Effects of Stimulation Rate and Attribute Cuing on Event-Related Potentials During Selective Auditory Attention

Auditory event-related potentials (ERPs) were recorded from subjects who attended selectively to a sequence of tones of one frequency and ignored a comparable sequence of tones having a different frequency and spatial origin. In one condition the tones consisted of randomized sequences of brief tone pips while in a second condition the tones were brief increments in intensity (pedestals) of continuous tones at the two frequencies. The tone pips and pedestals were delivered at comparable interstimulus intervals (ISIs), which were short (250–550 ms) in some runs and long (1250–2750 ms) in others. For both classes of stimuli, the subject's task was to detect occasional “target” tones of a slightly shorter duration than the more frequent “standard” tones. Stimuli of the attended frequency elicited a broad negative ERP component (Nd) relative to the unattended tone ERPs. The Nd wave had a considerably shorter onset latency and was smaller in overall amplitude at the faster rate of stimulation. However, the Nd wave did not differ in latency or amplitude between the tone pip and pedestal conditions at corresponding ISIs, suggesting that a high rate of information delivery is a more important factor in accelerating Nd onset than is the continuous reinforcement of the sensory cues that define the two classes of input.     

Within-Channel Selection and Event-Related Potentials During Selective Auditory Attention

Event-related potentials were recorded from subjects who listened selectively to stimuli in one of two input channels (ears). The stimuli were random sequences of five vowels and a tone pip. In separate experimental runs, the difficulty of within-channel selection was manipulated by designating either tone (T), one vowel (1V), or two vowels (2V) as targets. An attention-related negativity (Nd) was observed for attended nontarget vowels irrespective of the target difficulty, but the early, centrally maximal phase of Nd was substantial only for the one-vowel and two-vowel conditions. The Nd between its early and late peaks was significantly larger for the two-vowel condition than for the one-vowel and tone conditions. The 2V minus 1V difference in Nd had a closely similar distribution to the early Nd. These target difficulty effects were interpreted as suggesting that the early Nd recorded in two-selection tasks can be related to a within-channel selection process as well as a between-channel selection process. The more anteriorly distributed, later phase of Nd was suggested to be rather insensitive to the difficulty of the within-channel selection. The nature of the within-channel selection underlying the early Nd was discussed in relation to controlled memory search operations.     

Combined Use of Microreflexes and Event-Related Brain Potentials as Measures of Auditory Selective Attention

Two versions of a selective listening experiment were conducted in an attempt to specify the level of the nervous system at which selective attention first influences auditory information processing. Post-auricular reflexes (PARs), preputse inhibition of reflexes, and the N1 component of the event-related potential (ERP) were measured concurrently to assess auditory processing in the hindbrain. midbrain. and forebrain. respectively. Sequences of intense, reflex-eliciting tones were presented to the two ears in random order and at a rapid rate as subjects listened to a designated ear to detect rare tones of slightly lower intensity. The ERPs showed the typical enhancement of early and late negativity (Nd) to attended car tunes, with the early Nd overlapping the evoked N1 component. Although there was an overall effect of attention direction on the efferent limb of the post-auricular reflex, no effect of selective attention on the afferent limb was observed. A selective sensory attentional effect was found for prepulse inhibition of the post-auricular reflex: Inhibition of PAR amplitude was enhanced when the immediately preceding tone was in the attended ear relative to when it was in the unattended ear. These results, together with findings from prior studies of reflexes and ERPs. indicate that evoked auditorv activity in the lower brainstem is obligatory and invariant with attention, whereas later activity mediated in the upper brainstem can be modulated by attention.     

Event-Related Potential Indices of Selective Attention and Cortical Lateralization in Schizophrenia

Auditory event-related potentials (ERPs) from a multidimensional selective attention task were recorded from 10 unmedicated schizophrenic patients and 10 age- and sex-matched healthy controls. Tone pip stimuli varying on the dimensions of pitch (high or low) and location (left or right ear) formed four 'channels' of stimuli: left low, left high, right low, and right high. The pitch difference was considerably more difficult to discriminate than the location difference. Subjects were instructed to pay attention to a designated channel and press a button whenever they detected a long-duration, rare target tone that occurred amongst frequent short-duration standard tones. There were a number of differences between unmedicated schizophrenics and controls in processing negativity elicited by standard tones. There was no evidence of hierarchical processing of stimulus dimensions in the early processing negativity component, and the late frontal component was virtually absent in schizophrenics. Furthermore, there was evidence that in schizophrenics the processing of the location dimension was delayed for standard tones having the same pitch as the target. The P300 component to attended target tones was substantially reduced in schizophrenics over parietal sites but there was no difference between the two groups over frontal sites. The results are interpreted in terms of multiple attentional deficits in schizophrenics that are indicative of a failure in the planning and execution of selective listening strategies. Such a failure may result from a dysfunction in the prefrontal regions of the brain.     

