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PubMed1994

A sensory explanation for visual attention deficits in the elderly.

BACKGROUND: Reduced visual attention has been implicated as a major factor in age-related deficits of real-world functioning such as driving. However, the contribution of sensory factors to visual attention deficits has not been delineated. The magnocellular stream, which is diminished in aging, provides the dominant input to attention, and could provide a direct visual sensory explanation for these attentional losses. METHODS: We measured temporal response curves for transient visual attention in older and younger subjects. Attentional cues stimulated both the magnocellular and parvocellular streams. RESULTS: Older subjects exhibited slower, weaker responses than younger subjects. The time course in younger subjects agreed with that obtained for magnocellular(M)-biased stimuli, whereas that of older subjects agreed with parvocellular(P)-biased responses. CONCLUSIONS: The activation of transient visual attention is slower and weaker for elderly subjects, reflecting a reduced magnocellular input. This marks a primary visual cause for visual attention deficits of the elderly.

Adult↗
PubMed1983

Attention and autonomic self-regulation.

To examine how various aspects of attentional functioning are affected by autonomic self-regulation procedures, this study compared the effect of two treatment programs (EMG and thermal biofeedback used in conjunction with various somatic and cognitive relaxation/self-regulation strategies, and Benson's Relaxation Response procedure) and a Waiting List control group for essential hypertensive adults on three, perhaps overlapping, attentional dimensions: the capacity to disembed figure from ground (Embedded Figures Test, Block Design, and Picture Completion WAIS subtests); the capacity to voluntarily deploy attention (Digit Span subtest of the WAIS), and capacity to sustain attention or become absorbed (as measured by the Tellegen Absorption Scale). Thirty essential hypertensive men and women were randomly placed in one of the three groups. Attentional dimensions were assessed before and after the 10-week treatment program (or waiting period) and the relationship between blood pressure and attentional changes were assessed. The only group to evidence significant blood pressure reduction, the "Biofeedback Group," became significantly more Field Independent as measured by the EFT (p less than 0.001) and the Block Design measure (p less than 0.01) and evidenced a strong trend in the same direction on the Picture Completion measure (p less than 0.052, NS). No other significant pre-post attentional changes were found. A Pearson product correlation revealed that changes in diastolic blood pressure were significantly correlated with changes in EFT (r = 0.54, p less than 0.0001) and the Picture Completion measure (r = 0.32, p less than 0.05). The cognitive effect of autonomic self-regulation is discussed. In addition, the possible role of attention in autonomic self-regulation is examined.

Adult↗
PubMed2003

Why is joint attention a pivotal skill in autism?

Joint attention abilities play a crucial role in the development of autism. Impairments in joint attention are among the earliest signs of the disorder and joint attention skills relate to outcome, both in the 'natural course' of autism and through being targeted in early intervention programmes. In the current study, concurrent and longitudinal associations between joint attention and other social communication abilities measured in a sample of infants with autism and related pervasive developmental disorders at age 20 months, and language and symptom severity at age 42 months, were examined. Extending the findings from previous studies, joint attention ability was positively associated with language gains and (lower) social and communication symptoms, and imitation ability was also positively associated with later language. Some specificity in the association between different aspects of joint attention behaviours and outcome was found: declarative, triadic gaze switching predicted language and symptom severity but imperative, dyadic eye contact behaviours did not. Further, although joint attention was associated with later social and language symptoms it was unrelated to repetitive and stereotyped symptoms, suggesting the latter may have a separate developmental trajectory. Possible deficits in psychological and neurological processes that might underlie the impaired development of joint attention in autism are discussed.

Attention↗
PubMed2003

Autism and a deficit in broadening the spread of visual attention.

