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PubMed1987

Attention to central and peripheral visual space in a movement detection task: an event-related potential and behavioral study. I. Normal hearing adults.

The effects of focussed attention to peripherally and centrally located visual stimuli were compared via an analysis of event-related brain potentials (ERPs) while subjects detected the direction of motion of a white square in a specified location. While attention to both peripheral and foveal stimuli produced enhancements of the early ERP components, the distribution over the scalp of the attention-related changes varied according to stimulus location. The attention-related increase in the amplitude of the N1 wave (157 ms) to the peripheral stimuli was greater over the parietal region of the hemisphere contralateral to the attended visual field. By contrast, the largest effects of foveally directed attention occurred over the occipital regions where the increase was bilaterally symmetrical. Additionally, the effects of attention on the ERPs were significantly larger for moving than for stationary stimuli, and this effect was greater for peripheral than for central attention. A long-latency positive displacement component (300-600 ms) was larger over the right than the left hemisphere during attention to the lateral visual fields, but was symmetrical in amplitude when central stimuli were attended. These results suggest that different pathways are modulated when attention is deployed to different regions of the visual fields. Further, they suggest that the special role of the right hemisphere in spatial attention may be limited to analysis of information in the visual periphery.

Adolescent↗
PubMed1992

Intermodal selective attention. I. Effects on event-related potentials to lateralized auditory and visual stimuli.

The effects of intermodal selective attention on event-related brain potentials (ERPs) were examined in 2 experiments. In experiment 1, auditory ERPs were compared (1) when subjects responded to easy and difficult-to-detect target tones in sequences of tone bursts; and (2) when they ignored the same auditory sequences and played a demanding video game. In experiment 2, auditory ERPs to tone bursts and visual ERPs to vertical line gratings were compared as subjects responded to difficult-to-detect targets in one modality or the other. Attention to auditory stimuli resulted in biphasic enhancements in auditory ERPs, the Nda (negative auditory difference wave, latency 120-160 msec) and the Pda (positive auditory difference wave, latency 200-240 msec) waves. These had longer latencies and somewhat different scalp distributions than N1 and P2 components evoked by non-attended tones. The Nda and Pda could be contrasted with the monophasic processing negativities typically found in dichotic selective attention tasks. Nda amplitudes were larger for difficult-to-detect targets (closely resembling standards) than for standards themselves, but no Ndas were recorded to highly deviant targets. Deviant auditory stimuli evoked mismatch negativities (MMNs) that persisted during visual attention. MMN amplitudes to difficult-to-detect deviants were enlarged with attention, but no change was found in MMN amplitudes to easy-to-detect deviants. In experiment 2 intermodal attention was associated with biphasic changes in visual ERPs over the posterior scalp: the occipital Pdv (100-130 msec), and contralateral-temporal Ndv (120-320 msec) deflections. Deviant visual stimuli also elicited mismatch negativity/N2b components, largest over the inferotemporal cortex contralateral to the stimulated visual field. Like the auditory MMN, the MMN increased in amplitude with attention, but it was also evident during attend auditory conditions. The results suggest that sustained, intermodal attention depends primarily in processing modulations in modality-specific cortex. We found no evidence of the participation of modality non-specific cortex. This excludes the possibility that intermodal attention depends on a single, supramodal attention system. The relatively long latency of intermodal effects suggests that they may depend on the reafferent (top down) modulation, and do not index "template matching" operations.

Acoustic Stimulation↗
PubMed1995

ERP signs of early selective attention effects to check size.