The Effect of Repeated Testing on ERP Components During Auditory Selective Attention

The present study examined long-term repetition effects on human auditory event-related potentials (ERPs). ERPs were recorded from subjects performing the same multidimensional auditory selective attention task on six separate occasions spaced one week apart. The task required subjects to attend to tones that varied along the dimensions of location (L), pitch (P), and duration (D) and to detect prespecified target (L + P + D +) combinations of these attributes. Processing negativity (PN) between 100-400 ms did not change in amplitude or onset latency as a function of repeated experience with the task. In contrast, two measures of "very late" PN were reduced with practice. Specifically, the location effect measured over the 400-700-ms epoch was significant only for Weeks 1 and 2, and the separation of the L + P + D- ERP from other D- ERPs, measured over the 700-1000-ms epoch, was significantly reduced from Week 1 to Week 2. A late negative component (700-1000 ms) elicited by correctly identified targets increased between Weeks 1 and 2, consistent with subjects adopting the strategy of rehearsal of the target itself rather than the L + P + D- standard. P2 amplitude increased significantly for all standards, possibly due to decreased latency jitter in later weeks. N1 latency became significantly shorter over weeks, reflecting either increasing confidence in stimulus discrimination with repeated testing or the overlapping of an unchanging N1 with an increasing P2.     

Somatosensory Evoked Potential Changes With a Selective Attention Task

Somatosensory evoked potential (SEP) changes associated with selective attention were investigated. In 16 subjects, SEPs were recorded from five locations while they counted electrical stimuli to one of four randomly stimulated fingers. Sequential SEP events measured included peaks P30 (positivity at 30 msec). P45, N60, P100. N140. P190. N230, P400. Counting was associated with greater P45, P100. P190, N230, and P400 amplitudes; effects were not attributable to eye or tongue activity. Analyses designed to reveal changes associated with two conceptualized “channels” (finger class, hand) showed that the P45, P100, and P190 amplitude increases involved both channels. The P400 effect was limited to the target finger. Channel effects for N60 and N140 amplitudes resulted from decreases localized to the unattended element of one channel, suggesting “inhibition.” Latency effects involved mainly the hand channel; counted hand latencies were shorter for P30, P45, P100 and P190. The findings indicate modifications of both early and late electrocortical events with selective attention, and that changes can be of several kinds. They support the view that attention proceeds in more than one stage.     

Effects of Foveal Task Load on Visual-Spatial Attention: Event-Related Brain Potentials and Performance

The effects of foveal task difficulty on the processing of events in the visual periphery were investigated through an analysis of event-related brain potentials and performance measures. Subjects performed a foveally presented continuous monitoring task both separately and together with an arrow discrimination task that was presented at three different retinal eccentricities. The subjects detected occasional failures in the monitoring task while also responding to designated targets in the left and right visual fields. The analysis of the event-related brain potentials elicited by discrete events in the arrow discrimination task indicated that the amplitude of the N190 and P300 components decreased with both the introduction of the foveal task and an increase in its difficulty. The N160 component was sensitive to the distribution of attention within a task but was uninfluenced by dual task demands. These findings suggest that the N160 reflects the distribution of attention to different spatial locations within a task while the N190 may index the distribution of general purpose perceptual resources. P300 appears to index the allocation of perceptual/central processing resources. The implications of the results for models of resource allocation and attentional gradients are discussed.     

选择性注意的神经生理学解释

本文从听觉生理学的角度对以往的选择性注意理论模型进行宏观分析，提出了选择性注意的“多重选择理论”模型，并提供了相关的神经生理学理论依据。该模型进一步确认了人类选择性注意过程既存在着初期的过滤过程．也存在着其后的选择过程。认为在信息进入感觉器官之后．衰减的过程并不明显。同时通过丘脑的网状结构上行激动系统所具有只容许的单信息通过的门控功能，排除了能量分配理论中的关于大脑的能量分配限制的说法。     

Event-Related Brain Potentials in a Stimulus-Discrimination Learning Paradigm

Event-related brain potentials were recorded from human subjects performing a stimulus-discrimination learning task. Brain activity was averaged separately for different stimulus attributes, either relevant or irrelevant for the discrimination, and for different stages of learning. Learning-specific amplitude changes occurred in two positive peaks of the ERP (P160 and P330): a) the amplitudes of both components decreased continuously over blocks; b) with increasing practice the amplitudes to irrelevant attributes became significantly smaller than those to relevant attributes; and c) the point at which the amplitudes to relevant and irrelevant attributes diverged was earlier for P330 and later for P160. The different trends of the amplitudes of the two peaks suggest that they reflect functionally distinct processes of attentional set. Peak latencies and other amplitude measures of the ERP (baseline shift, N100, slow wave) showed no learning-specific, but systematic long- and short-term habituation/facilitation effects.     

