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PubMed2005

Selective auditory attention in 3- to 5-year-old children: an event-related potential study.

Behavioral and electrophysiological evidence suggests that the development of selective attention extends over the first two decades of life. However, much of this research may underestimate the attention abilities of young children. By providing strong, redundant attention cues, we show that sustained endogenous selective attention has similar effects on ERP indices of auditory processing in adults and children as young as 3 years old. All participants were cued to selectively attend to one of two simultaneously presented stories that differed in location (left/right), voice (male/female), and content. The morphology of the ERP waveforms elicited by probes embedded in the stories was very different for adults, who showed a typical positive-negative-positive pattern in the 300 ms after probe onset, and children, who showed a single broad positivity during this epoch. However, for 3- to 5-year-olds, 6- to 8-year-olds, and adults, probes in the attended story elicited larger amplitude ERPs beginning around 100 ms after probe onset. This attentional modulation of exogenously driven components was longer in duration for the youngest children. In addition, attended linguistic probes elicited a larger negativity 300-500 ms for all groups, indicative of additional attentional processing. These data show that with adequate cues, even children as young as 3 years old can selectively attend to one auditory stream while ignoring another and that doing so alters auditory sensory processing at an early stage. Furthermore, they suggest that the neural mechanisms by which selective attention affects auditory processing are remarkably adult-like by this age.

Adolescent↗
PubMed2006

Functional brain asymmetry, attentional modulation, and interhemispheric transfer in boys with Tourette syndrome.

We tested the hypothesis that children with Tourette syndrome (TS) would exhibit aberrant brain lateralization compared to a healthy control (HC) group in an attention-modulation version of a verbal dichotic listening task using consonant-vowel syllables. The modulation of attention to focus on the right ear stimulus in the dichotic listening situation is thought to involve the same prefrontal attentional and executive functions that are involved in the suppression of tics, whereas, performance when focusing attention on the left ear stimulus additionally involves a callosal transfer of information. In light of presumed disturbances in transfer of information across the corpus callosum, we hypothesized that children with TS would, however, have difficulty modulating the functional lateralization that ensues through a shift of attention to the left side. This hypothesis was tested by exploring the correlations between CC size and left ear score in the forced-left condition. Twenty boys with TS were compared with 20 age- and handedness-matched healthy boys. Results indicated similar performance in the TS and HC groups for lateralization of hemispheric function. TS subjects were also able to shift attention normally when instructed to focus on the right ear stimulus. When instructed to focus attention on the left ear stimulus, however, performance deteriorated in the TS group. Correlations with CC area further supported the hypothesized presence of deviant callosal functioning in the TS group.

Adolescent↗
PubMed2006

Parent attention versus distraction: impact on symptom complaints by children with and without chronic functional abdominal pain.

The objective of this study was to assess the impact of parent attention and distraction on symptom complaints by children with and without chronic functional abdominal pain. The water load symptom provocation task was used to induce visceral discomfort in pediatric patients with abdominal pain (N=104) and well children (N=119), ages 8-16 years. Parents were randomly assigned and trained to interact with their children according to one of three conditions: Attention, Distraction, or No Instruction. Children's symptom complaints and parents' responses were audiotaped and coded. Children completed a self-report measure of gastrointestinal (GI) symptoms before and after interacting with their parents. Parents' and children's perceptions of their interaction were assessed. Compared to the No Instruction condition, symptom complaints by pain patients and well children nearly doubled in the Attention condition and were reduced by half in the Distraction condition. The effect of attention on symptom complaints was greater for female pain patients than for male patients or well children. Findings for self-report GI symptoms were similar to those for audiotaped symptom complaints. Both pain patients and well children in the Distraction condition rated parents as making them feel better compared to ratings for the Attention condition. Parents of pain patients rated distraction as having greater potential negative impact on their children than attention. Parents' responses to children's symptom complaints can significantly increase or decrease those complaints. Girls with functional abdominal pain are particularly vulnerable to the symptom-reinforcing effects of parental attention.

Abdominal Pain↗
PubMed2006

Performance of galanin transgenic mice in the 5-choice serial reaction time attentional task.

