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PubMedDate not supplied

Use of the UFOV to evaluate and retrain visual attention skills in clients with stroke: a pilot study.

OBJECTIVE: The objective of this pilot study was to examine the use of a visual attention analyzer in the evaluation and retraining of useful field of view in clients with stroke. METHOD: Fifty-two clients with stroke referred to a driving evaluation service were evaluated with a visual attention analyzer referred to as the UFOV. The UFOV assesses three aspects of visual attention: processing speed, divided attention, and selective attention. Seven participants were retested to determine the test-retest reliability of the UFOV. Six participated in the development of a training protocol and in a 20-session visual attention retraining program. RESULTS: UFOV scores indicated substantial reduction in visual attention in clients after stroke, with older participants performing the most poorly. Test-retest reliability was moderate (ICC = .70). Mean UFOV scores improved significantly after retraining. CONCLUSION: Although UFOV scores indicated poor visual attention skills in clients with stroke, preliminary information suggests that UFOV scores significantly improve with training.

Adult↗
PubMed1999

Competitive mechanisms subserve attention in macaque areas V2 and V4.

It is well established that attention modulates visual processing in extrastriate cortex. However, the underlying neural mechanisms are unknown. A consistent observation is that attention has its greatest impact on neuronal responses when multiple stimuli appear together within a cell's receptive field. One way to explain this is to assume that multiple stimuli activate competing populations of neurons and that attention biases this competition in favor of the attended stimulus. In the absence of competing stimuli, there is no competition to be resolved. Accordingly, attention has a more limited effect on the neuronal response to a single stimulus. To test this interpretation, we measured the responses of neurons in macaque areas V2 and V4 using a behavioral paradigm that allowed us to isolate automatic sensory processing mechanisms from attentional effects. First, we measured each cell's response to a single stimulus presented alone inside the receptive field or paired with a second receptive field stimulus, while the monkey attended to a location outside the receptive field. Adding the second stimulus typically caused the neuron's response to move toward the response that was elicited by the second stimulus alone. Then, we directed the monkey's attention to one element of the pair. This drove the neuron's response toward the response elicited when the attended stimulus appeared alone. These findings are consistent with the idea that attention biases competitive interactions among neurons, causing them to respond primarily to the attended stimulus. A quantitative neural model of attention is proposed to account for these results.

Animals↗
PubMed1999

Spatial attention deficits in patients with acquired or developmental cerebellar abnormality.

Recent imaging and clinical studies have challenged the concept that the functional role of the cerebellum is exclusively in the motor domain. We present evidence of slowed covert orienting of visuospatial attention in patients with developmental cerebellar abnormality (patients with autism, a disorder in which at least 90% of all postmortem cases reported to date have Purkinje neuron loss), and in patients with cerebellar damage acquired from tumor or stroke. In spatial cuing tasks, normal control subjects across a wide age range were able to orient attention within 100 msec of an attention-directing cue. Patients with cerebellar damage showed little evidence of having oriented attention after 100 msec but did show the effects of attention orienting after 800-1200 msec. These effects were demonstrated in a task in which results were independent of the motor response. In this task, smaller cerebellar vermal lobules VI-VII (from magnetic resonance imaging) were associated with greater attention-orienting deficits. Although eye movements may also be disrupted in patients with cerebellar damage, abnormal gaze shifting cannot explain the timing and nature of the attention-orienting deficits reported here. These data may be consistent with evidence from animal models that suggest damage to the cerebellum disrupts both the spatial encoding of a location for an attentional shift and the subsequent gaze shift. These data are also consistent with a model of cerebellar function in which the cerebellum supports a broad spectrum of brain systems involved in both nonmotor and motor function.

Adolescent↗
PubMed2000

Early attention effects in human auditory-evoked potentials.

