3a lacked frontal predominance. The findings suggested that LDN is not linked with either the sensory or attentional processing. It might reflect cognitive, albeit preattentive, processing of sound change. The Nc1 appears to reflect cognitive attentive processing of salient stimuli and the Nc2 might reflect reorienting after distraction.

Early neural activity in Necker-cube reversal: Evidence for low-level processing of a gestalt phenomenon

Normally we experience the visual world as stable. Ambiguous figures provide a fascinating exception: On prolonged inspection, the "Necker cube" undergoes a sudden, unavoidable reversal of its perceived front-back orientation. What happens in the brain when spontaneously switching between these equally likely interpretations? Does neural processing differ between an endogenously perceived reversal of a physically unchanged ambiguous stimulus and an exogenously caused reversal of an unambiguous stimulus? A refined EEG paradigm to measure such endogenous events uncovered an early electrophysiological correlate of this spontaneous reversal, a negativity beginning at 160 ms. Comparing across nine electrode locations suggests that this component originates in early visual areas. An EEG component of similar shape and scalp distribution, but 50 ms earlier, was evoked by an external reversal of unambiguous figures. Perceptual disambiguation seems to be accomplished by the same structures that represent objects per se, and to occur early in the visual stream. This suggests that low-level mechanisms play a crucial role in resolving perceptual ambiguity.

Cortical control mechanisms in volitional swallowing: the Bereitschaftspotential

OBJECTIVE

This research sought to identify a well-defined pre-motor potential, the Bereitschaftspotential (BP), as a manifestation of cortical contribution to the pre-motor planning of volitional swallowing.

METHODS

EEG data were collected from 20 research participants during volitional execution of swallowing and finger movement tasks. A5 second pre-movement epoch for each task was triggered on EMG identification of movement onset. A grand average for each task representing approximately 2400 trials across all research participants was derived to compare and contrast morphological features of the derived waveform.

RESULTS

Volitional pharyngeal swallowing and finger movement generated similar waveform characteristics of duration and slope; however, statistically significant differences were identified in polarity and in amplitude at four points both early and late in the epoch. Additionally, swallowing produced a pre-motor waveform with a rapid declination of EEG activity in the final 500 msec prior to movement onset.

CONCLUSIONS

This study demonstrates activation of the supplementary motor cortex preceding the onset of volitional swallowing. However, unlike purely voluntary movements, the volitional pharyngeal swallowing task, as assessed with this methodology, does not appear to recruit the primary motor cortex. Thus engagement of the swallowing response appears to rely on indirect parallel pathways between extrapyramidal cortical motor planning regions and lower motor neurons.

Cortical and subcortical distribution of middle and long latency auditory and visual evoked potentials in a cognitive (CNV) paradigm

OBJECTIVE

This study concerned sensory processing (post-stimulus late evoked potential components) in different parts of the human brain as related to a motor task (hand movement) in a cognitive paradigm (Contingent Negative Variation). The focus of the study was on the time and space distribution of middle and late post-stimulus evoked potential (EP) components, and on the processing of sensory information in the subcortical-cortical networks.

METHODS

Stereoelectroencephalography (SEEG) recordings of the contingent negative variation (CNV) in an audio-visual paradigm with a motor task were taken from 30 patients (27 patients with drug-resistant epilepsy; 3 patients with chronic thalamic pain). The intracerebral recordings were taken from 337 cortical sites (primary sensorimotor area (SM1); supplementary motor area (SMA); the cingulate gyrus; the orbitofrontal, premotor and dorsolateral prefrontal cortices; the temporal cortex, including the amygdalohippocampal complex; the parietooccipital lobes; and the insula) and from subcortical structures (the basal ganglia and the posterior thalamus). The concurrent scalp recordings were obtained from 3 patients in the thalamic group. In 4 patients in the epilepsy group, scalp recordings were taken separately from the SEEG procedure. The middle and long latency evoked potentials following an auditory warning (S1) and a visual imperative (S2) stimuli were analyzed. The occurrences of EPs were studied in two time windows (200-300 ms; and over 300 ms) following S1 and S2.