In ERP literature on visual selective attention evidence has been provided that selectively directing attention to a spatial frequency affects the visual processing of the attended frequency, and of unattended frequencies within the same channel bandwidth, starting at a relatively late level of post-stimulus processing, i.e., after about 150 msec. Nevertheless, little knowledge is available about the topographic distribution of these attention effects. This study investigated attentional selection of stimulus relative size at occipital and latero-occipital sites, as well as at fronto-lateral sites. ERPs from posterior scalp electrode sites showed that attention to check sizes enhanced the early sensory components, thus indicating that feature-based attention may result in a modulation of sensory processing. Comparisons of the ERPs to relevant and irrelevant patterns showed an enhanced latero-occipital P90 positivity as well as an occipital N115 negativity to relevant patterns, thus also suggesting possible differential mechanisms of early attentional selectivity at these locations. Later effects of attention consisted of a selection negativity to relevant patterns at posterior electrodes, and a selection positivity at latero-frontal sites. A larger late positivity to irrelevant patterns at anterior sites also suggested an active suppression of attentional response to irrelevant information. Moreover, right-and left-sided asymmetries were found to be respectively consistent for the P90 and N115 with left hemispheric specialization for high, and right hemispheric specialization for low spatial frequencies. A stronger left-sided attentional selectivity has also been found.

Adult↗
PubMed1988

The effects of hemispatial and asymmetrically focused attention on dichotic listening with normal and learning-disabled children.

The effects of hemispatial and focused attention were examined with 50 normal and learning-disabled children to determine the extent of these two attentional strategies influenced perceptual laterality as reflected by the dichotic listening right-ear advantage (REA). Twenty-five normal children (8 females, 17 males, mean age 9.10 yr) matched with 25 learning-disabled children (8 females, 17 males, mean age 10.1 yr) were administered a dichotic consonant-vowel (CV) and consonant-vowel-consonant (CVC) syllable task. The two types of stimuli were compared across focused attention (free report, focused left, focused right) and hemispatial (central, left hemispace, right hemispace) conditions implemented independently and in systematic combinations. A four-factorial analysis of variance (groups x stimuli x conditions x ears) resulted in a significant REA for normal children across all attentional conditions whereas learning-disabled did not produce a consistent REA across all attentional conditions, and in several instances, produced equivalent left and right hemisphere processing. Right hemispatial orientation increased the magnitude of the REA (i.e., left hemisphere processing) for both groups, whereas left hemispatial orientation increased the magnitude of the left ear report (i.e., right hemisphere processing) only in learning-disabled subjects. Focused attention to the right ear also increased left hemisphere efficiency for both groups of children; however, focused attention to the left ear produced symmetrical functioning by learning-disabled subjects. Congruent combinations of focused attention and hemispatial orientation were not found to enhance the REA beyond its magnitude when each strategy was assessed independently. When focused attention and hemispatial conditions were employed in opposing directions, normal children were more susceptible to the "rightward" direction regardless of the strategy whereas learning-disabled subjects were more susceptible to the "verbal" nature of the strategy. Higher overall processing performance was exhibited for CVC stimuli when compared to CV stimuli. These findings lend support to the hypothesis that hemispatial and asymmetrically focused attention strategies interact with structural mechanisms in producing the observed REA in dichotic listening and do so differentially for normal and learning-disabled children.

Adolescent↗
PubMed1995

The role of attention in the programming of saccades.

Accurate saccadic programming in natural visual scenes requires a signal designating which of the many potential targets is to be the goal of the saccade. Is this signal controlled by the allocation of perceptual attention, or do saccades have their own independent selective filter? We found evidence for the involvement of perceptual attention, namely: (1) summoning perceptual attention to a target also facilitated saccades; (2) perceptual identification was better at the saccadic goal than elsewhere; and (3) attempts to dissociate the locus of attention from the saccadic goal were unsuccessful, i.e. it was not possible to prepare to look quickly and accurately at one target while at the same time making highly accurate perceptual judgements about targets elsewhere. We also studied the trade-off between saccadic and perceptual performance by means of a novel application of the "attentional operating characteristic" (AOC) to oculomotor performance. This analysis revealed that some attention could be diverted from the saccadic goal with virtually no cost to either saccadic latency or accuracy, showing that there is a ceiling on the attentional demands of saccades. The links we discovered between saccades and attention can be explained by a model in which perceptual attention determines the endpoint of the saccade, while a separate trigger signal initiates the saccade in response to transient changes in the attentional locus. The model will be discussed in the context of current neurophysiological work on saccadic control.

Attention↗
PubMed2006

Selective attention to sound location or pitch studied with fMRI.