A fundamental question in attention theory concerns the earliest processing stages that can be modulated by selective attention. A series of experiments is reported in which very early attention effects are found under specific conditions in the frequency-following potential (FFP), a brain stem response to low-frequency tone stimuli. In two experiments, stimuli of two different modalities were applied, and attention directed to one of the modalities. In two further experiments, only auditory stimuli were presented. In the first of these last two experiments, a dichotic paradigm with sustained attention to one ear was used, in the second a monotic paired-stimuli paradigm was used, in which the first stimulus served as reference for the second one. Only in the last experiment significant attention effects were found in the latency, but not in the amplitude of the FFP. The results show that a very early attention effect on the latency of the FFP can be demonstrated, but only under highly specific conditions. The size and preconditions of the attention effect suggest that it reflects subtle intramodal tuning mechanisms in the cochlea or in the lower brain stem.

Acoustic Stimulation↗
PubMed1999

An instrument to measure the attentional demands of community-dwelling elders.

The capacity to direct attention (CDA) is a pivotal facet of cognitive functioning that allows people to focus on trains of thought, complex tasks, and the daily business of life. According to a theoretical framework of directed attentional fatigue (DAF) and restoration, excessive demand for attention depletes CDA, a condition called DAF. Attentional demands are factors such as feelings of loss and worries that require intense or prolonged use of CDA and thus can lead to DAF. The purposes of this study were to determine reliability and validity for an instrument to measure attentional demands, the Attentional Demands Survey (ADS). The ADS was administered to 197 (142 females, 50 males) community-dwelling elderly (ages 65-98 years, M = 77). A factor analysis revealed 4 factors/subscales consistent with theorized domains. Internal consistency for each subscale ranged from .87 to .90 and test-retest reliability was .91. The ADS can be used to explore the relationships among attentional demands, CDA, and interventions to support and restore attentional functioning for elders.

Aged↗
PubMed2000

Cerebral asymmetry of the "top-down" allocation of attention to global and local features.

Neuropsychological and neuroimaging studies have indicated that global and local features of a visual scene are processed differentially by the two hemispheres. Although visual selective attention is suggested to play a role in the hemispheric asymmetry, the precise mechanism of attentional control for the global-local processing is not fully understood. We investigated the neural correlates of cerebral asymmetry in directing attention to the global pattern and local components of a hierarchical stimulus. Event-related brain potentials (ERPs) were recorded while the subjects shifted their attention to the global or local level of a hierarchically structured letter. The shift direction was controlled by a preceding cue stimulus. The ERPs to the cue stimuli demonstrated that the right temporal-parietal and left posterior temporal regions were differentially activated during attentional allocation to the global and local levels, respectively. These effects started 240 msec after the cue stimulus. The late ERP components to the target stimuli also manifested the hemispheric global-local asymmetry as seen during the attentional shift. These electrophysiological results provided an asymmetrical neural basis for the "top-down" allocation of attention to global and local features and revealed the contribution of the temporal-parietal cortex to this attentional mechanism.

Adult↗
PubMed2000

An event-related brain potential study of cross-modal links in spatial attention between vision and touch.

Event-related potential (ERP) evidence for the existence of cross-modal links in endogenous spatial attention between vision and touch was obtained in an experiment where participants had to detect tactile or visual targets on the attended side and to ignore the irrelevant modality and stimuli on the unattended side. For visual ERPs, attentional modulations of occipital P1 and N1 components were present when attention was directed both within vision and within touch, indicating that links in spatial attention from touch to vision can affect early stages of visual processing. For somatosensory ERPs, attentional negativities starting around 140 ms poststimulus were present at midline and lateral central electrodes when touch was relevant. No attentional somatosensory ERP modulations were present when vision was relevant and tactile stimuli could be entirely ignored. However, in another task condition where responses were also required to infrequent tactile targets regardless of their location, visual-spatial attention modulated somatosensory ERPs. Unlike vision, touch apparently can be decoupled from attentional orienting within another modality unless it is potentially relevant.

Adult↗
PubMedDate not supplied

[Selective attention deficit in schizophrenia].