The neuropeptide galanin impairs learning and memory in rodents. The mechanism underlying the cognitive effects of galanin may be related to inhibitory effects of galanin on cholinergic transmission. As cholinergic function is thought to modulate sustained attention, the present study examined whether galanin-overexpressing transgenic mice have impairments in sustained attention. Galanin transgenic (GAL-tg) mice and wild-type (WT) littermate controls were trained in a 5-choice serial reaction time task, modified to assess sustained attention. GAL-tg and WT mice performed similarly during acquisition with respect to accuracy, total omissions, and response speed. Attentional mechanisms were challenged by parametric changes including increased event rate, event asynchrony, or decreased stimulus duration. Singly, these challenges did not differentially affect performance between genotypes. Concurrent administration of these challenges, which represents an optimal test of sustained attention, also had similar effects on GAL-tg and WT mice. When stimulus discriminability was reduced by constant illumination of the house light, GAL-tg mice omitted more trials than WT mice, but other measures of performance did not differ by genotype. Moreover, intraventricular injection of galanin in WT mice did not affect sustained attention. These data indicate that previously reported learning and memory effects of galanin are not secondary to attentional dysfunction.

Acetylcholine↗
PubMed2005

Chronic nicotine interactions with clozapine and risperidone and attentional function in rats.

Although antipsychotic drugs are therapeutically effective in attenuating the hallmark symptoms of schizophrenia, these improvements do not return most patients to normative standards of cognitive function. Thus, complementary drug treatment may be needed to treat the attentional deficits of schizophrenia as well as to counteract the potential attentional impairments caused by some antipsychotic drugs. Nicotine, a drug commonly self-administered by a great majority of individuals with schizophrenia, has been shown to significantly improve cognitive function in some studies. The current study was conducted to determine the interactive effects of the atypical antipsychotic drugs clozapine and risperidone with chronic nicotine administration on attentional performance. Adult female Sprague-Dawley rats (N=35) were trained to perform an attentional task using an operant visual signal detection task. After training, rats were infused with a dose of 5 mg/kg/day (s.c.) nicotine base (n=18) or saline (n=17) for 28 consecutive days via osmotic pump. In Exp. 1, while being administered chronic nicotine or saline, rats were given acute doses of clozapine (0, 0.625, 1.25 and 2.5 mg/kg, s.c.) and were tested for attentional function. In Exp. 2, while on chronic nicotine or saline, other rats were challenged with acute doses of risperidone (0, 0.025, 0.05 and 0.1 mg/kg, s.c.) and were tested for attentional function. Results showed that acute administration of clozapine caused a significant dose-dependent impairment in choice accuracy (percent hit) in animals treated with chronic saline. Chronic nicotine treatment itself lowered accuracy, but attenuated further declines with acute clozapine treatment. Acute administration of risperidone at high dose significantly reduced performance (percent correct rejection) in chronically saline-treated rats, but in a similar fashion as in Exp. 1, chronic nicotine lowered accuracy but attenuated further impairment with acute risperidone. In summary, atypical antipsychotic drugs clozapine and risperidone significantly impaired choice accuracy in the visual signal detection task. Clozapine was more detrimental than risperidone but the adverse effects of both clozapine and risperidone on attentional performance were masked in rats chronically treated with nicotine.

Animals↗
PubMed2005

Selective impairment of attentional networks of orienting and executive control in schizophrenia.

BACKGROUND: Difficulty attending is a common deficit of schizophrenic patients. However, it is not known whether this is a global attentional deficit or relates to a specific attentional network. METHOD: This study used the attention network test to compare schizophrenic patients (N=77) with controls (N=53) on the efficiency of three anatomically defined attentional networks: alerting, orienting, and executive control. RESULTS: Schizophrenic patients showed a large and highly significant deficit in the executive network and a smaller but significant deficit in the orienting network as well as in overall RT and accuracy. There was no deficit in the alerting network. CONCLUSION: These results suggest some specificity in the attentional networks influenced by the disorder. The executive attention network has been shown in normal subjects to activate the anterior cingulate and lateral prefrontal areas. Previous data using neuroimaging with schizophrenic patients has shown abnormal control by the anterior cingulate. Our findings support this previous research by indicating that the major attentional deficit in schizophrenic patients is in a network that includes the anterior cingulate.