We used 3-T functional magnetic resonance imaging to compare the brain mechanisms underlying selective attention to sound location and pitch. In different tasks, the subjects (N = 10) attended to a designated sound location or pitch or to pictures presented on the screen. In the Attend Location conditions, the sound location varied randomly (left or right), while the pitch was kept constant (high or low). In the Attend Pitch conditions, sounds of randomly varying pitch (high or low) were presented at a constant location (left or right). Both attention to location and attention to pitch produced enhanced activity (in comparison with activation caused by the same sounds when attention was focused on the pictures) in widespread areas of the superior temporal cortex. Attention to either sound feature also activated prefrontal and inferior parietal cortical regions. These activations were stronger during attention to location than during attention to pitch. Attention to location but not to pitch produced a significant increase of activation in the premotor/supplementary motor cortices of both hemispheres and in the right prefrontal cortex, while no area showed activity specifically related to attention to pitch. The present results suggest some differences in the attentional selection of sounds on the basis of their location and pitch consistent with the suggested auditory "what" and "where" processing streams.

Acoustic Stimulation↗
PubMed2005

Spatio-temporal dynamics of top-down control: directing attention to location and/or color as revealed by ERPs and source modeling.

This study investigated the nature and dynamics of the top-down control mechanisms that afford attentional selection using event-related potentials (ERPs) and dipole-source modeling. Subjects performed a task in which they were cued to direct attention to color, location, a conjunction of color and location or no specific feature on a trial-by-trial basis. Overall, similar ERP patterns were observed for directing attention to color and location, suggesting that spatial and non-spatial attention rely to a great extent on similar control mechanisms. The earliest attention-directing effect, at 340 ms, was localized to ventral posterior cortex and may reflect processes by which the cue is linked to its associated feature. Only late in the cue-target interval, differences in ERP were observed between directing attention to color and location. These originated from anterior and ventral posterior areas and may represent differences in, respectively, maintenance and perceptual biasing processes. The ventral posterior sources estimated for these late effects of directing attention to location and color were located posterior to those estimated for the modulatory effects of, respectively, spatial and non-spatial attention. This suggests that the precise neural populations involved in perceptual biasing and attentional modulation may differ. Conjunction cues initially elicited less posterior positivity than color and location cues, but evoked greater central positivity from 540 ms on. This central effect may reflect feature integration or ongoing processes related to cue-symbol translation. These results extend our understanding of the spatio-temporal dynamics of top-down attentional control.

Adult↗
PubMed2007

Human brain activity associated with audiovisual perception and attention.

Coherent perception of objects in our environment often requires perceptual integration of auditory and visual information. Recent behavioral data suggest that audiovisual integration depends on attention. The current study investigated the neural basis of audiovisual integration using 3-Tesla functional magnetic resonance imaging (fMRI) in 12 healthy volunteers during attention to auditory or visual features, or audiovisual feature combinations of abstract stimuli (simultaneous harmonic sounds and colored circles). Audiovisual attention was found to modulate activity in the same frontal, temporal, parietal and occipital cortical regions as auditory and visual attention. In addition, attention to audiovisual feature combinations produced stronger activity in the superior temporal cortices than attention to only auditory or visual features. These modality-specific areas might be involved in attention-dependent perceptual binding of synchronous auditory and visual events into coherent audiovisual objects. Furthermore, the modality-specific temporal auditory and occipital visual cortical areas showed attention-related modulations during both auditory and visual attention tasks. This result supports the proposal that attention to stimuli in one modality can spread to encompass synchronously presented stimuli in another modality.

Adolescent↗
PubMed2004

What are you looking at? Impaired 'social attention' following frontal-lobe damage.

Humans are able to predict the behavior of others. Several studies have investigated this capability by determining if social cues, such as eye gaze direction, can influence the allocation of visual attention. When a viewer sees a face looking to the left, the viewer's attention is allocated in the gazed-at direction. These 'social attention' studies have asked if this allocation of attention is automatic or under voluntary control. In this paper, we show that a patient with frontal-lobe damage is impaired at allocating attention to peripheral locations voluntarily, although attention can be allocated there automatically. The patient, EVR, can use peripheral cues to selectively process one location over another but cannot use symbolic cues (words) to allocate attention. EVR is also impaired in using eye gaze cues to allocate attention, suggesting that 'social attention' may involve frontal-lobe processes that control voluntary, not automatic, shifts of visuospatial attention.