OBJECTIVE: To evaluate the cognitive deficits which have been linked with schizophrenia, particularly those related to selective attention from a neurocognitive point of view. DEVELOPMENT: We present a concept of attention consistent with a system of control of information processing composed of a group of neurone networks which carry out specific functions. Some functions are related to visual orientation, while others are involved in executive functions which are at the root of many cognitive skills. The convergence of data from behaviour studies and those made available by neuroimaging techniques have facilitated the identification of neuroanatomical areas responsible for these functions. Thus, the posterior parietal lobe, superior colliculus and pulvinar nucleus of the thalamus are responsible for directing visual attention to different spatial locations. The singular cortex, parts of the medial prefrontal area and supplementary motor area will be involved in executive functions. The question arises as to whether schizophrenia is related to a general attention deficit or to specific deficits linked to the different attention neurone networks. In the studies reviewed attention tasks for the evaluation of facilitatory and inhibitory functions related to the different attention networks were used. CONCLUSIONS: The studies showed that schizophrenic patients present deficits in inhibitory mechanisms which depend on the executive attention network. These results may contribute to a better understanding of the cognitive problems which occur in schizophrenia and also to design more effective strategies for the treatment of this disorder.

Attention↗
PubMed2001

Attention deficit hyperactivity disorder. Epidemiologic, pathophysiologic, diagnostic and treatment perspectives.

Although attention deficit hyperactivity disorder is a common child psychiatric disorder, the epidemiology and pathophysiology of attention deficit hyperactivity disorder is variable in different studies. Attention deficit hyperactivity disorder and comorbid disorders in children aided both by attention deficit hyperactivity disorder diagnostic criteria and assessment scales entails a comprehensive neuropsychiatric interview plus collection of information from different sources. Although psychosocial and behavioral therapies are of great therapeutic values, the psychopharmacological drugs are often used in the treatment of patients with attention deficit hyperactivity disorder. With a combined approach, a substantial proportion of patients with attention deficit hyperactivity disorder (90%) show good recovery. The patients with attention deficit hyperactivity disorder need careful evaluation and appropriate long-term treatment in order to prevent subsequent negative consequences. In rapidly developing countries, the researchers should carry out studies, which explore different aspects of attention deficit hyperactivity disorder in children, adolescents and adults.

Adolescent↗
PubMed2002

Visual attention in preschool children prenatally exposed to cocaine: implications for behavioral regulation.

The presence of cocaine during the prenatal period disrupts the development of neural systems involved in mediating visual attention; therefore, it is possible that prenatal cocaine exposure results in impairments in visual attention in early childhood. In the current study we hypothesized that preschool children with prenatal cocaine exposure would exhibit difficulties in the disengagement operation of visual attention and in sustaining attention, particularly for targets presented in the right visual field. Fourteen cocaine-exposed children and 20 control children between 14 and 60 months of age were assessed on measures of visual attention, cognition, and behavior. Cocaine-exposed children had slower reaction times on disengagement trials in the second half of our attention task, supporting our hypotheses that impairments in disengagement and sustained attention are associated with prenatal cocaine exposure. There was a trend for slower reaction times to targets presented in the right visual field, but not to targets presented in the left visual field. Cocaine-exposed children also exhibited greater difficulties in behavioral regulation. Overall, our findings suggest that children with prenatal cocaine exposure demonstrate specific impairments in visual attention and behavioral regulation.

Adult↗
PubMed2002

Evidence for anterior cingulate cortex involvement in monitoring preparatory attentional set.