RESULTS

Following S1, a high frequency of EP with latencies over 200 ms was observed in the primary sensorimotor area, the supplementary motor area, the premotor cortex, the orbitofrontal cortex, the cingulate gyrus, some parts of the temporal lobe, the basal ganglia, the insula, and the posterior thalamus. Following S2, a high frequency of EP in both of the time windows over 200 ms was observed in the SM1, the SMA, the premotor and dorsolateral prefrontal cortex, the orbitofrontal cortex, the cingulate gyrus, the basal ganglia, the posterior thalamus, and in some parts of the temporal cortex. The concurrent scalp recordings in the thalamic group of patients twice revealed potentials peaking approximately at 215 ms following S1. Following S2, EP occurred with latencies of 215 and 310 ms, respectively. Following S1, separate scalp recordings in 4 patients in the epilepsy group displayed EP 3 times in the 'over 300 ms' time window. Following S2, EP were presented once in the '200-300 ms' time window and 3 times in the 'over 300 ms' time window.

CONCLUSIONS

The SM1, the SMA, multiple sites of the frontal lobe, some parts of the temporal lobe, the cingulate gyrus, the basal ganglia, the insula, and the posterior thalamus all participate in a cortico-subcortical network that is important for the parallel cognitive processing of sensory information in a movement related task.

Functional specialization in the human frontal cortex observed during task anticipation

The purpose was to evaluate whether a scalp-recorded slow potential will show specificity during the anticipation of different types of visual tasks. One of the tasks required the comparison of pairs of familiar faces, and the other was the comparison of abstract dotted patterns. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Faces and patterns were superimposed, and the switching between tasks depended on the cue. The ERP analysis was done for the time window between S1 (cue) and S2 presentations. The major differences between tasks were found in the anterior scalp regions starting at 700 ms from S1 onset. During Pattern task anticipation, the proposed sources in the right frontal area were more anterior, inferior and lateral than those in Face task. The task-specific slow electric potentials may indicate the functional specialization for attentive anticipation in the human frontal lobe.

Speed-accuracy modulation in case of conflict: the roles of activation and inhibition

This study investigated how the speed-accuracy balance is modulated by changes in the time course of motor activation and inhibition of a primed response. Responses and event-related brain potentials were recorded in a paradigm in which the first stimulus indicated the correct response with 80% validity. The remaining 20% of the trials required no response (no-go) or a response opposite to the cued hand (change trials). Subjects were instructed either to balance speed and accuracy or to emphasize speed at the cost of accuracy. Analyses of error patterns, reaction time distributions and brain potentials show that subjects can modulate the amount of activation of the primed response. More surprisingly, the engagement of inhibition of the response also varied with the speed-accuracy instruction. The results are consistent with a model where the frontothalamic loop actively controls both the activation and the inhibition of responses, depending on the current task requirements.

The effects of alteration of effector and side of movement on the contingent negative variation

OBJECTIVE

The contingent negative variation (CNV) is a widespread electroencephalographic (EEG) potential that occurs during the interval between a warning stimulus and a subsequent imperative stimulus if a mental or motor response is required. The present study was designed to explore the impact of the previous trial on the CNV of the forthcoming trial, that is, how a previous movement affects brain activation preparing the next movement. Effects of alteration of finger (from index to middle, and vice versa) and hand (from left to right, and vice versa) were examined independently from each other.

METHODS

CNV was recorded in 20 right-handed healthy subjects with electrodes placed at F7, F5, F3, F4, F6, F8, FC5, FC3, FC1, FC2, FC4, FC6, T7, C5, C3, C1, C2, C4, C6, T8, CP5, CP1, CP2, CP6, P7, P3, P4 and P8. In a visual/visual S1-choice paradigm, an earlier informative (S1) stimulus which instructed for side and finger of the following movement was followed 3 s later by an imperative (S2) stimulus providing the command to move. Subjects had to respond to each imperative stimulus with an appropriate button press made by brisk flexion movements with the index or middle finger of each hand. The CNV recorded in the interval between the informative and the imperative stimulus was analysed with respect to finger and hand of the present and the preceding movement.