Temporal Dynamics of Human Auditory Selective Attention

Event-related potentials (ERPs) were recorded from human subjects in response to short trains of rapidly presented tone pips of two frequencies. Subjects listened selectively to tones of one frequency as directed by a visual cue prior to each train and responded to occasional longer-duration target tones of that frequency. The early negative difference (Nd) between ERPs elicited by the tones when attended versus unattended was minimal for the first stimulus in each train but developed rapidly, attaining stable values by about the third stimulus. The development of this early Nd was most rapid when two attended tones began a train. Long time-base averages revealed the concomitant development of a standing negativity over the course of each train. In contrast, late positive ERPs distinguished attended from unattended target tones even when they occurred in the first position of a train, prior to the development of Nd. The latency of this late positivity together with the reaction time to the targets decreased substantially as the Nd developed. It was concluded that subjects can select stimuli at various stages of analysis, but employment of the early selection mechanism indexed by Nd enables an economy of processing and faster and more accurate task performance. This mode of early selection is not pre-set in advance of a stimulus train, however, at least under the present conditions.     

Effects of eye position on event-related potentials during auditory selective attention

Event-related potentials (ERPs) were recorded from normal subjects who received random sequences of tone pips from loudspeakers located to the left and right of a central point. The task was to detect occasional higher pitched tones (targets) from one designated speaker. The negative difference (Nd) wave between ERPs for relevant and irrelevant tones was largest when subjects fixated on the relevant speaker, smallest when subjects fixated on the irrelevant speaker, and intermediate in a central fixation. In addition, the Nd modulation for the left tones was produced by the more negative (or less positive) shift of irrelevant-stimulus ERPs and the less negative shift of relevant-stimulus ERPs associated with fixating away from the relevant speaker. These findings suggest the possibility of both facilitatory and inhibitory effects of eye position on auditory spatial attention. The substantial modulation of ERPs due to eye position also indicated the necessity of fixation control in auditory attention ERP research.     

注意对冲突监测事件相关电位N270的影响

目的：探讨注意对冲突监测事件相关电位N270的影响。方法：30名健康志愿者分成两组,一组人判断连续呈现的一对数字的颜色是否相同,不考虑数值（注意颜色）;另一组人判断连续呈现的一对数字的数值是否相同,不考虑颜色（注意数值）,在头皮同步记录事件相关电位。结果：颜色不同和／或数值不同的数字对均可在第二个数字呈现后引起事件相关电位N270,颜色和数值完全相同的数字对则不引起该负波。与不被主动注意状态相比,刺激特征冲突被注意时引出的N270波幅更高,持续时间更长,起始潜伏期不变。结论：冲突监测系统的启动不受注意影响,而一旦启动后则受到注意系统的调节。     

Event-Related Potentials, Spatial Orienting, and Reading Disabilities

Event-related potentials (ERPs) were used to investigate the effects of visual-spatial orienting on selective neural processing in boys with learning disabilities. Twenty-seven 8-12 year old boys were classified into four groups depending on whether or not they had a reading disability or attention deficit disorder. Event-related potentials were recorded over the left and right occipital, central, and frontal cortical regions. The behavioral task required the subjects 1) to rapidly switch their attention from the center to the periphery of the visual field (spatial component), and 2) to selectively respond to a target versus a nontarget flash when the target was presented in the relevant visual field (nonspatial component). The amplitude of two ERP components was enhanced in response to relevant as compared to irrelevant stimuli. The enhancement of an early negative occipital-central component, which peaked 180-200 ms following targets (N1), indicated that selective neural processing associated with spatial attention could be switched in 600 ms. This enhancement of N1 was greater in boys with than without a reading disability, which implies that reading disability is associated with enhanced spatial attention. The enhancement of a later positive component, which peaked 300-340 ms following targets (P3), suggested that nonspatial target selection was reduced in boys with a reading disability, particularly over the left occipital hemisphere. Target relevance and reading disability also influenced trial-to-trial variability in the ERP waveform. The effects of reading disability on event-related potentials did not vary as a function of attention deficit disorder, indicating that these two disorders are distinct.     