An important cognitive function underlying unified, voluntary behavior is attentional control. Two frontal regions, anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC), appear to be particularly involved in attentional control and monitoring. In this study, we investigated whether ACC is involved in monitoring the preparatory allocation of attention during task switching, or whether ACC is active only when subjects are processing target stimuli and selecting a response, via a cued-attention design. Event-related BOLD fMRI activity was examined using a cue-target paradigm in which subjects performed task switches that selectively required reallocation of attention when tasks changed. There were three cue conditions: informative switch, informative repeat, and neutral. There were four target conditions: informatively cued switch, informatively cued repeat, neutrally cued switch, and neutrally cued repeat. Significant ACC activity was observed following both informative switch and informative repeat cues, but not after neutral cues. No significant ACC activity was observed following any of the target conditions. Significant DLPFC activity was observed following all three cue conditions and following neutrally cued switch targets. Overall, our results suggest that ACC is involved in monitoring the preparatory allocation of attention for conflict at the level of activation of competing attentional sets. The results also support the role of DLPFC in holding cognitive goals in working memory and allocating attention to the appropriate processing systems to meet those goals.

Adult↗
PubMed2004

Modeling segmentation of a visual scene via neural oscillators: fragmentation, discovery of details and attention.

The present study analyses the problem of binding and segmentation of a visual scene by means of a network of neural oscillators, laying emphasis on the problems of fragmentation, perception of details at different scales and spatial attention. The work is based on a two-layer model: a second layer of Wilson-Cowan oscillators is inhibited by information from the first layer. Moreover, the model uses a global inhibitor (GI) to segment objects. Spatial attention consists of an excitatory input, surrounded by an inhibitory annulus. A single object is identified by synchronous oscillatory activity of neural groups. The main idea of this work is that segmentation of objects at different detail levels can be achieved by linking parameters of the GI (i.e. the threshold and the inhibition strength) with the dimension of the zone selected by attention and with the dimension of the smaller objects to be detected. Simulations show that three possible kinds of behavior can be attained with the model, through proper choice of the GI parameters and attention input: (i) large objects in the visual scene are perceived, while small details are suppressed; (ii) large objects are perceived, while details are assembled together to constitute a single 'noise term'; (iii) if attention is focused on a smaller area and the GI parameters modulated accordingly (i.e. the threshold and attention strength are reduced) details are individually perceived as separate objects. These results suggest that the GI and attention may represent two concurrent aspects of the same attentive mechanism, i.e. they should work together to provide flexible management of a visual scene at different levels of detail.

Attention↗
PubMed1988

[The computer as an aid in attention training--a clinico-experimental study].

Reported is the evaluation of a computer-directed training programme for visual attention, that is based on the results of experimental studies by Zubin (1975) and Shakow (1979). With reference to Zubin's model, this training programme addresses active maintenance of selective visual attention (in terms of "sustained attention"), applying Shakow's diagnostic research paradigm (with a preparatory stimulus, an RT stimulus, and a variable preparatory interval) in a behavioural setting (learning of strategies for attention) for clinical purposes. In a pre-post-study carried out for a three-week programme, the results of single case experiments showed a significant decrease of reaction time variability, which partly persisted in follow-up studies. It was found that attentional performance increased in both psychotic patients and patients with cerebral dysfunction. In the second phase of statistical validation on patients with psychotic attention deviations, both attention performance and transfer effects were verified. The behavioural training methods, which were implemented to foster attention, proved helpful in the majority of cases. For greater practicability, a programme version for use on the home computer has been developed. The study on the whole illustrates the growing utilization of computer technology in neuropsychological rehabilitation.

Adult↗
PubMed1993

Development of an intervention to restore attention in cancer patients.

Developing interventions to maintain or restore attentional capacity during demanding phases of illness will help promote effective functioning in people with cancer. This study tested the effects of an experimental intervention aimed at maintaining or restoring attentional capacity in 32 women during the 3 months after surgery for localized (Stage I or II) breast cancer. The intervention was designed to minimize or prevent attentional fatigue through regular participation in activities that engage fascination and have other restorative properties. Attentional capacity was assessed using objective and subjective measures at four time points, approximately 3, 18, 60, and 90 days after breast cancer surgery. After the first observation, subjects were randomly assigned to receive the intervention (n = 16) or not to receive intervention (n = 16). Repeated measures ANOVA showed a significant interaction of experimental intervention and time on attentional capacity. Specifically, subjects in the intervention group showed significant improvement in attentional capacity over the four time points, while the nonintervention group showed a pattern of inconsistent performance over time. Findings suggest that nurses can intervene to maintain or restore attentional capacity in women after surgery for localized breast cancer. The theoretical basis for further development of attention-restoring interventions in patients with cancer is discussed.