Adult↗
PubMed2003

Attentional modulation of threshold sensitivity to first-order motion and second-order motion patterns.

Previous studies [e.g. Vision Research 40 (2000) 173] have shown that when observers are required to selectively attend to one of two, spatially-adjacent patches containing either first-order (luminance-defined) or second-order (contrast-defined) motion, threshold sensitivity for identifying the direction of second-order motion, but not first-order motion, is enhanced for the attended stimuli. The processing of second-order motion, unlike first-order motion, may, therefore, require attention. However, other studies have found little evidence for differential effects of attention on the processing of first-order and second-order motion [Investigative Ophthalmology and Visual Science 42(4) (2001) 5061]. We investigated the effects of attention instructions on the ability of observers to identify the directions and spatial orientations of luminance-defined and contrast-defined motion stimuli. Pairs of motion stimuli were presented simultaneously and threshold performance was measured over a wide range of drift temporal frequencies and stimulus durations. We found: (1) direction discrimination thresholds for attended motion stimuli were lower than those for unattended stimuli for both types of motion. The magnitude of this effect was reduced when the observers were not given prior knowledge of which patch of motion (attended or unattended) they had to judge first. (2) Direction discrimination for first-order motion was similarly affected at all temporal frequencies and durations examined, but for second-order motion the effects of attention depended critically on the drift temporal frequency and stimulus duration used. (3) Orientation discrimination showed little or no influence of attention instructions. Thus, whether or not attention influences the processing of second-order motion depends crucially on the precise stimulus parameters tested. Furthermore under appropriate conditions the processing of first-order motion is also influenced by attention, albeit to a lesser extent than second-order motion.

Attention↗
PubMed2004

The spatial distribution of visual attention.

We use a novel search task to investigate the spatial distribution of visual attention, developing a general model from the data. Observers distribute attention to locations defined by stripes with a high penalty for attention to intervening areas. Attended areas are defined by a square-wave grating. A target is in one of the even stripes, and ten false targets (identical to the real target) are in the odd stripes; the observer must attend the even stripes and strongly ignore the odd, reporting the location of the target. As the spatial frequency of the grating increases, performance declines. Variations on this task inform a model that incorporates stimulus input, a "low pass" attentional modulation transfer function, and an acuity function to produce a strength map from which the location with the highest strength is selected. A feature-strength map that adds to the attention map enables the model to predict the results of attention-cued conjunction search experiments, and internal noise enables it to predict the outcome of double-pass experiments and of variations in the number of false targets. The model predicted performance on a trial-by-trial basis for three observers, accounting for approximately 70% of the trials. Actual trial-to-trial variation for an observer, using the double-pass method, is about 76%. For any requested distribution of spatial attention, this general model makes a prediction of the actually achieved distribution.

Attention↗
PubMed2004

Adaptation to spiral motion: global but not local motion detectors are modulated by attention.

In this study, we investigated the effect of attention on local motion detectors. For this purpose we used logarithmic spirals previously used by Cavanagh and Favreau [Perception, 1980, 9(2), 175-182]. While the adapting stimulus was a rotating logarithmic spiral, the test stimulus was either the same spiral or its mirror image. When superimposed, all contours of the spiral stimulus and its mirror image are 90 degrees apart. Presenting the same spiral during the test period shows adaptation of both local motion detectors and global rotation detectors, whereas showing the mirror-spiral stimulates another set of local motion detectors, and therefore illustrates adaptation at only the global motion level. To manipulate the attentional state of observers, a secondary task was presented during the adaptation phase and observers either performed the task or ignored it. Motion aftereffect (MAE) duration was measured afterwards. While the effects of attention and test stimulus type on MAE duration were both significant, the difference in the MAE strength between the attention-distracted and attention-not-distracted conditions was equal when the test stimulus was the same-spiral or the mirror-spiral, suggesting that attention to spiral motion modulates only global rotation units and does not affect local motion detectors located at V1. Our results are in accord with those reported by Watanabe et al. [Proceedings of the National Academy of Sciences of the USA, 1998, 95(19), 11489-11492] which showed differential modulation of motion processing areas depending on the type of motion being attended. Therefore our data are supportive of the notion that attentional modulation of V1 is highly task-dependent.

