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PubMed2004

Early focused attention predicts outcome for children born prematurely.

There is evidence that early focused, but not casual, attention to objects reflects concurrent regulation of attention and active learning. Because attentional abilities are of particular relevance in preterm infants, we evaluated whether early focused attention would be a better predictor of later attention and cognitive function than casual attention in 55 children born at very low birth weight. Participants were tested initially at 7 months and then at 2, 3, and/or 4/5 years of age. Focused attention was defined as the duration of concentrated examination of objects during independent play. Outcome measures were maternal ratings on standard attention-deficit hyperactivity disorder rating scales and standardized cognitive assessments. Results indicate that 7-month focused attention was predictive of reported problems in hyperactivity/impulsivity at age 4/5 years and cognitive abilities at 2, 3, and 4/5 years; casual attention measures were not related to these outcomes. Early focused attention appears continuous with later attentional skills in at-risk infants and is related to cognitive abilities through the preschool years.

Age Factors↗
PubMedDate not supplied

Is attention deficit hyperactivity disorder familial?

Using two sources of data, we review methodologic issues pertinent to family studies of attention deficit hyperactivity disorder to evaluate whether such studies define attention deficit hyperactivity disorder as a familial disorder. We systematically evaluate the relevant literature and provide a detailed overview of the Massachusetts General Hospital family-genetic studies of attention deficit disorder as defined in DSM-III and attention deficit hyperactivity disorder as defined in DSM-III-R. The available literature, and our double-blind, controlled studies indicate that attention deficit disorder and attention deficit hyperactivity disorder are familial. Moreover, the pattern of transmission of comorbid disorders suggests that attention deficit hyperactivity disorder is, from a familial perspective, distinct from anxiety disorders and learning disabilities. In contrast, attention deficit hyperactivity disorder with conduct disorder appears to be a familial subtype, and major depression appears to be a variable expression of the familial predisposition to attention deficit hyperactivity disorder. Although the available literature provides strong evidence for the familial transmission of attention deficit hyperactivity disorder, the mode of transmission requires further clarification. In addition, attention deficit hyperactivity disorder appears to be genetically heterogeneous, indicating that more work is needed to delineate genetically homogeneous subtypes and to describe the range of expression of their underlying genotypes. Family-genetic studies will continue to clarify the etiology and nosology of attention deficit hyperactivity disorder.

Adult↗
PubMed2005

Brain mechanisms of involuntary visuospatial attention: an event-related potential study.

The brain mechanisms mediating visuospatial attention were investigated by recording event-related potentials (ERPs) during a line-orientation discrimination task. Nonpredictive peripheral cues were used to direct participant's attention involuntarily to a spatial location. The earliest attentional modulation was observed in the P1 component (peak latency about 130 ms), with the valid trials eliciting larger P1 than invalid trials. Moreover, the attentional modulations on both the amplitude and latency of the P1 and N1 components had a different pattern as compared to previous studies with voluntary attention tasks. In contrast, the earliest visual ERP component, C1 (peak latency about 80 ms), was not modulated by attention. Low-resolution brain electromagnetic tomography (LORETA) showed that the earliest attentional modulation occurred in extrastriate cortex (middle occipital gyrus, BA 19) but not in the primary visual cortex. Later attention-related reactivations in the primary visual cortex were found at about 110 ms after stimulus onset. The results suggest that involuntary as well as voluntary attention modulates visual processing at the level of extrastriate cortex; however, at least some different processes are involved by involuntary attention compared to voluntary attention. In addition, the possible feedback from higher visual cortex to the primary visual cortex is faster and occurs earlier in involuntary relative to voluntary attention task.

Adolescent↗
PubMed2002

The effects of spatial attention on motion processing in deaf signers, hearing signers, and hearing nonsigners.

