Disorder-specific functional abnormalities during sustained attention in youth with Attention Deficit Hyperactivity Disorder (ADHD) and with Autism

Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are often comorbid and share behavioural-cognitive abnormalities in sustained attention. A key question is whether this shared cognitive phenotype is based on common or different underlying pathophysiologies. To elucidate this question, we compared 20 boys with ADHD to 20 age and IQ matched ASD and 20 healthy boys using functional magnetic resonance imaging (fMRI) during a parametrically modulated vigilance task with a progressively increasing load of sustained attention. ADHD and ASD boys had significantly reduced activation relative to controls in bilateral striato–thalamic regions, left dorsolateral prefrontal cortex (DLPFC) and superior parietal cortex. Both groups also displayed significantly increased precuneus activation relative to controls. Precuneus was negatively correlated with the DLPFC activation, and progressively more deactivated with increasing attention load in controls, but not patients, suggesting problems with deactivation of a task-related default mode network in both disorders. However, left DLPFC underactivation was significantly more pronounced in ADHD relative to ASD boys, which furthermore was associated with sustained performance measures that were only impaired in ADHD patients. ASD boys, on the other hand, had disorder-specific enhanced cerebellar activation relative to both ADHD and control boys, presumably reflecting compensation. The findings show that ADHD and ASD boys have both shared and disorder-specific abnormalities in brain function during sustained attention. Shared deficits were in fronto–striato–parietal activation and default mode suppression. Differences were a more severe DLPFC dysfunction in ADHD and a disorder-specific fronto–striato–cerebellar dysregulation in ASD.

Abnormal functional activation and maturation of fronto-striato-temporal and cerebellar regions during sustained attention in autism spectrum disorder

Objective Sustained attention problems are common in people with autism spectrum disorder (ASD) and may have significant implications for the diagnosis and management of ASD and associated comorbidities. Furthermore, ASD has been associated with atypical structural brain development. The authors used functional MRI to investigate the functional brain maturation of attention between childhood and adulthood in people with ASD. Method Using a parametrically modulated sustained attention/vigilance task, the authors examined brain activation and its linear correlation with age between childhood and adulthood in 46 healthy male adolescents and adults (ages 11–35 years) with ASD and 44 age- and IQ-matched typically developing comparison subjects. Results Relative to the comparison group, the ASD group had significantly poorer task performance and significantly lower activation in inferior prefrontal cortical, medial prefrontal cortical, striato-thalamic, and lateral cerebellar regions. A conjunction analysis of this analysis with group differences in brain-age correlations showed that the comparison group, but not the ASD group, had significantly progressively increased activation with age in these regions between childhood and adulthood, suggesting abnormal functional brain maturation in ASD. Several regions that showed both abnormal activation and functional maturation were associated with poorer task performance and clinical measures of ASD and inattention. Conclusions The results provide first evidence that abnormalities in sustained attention networks in individuals with ASD are associated with underlying abnormalities in the functional brain maturation of these networks between late childhood and adulthood.

Learning a procedural task: effectiveness of multimedia presentations

Three experiments investigated the effectiveness of presenting procedural information through different media and their combinations. Experiment 1 examined the effectiveness of text, line drawings, text and line drawings, video. and video stills for learning a first aid task. The results showed an advantage of text and line drawings and of the video presentation over the other three conditions for both bandaging performance and answering questions about the task. Experiment 2 showed that the beneficial effect of the combination of text and pictures could not be accounted for simply in terms of a dual coding explanation. Rather, the effectiveness of the media and their combinations was influenced by the extent to which they conveyed action information. Finally, Experiment 3 showed no evidence of a contiguity effect: text and pictures were as effective when presented together on the same screen as when they were presented separately. Copyright © 2000 John Wiley & Sons, Ltd.

Implicit and explicit processes in a second-language learning task

Two experiments examined the learning of a set of Greek pronunciation rules through explicit and implicit modes of rule presentation. Experiment 1 compared the effectiveness of implicit and explicit modes of presentation in two modalities, visual and auditory. Subjects in the explicit or rule group were presented with the rule set, and those in the implicit or natural group were shown a set of Greek words, composed of letters from the rule set, linked to their pronunciations. Subjects learned the Greek words to criterion and were then given a series of tests which aimed to tap different types of knowledge. The results showed an advantage of explicit study of the rules. In addition, an interaction was found between mode of presentation and modality. Explicit instruction was more effective in the visual than in the auditory modality, whereas there was no modality effect for implicit instruction. Experiment 2 examined a possible reason for the advantage of the rule groups by comparing different combinations of explicit and implicit presentation in the study and learning phases. The results suggested that explicit presentation of the rules is only beneficial when it is followed by practice at applying them.

New strings for old : the role of similarity processing in an incidental learning task

This paper reports three experiments that examine the role of similarity processing in McGeorge and Burton's (1990) incidental learning task. In the experiments subjects performed a distractor task involving four-digit number strings, all of which conformed to a simple hidden rule. They were then given a forced-choice memory test in which they were presented with pairs of strings and were led to believe that one string of each pair had appeared in the prior learning phase. Although this was not the case, one string of each pair did conform to the hidden rule. Experiment 1 showed that, as in the McGeorge and Burton study, subjects were significantly more likely to select test strings that conformed to the hidden rule. However, additional analyses suggested that rather than having implicitly abstracted the rule, subjects may have been selecting strings that were in some way similar to those seen during the learning phase. Experiments 2 and 3 were designed to try to separate out effects due to similarity from those due to implicit rule abstraction. It was found that the results were more consistent with a similarity-based model than implicit rule abstraction per se.