Adaptation, Ocular↗
PubMed2003

Selective attention in social phobia and the moderating effect of a concurrent depressive disorder.

Studies using the modified Stroop colour naming task have provided results consistent with the hypothesis that social phobia is associated with an attentional bias towards negative social-evaluative words. However, these results could also have arisen as a consequence of non-attentional processes. For this reason, the present study uses a modified version of MacLeod et al.'s (J. Abnorm. Psychol. 95 (1986) 15) dot-probe task, which provides a more direct measure of attention. Patients with social phobia (n=28), patients with social phobia and a concurrent depressive disorder (n=33), and non-patients (n=40) were presented with word pairs each consisting of a neutral word and a threat word. The results indicated that patients with social phobia show an attentional bias towards social-threat words while non-patients tend to avoid social-threat words. Patients with social phobia and a concurrent depressive disorder behaved like non-patients, indicating that concurrent depression abolishes the attentional bias. Physical threat words were also included in the study. The main analysis indicated that social phobia is also associated with an attentional bias to physical threat. However, a post hoc analysis (which requires replication) suggested that the physical threat bias might have arisen because some social phobia patients also had another anxiety disorder in which physical concerns are likely to have been prominent. Overall, the results emphasise the importance of assessing comorbidity when investigating attentional biases.

Adult↗
PubMed2000

Smooth pursuit eye movements in schizophrenia and attentional dysfunction: adults with schizophrenia, ADHD, and a normal comparison group.

BACKGROUND: Smooth pursuit eye movement (SPEM) abnormalities are found in schizophrenia. These deficits often are explained in the context of the attentional and inhibitory deficits central to schizophrenia psychopathology. It remains unclear, however, whether these attention-associated eye movement abnormalities are specific to schizophrenia or are a nonspecific expression of attentional deficits found in many psychiatric disorders. Adult attention-deficit/hyperactivity disorder (ADHD) is an alternative disorder with chronic attentional and inhibitory dysfunction. Thus, a comparison of SPEM in adult schizophrenia and adult ADHD will help assess the specificity question. METHODS: SPEM is recorded during a 16.7 degrees per second constant velocity task in 17 adults with ADHD, 49 adults with schizophrenia, and 37 normal adults; all groups included individuals between ages 25-50 years. RESULTS: Smooth pursuit gain and the frequency of anticipatory and leading saccades are worse in schizophrenic subjects, with normal and ADHD subjects showing no differences on these variables. CONCLUSIONS: Many attention-associated SPEM abnormalities are not present in most subjects with ADHD, supporting the specificity of these findings to the attentional deficits seen in schizophrenia.

Adult↗
PubMed1996

The role of attention in visual bilateral matching tasks.

The consistent finding of studies employing visual matching tasks has been a reaction time and accuracy advantage for judgements about stimuli presented bilaterally when compared to the average performance of the two unilateral field presentations. As with recent studies showing the influence of attention on reaction times to unilateral presentations, we hypothesized that attentional mechanisms may also play a role in the speed advantage seen with bilateral letter presentations. The present study employed random dot-patterns ("dot-primes"), presented in the upper half of the LVF, RVF, Bilateral VF, or absent, as abrupt onset peripheral cues to attract attention automatically. Letter pairs followed immediately (14 msecs) after the dot-primes in the lower half of the LVF, RVF, or Bilateral VF. The results for unilateral dot-primes, followed by unilateral letter pairs, were consistent with previous studies showing that the field advantage for a particular task can be altered using abrupt onset attentional cues, with the advantage going to the field where the attentional prime is presented. Bilateral dot-primes did reduce latencies to subsequent bilateral letter pairs, but bilateral primes also reduced latencies to both LVF and RVF letter pairs, in nearly the same proportion as for bilateral letter pairs. Latencies for RVF-primes/Bilateral-letters were as fast as for Bilateral-primes/Bilateral-letters, and both of these conditions were significantly faster than LVF-primes/Bilateral-letters. The results suggest that attention plays a relatively minor role in the bilateral field advantage, and that non-attentional factors (i.e. interhemispheric dynamics) account for most of the asymmetric unilateral-prime influence on bilateral performance. Possible interhemispheric factors which may contribute to these results are discussed.