BACKGROUND: This study examines if visual attention in autism is spatially overfocused (Townsend & Courchesne, 1994) and if there is an associated deficit in broadening the spatial spread of attention. METHOD: Two crosshairs were presented on each trial separated by a brief (500 ms) interval. There was a modest difference in the lengths of the two hairs in each crosshair and participants had to decide which one was longest. Previous research (Mack & Rock, 1998) has revealed that in making this judgement people spread their visual attention to embrace the whole crosshair. Varying the overall size of each crosshair was intended to control participants' spread of attention. The impact of the size of the first crosshair gave an indication of participants' default setting for the spread of attention. The impact of the size transition between the first and second crosshair gave an indication of the fluency with which participants could change the spatial spread of visual attention. RESULTS: Based on the first proposal it was predicted that individuals with autism (N = 13), relative to ability-matched moderately learning disabled (N = 15) and typically developing individuals (N = 15), would be more accurate and quicker to respond when the first crosshair was small rather than large. However, the results revealed no effects of the size of the first crosshair and no group differences. Based on the second proposal it was predicted that individuals with autism, relative to both control groups, would be less accurate and slower to respond to the second crosshair when the size transition from the first crosshair involved a change from small to large (in comparison with large to large), but would not differ when the change was from large to small (in comparison with small to small). This prediction was confirmed. CONCLUSION: Autism is associated with a deficit in broadening the spatial spread of visual attention. The implications of this for other visual and attentional anomalies observed in autism are discussed.

Adolescent↗
PubMed2003

Joint attention training for children with autism using behavior modification procedures.

BACKGROUND: Deficits in joint attention are considered by many researchers to be an early predictor of childhood autism (e.g., Osterling & Dawson, 1994) and are considered to be pivotal to deficits in language, play, and social development in this population (Mundy, 1995). Although many researchers have noted the importance of joint attention deficits in the development of children with autism (e.g., Mundy, Sigman, & Kasari, 1994) and have called for intervention strategies (e.g., Mundy & Crowson, 1997), few studies have attempted to target joint attention. In this study, joint attention behaviors were taught to children with autism using a behavior modification procedure. METHODS: A multiple-baseline design was implemented to evaluate intervention effects. The following target behaviors were included in the intervention: 1) Responding to showing, pointing, and gaze shifting of adult; 2) Coordinated gaze shifting (i.e., coordinated joint attention); and 3) Pointing (with the purpose of sharing, not requesting). Generalization to setting and parent, follow-up sessions, and social validation measures were also analyzed. RESULTS: Joint attention behaviors were effectively trained and targeted behaviors generalized to other settings. In addition, positive changes were noted by naive observers using social validation measures. CONCLUSIONS: Integrating joint attention training into existing interventions may be important for children with autism. In addition, training parents in these techniques may help to maintain joint attention skills outside of the treatment setting.

Attention↗
PubMed2005

Coordination of voluntary and stimulus-driven attentional control in human cortex.

Visual attention may be voluntarily directed to particular locations or features (voluntary control), or it may be captured by salient stimuli, such as the abrupt appearance of a new perceptual object (stimulus-driven control). Most often, however, the deployment of attention is the result of a dynamic interplay between voluntary attentional control settings (e.g., based on prior knowledge about a target's location or color) and the degree to which stimuli in the visual scene match these voluntary control settings. Consequently, nontarget items in the scene that share a defining feature with the target of visual search can capture attention, a phenomenon termed contingent attentional capture. We used functional magnetic resonance imaging to show that attentional capture by target-colored distractors is accompanied by increased cortical activity in corresponding regions of retinotopically organized visual cortex. Concurrent activation in the temporoparietal junction and ventral frontal cortex suggests that these regions coordinate voluntary and stimulus-driven attentional control settings to determine which stimuli effectively compete for attention.

Adult↗
PubMed2006

Attentional bias predicts heroin relapse following treatment.

