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PubMed2002

Attentional recruitment of inter-areal recurrent networks for selective gain control.

There is strong anatomical and physiological evidence that neurons with large receptive fields located in higher visual areas are recurrently connected to neurons with smaller receptive fields in lower areas. We have previously described a minimal neuronal network architecture in which top-down attentional signals to large receptive field neurons can bias and selectively read out the bottom-up sensory information to small receptive field neurons (Hahnloser, Douglas, Mahowald, & Hepp, 1999). Here we study an enhanced model, where the role of attention is to recruit specific inter-areal feedback loops (e.g., drive neurons above firing threshold). We first illustrate the operation of recruitment on a simple example of visual stimulus selection. In the subsequent analysis, we find that attentional recruitment operates by dynamical modulation of signal amplification and response multistability. In particular, we find that attentional stimulus selection necessitates increased recruitment when the stimulus to be selected is of small contrast and of small distance away from distractor stimuli. The selectability of a low-contrast stimulus is dependent on the gain of attentional effects; for example, low-contrast stimuli can be selected only when attention enhances neural responses. However, the dependence of attentional selection on stimulus-distractor distance is not contingent on whether attention enhances or suppresses responses. The computational implications of attentional recruitment are that cortical circuits can behave as winner-take-all mechanisms of variable strength and can achieve close to optimal signal discrimination in the presence of external noise.

Animals↗
PubMed2005

Endogenous attention prolongs dominance durations in binocular rivalry.

We investigated the effects of attention on dominance durations during binocular rivalry. In a series of three experiments, observers performed several tasks while viewing rival stimuli to ensure and control deployment of attention. We found that endogenous attention can prolong dominance durations of attended stimulus. We developed a novel single-task procedure where observer's responses in an attentional task were used to objectively estimate dominance durations of the attended stimulus. Using this procedure, we showed that paying attention to the stimulus features involved in rivalry is necessary for prolonging dominance durations--mere engagement of attention during rivalry was insufficient. Finally, we were able to simulate the effects of endogenous attention by doubling the contrast of the attended stimulus while it was dominant. Attention may increase the apparent contrast of the attended stimulus, thereby prolonging its dominance duration. Overall, our results indicate that dominance durations in rivalry can be prolonged when observers are performing an attentionally demanding task on the rival stimulus.

Attention↗
PubMed1991

A family-genetic study of girls with DSM-III attention deficit disorder.

OBJECTIVE: The authors evaluated family-genetic risk factors in girls with attention deficit disorder and compared these results to findings in the authors' previous study of boys with attention deficit disorder. METHOD: Twenty-one girls with attention deficit disorder and 20 normal comparison girls were consecutively ascertained from a pool of existing and new referrals from a pediatric psychopharmacology unit and a medical pediatric unit of the same urban hospital. First-degree relatives of the attention deficit disordered girls (N = 69) and of the normal girls (N = 71) were also assessed. Both groups of girls and their relatives were evaluated on the basis of structured diagnostic interviews conducted by raters who were blind to the clinical status of the probands. RESULTS: The relatives of the girls with attention deficit disorder had higher risks for attention deficit disorder, antisocial disorders, major depression, and anxiety disorders. The higher risk for attention deficit disorder could not be accounted for by gender or generation of relative, age of proband, social class, or family intactness. These findings are highly consistent with the findings in the authors' previous study of boys with attention deficit disorder, which was conducted with identical methods. CONCLUSIONS: This study provides further support for the validity of the diagnosis of attention deficit disorder in girls and suggests that the genders share a common biological substrate.

Adolescent↗
PubMed2005

Attention bias to threat in maltreated children: implications for vulnerability to stress-related psychopathology.

OBJECTIVE: Previous research in adults implicates attention bias in posttraumatic stress disorder (PTSD). To study attention bias in children, the authors used picture-based versions of the visual-probe attention bias task previously used with adults. They tested the hypothesis that attention bias to threatening facial photographs is associated with maltreatment and PTSD. METHOD: A visual-probe task that manipulated threat levels was used to test 34 children who had been maltreated and 21 children who had not been maltreated. The visual-probe task involved showing photographs of actors with faces depicting neutral, angry/threatening, or happy expressions for 500 msec each. RESULTS: Attention bias away from threat was associated with severity of physical abuse and diagnosis of PTSD. This association reflected the tendency for high levels of abuse or PTSD to predict attention avoidance of threatening faces. CONCLUSIONS: Previous studies examined the engagement of specific brain regions associated with attention orientation to angry/threatening faces. The current study used similar methods to document associations between attention bias and maltreatment in children. This sets the stage for studies examining relationships in children among perturbed brain function, psychopathology, attention bias, and maltreatment.