Visual abilities in deaf individuals may be altered as a result of auditory deprivation and/or because the deaf rely heavily on a sign language (American Sign Language, or ASL). In this study, we asked whether attentional abilities of deaf subjects are altered. Using a direction of motion discrimination task in the periphery, we investigated three aspects of spatial attention: orienting of attention, divided attention, and selective attention. To separate influences of auditory deprivation and sign language experience, we compared three subject groups: deaf and hearing native signers of ASL and hearing nonsigners. To investigate the ability to orient attention, we compared motion thresholds obtained with and without a valid spatial precue, with the notion that subjects orient to the stimulus prior to its appearance when a precue is presented. Results suggest a slight advantage for deaf subjects in the ability to orient spatial attention. To investigate divided attention, we compared motion thresholds obtained when a single motion target was presented to thresholds obtained when the motion target was presented among confusable distractors. The effect of adding distractors was found to be identical across subject groups, suggesting that attentional capacity is not altered in deaf subjects. Finally, to investigate selective attention, we compared performance for a single, cued motion target with that of a cued motion target presented among distractors. Here, deaf, but not hearing, subjects performed better when the motion target was presented among distractors than when it was presented alone, suggesting that deaf subjects are more affected by the presence of distractors. In sum, our results suggest that attentional orienting and selective attention are altered in the deaf and that these effects are most likely due to auditory deprivation as opposed to sign language experience.

Adult↗
PubMed1997

Cortical sites of sustained and divided attention in normal elderly humans.

Human brain mechanisms subserving attention have been assigned to prefrontal, midfrontal, and posterior parietal cortices, as well as to the anterior cingulate and the thalamus. To map these mechanisms in the brain, most studies have used selective attention tasks; few studies have mapped the brain under sustained or divided attention. The present study was designed to create maps of regional activity associated with sustained and divided attention using two different sensory modalities: visual checkerboard stimulation and vibrotactile stimulation of the right hand. Five cerebral PE-tomograms of 15O-labeled water uptake were acquired from 16 elderly healthy subjects during sustained or divided attention to the frequency of stimulation. To locate active brain regions, the t-statistic map of relative changes in cerebral blood flow was coregistered to the subjects' averaged brain MR images and to the standard Talairach brain coordinate system. Attention was associated with activity in two sites, the right middle frontal gyrus (Brodmann area 46) and the right inferior parietal lobule (Brodmann area 40). The frontal site was more active when the subjects attended to the visual stimulus and when the attention was divided, while the parietal site was more active during attention to the vibrotactile stimulus and during simple sustained attention. Our observations are consistent with the hypotheses (1) that the right posterior parietal attention center subserves attention to several sensory modalities and (2) that a cortical network of specific neuronal sites subserves both sustained and divided attention. These hypotheses must be tested in further studies.

Aged↗
PubMed2003

Modulations of early somatosensory ERP components by transient and sustained spatial attention.

To investigate when and how spatial attention affects somatosensory processing, event-related brain potentials (ERPs) were recorded in response to mechanical tactile stimuli delivered to the left and right hand while attention was directed to one of these hands. The attended hand either remained constant throughout an experimental block (sustained attention), or was changed across successive trials (transient attention). Attentional modulations of the N140 component and a sustained 'processing negativity' for attended stimuli were observed in both attention conditions. However, attentional effects on earlier somatosensory components differed systematically. Sustained attention resulted in a contralateral negativity overlapping with the N80 component, while transient attention was reflected by a bilateral positivity overlapping with the P100 component. This dissociation indicates that sustained and transient attention affect different somatosensory areas. It is suggested that sustained attention can modulate tactile processing within primary somatosensory cortex (S1), while effects of transient attention are located beyond S1. Overall, results demonstrate that spatial selectivity in touch is mediated by activity modulations in modality-specific somatosensory cortex.

Adult↗
PubMed2006

Latent structure of the Test of Everyday Attention in a non-clinical Chinese sample.