Adult↗
PubMed1995

Alzheimer disease, attention, and the cholinergic system.

Recent neuropsychological studies suggest that, in addition to prominent mnemonic dysfunction, attentional impairments are a core feature of Alzheimer disease (AD). As is the case for memory, attention is not a unitary process, and only certain components of attention are disrupted in mild AD, particularly sustained and spatial attention. In this article we review evidence from both human and nonhuman neuropsychopharmacology that leads us to suggest that (at least some of) the attentional impairments seen in AD can be related to damage to the basal forebrain cholinergic system (BFCS), in particular the nucleus basalis of Meynert (nbM), which undergoes significant neuronal loss in AD. The BFCS provides the major cholinergic innervation to the cortex and innervates brain regions such as the thalamus, prefrontal cortex, and parietal lobes known to be involved in attentional operations. In addition, studies conducted by our group suggest that drugs acting to stimulate the cholinergic system, in particular tacrine and nicotine, can significantly improve attentional function in patients with AD as measured by improved performance on objective computerised cognitive tasks. Furthermore, cholinergic drugs may also have some utility in other disorders with attentional pathology, such as Parkinson's disease.

Alzheimer Disease↗
PubMed1996

Effects of prenatal exposure to opioids on focused attention in toddlers during free play.

The goals of this study were: (1) to determine if 24-month-old children exposed to opioids show decreased focused attention during free play compared with children of the same age who were not prenatally exposed; (2) to identify medical and social risk factors other than drug exposure that are related to focused attention; and (3) to determine if mothers' teaching ability had an effect on attention. Focused attention was rated during a 3-minute free play session for 30 toddlers who were methadone-exposed and for 44 comparison toddlers. The mother teaching the child to use a toy was also rated separately from the free play session. There was no difference in focused attention of 24 month olds during free play based only on prenatal exposure. Despite group differences in medical and social risk factors, only maternal IQ was significantly related to focused attention. Maternal instruction was strongly related to focused attention and mediated the effects of maternal IQ on attention.

Attention↗
PubMed1997

Spatial attention effects in macaque area V4.

Focal visual attention typically produces enhanced perceptual processing at the psychological level and relatively stronger neural responses at the physiological level. A longstanding mechanistic question is whether these attentional effects pertain specifically to the attended (target) object or to the region of space it occupies. We show here that attentional response enhancement in macaque area V4 extends to behaviorally irrelevant objects in the vicinity of the target object, indicating that focal attention has a strong spatial component at the physiological level. In addition, we find that spatial attention effects typically show a striking directional asymmetry. The direction of the asymmetry varies between cells, so that some cells respond best when attention is directed to the left of the stimulus, some when attention is directed to the right, etc. Thus, attention involves not only enhanced responses to behavioral targets but also a complex modulation of responses to other stimuli in the surrounding visual space.

Animals↗
PubMedDate not supplied

The phenomenology of attention. 2. Brightness and contrast.

The effect of attention on perceived brightness and contrast was investigated in eight experiments. Attention was manipulated by engaging observers in an attention-demanding concurrent task (letter detection) or by directing attention to a location with a peripheral cue. In all of the dual-task manipulations, attention reduced the variability of responses. However, attention did not affect the brightness of stimuli, nor did it affect the amount of simultaneous brightness contrast. Results with peripheral location cues were similar; however, the effect of attention in these experiments could be attributed to nonperceptual factors. The metaphorical "spotlight" of attention reduces observers' uncertainty about the brightness of a stimulus, but it does not "illuminate" in terms of brightness or contrast.

Attention↗