AIMS: Previous studies have shown that abstinent heroin addicts exhibit an attentional bias to heroin-related stimuli. It has been suggested that attentional bias may represent a vulnerability to relapse into drug use. In the present study, the predictive value of pre-treatment attentional bias on relapse was examined in a population of abstinent heroin addicts. Further, the effect of cue exposure therapy (CET) on attentional bias was studied. DESIGN: Participants were assigned randomly to receive nine sessions of CET or placebo psychotherapy. SETTING: An in-patient drug abuse treatment setting. PARTICIPANTS: Abstinent heroin-dependent patients. MEASUREMENTS: Participants completed the emotional Stroop task both before and after completing treatment. FINDINGS: Pre-treatment attentional bias predicted relapse at 3-month follow-up, even when controlling for self-reported cravings at the test session. Further, attentional bias was reduced in both groups after therapy, independent of treatment condition. CONCLUSIONS: Attentional bias may tap an important component of drug dependence as it is a predictor of opiate relapse. However, CET does not specifically reduce attentional bias.

Attention↗
PubMed2006

Attention difficulties and mood-related ruminative response style in adolescents with unipolar depression.

BACKGROUND: Depressed adults may show impairment in switching attention from one task to another. Rumination on negative thoughts is associated with the onset and persistence of depressive episodes. It is unclear if such mood-related ruminations are specifically associated with slowed ability in switching attention from one task to another. METHOD: Adolescents with current unipolar depression (n = 40) were compared with age and sex-matched controls (n = 38) on tests of attention and general cognitive abilities and completed the mood-related ruminative response style questionnaire. RESULTS: Compared to controls, depressed participants were significantly slower at switching attention. There was no association between attentional switching and mood-related ruminations and both processes contributed to the likelihood of being depressed. Findings were not accounted for by slowness in reading and speaking, the effects of antidepressants nor being more careful on tasks. CONCLUSIONS: Depressed adolescents demonstrate dual deficits in mood-related ruminative thinking and attention. Further studies are needed to investigate whether higher ruminations are associated with attention impairments in emotionally-valent attentional switching tasks, and whether both processes precede the emergence of clinical disorder.

Adolescent↗
PubMed2006

Strain specificity and cholinergic modulation of visuospatial attention in three inbred mouse strains.

The tremendous increase in the use of mouse inbred strains and mutant mice to study the molecular basis of psychiatric disorders urges for a better understanding of attentional performance in mice. To this aim, we investigated possible strain differences in performance and cholinergic modulation of visuospatial attention in three widely used mouse inbred strains (129S2/SvHsd, C57BL/6JOlaHsd and DBA/2OlaHsd) in the five-choice serial reaction time task. Results indicated that after extended training, performance of 129S2/SvHsd mice was superior to that of C57BL/6JOlaHsd and DBA/2OlaHsd mice in terms of attention, omission errors, inhibitory control and latencies to correct choice. Increasing the attentional load resulted in comparable decrements in attention in all strains and inhibitory control impairments that were most pronounced in DBA/2OlaHsd mice. Further pharmacological evaluation indicated that all strains showed attentional impairments after treatment with the muscarinic and nicotinic antagonists scopolamine and mecamylamine, respectively. 129S2/SvHsd mice were less sensitive, whereas DBA/2OlaHsd mice appeared more sensitive to the detrimental effects of mecamylamine. In addition, subchronic, but not acute, nicotine treatment slightly improved attentional performance in all strains to the same extent. In conclusion, our data indicate strain specificity with particularly good performance of 129S2/SvHsd mice and strong cholinergic involvement in visuospatial attention in mice.

Animals↗
PubMed1995

Attention related performance in two cognitively different subgroups of patients with multiple sclerosis.

To evaluate the underlying mechanisms of cognitive decline in multiple sclerosis, two clinically and demographically matched multiple sclerosis groups differing in cognitive status were assessed with attention related tasks. In addition to the attention tests recommended by the Cognitive Function Study Group of the American National Multiple Sclerosis Society, a test of sustained attention was used to evaluate the role of possible fatigue on cognitive performance. The cognitively mildly deteriorated group was slower than the cognitively preserved group and the controls on all tests of attention. The mildly deteriorated group did not, however, consistently differ from the other groups in the error scores of the attention tests. The preserved group exhibited slowness at the end of the visual vigilance test, but no deficits were found on the other attention related tests in this group. It is suggested that dissociable kinds of processing slowness are the origin of the deficits found on the attention tests in the two multiple sclerosis groups. Our preserved group exhibited signs of motor and fatigue related slowness, whereas the mildly deteriorated group also had extensive cognitive slowness. As sensitive indicators of cognitive slowness, attentional tests should be included in evaluation of the cognitive status of patients with multiple sclerosis.