The validity and clinical viability of Posner and Petersen's (1999) 3-factor model of attention was tested through a confirmatory factor analysis of attentional performance (Test of Everyday Attention [Robertson, I. H., Ward, T., Ridgeway, V., & Nimmo-Smith, I. (1996). The structure of normal human attention: The Test of Everyday Attention. Journal of the International Neuropsychological Society, 2, 525-534]) in a sample of 133 Chinese participants. This study served both as a cross-cultural replication of the clinical implementation of this leading theoretical model of attention, and as a more stringent test of the validity of the hypothesized attentional processes underlying human cognitive control. The results support the validity of a 3-factor model of attention consistent with that proposed by Posner and Petersen (selective attention, sustained attention, and attentional switching/control), and demonstrate that clinical assessment of neuroanatomically-distinct attentional processes using simulated real life activities is possible.

Activities of Daily Living↗
PubMed2005

On the neural basis of focused and divided attention.

Concepts of higher attention functions distinguish focused and divided attention. The present study investigated whether these mental abilities are mediated by common or distinct neural substrates. In a first experiment, 19 healthy subjects were examined with functional brain imaging (fMRI) while they attended to either one or both of two simultaneously presented visual information streams and responded to repetitive stimuli. This experiment resembled a typical examination of these mental functions with the single task demanding focused and the dual task conditions requiring divided attention. Both conditions activated a widespread, mainly right-sided network including dorso- and ventrolateral prefrontal structures, superior and inferior parietal cortex, and anterior cingulate gyrus. Under higher cognitive demands of divided attention, activity in these structures was enhanced and left-sided homologues were recruited. In a second experiment investigating another 17 subjects with almost the same paradigm, it was accounted for that in most dual task investigations of focused and divided attention the single tasks are easier to process than their combined presentation. Therefore, the task difficulty of focused attention tasks was increased. Almost the same activity pattern observed during division of attention was now found during focusing attention. Comparing both attentional states matched for task difficulty, differences were found in visual but not in prefrontal or parietal cortex areas. Our results suggest that focused and divided attention depend on largely overlapping neuronal substrates. Differences in activation patterns, especially in prefrontal and parietal areas, may result from unequal demands on executive control due to disparate processing requirements in typical tasks of focused and divided attention: Easier conditions begin with mainly right-sided activity within the attention network. As conditions become more difficult, left-lateralized homologue areas activate.

Adult↗
PubMed2006

Neural substrates for dividing and focusing attention between simultaneous auditory and visual events.

With information constantly bombarding the human sensory systems, how is it that we attend to behaviorally relevant information? The present study examined the behavioral and neural bases of attending to one sense while ignoring another sense (bimodal selective attention) contrasted with attending simultaneously to two senses (bimodal divided attention). In a functional magnetic resonance imaging (fMRI) study, subjects simultaneously heard novel melodies and viewed geometric shapes. They were instructed to actively attend to only one or to both senses (selective or divided attention) or as a baseline condition, passively observe both (bimodal passive). Memory tests for both attended and unattended stimuli validated that subjects were following the attention instructions. Selective attention led to increased activity in relevant sensory cortices while simultaneously leading to decreased activity in irrelevant sensory cortices. The divided attention instruction did not lead to a global increase in sensory cortex activity compared to the bimodal passive baseline condition. However, divided attention did recruit heteromodal areas in the left dorsolateral prefrontal cortex, while selective attention did not recruit any frontal areas. We propose that sustained selective and divided bimodal attention were achieved via distinct neural processes. Selective attention was achieved primarily via modulation of the sensory cortices. Divided attention was achieved for most individuals via recruitment of the middle-dorsolateral prefrontal cortex. However, there was also a trade-off between activity in posterior-dorsolateral prefrontal cortex and sensory regions, such that individuals who demonstrated the best performance during divided attention also showed the greatest recruitment of sensory cortices.

Acoustic Stimulation↗
PubMed2005

Sustained and transient covert attention enhance the signal via different contrast response functions.