Adolescent↗
PubMedDate not supplied

Effect of attention therapy on reading comprehension.

This study quantified the influence of visual attention therapy on the reading comprehension of Grade 6 children with moderate reading disabilities (RD) in the absence of specific reading remediation. Thirty students with below-average reading scores were identified using standardized reading comprehension tests. Fifteen children were placed randomly in the experimental group and 15 in the control group. The Attention Battery of the Cognitive Assessment System was administered to all participants. The experimental group received 12 one-hour sessions of individually monitored, computer-based attention therapy programs; the control group received no therapy during their 12-week period. Each group was retested on attention and reading comprehension measures. In order to stimulate selective and sustained visual attention, the vision therapy stressed various aspects of arousal, activation, and vigilance. At the completion of attention therapy, the mean standard attention and reading comprehension scores of the experimental group had improved significantly. The control group, however, showed no significant improvement in reading comprehension scores after 12 weeks. Although uncertainties still exist, this investigation supports the notion that visual attention is malleable and that attention therapy has a significant effect on reading comprehension in this often neglected population.

Attention↗
PubMed2001

Age effects in dichotic listening to consonant-vowel syllables: interactions with attention.

A relatively large sample of individuals (N = 240) ranging from 7 to 70 years were studied with the dichotic listening (DL) technique as a measure of language lateralization. Two questions were asked: (a) Is there a developmental effect for the right-ear advantage (REA) with age? (b) Is there a developmental effect for attentional modulation of the REA? The participants were all right-handed, healthy individuals tested in Sweden and Norway. The stimuli were dichotic presentations of consonant-vowel (CV) syllable pairs. There were 3 different attentional conditions: nonforced (NF) attention, with no specific instructions about focusing of attention; forced-right (FR) attention, with instructions to focus attention on the right-ear stimulus; and forced-left (FL) attention, with instructions to focus attention on the left-ear stimulus. The results showed a REA in all age groups, except for the 9-year-olds, in the NF condition. In the FR condition, all age groups showed a REA. The youngest age groups did not, however, increase the REA to the same degree as the older age groups, as indicated by the significant age x ear interaction. In the FL condition, all age groups, with the exception of the youngest groups, showed a left-ear advantage (LEA). It is concluded that the REA effect in DL is subject to developmental effects and that attentional effects on laterality also develop with increasing age.

Adolescent↗
PubMed2006

Alpha-band electroencephalographic activity over occipital cortex indexes visuospatial attention bias and predicts visual target detection.

Covertly directing visual attention toward a spatial location in the absence of visual stimulation enhances future visual processing at the attended position. The neuronal correlates of these attention shifts involve modulation of neuronal "baseline" activity in early visual areas, presumably through top-down control from higher-order attentional systems. We used electroencephalography to study the largely unknown relationship between these neuronal modulations and behavioral outcome in an attention orienting paradigm. Covert visuospatial attention shifts to either a left or right peripheral position in the absence of visual stimulation resulted in differential modulations of oscillatory alpha-band (8-14 Hz) activity over left versus right posterior sites. These changes were driven by varying degrees of alpha-decreases being maximal contralateral to the attended position. When expressed as a lateralization index, these alpha-changes differed significantly between attention conditions, with negative values (alpha_right < alpha_left) indexing leftward and more positive values (alpha_left < or = alpha_right) indexing rightward attention. Moreover, this index appeared deterministic for processing of forthcoming visual targets. Collapsed over trials, there was an advantage for left target processing in accordance with an overall negative bias in alpha-index values. Across trials, left targets were detected most rapidly when preceded by negative index values. Detection of right targets was fastest in trials with most positive values. Our data indicate that collateral modulations of posterior alpha-activity, the momentary bias of visuospatial attention, and imminent visual processing are linked. They suggest that the momentary direction of attention, predicting spatial biases in imminent visual processing, can be estimated from a lateralization index of posterior alpha-activity.

Adult↗
PubMed2004

Control of attention shifts between vision and audition in human cortex.