RESULTS/CONCLUSIONS

(1) A change of the side of movement is associated with a widespread increase of negativity contralateral to the currently prepared movement. (2) A change of finger is associated with a focal increase of negativity contralateral to the side of the current movement over temporoparietal and mid-parietal areas. (3) A change of finger results in a widespread increase of negativity over the left hemisphere.

Lie detection with contingent negative variation

topographies of contingent negative variation (CNV) were recorded in a paradigm of delayed response with feedback for three kinds of faces: familiar, strange and target. Subjects made responses to the faces according to whether the faces were familiar or not, but also, gave deliberately deceptive responses to target faces to 'cheat the computer'. Subjects were told that the computer could judge whether they were being honest or not. For each trial of the experiment, if subjects cheated the computer successfully and their responses were judged as honest and they were given a reward, otherwise they received a penalty. In this simulated lie detection test, CNV exhibited more negative shifts for target than those for non-target (familiar and strange). These differences could be accounted for by subjects' motivation and uncertainty about passing the test. With the results of further paired t-tests between target and non-target faces at each electrode, CNV was demonstrated as a reliable indicator for lie detection. In addition, vector length was used to capture global CNV information and was found to be a very good indicator, even better than the CNV information at the individual electrode sites.

The CNV peak: An index of decision making and temporal memory

A slow brain potential change, the contingent negative variation (CNV), was recorded in a temporal generalization schedule. The task was to judge the duration of a signal (1.250 to 3.125 s) as being equal or not to that of a 2-s target that had been previously memorized. Two signal modalities, visual and tactile, were contrasted in distinct trial blocks, in order to explore possible localization differences. Significant results were found at CPz, irrespective of signal modality. The CNV that developed during signal presentation peaked around 2 s and then declined when the current signal was longer than the 2-s target, instead of peaking at signal extinction as was the case for shorter signals. Thus, for signals longer than the target, the CNV peak and the following slope change provide a memory trace of the encoded target duration, leading to decision making.

Evidence for the different additivity of the temporal and frontal generators of mismatch negativity: a human auditory event-related potential study

The auditory sensory-memory mechanisms in the human brain were investigated using the mismatch negativity (MMN) component of the event-related potential. MMNs were recorded to stimuli deviating from the repetitive standard stimuli simultaneously either in one or two features (frequency, intensity). If the processing of these two features is independent of each other, the MMN to the double deviant should equal the sum of the MMNs elicited by the corresponding single deviants. The double-deviant MMNs were found to be additive at the electrode sites below the Sylvian fissure but not at the frontal scalp areas. The results suggest that the temporal subcomponent of MMN is additive whereas the frontal is non-additive. The pattern of results was similar in ignore and attend conditions, suggesting that the components were not attentionally modulated.

Which stages of processing are speeded by a warning signal?

This article reviews psychophysiological and behavioral studies that attempt to identify which stages of processing are speeded by a neutral warning signal (WS), that is to say, one that conveys no information about the nature of the imperative stimulus or the required response. Experiments involving the lateralized readiness potential (LRP) provide evidence against the widely held view that warning effects on reaction time (RT) are due to facilitation of low-level motor processes. Studies of modality-specific evoked potentials similarly rule out a locus within sensory-perceptual processing. It is concluded that the speeding of RT by a neutral WS is most likely due to nonspecific motor priming within an early phase of response selection. In addition, fast-guess responses, in which subjects choose a response without fully analyzing the stimulus, are assumed to contribute to warning effects.

Auditory evoked potentials from the cortex: audiology applications

PURPOSE OF REVIEW

The audiological applications of cortical auditory evoked potentials are reviewed. Cortical auditory evoked potentials have some advantages compared with more commonly used techniques such as the auditory brainstem response, because they are more closely tied to perception and can be evoked by complex sounds such as speech. These response characteristics suggest that these potentials could be used clinically in the estimation of threshold and also to assess speech discrimination and perception.

RECENT FINDINGS

Clinical uses of auditory evoked potentials include threshold estimation and their use as an electrophysiological index of auditory system development, auditory discrimination and speech perception, and the benefits from cochlear implantation, auditory training, or amplification.