We investigated the mechanisms underlying the effects of sustained and transient covert attention on contrast sensitivity. The aim of this study was twofold: (1) Using a zero-noise display, we assessed whether sustained (endogenous) attention enhances contrast sensitivity via signal enhancement, and compared the magnitude of the effect with that of transient (exogenous) attention. (2) We compared the contrast psychometric functions for both sustained and transient attention and evaluated them in terms of contrast gain and response gain models. Observers performed a 2AFC orientation discrimination task on a tilted target Gabor, presented alone at 1 of 8 iso-eccentric locations. Either a neutral (baseline), peripheral (to manipulate transient attention), or a central cue (to manipulate sustained attention) preceded the target. Even in the absence of external noise, and using suprathreshold stimuli, observers showed an attentional effect, evidence in support of signal enhancement underlying both sustained and transient attention. Moreover, sustained attention caused a strictly leftward threshold shift in the psychometric function, supporting a contrast gain model. Interestingly, with transient attention we observed a change in asymptote in addition to a threshold shift. These findings suggest that whereas sustained attention operates strictly via contrast gain, transient attention may be better described by a mixture of response gain and contrast gain.

Attention↗
PubMed2001

Attention-dependent suppression of distracter visual input can be cross-modally cued as indexed by anticipatory parieto-occipital alpha-band oscillations.

Recent studies show that in addition to enhancing neural processing for attentionally relevant stimuli, selective attention also operates by suppressing the processing of distracter stimuli. When subjects are pre-cued to selectively deploy attention during voluntary (endogenous) attentional tasks, these mechanisms can be set up in advance of actual stimulus processing. That is, the brain can be placed in a biased attentional state. Two recent cueing studies have provided evidence for the deployment of such biased attentional states [J.J. Foxe, G.V. Simpson, S.P. Ahlfors, Neuroreport 9 (1998) 3929-3933; M.S. Worden, J.J. Foxe, N. Wang, G.V. Simpson, J. Neurosci. 20:RC63 (2000) 1-6]. Specifically, these studies implicated oscillatory activity in the alpha frequency-band (8-14 Hz) as an anticipatory mechanism for suppressing distracter visual stimulation. The current study extends these findings by showing that this alpha-suppressive effect is also invoked by cross-modal cues. Auditory symbolic cues were used in an intermodal attention task, to direct subjects' attention to a subsequent task in either the visual or auditory modality. Cueing attention to the auditory features of the imminent task stimuli resulted in significantly higher parieto-occipital alpha amplitude in the period preceding onset of this stimulus than when attention was cued to the visual features. Topographic mapping suggests that this effect is generated in regions of the inferior parietal cortex, areas that have been repeatedly implicated in the engagement and maintenance of visual attention. Taken together, the results of this series of studies suggest that these parietal regions are capable of integrating sensory cues from multiple sensory modalities in order to program the subsequent deployment of visual attention.

Acoustic Stimulation↗
PubMed2004

Supervisory attentional control following carbon monoxide poisoning.

This study tested the hypothesis that carbon monoxide poisoning would produce a deficit of attentional control, the supervisory attention system, as indexed by attention switching and attentional scheduling, and that routine attentional orienting would be unaffected. Seventy-three cases of carbon monoxide poisoning were assessed at 3 days and 1 month post poisoning on tasks of attentional orienting, and tasks of the supervisory attention system. The results were compared to a group of 53 healthy community participants. A deficit of the supervisory attentional system was documented on a task of attention switching in survivors of both deliberate and accidental CO poisoning, leaving attentional scheduling intact. There was no deficit of attentional orienting in the current study. Alteration of consciousness was found to predict subsequent supervisory attention system impairment in correlation analyses, and the deficit was persistent for a 1 month follow-up period.

Adolescent↗
PubMed2005

Atypical hemispheric dominance for attention: functional MRI topography.