Adult↗
PubMed2006

Eye gaze does not produce reflexive shifts of attention: evidence from frontal-lobe damage.

Humans are able to predict the behavior of others using visual information. Several studies have argued that social cues, such as eye gaze direction, can influence the allocation of visual attention in a reflexive manner. We have previously shown that a patient with frontal-lobe damage, patient EVR, can use peripheral cues to direct attention but cannot use either word cues or gaze cues to allocate attention. These findings suggest that 'social attention' may involve frontal-lobe processes that control voluntary, not automatic, shifts of visuospatial attention. In the current paper, we further examine 'social attention' in EVR and demonstrate that his failure to orient attention voluntarily cannot be attributed to either cue predictability or a 'sluggish' attentional system. EVR exhibits a general impairment in orienting attention endogenously, and this impairment includes orienting from gaze cues. Gaze cues direct attention in a voluntary, not a reflexive, manner.

Aged↗
PubMed2005

Effects of gonadectomy and androgen supplementation on attention in male rats.

Androgens are hypothesized to enhance aspects of mnemonic processing. However, it is unclear whether the memory improvement is associated with changes in earlier aspects of information processing, such as attention. The present experiments examined the effects of gonadectomy or supplementation with testosterone or dihydrotestosterone on performance of male rats in a two-lever attention task that required discrimination of visual signals and non-signals. In Experiment 1, Long-Evans rats were trained in the attention task and then underwent gonadectomy or sham-surgery. Postsurgically, animals were tested for 20 sessions in the attention task and then received manipulations designed to increase attentional demands. Gonadectomized and sham-treated animals performed similarly during immediate postsurgical testing and across all manipulations. Finally, the effects of administering the muscarinic receptor antagonist scopolamine (0, 0.1, and 0.2 mg/kg) on attentional performance were assessed for all animals. Scopolamine decreased accuracy of signal detection but did not differentially affect gonadectomized and sham-treated animals. In Experiment 2, a new group of rats (not gonadectomized) was trained to perform the attention task and subsequently administered testosterone (0, 0.1, and 0.5 mg/kg) or dihydrotestosterone (0, 0.1, and 0.5mg/kg) prior to performing the standard version of the attention task and in the presence of a visual distractor. Testosterone (0.5 mg/kg) decreased accuracy on non-signal trials and, at 0.1 mg/kg, decreased latencies to retrieve a reward. Dihydrotestosterone (0.5 mg/kg) decreased accuracy on non-signal trials during visual distractor sessions. The present data do not support the hypothesis that alterations in attention critically mediate androgen-induced changes in mnemonic processing. Supra-physiological androgen levels appear to be capable of impairing attentional processing.

Acetylcholine↗
PubMed2005

Resting EEG theta activity predicts cognitive performance in attention-deficit hyperactivity disorder.

Quantitative electroencephalography has contributed significantly to elucidating the neurobiologic mechanisms of attention-deficit hyperactivity disorder. The most consistent and robust electroencephalographic disturbance in attention-deficit hyperactivity disorder has been abnormally increased theta band during resting conditions. Separate research using attention-demanding tests has elucidated cognitive disturbances that differentiate attention-deficit hyperactivity disorder. This study attempts to integrate electroencephalographic and neuropsychological indices to determine whether cognitive performance is specifically related to increased theta. Theta activity was recorded during a resting condition for 46 children/adolescents with attention-deficit hyperactivity disorder and their sex- and age-matched control subjects. Accuracy and reaction time during an auditory oddball and a visual continuous performance test were then recorded. Compared with control subjects, the attention-deficit hyperactivity disorder group manifested significantly increased (primarily left) frontal theta. Furthermore, the attention-deficit hyperactivity disorder group scored significantly delayed reaction time and decreased accuracy in both tasks. Correlation analysis revealed a significant relationship between frontal (primarily left) theta and oddball accuracy for the attention-deficit hyperactivity disorder group compared with a significant relationship between posterior (primarily right) theta and reaction time in the continuous performance test for the control group. These results indicate that spatial neurophysiologic deficits in attention-deficit hyperactivity disorder may be related to disturbances in signal detection. This observation has important implications for the role of trait-like biologic deficits in attention-deficit hyperactivity disorder predicting performance in information processing.

