The N1 wave of the human electric and magnetic response to sound: a review and an analysis of the component structure.
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Results for “Contingent Negative Variation”
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Changes in heart rate and slow brain potentials related to motor preparation and stimulus anticipation in a time estimation task.
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Adolescent↗
Functional differences between members of the P300 complex: P3e and P3b.
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Baroreceptor stimulation alters pain sensation depending on tonic blood pressure.
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Adult↗
Event-related potentials to different feedback stimuli.
Event-related potentials (ERPs) were recorded in a time estimation task under different feedback conditions, in which the informative value of the feedback signals (true versus false) was manipulated. A control condition was added in which no signal was presented. Fifteen subjects pressed a button 3 seconds after presentation of a warning signal. Two seconds after the response, a visual feedback signal was presented, indicating whether the preceding interval was estimated correctly. Two different slow waves were observed: the response was preceded by a readiness potential and the feedback stimulus was preceded by a negative slow wave called the stimulus-preceding negativity. The readiness potential was not influenced by the different feedback conditions. The stimulus-preceding negativity was larger in the true feedback condition compared to the false feedback and no feedback conditions. The P300 to the feedback signal was also larger following a true as compared to a false feedback signal. The conclusion is that the stimulus-preceding negativity is an anticipatory component contingent upon the presentation of an informative feedback signal.
Adult↗
The processing of temporal intervals reflected by CNV-like brain potentials.
The present study employed event-related potentials (ERPs) of the brain to improve the understanding of temporal processing. A reproduction paradigm was realized by presenting a visual stimulus (illuminated screen) for intervals of varying length. A few seconds after presentation of such standard intervals the visual stimulus was switched on again and subjects were asked to reproduce the duration of the standard interval by turning off the illumination after a corresponding interval had elapsed. The length of standard intervals varied randomly with each of the following lengths being presented 20 times: 1, 2, 3, 4, 6, and 8 s. Reproduction was accurate for standard intervals up to 3 s but deteriorated with increasing interval length. Brain potentials during reproduction intervals of 1-3 s differed from those recorded during the longer intervals. A CNV-like slow negative shift developed during the shorter reproduction intervals. Negatively was reduced or even absent, when subjects had to reproduce standard intervals of 4 s or longer. The ERP results suggest that intervals shorter than 3-4 s may evoke a processing mode that is qualitatively different from the one dominating when periods in the range of several seconds have to be processed.
Adult↗
Waiting in readiness: gating in attention and motor preparation.
In this paper the similarities in the structural and functional organization of motor preparation and attention are discussed. A crucial structure in this organization is the thalamus, a complex of sensory and motor nuclei that transmits information from subcortical origins to the cortex. For the most part, the thalamus is overlapped by the nucleus reticularis, which has a local inhibitory influence on the underlying nuclei. This serves as a gating mechanism for the transmission of sensory information to the cortex. Skinner and Yingling (1977) have provided arguments in favor of a frontal control in the gating of sensory information. The present paper extends their suggestions to the motor system: a similar gating mechanism for the transmission of subcortical motor information to the cortex is hypothesized, also under frontal control. Slow potentials recorded during motor preparation and attention for an upcoming stimulus show a different distribution over the scalp. These distributions are interpreted as an indication of which thalamic gates are open to transmit information to the cortex. Probe responses (spinal reflexes, evoked potentials, and the startle reflex) can also be used to investigate which thalamocortical gates are open under certain experimental conditions. It is concluded that the sensory and motor input to the cortex are subjected to a similar control mechanism.
Attention↗
Detection of EMG onset in ERP research.
Many researchers have used off-line techniques for the automatic detection of electromyogram (EMG) onset. However, very little is known about the accuracy of these methods. In the present study, five such methods are evaluated and their accuracy is reported. Five subjects were asked to produce fast (ballistic) and slow (ramp) contractions with thumb and index finger of the right hand in a simple reaction time task. EMG was recorded from the first dorsal interosseus muscle, and onsets were visually determined in the raw EMG. These onsets were compared with the onsets produced by the automated methods on the rectified and low-pass filtered EMG. Four of the automated methods produced very reliable estimates of the visually determined onsets, at least when additional constraints upon the initial estimates were made. Studies using automated methods for EMG onset detection should report findings about their accuracy.