Adult↗
PubMed1998

Computer assisted retraining of attentional impairments in patients with multiple sclerosis.

OBJECTIVE: To evaluate the efficacy of a computer based retraining of specific impairments of four different attentional domains in patients with multiple sclerosis. METHODS: Twenty two outpatients with multiple sclerosis received consecutively a specific training comprising 12 sessions in each of the two most impaired attention functions. The baseline of attentional deficits, the performance after each training period, and the course of performance in the next nine weeks was assessed by a computerised attention test battery. Additionally, the impact of the training on daily functioning was evaluated with a self rating inventory. RESULTS: Subgroups of patients with multiple sclerosis showing different patterns of attentional impairment could be separated. Significant improvements of performance could almost exclusively be achieved by the specific training programmes. The increase of performance remained stable for at least nine weeks. For quality of life patients reported less attention related problems in everyday situations. CONCLUSIONS: In patients with multiple sclerosis it seems worthwhile to assess attentional functions in detail and to train specific attention impairments selectively.

Activities of Daily Living↗
PubMed2002

Effects of a cross-modal manipulation of attention on somatosensory cortical neuronal responses to tactile stimuli in the monkey.

The role of attention in modulating tactile sensitivity in primary (SI) and secondary somatosensory cortex (SII) was addressed using a cross-modal manipulation of attention, somatosensory versus visual. Two adult monkeys (Macaca mulatta) were trained to perform two tasks: tactile discrimination of a change in the texture of a surface presented to digits 3 and 4 and visual discrimination of a change in the intensity of a light. In each trial, standard texture (2 mm spatial period, SP) and visual stimuli were presented. These were followed by an increase in SP and/or luminance. Each trial was preceded by an instruction cue (colored light) that directed the animal to attend and respond to the change in one modality while ignoring any change in the other modality. The two tasks were interleaved during the recording, on a trial-by-trial basis. Extracellular recordings were made from 178 neurons (SI, 102; SII, 76), all with a cutaneous receptive field on the stimulated digit tips. Discharge was quantified in both tasks during the instruction, the standard-stimuli, and the texture-change periods. The results showed that selective attention to tactile stimuli had qualitatively and quantitatively greater and earlier effects in SII than SI. Twenty-four of 102 SI cells showed a significant change in discharge with the direction of attention. For almost all cells (20/24), discharge was enhanced when attention was directed toward the tactile stimuli; the effects were most frequent in the analysis interval that encompassed the change in SP (16/24). A significantly higher proportion of SII cells were attention-sensitive (47/76). The effects were concentrated in the texture-change period (39/47) but also included earlier periods in the trial (instruction period, n = 15; standard-stimuli period, n = 32). Attention-related modulation that spanned all three intervals (n = 11) likely reflected baseline changes in discharge. For the texture-sensitive cells (43 in SI, 37 in SII), the mean change in discharge frequency (post texture change - pre-texture change) in each task was significantly increased in SII but not SI with selective attention. The results are consistent with a two-stage modulation of parietal cortical discharge, an initial stage (SI) in which there is some enhancement of sensory responses to the salient feature, the texture change, and a second stage (SII) in which baseline changes occur, along with further feature selection. These controls may be independently exerted on SI and SII, or they may reflect top-down controls from SII to SI.

Animals↗
PubMed2005

Independent controls of attentional influences in primary and secondary somatosensory cortex.