Scopolamine Effects on Visual Information Processing, Attention, and Event-Related Potential Map Latencies

We measured performance and event-related brain potential (ERP) map latencies in 12 subjects during four visual discrimination tasks to compare the timing of scopolamine effects on information processing and attention. "Topographic component recognition" found ERP map latencies at times of best fit with a component model map. This "common topography" criterion minimized topographic differences among conditions to facilitate latency interpretations. Scopolamine slowed N1 latency in all tasks, and P3 and reaction time in some tasks. The drug delayed responses to easy targets more than to hard targets. It also induced a disproportionate N1 delay for unilateral high spatial frequency gratings. Both effects reflect a scopolamine-induced impairment when processing targets that usually capture attention. Scopolamine also impaired accuracy for unilateral high spatial frequency gratings, and for gratings presented at probable locations, confirming and extending previous findings. Scopolamine-induced P1 and N1 delays showed that visual processing was affected. Several results were inconsistent with a serial stage model. We suggest that scopolamine both delays selected processes and impairs a processing mode based on automatic capture of attention, inducing more serial processing.     

The Effects of Practice and Task Structure on Components of the Event-Related Brain Potential

The present study focused on the effects of, and the interactions between, practice and task structure on human performance. The development of automatic processing through consistent stimulus-response mapping (CM) was assessed by means of measures of reaction time and event-related brain potentials. The subjects performed a visual search task in which they responded by pressing a button whenever a probe matched a memory set item. The variables manipulated in the study included the number of memory set items (1 or 4), the task structure (CM or VM), and the probability of occurrence of a memory set item (.2 or .8). Set size had a significant effect on RT in both CM and VM conditions prior to practice and in the VM condition following extensive practice. P300 latency mirrored RT, suggesting that the development of automatic processing substantially reduced stimulus evaluation time. The commonly observed relationship between probability and P300 amplitude, with larger P300s elicited by infrequent events, was found in the VM conditions but not in the CM condition after practice. Two different negative components were affected by stimulus mismatch. The N200 component behaved in a similar manner during automatic and controlled processing. However, a late frontally negative component was sensitive to the degree of mismatch only during controlled processing.     

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.     

搜索威胁:负性情绪图片的选择性注意

快速搜索和探测具有威胁的刺激是人类生存的基础。威胁刺激能激起恐怖、焦虑等负性情绪,搜索表达负性情绪图片中的选择性注意是近期研究的焦点。负性情绪刺激的搜索较快,其作为干扰物又会影响其他靶子的搜索成绩。研究者提出注意获得和注意固着两种观点加以解释。时间进程的分析表明,警戒-回避模式能较好说明恐怖/焦虑个体对威胁刺激的加工。     

Cardiac Response During Auditory Selective Attention to Tones and Affective Sounds

We conducted an experiment to determine if attention to affective sounds showed a lateral bias. Twenty‐two participants were instructed to respond to one of two pure tones presented monaurally and to a set of pleasant and unpleasant sounds from the International Affective Digitized Sounds set. Participants were instructed to respond to pleasant or unpleasant sounds in the right or left ear, attending to pleasant/right, pleasant/left, unpleasant/right, and unpleasant/left sounds in separate blocks. Evoked cardiac response to the tones showed significant cardiac deceleration in response to attended sounds in the attended ear. In addition, pleasant sounds elicited significant cardiac deceleration when attended in the right ear, but not in the left. Unpleasant sounds elicited significant cardiac deceleration when attended in both ears. Consistent with the anterior valence hypothesis, our data suggests that pleasant sounds are mainly processed in the left hemisphere, but in contrast to this hypothesis, unpleasant sounds are processed bilaterally.     

基于三维层析技术的选择性注意脑电研究

利用脑电三维层析技术对左右视野空间选择性注意的ERP进行了研究。结果表明,层析得到的电源强度与头表的脑电数据相比,能更好地反映注意导致的P1、N1相对增强效应,其中尤以N1的增强比较明显。此外,层析结果中还能观察到在该头表数据中未能反映出来的C1成分。     

Event-Related Brain Potentials in Selective Listening to Frequent and Rare Stimuli

Our previous event-related brain potential (ERP) results suggest that during selective listening, relevant stimuli are selected for further processing by comparing each stimulus to an “attentional trace,” a neuronal representation of the physical features of the relevant stimuli that distinguish them from the irrelevant stimuli. This comparison process is reflected by the early component of the processing negativity (PN), which is largest and longest to the relevant stimuli (perfectly matching with the trace). In the present study, the subjects selectively listened to designated tone stimuli which randomly appeared among irrelevant tones of a different pitch. The probability of relevant stimuli in a block was varied. The processing negativity elicited by relevant stimuli was smaller the less frequent they were. The results support the attentional-trace theory of selective attention, which proposes that, in addition to active maintenance, the trace also depends on the rate of sensory reinforcement provided by the relevant stimuli.