Selective attention contributes to perceptual efficiency by modulating cortical activity according to task demands. Visual attention is controlled by activity in posterior parietal and superior frontal cortices, but little is known about the neural basis of attentional control within and between other sensory modalities. We examined human brain activity during attention shifts between vision and audition. Attention shifts from vision to audition caused increased activity in auditory cortex and decreased activity in visual cortex and vice versa, reflecting the effects of attention on sensory representations. Posterior parietal and superior prefrontal cortices exhibited transient increases in activity that were time locked to the initiation of voluntary attention shifts between vision and audition. These findings reveal that the attentional control functions of posterior parietal and superior prefrontal cortices are not limited to the visual domain but also include the control of crossmodal shifts of attention.

Adult↗
PubMed2006

Attention in athletes of high and low experience engaged in different open skill sports.

In this study were examined differences in attentional style of athletes engaged in two open skill sports requiring high reactivity (karate and volleyball) in groups with high or low experience. 42 healthy men, 24 volleyball players, 12 of High Experience (first division Italian League players whose M age was 28 yr. (SD=5) and 12 of Low Experience (prejunior Italian team athletes whose M age was 19 yr. (SD= 2). and 18 karateka, 9 of High Experience (3rd and 4th dan black belt athletes whose M age was 31 yr., SD=5) and 9 of Low Experience (1st and 2nd dan black belt karateka whose M age was 32 yr., SD=5). Tests involved different types of attention: Alert, Go/No-Go, Divided Attention, and Working Memory. For each one, the reaction time (RT), variability, change in RT, and number of errors were analysed. Karateka of High Experience reacted faster than those of Low Experience on the simple RT test, Alert (M RT: 204 vs 237 msec., p< .01), while on the Divided Attention test, the High Experience subjects performed more poorly and committed more errors (M errors: 4.89 vs 1.44, p <.003). Young volleyball players of Low Experience reacted faster than colleagues of High Experience on the Alert (M RT: 187 vs 210 msec., p<.01) and Divided Attention tests (M RT: 590 vs 688 msec., p<.001) but committed more errors (Divided Attention test, M errors: 6.50 vs 3.08, p<.007). For the Divided Attention and Working Memory tests, correlations were positive among errors, RT, and RT variability but only for volleyball athletes of High Experience, suggesting they showed higher attention and stability in complex reactions than the group with Low Experience. No significant correlations were noted for either group of karateka on complex reactions. Results suggested that the attentional resources were engaged in different ways in the two groups of athletes and, in each group, there were differences between persons of High and Low Experience.

Attention↗
PubMed2001

Selective attention in Alzheimer's disease.

This chapter presents a review of selective attention functioning in Alzheimer's disease (AD). The primary focus is on work conducted into this complex topic within the author and colleagues' laboratories (i.e. studies of simple and conjoined visual search). Findings obtained by the author and colleagues investigating simple and conjoined feature visual search in AD are related to findings obtained in the same laboratories in the healthy elderly and in patients with Parkinson's disease. Selective attention is a complex, multifactorial entity. Impairment of selective attention may be an early feature of AD and a prominent clinical characteristic of some patients. However, there are currently few reliable clinical measures of attentional dysfunction in AD. The experimental literature implicates some aspects of selective attention more reliably in AD than others. With respect to our own empirical studies, more effortful or controlled aspects of selective attention (as characterized by conjoined feature visual search) are impaired in AD. Furthermore, on the basis of our experimental observations, these aspects of selective attention appear to be disproportionately impaired relative to deficits in other cognitive domains that have previously been reported in the AD literature. By contrast, conjoined feature visual search deficits were not observed in our studies in patients with Parkinson's disease. The selective attention deficits that we have noted in AD patients represent an extension of the types of impairments that we have also observed in healthy aging; that is, compared with the healthy elderly, AD patients were quantitatively but not qualitatively more impaired on conjoined feature visual search. This is an important observation. The ways in which these findings relate to the wider AD selective attention literature are also considered, drawing out several common theoretical strands across a range of empirical studies.

Aged↗
PubMed2006

Reinstating object-based attention under positional certainty: the importance of subjective parsing.