Understanding the dimensional change card sort: Perspectives from task success and failure

Four experiments consider some of the circumstances under which children follow two different rule pairs when sorting cards. Previous research has repeatedly found that 3-year-olds encounter substantial difficulties implementing the second of two conflicting rule sets, despite their knowledge of these rules. One interpretation of this phenomenon [Cognitive Complexity and Control (CCC) theory] is that 3-year-olds have problems establishing an appropriate hierarchical ordering for rules. The present data suggest an alternative account of children's card sorting behaviour, according to which the cognitive salience of test card features may be more important than inflexibility with respect to rule representation.

Noise, predation risk compensation and vigilance in the chaffinch Fringilla coelebs

Background noise should in theory hinder detection of auditory cues associated with approaching danger. We tested whether foraging chaffinches Fringilla coelebs responded to background noise by increasing vigilance, and examined whether this was explained by predation risk compensation or by a novel stimulus hypothesis. The former predicts that only inter-scan interval should be modified in the presence of background noise, not vigilance levels generally. This is because noise hampers auditory cue detection and increases perceived predation risk primarily when in the head-down position, and also because previous tests have shown that only interscan interval is correlated with predator detection ability in this system. Chaffinches only modified interscan interval supporting this hypothesis. At the same time they made significantly fewer pecks when feeding during the background noise treatment and so the increased vigilance led to a reduction in intake rate, suggesting that compensating for the increased predation risk could indirectly lead to a fitness cost. Finally, the novel stimulus hypothesis predicts that chaffinches should habituate to the noise, which did not occur within a trial or over 5 subsequent trials. We conclude that auditory cues may be an important component of the trade-off between vigilance and feeding, and discuss possible implications for anti-predation theory and ecological processes

Sex differences in common marmosets (Callithrix jacchus) in response to an unfamiliar food task

There is a growing body of information on sex differences In callitrichid behaviour that includes the animals' performance in food tasks. For example, both reproductive and non-reproductive adult females have been found to be more successful than adult males in solving food tasks. In this study ten adult male and ten adult female common marmosets (Callithrix jacchus), housed individually, were tested with an unfamiliar task that involved the extraction of an embedded food. The task was to open a plastic canister that contained a raisin; the open end was covered with parchment paper. Each marmoset was given 15 trials in three blocks of 5 consecutive days. We measured the latency for each animal to open the lid and get the raisin-by one of five strategies that spontaneously emerged. The females learned the task faster and more efficiently than males; all the females opened the canister on day 1, for instance, in contrast to seven of the males on the same day. Females also progressively decreased the time that they took to open the tube. The final latency on day 15, for instance, was significantly shorter for the females. These results are consistent with relevant literature for callitrichids and cannot be accounted for in terms of differences in mental abilities, strength, hand morphology, or energy requirements. Further investigation is necessary to clarify the reasons for these differences.

A demonstration of attentional bias, using a novel dual task paradigm, towards clinically salient material in recovering alcohol abuse patients?

Background. This study examined whether alcohol abuse patients are characterized either by enhanced schematic processing of alcohol related cues or by an attentional bias towards the processing of alcohol cues. Method. Abstinent alcohol abusers (N = 25) and non-clinical control participants (N = 24) performed a dual task paradigm in which they had to make an odd/even decision to a centrally presented number while performing a peripherally presented lexical decision task. Stimuli on the lexical decision task comprised alcohol words, neutral words and non-words. In addition, participants completed an incidental recall task for the words presented in the lexical decision task. Results. It was found that, in the presence of alcohol related words, the performance of patients on the odd/even decision task was poorer than in the presence of other stimului. In addition, patients displayed slower lexical decision times for alcohol related words. Both groups displayed better recall for alcohol words than for other stimuli. Conclusions. These results are interpreted as supporting neither model of drug cravings. Rather, it is proposed that, in the presence of alcohol stimuli, alcohol abuse patients display a breakdown in the ability to focus attention.

Redintegration and lexicality effects in children: do they depend upon the demands of the memory task?

The effect of long-term knowledge upon performance in short-term memory tasks was examined for children from 5 to 10 years of age. The emergence of a lexicality effect, in which familiar words were recalled more accurately than unfamiliar words, was found to depend upon the nature of the memory task. Lexicality effects were interpreted as reflecting the use of redintegration, or reconstruction processes, in short-term memory. Redintegration increased with age for tasks requiring spoken item recall and decreased with age when position information but not naming was required. In a second experiment, redintegration was found in a recognition task when some of the foils rhymed with the target. Older children were able to profit from a rhyming foil, whereas younger children were confused by it, suggesting that the older children make use of sublexical phonological information in reconstructing the target. It was proposed that redintegrative processes in their mature form support the reconstruction of detailed phonological knowledge of words.