Adult↗
PubMed2001

Cerebral blood flow velocity changes during dichotic listening with directed or divided attention: a transcranial Doppler ultrasonography study.

Simultaneous bilateral transcranial Doppler ultrasonography (TCD) monitoring of blood flow velocity (BFV) in the middle cerebral arteries was performed in 28 normal right-handed volunteers during linguistic dichotic listening tasks to investigate the effect of hemispheric specialisation and allocation of attention. A control task that required the repetition of monaurally presented words was followed by three randomised dichotic listening tasks in which the subjects were instructed to direct their attention to the word stimuli of the right ear, the left ear, or to divide their attention between both ears. Behavioural data indicated that the subjects used the required attentional strategies. A significant right ear advantage was not obtained in the divided attention condition due to a ceiling effect. Each task resulted in a significant bilateral increase in BFV. We found no significant lateralisation of BFV change for any of the tasks. We noted marked differences in BFV change between the different conditions that were significant in the right hemisphere, showed a borderline significance in the left hemisphere and appeared to be related with the difficulty of the task. We conclude that the hemodynamic changes caused by attentional strategies or hemispheric specialisation in processing dichotic stimuli over and above the effect of bilateral auditory stimulation, are too subtle to be detected as lateralised changes in BFV. Functional TCD could be used for the evaluation of a task's workload relative to other tasks, and may contribute to elucidate the role of the right hemisphere in attention and arousal.

Adult↗
PubMed2001

What can functional imaging reveal about the role of attention in visual awareness?

This review focuses on neuroimaging studies that address the relationship between selective attention, neural activity and visual awareness. Withdrawing attention from particular visual stimuli reduces modality-specific processing in posterior visual cortex, and when attention is fully engaged elsewhere, even highly salient but task-irrelevant stimuli can fail to evoke activity and reach awareness. However, the link between visual attention and awareness extends beyond posterior visual cortex to also encompass regions of parietal and prefrontal cortex. Activity in the posterior visual cortex may be necessary but not sufficient for awareness, without a contribution from frontal and parietal cortex. Consistent with this, enhanced interactions between parietal, frontal and posterior visual cortex are observed as a function of both visual attention and visual awareness; and lesions of parietal cortex disrupt both visual attention and awareness. Taken together, these data suggest that distributed interactions between modality-specific posterior visual cortex and frontoparietal areas subserve both visual attention and visual awareness.

Attention↗
PubMed2002

Perceived gaze direction in faces and spatial attention: a study in patients with parietal damage and unilateral neglect.

Perceived gaze in faces is an important social signal that may influence orienting of attention in normal observers. Would such effects of gaze still occur in patients with right parietal damage and left neglect who usually fail to attend to contralesional space? Two experiments tested for effects of perceived gaze on visual extinction. Face or shape stimuli were presented in the right, left, or both hemifields, with faces looking either straight ahead or toward the opposite field. On bilateral trials, patients extinguished a left shape much less often when a concurrent right face looked leftward rather than straight ahead. This occurred, even though gaze was not relevant to the task and processing of facial signals implied attention to a competing ipsilesional stimulus. By contrast, rightward gaze in faces presented on the left side had no effect on extinction, suggesting that gaze cues are not extracted without attention. Two other experiments examined effects of perceived gaze on the detection of peripheral targets. Targets appeared at one of four possible locations to the right or left of a central face looking either toward the target location, another location on the same side, the opposite side, or straight ahead. Face and gaze were not relevant to the task and not predictive of target location. Patients responded faster when the face looked toward the target on both the contralesional and ipsilesional sides. In contralesional space, gaze allowed shifting of attention in a specific quadrant direction, but only to the first target along the scan path when there were different possible locations on the same side. By contrast, in intact ipsilesional space, attention was selectively directed to one among different eccentric locations. Control experiments showed that symbolic arrow cues did not produce similar effects. These results indicate that even though parietal damage causes spatial neglect and impairs the representation of location on the contralesional side, perceived gaze in faces can still trigger automatic shifts of attention in the contralesional direction, suggesting the existence of specific and anatomically distinct attentional mechanisms.