Previous studies have shown that interference from flanking distractors can be modulated by the object organization of the scene. The experiments reported here test for object-based attention under conditions of positional certainty, which allow a narrow focus of attention to the target. Prior research has suggested that object-based attention does not arise in these circumstances, but the experiments presented here show that object-based attention can still appear if previous experience with the stimuli leads participants to interpret the stimulus pattern as two separate objects. Two control experiments demonstrate that the appearance of object-based attention is not due simply to a widening of the focus of spatial attention. The presence of object-based attention in such a focused-attention task argues against Shomstein and Yantis's (2002) proposed explanation of object-based attention based on priority in the order of visual search.

Attention↗
PubMed2001

Attentional capture by globally defined objects.

The abrupt appearance of a new perceptual object in the visual field typically captures visual attention. However, if attention is focused in advance on a different location, onsets can fail to capture attention (Yantis & Jonides, 1990). In the present experiments, we investigated the extent to which the deployment of attention to the local level of a hierarchical scene may be affected by the abrupt appearance of a new object at the global level. Participants searched for a semi-disk target in an array of randomly oriented segmented disks ("pacmen"). On half the trials, a subset of the segmented disks induced a subjective square. On these critical trials, participants were significantly slower to respond to the presence of a local target even though the local features of the display were qualitatively identical across all conditions. This slowing was absent when outline pacmen were used (which do not induce subjective figures) and when the subjective square was perceptually old. When the participants' task was defined at the global level of the display, a new local element failed to capture attention, suggesting an asymmetry in the ability of objects at different levels of a hierarchical scene to capture attention. In a control experiment, a new local element captured attention, however, when the participants' task was defined at the local level, indicating that the local item was in principle capable of capturing attention. It is argued that global objects capture attention because they convey important information about the environment that is not available at the local level.

Adolescent↗
PubMed2004

The scaling of spatial attention in visual search and its modification in healthy aging.

A model of visual search (Greenwood & Parasuraman, 1999) postulating that visuospatial attention is composed of two processing components--shifting and scaling of a variable-gradient attentional focus--was tested in three experiments. Whereas young participants are able to dynamically constrict or expand the focus of visuospatial attention on the basis of prior information, in healthy aging individuals visuospatial attention becomes a poorly focused beam, unable to be constricted around one array element. In the present work, we sought to examine predictions of this view in healthy young and older participants. An attentional focus constricted in response to an element-sized precue had the strongest facilitatory effect on visual search. However, this was true only when the precue correctly indicated the location of a target fixed in size. When precues incorrectly indicated target location or when target size varied, the optimal spatial scale of attention for search was larger, encompassing a number of array elements. Healthy aging altered the deployment of attentional scaling: The benefit of valid precues on search initially (in participants 65-74 years of age) was increased but later (in those 75-85 years of age) was reduced. The results also provided evidence that cue size effects are attentional, not strategic. This evidence is consistent with the proposed model of attentional scaling in visual search.

Adult↗
PubMed2003

The word frequency effect for recognition memory and the elevated-attention hypothesis.

Empirical tests were conducted on the elevated-attention hypothesis that low-frequency (LF) words are better recognized than high-frequency (HF) words because LF words attract more attention than do HF words (e.g., Glanzer & Adams, 1990). The elevated-attention hypothesis predicts that the hit rate advantage for LF words should be reduced by increases in attentional strain at study. We first tested this prediction in two experiments by varying the amount of experimenter-controlled study time (on the basis of the assumption that a decrease in study time would reduce the amount of resources available for studying a word). The elevated-attention hypothesis was confirmed, but only when words were studied for relatively short durations. This finding led us to formulate an early-phase elevated-attention hypothesis that proposes that more attentional resources are allocated to LF words than to HF words only during the early phase of encoding (which produces the LF hit rate advantage in subsequent recognition) and that the allocation of attentional resources during the late phase of encoding is not greater for LF words than for HF words. An additional empirical test of this revised hypothesis was conducted: Experimenter-controlled study time and the composition of the to-be-remembered pairs of words were varied orthogonally. The results confirmed the early-phase elevated-attention hypothesis.

Attention↗
PubMed1990

Voluntary allocation versus automatic capture of visual attention.