Acoustic Stimulation↗
Is a stimulus conveying task-relevant information a sufficient condition to elicit a stimulus-preceding negativity?
Movement-preceding and stimulus-preceding negativities were recorded when a movement was followed by one of three informative visual stimuli. The meaning of the visual stimulus alternated between (a) conveying a task-relevant instruction about a subsequent time production task and (b) providing feedback (knowledge of results) about performance on the current time production task. In a control condition, premovement and postmovement scalp potentials were recorded when subjects made the same movements but in a voluntary, self-paced manner. Under all conditions, movements were preceded by a movement-preceding negativity, and neither the amplitude nor the lateral asymmetry of this negativity was affected by the subsequent presentation of either kind of informative stimulus. When the movement was followed by a stimulus conveying knowledge of results, the negativity in the postmovement epoch was enhanced, but this enhancement was not evident in epochs preceding instruction stimuli. We conclude that not all task relevant stimuli elicit a stimulus-preceding negativity, and we provide a functional interpretation of this negativity in terms of emotional anticipation and the contingency of the stimulus on a previous event.
Adult↗
An ERP study on visual spatial priming with peripheral onsets.
Visual event-related potentials were measured for peripheral target stimuli that were preceded by a peripheral square. Targets appeared either at the same location as the square or in the opposite visual hemifield. In Experiment 1, 75% of the trials were same-location trials, and in Experiment 2, same- and opposite-location trials were equiprobable. The subject's overt response was dependent either on the identity or on the location of the target. In both experiments, opposite-location targets elicited an enhanced P1 at posterior electrodes ipsilateral to the position of the letter. This enhancement may be due to a sensory inhibition of same-location targets. Same-location targets elicited an enhanced negativity between 130 and 300 ms, with a first peak located parietally and a second peak broadly distributed over midline electrodes. This effect was larger in Experiment 1 than in Experiment 2 and is interpreted as enhanced processing of same-location targets due to an attentional orienting process elicited by the peripheral square.
Adult↗
An event-related potential study of sensory representations of unfamiliar tonal patterns.
Tonal patterns were delivered to 17 subjects instructed to read a self-selected book and to ignore the auditory stimuli. The standard pattern contained eight 50-ms segments differing in frequency. Infrequent changes of single segments within the pattern elicited negative modulations of the event-related brain potentials (ERPs) as compared with the ERPs elicited by the standard pattern. The change consisted of either a duplication of a single segment or an interchange of two segments within the pattern. Because of the nature of the change, the ERP modulation cannot be explained by a simple refractoriness mechanism or by assuming that the mechanism generating the negative modulation relies on representations of only the spectral but not the temporal information of the pattern. Therefore, the spectral and the temporal information of the tonal patterns were represented by the information processing system on a grain of single segments.
Adult↗
The lateralized readiness potential preceding brief isometric force pulses of different peak force and rate of force production.
Previous studies have reported that the lateralization of the readiness potential is unaffected by force amplitude of brief unimanual responses. However, because those studies did not specify rate of force production, response force probably was mainly controlled by force unit duration rather than by recruitment of force units, which may explain this negative finding. To enforce recruitment control, we factorially combined peak force (10% or 50% of maximal voluntary finger force) and time to peak force (100 or 200 ms). A precue provided advance information about the responding index finger (left vs. right). After 1 s, the imperative stimulus followed, requiring a brisk isometric flexion of the specified index finger. Symmetric effects, maximal at the vertex, of both force and rate of force production were observed 200-100 ms before the imperative stimulus in stimulus-synchronized averages and 200-100 ms before response onset in response-synchronized averages. However, neither force nor rate of force production affected the lateralized readiness potential. We conclude that this measure does not reflect movement parameters but appears to indicate an abstract preparation of lateralized response channels.