SUMMARY

Cortical auditory evoked potentials obtained in passively alert adults have a remarkably high correspondence with perceptual threshold. Acoustic features of complex sounds may be reflected in the waveform and latency of these potentials and so might be used to determine the integrity of neural encoding for such features and thus contribute to speech perception assessment. MMN and P3 have been used to discern discrimination abilities among groups of normal-hearing and hearing-impaired individuals; however, their sensitivity and specificity for testing an individual's abilities has not yet been established. Cortical auditory potentials are affected by listening experience and attention and so could be used to gauge the effects of aural habilitation. The presence of cortical potentials in children with auditory neuropathy appears to indicate residual hearing abilities. Parametric and developmental research is needed to further establish these applications in audiology.

Effects of alcohol consumption and alcohol susceptibility on cognition: a psychophysiological examination

The present study sought to examine acute effects of alcohol on cognitive processing and performance within the context of two prominent theories of alcohol's effects; namely, that alcohol restricts the focus of attention (e.g. Steele and Josephs, 1990. Journal of Abnormal Psychology, 97, 196-205) and that alcohol impairs response inhibition (e.g. Fillmore and Vogel-Sprott, 1999. Experimental and Clinical Psychopharmacology, 7, 49-55; Fillmore and Vogel-Sprott, 2000. Journal of Studies on Alcohol, 61, 239-246). Forty-five participants were randomly assigned to receive either a placebo level of alcohol (0.04 g/kg), a moderate dose (0.40 g/kg), or a higher dose (0.80 g/kg). Brain electrical activity (ERPs) and behavioral responses (reaction time and accuracy) were measured while participants performed a modified flanker task, in which a target letter was flanked by response-compatible or response-incompatible letters. Analyses of behavioral data showed that alcohol increased response competition in accuracy but not response times, suggesting that alcohol influences response selection more than attentional processes per se. This finding is in-line with predictions derived from the response inhibition model. ERP latency data provided mixed support for both models. ERP amplitude data showed that the high dose of alcohol primarily influenced a mostly frontal negativity in the ERP, present on both correct and incorrect response trials. Differences in self-reported susceptibility to alcohol were most evident in the amplitude of the P3 component. Findings are discussed in terms of the differential effects of acute dose and susceptibility on information processing.

Attention capture by auditory significant stimuli: semantic analysis follows attention switching

Event-related potentials (ERPs) were recorded from the scalp to investigate a long-standing controversy in auditory attention research, namely when the 'breakthrough of the unattended' takes place in the human brain. Nine subjects classified visual stimuli appearing 300 ms after task-irrelevant standard tones (80%, i.e. P = 0.8) or novel sounds (20%, i.e. P = 0.2) into odd/even categories. After the recording session, subjects scored the novel sounds as to whether they had any particular meaning (identifiable) or were perceived as a burst of noise (non-identifiable), and performance and ERPs were analysed according to this classification. A control condition, in which the visual stimuli were presented with no sounds, showed that subjects covertly monitored the task-irrelevant sounds during visual task-performance, and a further condition, in which the auditory and visual stimuli appeared regardless of each other, made it possible to trace the processing of the distracters during allocation of attention outside the auditory environment. Results yielded identical N1-enhancement for the two types of novel sounds, indicating similar attention switching triggered to these two types of unexpected sounds. However, there was a stronger orientating of attention towards identifiable novel sounds, as indicated both by behavioural distraction and by larger novelty-P3. Furthermore, this stronger orientating of attention was due to the sounds being contingent on the visual stimuli, as no increase in novelty-P3 to identifiable novel sounds was observed in the control condition, in which the sounds occurred outside the attentional set. Therefore, provided that the N1-enhancement reflects a call for focal attention, and novelty-P3 the effective orientating of attention towards the eliciting sounds, the present results suggest that semantic analysis of significant sounds occurs after a transitory switch of attention towards the eliciting stimuli. Moreover, as the novelty-P3 increase in amplitude was observed only when subjects covertly monitored the sounds, the present data suggest that semantic analysis of irrelevant sounds depends on the top-down cognitive influences of the attentional set.