Adolescent↗
PubMed2005

The relationship between visual-perception and attention in Chinese with schizophrenia.

Previous studies suggest possible visual-perceptual deficits associated with schizophrenia, and co-existing impairments in attention and visual-perceptual function in people with schizophrenia. This study examines if people with schizophrenia show visual-perceptual difficulty and whether different components of attention, namely sustained attention, selective attention, switching attention and attentional control processing, relate to the visual-perceptual function of people with schizophrenia differently. A total of 94 participants voluntarily participated in this study: 47 of them were diagnosed with schizophrenia and 47 were normal controls. Visual-perceptual abilities were measured by the Hooper Visual Organization Test (HVOT) for visual organization ability and the Judgment of Line Orientation Test (JLOT) for spatial perception and orientation. Tests for measuring different components of attention were also administered. We observed that our clinical participants performed significantly poorer in both the HVOT and the JLOT. We further noticed that nonverbal intelligence had a significant influence on our participants' performance in these two administered tests. Regarding the relationship between attention and visual-perceptual function, our findings indicated that such a relationship existed only among our clinical participants, not the normal controls. The attention control process significantly predicted the performance in the HVOT and switching attention efficiency significantly predicted the performance in the JLOT.

Adult↗
PubMed2004

Isoluminant stimuli and red background attenuate the effects of transient spatial attention on temporal resolution.

The effects of transient spatial attention on temporal resolution were recently studied and compared with attentional effects on spatial resolution. It was found that in contrast to the attentional enhancement of spatial resolution, transient attention impairs temporal resolution. To account for these findings a novel attentional mechanism was suggested. This attentional mechanism facilitates parvocellular neurons at the attended location, which in turn inhibit the activity of magnocellular neurons at the same location [Yeshurun & Levy, Psychol. Sci. 14 (3) (2003a) 225]. The goal of the present study was to replicate the attentional decrement in temporal resolution (Experiment 1), and perform direct tests of this 'parvo facilitation-magno inhibition' hypothesis. The employment of isoluminant stimuli (Experiments 2a and 2b) or a red background (Experiment 3) ensured that the parvo system was the main system mediating performance. Consequently, any parvo-magno inhibitory processes elicited by the attentional mechanism should only have a minor effect on performance. As predicted, these manipulations either significantly attenuated or completely eliminated the attentional decrement in temporal resolution. These findings provide direct support to the hypothesis that attention favors parvocellular over magnocellular neurons.

Attention↗
PubMed2000

A neuropsychological profile of attention deficits in young males with fragile X syndrome.

Different processes of attention were examined in a group of 25 fragile X boys with FMR-1 full mutation and compared with three control groups: a learning disabled comparison group comprising 25 boys with Down's syndrome, matched to the fragile X boys on verbal mental age; and 50 mainstream school boys (controls) matched to the fragile X boys on verbal mental age. The controls were further divided into those matched on "poor attention" to the fragile X boys and a "good" attention group, as rated by the ACTeRS questionnaire. Four categories of attention tasks were employed: selective attention, divided attention, sustained attention and executive functioning. The main findings of the study indicate that fragile X boys display an attention deficit at higher levels of attention function/executive functioning and that this profile is different from the profile identified in Down's syndrome boys and more extreme than the profile identified in the poor attention control group. These findings are discussed in the context of functional neuroimaging and brain-behaviour correlates in fragile X syndrome.

Adolescent↗
PubMed2001

Controlling attentional priority by preventing changes in oculomotor programs: a job for the premotor cortex?