The neuronal mechanisms underlying enhanced perception of tactile stimuli with directed attention were investigated using single-unit recordings from primary (S1, n = 53) and secondary (S2, n = 50) somatosensory cortex in macaque monkeys. Neuronal responses to textures scanned under the digit tips (spatial periods, SP, of 2, 3.7 or 4.7 mm) were recorded while attention was directed either to discriminating a change in texture or to the reward and also in a neutral no-task condition. Cell discharge was quantified in three periods of the trials: salient Delta texture (directed attention), postreward, and static (both cases, attention directed to the reward). S1 texture- and non-texture-sensitive cells, as well as S2 non-texture-sensitive cells, showed a modest enhancement of discharge during the salient Delta texture period (approximately 25%) but no change in response gain, consistent with an additive increase in neuronal responsiveness with directed attention. In contrast, S2 texture-related cells showed a larger enhancement with directed attention to salient inputs (82%) and increased response gain, suggesting that directed attention produces a multiplicative increase in S2 responsiveness. During the postreward period, and also in no-task testing, S1 texture-sensitive cells preserved their sensitivity to SP. In contrast, S2 texture-, but not non-texture-, sensitive cells showed a marked suppression of discharge and decreased gain after the discrimination response. Together, the results support the notion that S2 discharge reflects stimulus parameters in relation to ongoing behavioral demands. The results also support the existence of two independent attentional mechanisms in somatosensory cortex, one generalized (S1 and S2), and the other focused on S2 texture-related cells.

Action Potentials↗
PubMed1996

Responses in area V4 depend on the spatial relationship between stimulus and attention.

1. We studied the spatial interaction between stimulus and attention in macaque area V4. Monkeys were required to fixate a small spot while continuously attending to a ring-shaped target within a large array of identical rings. Meanwhile, the response of the V4 cell under study was tested by flashing behaviorally irrelevant bar stimuli in the cell's classical receptive field (CRF). The location of the attended ring was varied across four positions surrounding the CRF, and the location of the bar stimulus was varied across five positions spanning the CRF. 2. Response strength depended on two aspects of the spatial relationship between the stimulus driving the cell (the bar) and the position of attention (the target ring). First, for 49% of the cells studied, responses were greater for bar stimuli near the attended ring; i.e., the receptive field profile shifted toward the attentional focus. Second, for 84% of the cells, the overall response level depended on the direction in which attention lay relative to the stimulus in the CRF (e.g., to the left, right, above, or below). 3. This study confirms a key prediction of spatial models of attention, which postulate enhanced processing of all stimuli near the attentional focus. It also introduces the novel finding that responses are influenced by the relative direction of attention. This result indicates that area V4 carries information about the spatial relationship between visual stimuli and attention.

Animals↗
PubMed1997

Neural mechanisms of spatial selective attention in areas V1, V2, and V4 of macaque visual cortex.

Many neurons in extrastriate visual cortex have large receptive fields, and this may lead to significant computational problems whenever multiple stimuli fall within a single field. Previous studies have suggested that when multiple stimuli fall within a cell's receptive field, they compete for the cell's response in a manner that can be biased in favor of attended stimuli. In the present study we examined this role of attention in areas V1, V2, and V4 of macaque monkeys with the use of a behavioral paradigm in which attention was directed to one of two stimulus locations. When two stimuli were presented simultaneously inside the cell's receptive field (which could be accomplished only in areas V2 and V4), we found that the cell's response was strongly influenced by which of the two stimuli was attended. The size of this attention effect was reduced when the attended and ignored stimuli were presented sequentially rather than simultaneously. In addition, the effects became very weak and inconsistent in these areas when only one of the two stimuli was located inside the receptive field. Attention thus modulated sensory responses primarily when two or more simultaneous stimuli competed for access to a neuron's receptive field. As in areas V2 and V4, attention did not modulate sensory responses in area V1 when only a single stimulus was inside the receptive field. In addition, the small receptive fields in this area precluded the simultaneous presentation of attended and ignored stimuli inside the receptive field, making it impossible to determine whether attention effects would be observed under the conditions that led to consistent attention effects in areas V2 and V4. Spontaneous firing rates in areas V2 and V4 were found to be 30-40% higher when attention was directed inside rather than outside the receptive field, even when no stimulus was present in the receptive field. Spontaneous firing rates also varied according to the particular location within the receptive field that was attended. These shifts in spontaneous activity may reflect a top-down signal that biases responses in favor of stimuli at the attended location.