Temporal organization of covert motor processes during response selection and preparation

Onset of a movement-related brain potential (lateralized readiness potential, LRP) was used to divide reaction time (RT) into two intervals: (1) stimulus onset to LRP onset, and (2) LRP onset to onset of the overt response. Effects on these intervals of advance information about the to-be-signaled response and of the mapping between fingers and response buttons were examined. These effects were used to reach conclusions about the organization of response preparation and about the identity of the processes influenced by advance information. In the absence of advance information, response preparation involved two steps. First, two of the four possible response alternatives were prepared, then one of these two was prepared further. Which pair of responses was prepared during the first step depended on the spatial arrangement of the fingers on the buttons, rather than on any common anatomical feature. Advance information about the upcoming response allowed the first step to be performed prior to the response signal, thus removing its contribution to RT. The second step, however, remained unaffected.

The late posterior negativity in ERP studies of episodic memory: action monitoring and retrieval of attribute conjunctions

The focus of the present paper is a late posterior negative slow wave (LPN) that has frequently been reported in event-related potential (ERP) studies of memory. An overview of these studies suggests that two broad classes of experimental conditions tend to elicit this component: (a) item recognition tasks associated with enhanced action monitoring demands arising from response conflict and (b) memory tasks that require the binding of items with contextual information specifying the study episode. A combined stimulus- and response-locked analysis of data from two studies mapping onto these classes allowed a temporal and functional decomposition of the LPN. While only the LPN observed in the item recognition task could be attributed to the involvement of a posteriorly distributed response-locked error-related negativity (or error negativity; ERN/Ne) occurring immediately after the response, the source-memory task was associated with a stimulus-locked negative slow wave occurring prior and during response execution that was evident when data were matched for response latencies. We argue that the presence of the former reflects action monitoring due to high levels of response conflict, whereas the latter reflects retrieval processes that may act to reconstruct the prior study episode when task-relevant attribute conjunctions are not readily recovered or need continued evaluation.

Anxiety and error-related brain activity

Error-related negativity (ERN/Ne) is a component of the event-related brain potential (ERP) associated with monitoring action and detecting errors. It is a sharp negative deflection that generally occurs from 50 to 150 ms following response execution and has been associated with anterior cingulate cortex (ACC) activity. An enhanced ERN has been observed in patients with obsessive-compulsive disorder (OCD)--reflecting abnormal ACC activity hypothesized as part of the pathophysiology of OCD. We recently reported that the ERN is also enhanced in a group of college students with OC characteristics. The present study extended these findings by measuring the ERN in college undergraduates who scored high on either the Penn State Worry Questionnaire (PSWQ) or a combined version of the Snake (SNAQ) and Spider (SPQ) Questionnaires. Results indicate that, like OC subjects, subjects who score high on a measure of general anxiety and worry have enhanced error-related brain activity relative to both phobic and non-anxious control subjects. The enhanced ERN was found to generalize beyond OCD within the anxiety spectrum disorders but also shows some specificity within these disorders.

Scalp-recorded contingent negative variation (CNV) increases during experimentally induced sustained ischemic pain in humans

Contingent negative variations (CNV) after acoustic stimuli (S1) followed by optical ones (S2) were recorded using electroencephalography in 22 healthy students both under control conditions and during ischemic pain to study the effects of sustained pain on CNV. Mean negative CNV-amplitudes and integrated areas below CNV were significantly larger during periods of ischemic pain than under control conditions (16.53 versus 13.11 microV, respectively (P=0.0028) and 8.318 versus 6.357 microV*s, respectively (P=0.00071)). We conclude that deep somatic pain augments CNV. Reduced CNV amplitudes occurring during migraine attacks, however, reflect other mechanisms which may mask the effects of migraine headache on CNV.