Adult↗
Brain event-related potential correlates of overfocused attention in obsessive-compulsive disorder.
A hypothesis of overfocused attention in obsessive-compulsive disorder was investigated by measuring auditory event-related potentials (ERPs) during a selective attention task. Unmedicated patients (n = 18) with this disorder showed significantly larger attention-related processing negativity (PN), with earlier onset and longer duration, than did normal controls (n = 15). In the N200 region (160-250 ms), PN was larger in patients with fewer nonspecific neurological soft signs. This task, however, did not yield any group differences in mismatch negativity (N2a) or classical N200 (N2b). P300 amplitudes for attended targets were smaller for patient than normal groups, but the reverse was true for P300 and positive slow wave amplitudes for unattended nontargets. Collectively, these ERP abnormalities suggest a misallocation of cognitive resources. Because of the importance of the frontal lobe in the control of selective attention, PN enhancement in patients with obsessive-compulsive disorder may reflect hyperactivation of this region. This conceptualization is consistent with recent functional neuroimaging findings.
Adult↗
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.
Adult↗
Response complexity and precue interval effects on the lateralized readiness potential.
Fundamental properties of an important new tool in cognitive electrophysiology, the lateralized readiness potential (LRP), were examined in two experiments. Experiment 1 resolved an apparent inconsistency in the literature by demonstrating that this response-specific lateralization is larger preceding complex then preceding simple finger movements. In Experiment 2, the foveally presented precue, which indicated hand of response, preceded the go/no-go stimulus by 0, 100, 300, or 1,400 ms. Analyses of LRP latency indicated that hand-specific preparation began earlier with longer foreperiods but was temporally linked to the reaction stimulus as well as the precue. Although the degree of lateralization did not predict reaction speed in either study, a nonlateralized, response-locked negativity was larger prior to faster reactions.
Adult↗
Processing of auditory deviants with changes in one versus two stimulus dimensions.
Auditory event-related potentials (ERPs) in response to 50-ms tones were recorded from the human scalp. A standard stimulus (p = .88) and three different deviants were randomly presented via earphones. There were two one-dimensional deviants (one frequency and one location deviant) and one two-dimensional deviant, with changes in both frequency and location. In one condition, subjects read a book and ignored the auditory stimuli, whereas in another condition they tried to discriminate deviants from standards. In the ignore condition, the two-dimensional deviant elicited an enhanced mismatch negativity (MMN) as compared with the MMNs elicited by the one-dimensional deviants. The temporal and the topographic distributions of the two-dimensional MMNs could be modeled by adding the one-dimensional MMNs. This activity of the MMNs probably results from the independent activity of separate neural populations generating the frequency and the location MMN. In the attend condition, the deviance-related ERP effects were not additive in the N2b and P3 range, implicating that the neural processes involved in the conscious detection of changes in location and frequency were not independent.
Adolescent↗
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.
Adult↗
Word-specific cortical activity as revealed by the mismatch negativity.
Neurophysiological brain activity evoked by individual spoken words and pseudowords was recorded and the mismatch negativity (MMN), an automatic index of experience-dependent auditory memory traces, was calculated. Consistent with earlier reported results, the MMN response to word-final syllables was enhanced compared with that elicited by the same syllables placed in a pseudoword context. Here we now demonstrate that the enhancement of the MMN elicited by two individual words showed different scalp topographies. The early word-specific brain activity is consistent with the assumption that the memory traces activated by individual words are carried by large neuronal ensembles that differ in their distributions over the cortex. Current source estimates localized the between-word differences in the right hemisphere and in parieto-occipital left-hemispheric areas. The differential brain responses to individual words appeared as early as approximately 100 ms after the recognition points of the words, suggesting that their specific memory traces become active almost immediately after the information in the acoustic input is sufficient for word identification.
Adult↗