Animals↗
PubMed2000

Effects of attention on MT and MST neuronal activity during pursuit initiation.

The responses of neurons in monkey extrastriate areas MT (middle temporal) and MST (medial superior temporal), and the initial metrics of saccadic and pursuit eye movements, have previously been shown to be better predicted by vector averaging or winner-take-all models depending on the stimulus conditions. To investigate the potential influences of attention on the neuronal activity, we measured the responses of single MT and MST neurons under identical stimulus conditions when one of two moving stimuli was the target for a pursuit eye movement. We found the greatest attentional modulation across neurons when two stimuli moved through the receptive field (RF) of the neuron and the stimulus motion was initiated at least 450 ms before reaching the center of the RF. These conditions were the same as those in which a winner-take-all model better predicted both the eye movements and the underlying neuronal activity. The modulation was almost always an increase of activity, and it was about equally frequent in MT and MST. A modulation of >50% was observed in approximately 41% of MT neurons and 27% of MST neurons. Responses to all directions of motion were modulated so that the direction tuning curves in the attended and unattended conditions were similar. Changes in the background activity with target selection were small and unlikely to account for the observed attentional modulation. In contrast, there was little change in the neuronal response with attention when the stimulus reached the RF center 150 ms after motion onset, which was also the condition in which the vector average model better predicted the initial eye movements and the activity of the neurons. These results are consistent with a competition model of attention in which top-down attention acts on the activity of one of two competing populations of neurons activated by the bottom-up input from peripheral stimuli. They suggest that there is a minimal separation of the populations necessary before attention can act on one population, similar to that required to produce a winner-take-all mode of behavior in pursuit initiation. The present experiments also suggest that it takes several hundred milliseconds to develop this top-down attention effect.

Animals↗
PubMed2004

Causes and consequences of limited attention.

This review focuses on the evolutionary causes and consequences of limited attention, defined as the restricted rate of information processing by the brain. The available data suggest, first, that limited attention is a major cognitive constraint determining animals' search for cryptic food, and, second, that limited attention reduces animals' ability to detect predators while involved in challenging tasks such as searching for cryptic food. These two effects of limited attention probably decrease animal fitness. Furthermore, a simulated evolutionary study provides empirical support for the prediction that focused attention by predators selects for prey polymorphism. The neurobiological mechanisms underlying limited attention have been widely studied. A recent incorporation of that mechanistic knowledge into an ecological model suggests that limited attention is an optimal strategy that balances effective yet economical search for cryptic objects. The review concludes with a set of testable predictions aimed to expand the currently limited empirical knowledge on the evolutionary ecology of limited attention.

Animals↗
PubMedDate not supplied

Effects of aging on visual attentional focusing.

BACKGROUND: Visual attentional performance is affected by aging, but there are methodological barriers to the understanding of this phenomenon that are due, above all, to the concomitant deterioration of sensory or central factors such as visual acuity and information processing speed. OBJECTIVE: The aim of the present study was to verify the effects of aging on visual attentional focusing by analyzing the space- and object-based components as well as the exogenous and endogenous dimensions of the attentional allocation. METHODS: Focusing of visual attention was investigated in 14 youngsters, 14 younger adults and 14 older adults (age ranges 12-15, 24-38 and 60-75 years, respectively). In two discrimination reaction time (RT) experiments, attention was cued by means of spatial cues of different size followed by compound stimuli at a shorter (150 ms) and a longer (500 ms) stimulus-onset asynchrony (SOA). The compound stimuli contained a predefined target letter at a local or global level. RESULTS: Older adults showed generally slower RTs and higher rates of delayed responses than younger individuals and reduced discrimination speed of local objects at 150-ms SOA, particularly when attention was invalidly cued to focus at a larger spatial scale. CONCLUSIONS: This pattern of results suggests that aging causes a dysfunction of the space-based and the object-based components of the attentional 'zooming in'. Such information may be of practical relevance for developing attentional training programs for older adults.

Adolescent↗