Preparatory visuo-motor cortical network of the contingent negative variation estimated by current density

The present report studied the intracerebral current density of the contingent negative variation (CNV) during a visuo-manual task using the gap paradigm. The CNV is usually obtained during preparatory periods for perception and action. In this experiment right-hand responses were required. The CNV potential was obtained during the preparatory period from electrodes placed at 58 scalp sites. The CNV showed an early and a late phase. Scalp voltage and source current density maps showed that the early phase was focused on frontal midline sites. The late phase had two foci, one overlying the primary motor cortex and one over occipital sites. When analyzed by low-resolution tomography, the early phase of the CNV showed activations in the supplementary motor area (SMA), the anterior cingulate cortex (ACC), and some posterior areas. The late phase had anterior activations in the left prefrontal cortex, middle frontal cortex, primary motor cortex, ACC, and SMA; and several posterior activations including those in the medial occipital cortex, middle inferior occipital cortex, posterior cingulate cortex, and temporal and parietal areas. Results from the activated areas and their temporal dynamics during the preparatory period suggest that the ACC and the SMA areas recruit the action- and perception-related areas needed to process the expected subsequent imperative task.

Event-related potentials associated with second language learning in children

OBJECTIVE

In this study, we investigated learning-related changes in auditory event-related potentials (ERPs) of Finnish-speaking 3-6-year-old children caused by learning French language.

METHODS

Using an oddball paradigm, ERPs to sounds of French language were recorded in the two groups of healthy children: those who were learning French (experimental group) and those who were not learning any foreign language (control peers).

RESULTS

When the children from the experimental group were exposed to the foreign language, they automatically developed French-specific memory traces that helped them to discriminate, categorize, and pronounce utterances of the new language as indicated by the mismatch negativity (MMN) component of the ERPs in a previous study. We found that the learning process was also reflected by changes in P3a and late difference negativity (LDN) responses. Unlike MMN and P3a, the LDN has been discovered relatively recently and its functional role remains unclear. Similarly, as the MMN magnitude increased during the learning process, an increase of the P3a (known to reflect the involuntary attention switching toward deviant stimuli) and LDN amplitudes was observed. The ERPs of the control peers did not change significantly over the test period.

CONCLUSIONS

When phonemes of a foreign language are learned, this process is accompanied with the increase in the MMN, P3a, and LDN amplitudes in children. Though the functional significance of LDN remains to be further investigated, our results support its possible link to reorienting processes following distraction.

Simultaneous ERP and fMRI of the auditory cortex in a passive oddball paradigm

Infrequent occurrences of a deviant sound within a sequence of repetitive standard sounds elicit the automatic mismatch negativity (MMN) event-related potential (ERP). The main MMN generators are located in the superior temporal cortex, but their number, precise location, and temporal sequence of activation remain unclear. In this study, ERP and functional magnetic resonance imaging (fMRI) data were obtained simultaneously during a passive frequency oddball paradigm. There were three conditions, a STANDARD, a SMALL deviant, and a LARGE deviant. A clustered image acquisition technique was applied to prevent contamination of the fMRI data by the acoustic noise of the scanner and to limit contamination of the electroencephalogram (EEG) by the gradient-switching artifact. The ERP data were used to identify areas in which the blood oxygenation (BOLD) signal varied with the magnitude of the negativity in each condition. A significant ERP MMN was obtained, with larger peaks to LARGE deviants and with frontocentral scalp distribution, consistent with the MMN reported outside the magnetic field. This result validates the experimental procedures for simultaneous ERP/fMRI of the auditory cortex. Main foci of increased BOLD signal were observed in the right superior temporal gyrus [STG; Brodmann area (BA) 22] and right superior temporal plane (STP; BA 41 and 42). The imaging results provide new information supporting the idea that generators in the right lateral aspect of the STG are implicated in processes of frequency deviant detection, in addition to generators in the right and left STP.

The disruptive effect of chronic pain on mismatch negativity

OBJECTIVE

To investigate the effect of chronic pain on processes that generate the mismatch negativity (MMN).

METHODS

Twelve participants with a diagnosis of chronic intractable pain were tested before and after pain treatment. During testing, event-related potentials were recorded while participants performed tasks of varying difficulty.

RESULTS

The amplitude of the MMN was found to be greater following a nerve block procedure compared to MMN amplitude when participants were experiencing chronic pain. This effect was found to occur in the MMN for difficult-to-detect tones elicited while participants were performing a simultaneous cognitively demanding visual task. MMN amplitude was found to be greater with attention to difficult-to-detect deviants during pain but not in no pain conditions.

CONCLUSIONS

These results provide an electrophysiological correlate of previous findings that high levels of pain disrupt cognition during the performance of demanding tasks.