The right hemisphere is predominantly involved in tasks associated with spatial attention. However, left hemispheric dominance for spatial attention can be found in healthy individuals, and both spatial attention and language can be lateralized to the same hemisphere. Little is known about the underlying regional distribution of neural activation in these 'atypical' individuals. Previously a large number of healthy subjects were screened for hemispheric dominance of visuospatial attention and language, using functional Doppler ultrasonography. From this group, subjects were chosen who were 'atypical' for hemispheric dominance of visuospatial attention and language, and their pattern of brain activation was studied with functional magnetic resonance imaging during a task probing spatial attention. Right-handed subjects with the 'typical' pattern of brain organization served as control subjects. It was found that subjects with an inverted lateralization of language and spatial attention (language right, attention left) recruited left-hemispheric areas in the attention task, homotopic to those recruited by control subjects in the right hemisphere. Subjects with lateralization of both language and attention to the right hemisphere activated an attentional network in the right hemisphere that was comparable to control subjects. The present findings suggest that not the hemispheric side, but the intrahemispheric pattern of activation is the distinct feature for the neural processes underlying language and attention.

Adult↗
PubMed1999

Haemodynamic brain responses to acute pain in humans: sensory and attentional networks.

Turning attention towards or away from a painful heat stimulus is known to modify both the subjective intensity of pain and the cortical evoked potentials to noxious stimuli. Using PET, we investigated in 12 volunteers whether pain-related regional cerebral blood flow (rCBF) changes were also modulated by attention. High (mean 46.6 degrees C) or low (mean 39 degrees C) intensity thermal stimuli were applied to the hand under three attentional conditions: (i) attention directed towards the stimuli, (ii) attention diverted from the stimuli, and (iii) no task. Only the insular/second somatosensory cortices were found to respond whatever the attentional context and might, therefore, subserve the sensory-discriminative dimension of pain (intensity coding). In parallel, other rCBF changes previously described as 'pain-related' appeared to depend essentially on the attentional context. Attention to the thermal stimulus involved a large network which was primarily right-sided, including prefrontal, posterior parietal, anterior cingulate cortices and thalamus. Anterior cingulate activity was not found to pertain to the intensity coding network but rather to the attentional neural activity triggered by pain. The attentional network disclosed in this study could be further subdivided into a non-specific arousal component, involving thalamic and upper brainstem regions, and a selective attention and orientating component including prefrontal, posterior parietal and cingulate cortices. A further effect observed in response to high intensity stimuli was a rCBF decrease within the somatosensory cortex ipsilateral to stimulation, which was considered to reflect contrast enhancing and/or anticipation processes. Attentional processes could possibly explain part of the variability observed in previous PET reports and should therefore be considered in further studies on pain in both normal subjects and patients with chronic pain.

Acoustic Stimulation↗
PubMed2005

Coherent oscillatory activity in monkey area v4 predicts successful allocation of attention.

Attention serves to select objects from often complex scenes for enhanced processing and perception. In particular, the perception of shape depends critically on attention for integrating the various parts of the selected object into a coherent representation of object shape. To study whether oscillatory neuronal synchrony may serve as a mechanism of attention in shape perception, we introduced a novel shape-tracking task requiring sustained attention to a morphing shape. Attention was found to strongly increase oscillatory currents underlying the recorded field potentials in the gamma-frequency range, thus indicating enhanced neuronal synchrony within the population of V4 neurons representing the attended stimulus. Errors indicating a misdirection of attention to the distracter instead of the target were preceded by a corresponding shift of oscillatory activity from the target's neuronal representation to that of the distracter. No such effect was observed for errors unrelated to attention. Modulations of the attention-dependent enhancement of oscillatory activity occurred in correspondence with changing attentional demands during the course of a trial. The specificity of the effect of attentional errors together with the close coupling between attentional demand and oscillatory activity support the hypothesis that oscillatory neuronal synchrony serves as a mechanism of attention.

Algorithms↗
PubMed2005

Tuning curve shift by attention modulation in cortical neurons: a computational study of its mechanisms.