Abruptly presented items capture attention automatically so they constitute the first items to be examined [Yantis and Jonides, Journal of Experimental Psychology: Human Perception and Performance, 1984;10:601; Jonids and Yantis, Perception and Psychophysics, 1988;43:346; Theeuwes, Perception and Psychophysics, 1992;51:599; Theeuwes, Journal of Experimental Psychology: Human Perception and Performance, 1994;20:799]. This attentional priority can be controlled in a top-down manner by directing attention towards the locus of interest [Yantis and Johnson, Journal of Experimental Psychology: Human Perception and Performance, 1990;16:812; Theeuwes. Perception and Psychophysics, 1991;49:83; Miller, Perception and Psychophysics, 1989;45:567; Folk et al., Journal of Experimental Psychology: Human Perception and Performance, 1992; 18:1030]. The premotor theory of attention [Rizzolatti et al., Neuropsychologia 1987;25:31; Rizzolatti et al., Attention and Performance XV, 1994, p. 231] assumes that the mechanism responsible for the attentional shifts is strictly linked to that responsible for eye movements, and several studies [Corbetta et al., Society of Neuroscience Abstracts 1997;23:122.12; Nobre et al., Brain 1997;120:515; Theeuwes et al., Journal of Experimental Psychology: Human Perception and Performance, 1999;25:1595] suggested that the premotor cortex plays a role in the control of attention. However, the nature of this involvement is still unclear. We have been asking a patient (RJ) with a damage of the right premotor cortex to decide whether a target had a discontinuity on its right or left side. The absolute location of the target was pre-cued. In Section 2, an interference was observed when a sudden onset occurred in the visual space, suggesting that RJ was not able to control attentional capture. The possibility to attribute this interference to an insufficient focalization of attention or a grouping effect were discarded by Sections 3 and 4, respectively. Section 5 revealed that this interference followed exclusively the onset occurring in the hemifield opposite the one containing the target (meridian effect [Rizzolatti et al., Neuropsychologia 1987;25:31]). The results suggest that the control of attentional capture may be achieved by keeping constant the parameters of the appropriate oculomotor program.

Adult↗
PubMed2002

Event-related potential measures of the inhibition of information processing: I. Selective attention in the waking state.

This article reviews the effects of selective attention on event-related potentials (ERPs). Attention has little, if any, effect on short-latency exogenous ERPs. The longer-latency ERPs can be markedly affected by manipulation of the subject's level of attention. For example, a late positive wave, P300, appears to occur only if subjects actively detect an infrequently occurring target stimulus. However, a number of other late positive waves may also occur independently of the direction of attention, particularly if elicited by highly biologically or psychologically relevant stimuli. Attention may also interact with an earlier, apparently exogenous, negative waveform, N1. This could be due to the overlapping and summating effect of an attentional-related waveform, the processing negativity. The presentation of a physically deviant stimulus occurring among a train of homogeneous standard stimuli will elicit another negative wave, the mismatch negativity (MMN). The MMN has traditionally been thought to occur independently of attention. More recent studies have, however, shown that attention can modulate the MMN. This may, however, be explained by the summating effects of other overlapping components. Interpreting the scalp-recorded ERP can therefore require judicious care. Design of experiments must take into account the fact that the magnitude of attentional effects will depend on a number of different influences, some of which are very subtle and complex. A problem with any study in the waking and alert human is that the subject may not be able to completely ignore stimuli, in spite of instructions to do so. For this reason, the study of unconscious states, such as sleep, may prove to be especially fruitful in understanding the effects of attention in the waking state.

Animals↗
PubMed2003

Natural imitation induced by joint attention in Japanese monkeys.

To examine whether joint attention enables Japanese monkeys to imitate human actions, we presented an oral action and manual actions directed towards targets to three monkeys who had joint attention through communicative eye-gaze and pointing gestures and to one monkey who had incomplete joint attention and who had acquired imperative pointing but not the use of eye-gaze gestures. Two of the monkeys who were already capable of joint attention were also able to imitate naturally, while the monkey who did not previously show joint attention was not able to imitate until acquiring joint attention capacity. We suggest that joint attention induces natural imitation during interaction between different species--in this case, between monkeys and humans--while individuals not showing joint attention but only attention to a target or movement are only able to follow motion. The monkey may be endowed by nature with motion-following capacity. We speculate that motion-following capacity is developed and controlled through joint attention, and is connected with natural imitation.

Animals↗