Aged↗
PubMed2002

Hemispheric lateralization of the processing of consonant-vowel syllables (formant transitions): effects of stimulus characteristics and attentional demands on evoked magnetic fields.

It is still unsettled in how far temporal resolution of dynamic acoustic events (formant transitions) or phonetic/linguistic processes contribute to predominant left-hemisphere encoding of consonant-vowel syllables. To further elucidate the underlying mechanisms, evoked magnetic fields in response to consonant-vowel events (synthetic versus spoken) were recorded (oddball design: standards=binaural/ba/, deviants=dichotic/ba/-/da/; 20 right-handed subjects) under different attentional conditions (visual distraction versus stimulus identification). Spoken events yielded a left-lateralized peak phase of the mismatch field (MMF; 150-200ms post-stimulus onset) in response to right-ear deviants during distraction. By contrast, pre-attentive processing of synthetic items gave rise to a left-enhanced MMF onset (100ms), but failed to elicit later lateralization effects. In case of directed attention, synthetic deviants elicited a left-pronounced MMF peak resembling the pre-attentive response to natural syllables. These interactions of MMF asymmetry with signal structure and attentional load indicate two distinct successive left-lateralization effects: signal-related operations and representation of 'phonetic traces'. Furthermore, a right-lateralized early MMF component (100ms) emerged in response to natural syllables during pre-attentive processing and to synthetic stimuli in case of directed attention. Conceivably, these effects indicate right hemisphere operations prior to phonetic evaluation such as periodicity representation. Two distinct time windows showed correlations between dichotic listening performance and ear effects on magnetic responses reflecting early gain factors (ca. 75ms post-stimulus onset) and binaural fusion strategies (ca. 200ms), respectively. Finally, gender interacted with MMF lateralization, indicating different processing strategies in case of artificial speech signals.

Adult↗
PubMed1997

Auditory sustained attention is a marker of unilateral spatial neglect.

The relationships between performance on a non-spatially-lateralized measure of sustained attention and spatial bias on tests sensitive to unilateral neglect were considered in a group of 44 patients with right hemisphere lesions following stroke. As predicted from earlier studies showing a strong association between unilateral spatial neglect and sustained attention, performance on a brief and monotonous tone-counting measure formed a significant predictor of spatial bias across a variety of measures of unilateral visual neglect. This study provides further evidence for a very close link between two attentional systems hitherto regarded as being quite separate, namely a spatial attention system implicated in unilateral neglect and a sustained attention system. A close connection between these two systems was predicted by Posner, who argued that the right hemisphere-dominant sustained attention system provides a strong modulatory influence on the functioning of the lateralized posterior attention system.

Acoustic Stimulation↗
PubMed2001

Effects of set-size and selective spatial attention on motion processing.

In order to investigate the effects of divided attention and selective spatial attention on motion processing, we obtained direction-of-motion thresholds using a stochastic motion display under various attentional manipulations and stimulus durations (100-600 ms). To investigate divided attention, we compared motion thresholds obtained when a single motion stimulus was presented in the visual field (set-size=1) to those obtained when the motion stimulus was presented amongst three confusable noise distractors (set-size=4). The magnitude of the observed detriment in performance with an increase in set-size from 1 to 4 could be accounted for by a simple decision model based on signal detection theory, which assumes that attentional resources are not limited in capacity. To investigate selective attention, we compared motion thresholds obtained when a valid pre-cue alerted the subject to the location of the to-be-presented motion stimulus to those obtained when no pre-cue was provided. As expected, the effect of pre-cueing was large when the visual field contained noise distractors, an effect we attribute to "noise reduction" (i.e. the pre-cue allows subjects to exclude irrelevant distractors that would otherwise impair performance). In the single motion stimulus display, we found a significant benefit of pre-cueing only at short durations (< or =150 ms), a result that can potentially be explained by a "time-to-orient" hypothesis (i.e. the pre-cue improves performance by eliminating the time it takes to orient attention to a peripheral stimulus at its onset, thereby increasing the time spent processing the stimulus). Thus, our results suggest that the visual motion system can analyze several stimuli simultaneously without limitations on sensory processing per se, and that spatial pre-cueing serves to reduce the effects of distractors and perhaps increase the effective processing time of the stimulus.

Analysis of Variance↗