Physiological studies of visual attention have demonstrated that focusing attention near a visual cortical neuron's receptive field (RF) results in enhanced evoked activity and RF shift. In this work, we explored the mechanisms of attention induced RF shifts in cortical network models that receive an attentional 'spotlight'. Our main results are threefold. First, whereas a 'spotlight' input always produces toward-attention shift of the population activity profile, we found that toward-attention shifts in RFs of single cells requires multiplicative gain modulation. Secondly, in a feedforward two-layer model, focal attentional gain modulation in first-layer neurons induces RF shift in second-layer neurons downstream. In contrast to experimental observations, the feedforward model typically fails to produce RF shifts in second-layer neurons when attention is directed beyond RF boundaries. We then show that an additive spotlight input combined with a recurrent network mechanism can produce the observed RF shift. Inhibitory effects in a surround of the attentional focus accentuate this RF shift and induce RF shrinking. Thirdly, we considered interrelationship between visual selective attention and adaptation. Our analysis predicts that the RF size is enlarged (respectively reduced) by attentional signal directed near a cell's RF center in a recurrent network (resp. in a feedforward network); the opposite is true for visual adaptation. Therefore, a refined estimation of the RF size during attention and after adaptation would provide a probe to differentiate recurrent versus feedforward mechanisms for RF shifts.

Adaptation, Physiological↗
PubMed2006

The relationship of otitis media in early childhood to attention dimensions during the early elementary school years.

This study examined the impact of otitis media with effusion (OME) and associated hearing loss between 6 and 48 months of age on attention dimensions (i.e., selective/focus, sustained) during the elementary school years. A prospective cohort design in which 74 African American infants were recruited between ages 6 and 12 months. Ear examinations were done repeatedly using both otoscopy and tympanometry, and hearing was assessed using standard audiometric procedures between 6 and 48 months. Multiple measures of attention (i.e., direct assessment, behavioral observations, parent/teacher ratings) were administered from kindergarten through second grade to assess two theoretical dimensions of attention: selective/focused and sustained. The home environment was assessed annually. Results indicated that neither early childhood OME nor hearing loss showed significant correlations with any of the longitudinal or cross-sectional measures of selective/focused attention and sustained attention. In contrast, children with mothers who had fewer years of education and who lived in less responsive and supportive home environments scored higher on both parent and teacher ratings of sustained attention (i.e., hyperactivity) through the second grade of elementary school. For NEPSY Auditory Attention in second grade, a significant interaction between the Home Observation for Measurement of the Environment and hearing loss was uncovered. This interaction showed that children with hearing loss from poor home environments experienced greater difficulties on the NEPSY Auditory Attention task than those with hearing loss from good home environments. These findings do not support a direct linkage of a history of OME and associated hearing loss to difficulties in selective/focused attention or sustained attention in early elementary school children. Relationships between sociodemographic variables and attention-related functions appear stronger and should be considered as mediators in any examination of the linkages between early OME and subsequent attention functions.

Attention↗
PubMed1994

Residual rightward attentional bias after apparent recovery from right hemisphere damage: implications for a multicomponent model of neglect.

Unilateral neglect may be a multicomponent attentional disorder consisting of an initial automatic orienting of attention toward the ipsilesional side and a subsequent impairment in contralesionally reorienting attention, both of which are superimposed on a generalised reduction in attention resources. It has been hypothesised that patients' ability to reorient attention contralesionally may recover relatively quickly, but that the ipsilesional attention bias may be relatively persistent. This hypothesis was tested by consecutively examining 13 patients who had had a right hemisphere stroke, and who had left unilateral neglect. They were examined once shortly after the stroke and again 12 months later, using a battery of standard clinical and experimental tasks. Patients initially showed a strong and consistent rightward attentional bias in addition to a failure to reorient their attention leftward. After 12 months patients continued to show an abnormal ipsilesional attentional bias, though most were now able to fully reorient their attention toward the contralesional side. These results suggest that restitution of the capacity to reorient attention contralesionally may underlie the apparent recovery from clinical signs of unilateral neglect. The presence of a residual ipsilesional attentional bias in most patients, however, may, at least in part, account for the poor functional outcomes in some apparently "recovered" patients.

Adult↗