Is there a difference in the kind of attention elicited by an abrupt-onset peripheral cue and that elicited by an instruction (e.g., a central arrow cue) to move attention to a peripheral location? In Experiment 1, we found that peripheral cues are no more effective in orienting attention than are central cues. No evidence was found for separable attentional systems consisting of a volitional response to central cues and an automatic response triggered only by peripheral cues. Rather, an identical or similar attentional process seems to be activated by either type of cue, although perhaps in different ways. Peripheral cues seem to have an automatic component, however, in that once attention is engaged by a peripheral cue, it cannot easily be disengaged for refocus elsewhere. In Experiment 2, after several sessions of practice, subjects were able to circumvent automatic attentional capture by an abrupt-onset peripheral cue and to volitionally redirect the focus of attention. Thus, attentional capture by abrupt-onset stimuli is not strongly automatic.

Adult↗
PubMed1997

[Modulation of evoked potentials following electrical tooth and finger stimulation at selective attention task].

To investigate the effect of attention and novelty change of stimulus, modulation of evoked potentials following electrical tooth stimulus (EP-TS) and finger stimulus (EP-FS) by selective attention task were studied in 17 healthy adult volunteers. Stimulus in this study were electrical tooth and finger stimulus, tone beep in constant (2.0 sec.) interval in random order, and delivering percentage of tooth and finger stimulus was 10, 20, 30, 40, and 50% and tone beep was 80, 60, 40, 20, and 0%. The results were as follows: 1) P2 latency and N 2-P2 amplitude were increased while the subject's attention was toward each stimulus (attention), decreased while the subject's attention was not toward each stimulus (non-attention) at EP-TS and EP-FS. 2) When paying attention, P 2 latency and N 2-P 2 amplitude were increased as delivering percentage of tooth and finger stimulus were decreased. These findings suggested that attention and novelty change of stimulus when paying attention were one of the factors that influence psychological factors and modulate EP-TS and EP-FS results.

Adult↗
PubMed1999

Effects of attention on the processing of motion in macaque middle temporal and medial superior temporal visual cortical areas.

The visual system is continually inundated with information received by the eyes. Only a fraction of this information appears to reach visual awareness. This process of selection is one of the functions ascribed to visual attention. Although many studies have investigated the role of attention in shaping neuronal representations in cortical areas, few have focused on attentional modulation of neuronal signals related to visual motion. We recorded from 89 direction-selective neurons in middle temporal (MT) and medial superior temporal (MST) visual cortical areas of two macaque monkeys using identical sensory stimulation under various attentional conditions. Neural responses in both areas were greatly influenced by attention. When attention was directed to a stimulus inside the receptive field of a neuron, responses in MT and MST were enhanced an average of 20 and 40% compared with a condition in which attention was directed outside the receptive field. Even stronger average enhancements (70% in MT and 100% in MST) were observed when attention was switched from a stimulus moving in the nonpreferred direction inside the receptive field to another stimulus in the receptive field that was moving in the preferred direction. These findings show that attention modulates motion processing from stages early in the dorsal visual pathway by selectively enhancing the representation of attended stimuli and simultaneously reducing the influence of unattended stimuli.

Animals↗
PubMed1999

Individual differences in auditory and visual attention among fetal alcohol-affected adults.

BACKGROUND: Deficits in attention are commonly identified among patients who have been prenatally exposed to alcohol, and they often affect the ability of the patients to function appropriately in society. METHODS: Eleven adult patients with fetal alcohol syndrome (FAS) or fetal alcohol effects (FAE) were compared with nine adult subjects with no history of prenatal alcohol exposure, using four tests of visually and auditorially mediated attention. RESULTS: In relation to the comparison group, patients with FAS/FAE exhibited substantial deficits in both auditory and visual attention; the auditory deficits were greater. We observed two predominant patterns of deficits among patients with FAS/FAE, one involving both auditory and visual attention problems and the other involving less severe auditory problems and even fewer visual problems. Most subjects with FAS or FAE had some manifestations of attention problems in at least one of the tests of attention used in this study. We present a new graphical representation of individual auditory Continuous Performance Test data across a 6-min period, which, compared with conventional scores, more clearly reveals the markedly disrupted and variable attention patterns displayed by some individuals with FAS or FAE. CONCLUSIONS: These findings suggest that detailed analysis of the pattern of individual performance for each subject is an important aspect of Continuous Performance Test assessment. Our findings further suggest that intellectual performance (intelligence quotient score) alone is not sufficient to account for the patterns of disrupted attention for individuals with FAS/FAE. Assessment of individuals with FAS or FAE should include measurement of attentional functioning in both the visual and auditory modalities.

Adult↗