The breathing bear with preterm infants: Effects on sleep,respiration, and affect

This study investigated the sleep/wake states, respiration, and affective behaviors of premature infants who were provided à “breathing” bear in the isolette from 33 to 35 weeks conceptional age (CA). The Breathing Bear is à source of rhythmic stimulation that is optional for the infants. Its “breathing” reflects the breathing rate of the individual infant. At 33 weeks CA, 27 premature infants were provided à Breathing Bear (BrBr) and 26 were given à Non-Breathing Bear (N-BrBr). At 35 weeks, interfeed observations for an average of 1.7 hours were made of the babies' states and state-specific behaviors, along with respiration recordings. By 35 weeks, the BrBr babies showed less wakefulness, more quiet sleep, fewer startles in quiet sleep, and less crying than the N-BrBr babies. In addition, they were more likely to smile and N-BrBr babies were more likely to grimace in active sleep. These findings replicate and extend previous reports of effects of the Breathing Bear on neurobehavioral organization. They also suggest that less negative affect is expressed by the BrBr babies; and they point to the importance of future study of preterm infants' affective expressions, both in sleep and in waking.     

The man who executed "imagined" movements: evidence for dissociable components of the body schema

We examined the nature of representations underlying motor imagery and execution in a patient (CW) with bilateral parietal lesions. When imagining hand movements, CW executed the imagined motor act but was unaware of the movements. These movements were significantly more accurate than volitional movements for the left but not right hand. CW also exhibited preserved motor imagery for the left but not right hand. Consistent with previous accounts, these findings suggest that motor imagery may normally involve the inhibition of movements. CW's unawareness of movements during motor imagery may reflect inattention or misattribution of the unexpected sensory feedback. Furthermore, in line with current models of motor control, motor imagery may depend on the integrity of a "forward model" derived from motor outflow information to generate a prediction of the consequences of a motor command. Such predictions appear to be preserved for imagery of left but not right hand movements in CW. Action may additionally depend on precise updating of effector position derived from the comparison of predicted and actual sensory information. We propose that CW's impaired volitional movements may be attributable to the degradation of such an updating mechanism.     

Action-based and vision-based selection of input: Two sources of control

In the first part of this paper we review evidence suggesting that there exists a mechanism that selects input on the basis of its similarity to the required action. This response-based input selection differs from the more established space- and object-based input selection in that it is not constrained by the structure of the input. Our evidence suggests that the two-choice Stroop effect is caused by this response-based selection mechanism. By contrast, it is known that the flanker effect is determined by the space- and object- based selection mechanisms. We explore whether the conflict resolution of the Stroop and flanker tasks is different as well by embedding these two tasks in a PRP (Psychological Refractory Period) paradigm. We show that the Stroop and the PRP effects are additive whereas the flanker and the PRP effects are underadditive, suggesting that the processes in charge of the conflict resolution in the Stroop and the flanker tasks are indeed different. We discuss possible reasons for this difference, and discuss possible ways in which the response-based mechanism can be implemented in information processing models.     

Hippocampal damage and exploratory preferences in rats: memory for objects, places, and contexts

Rats have a natural tendency to spend more time exploring novel objects than familiar objects, and this preference can be used as an index of object recognition. Rats also show an exploratory preference for objects in locations where they have not previously encountered objects (an index of place memory) and for familiar objects in contexts different from those in which the objects were originally encountered (an index of context memory). In this experiment, rats with cytotoxic lesions of the hippocampal formation were tested on all three versions of the novelty-preference paradigm, with a 5-min retention interval between the familiarization and test phases. Rats with sham lesions displayed a novelty preference on all three trial types, whereas the rats with hippocampal lesions displayed a novelty preference on Object trials but did not discriminate between the objects on Place trials or Context trials. The findings indicate that hippocampal damage impairs memory for contextual or spatial aspects of an experience, whereas memory for objects that were part of the same experience are left relatively intact.     

Win-shift and win-stay learning in the short-beaked echidna (<Emphasis Type="Italic">Tachyglossus aculeatus</Emphasis>)

Numerous previous investigators have explained species differences in spatial memory performance in terms of differences in foraging ecology. In three experiments we attempted to extend these findings by examining the extent to which the spatial memory performance of echidnas (or "spiny anteaters") can be understood in terms of the spatio-temporal distribution of their prey (ants and termites). This is a species and a foraging situation that have not been examined in this way before. Echidnas were better able to learn to avoid a previously rewarding location (to "win-shift") than to learn to return to a previously rewarding location (to "win-stay"), at short retention intervals, but were unable to learn either of these strategies at retention intervals of 90 min. The short retention interval results support the ecological hypothesis, but the long retention interval results do not. Electronic Publication     

Psychosocial Treatment Strategies in the MTA Study: Rationale, Methods, and Critical Issues in Design and Implementation

The Collaborative Multimodal Treatment Study of Children with Attention Deficit Hyperactivity Disorder (ADHD), the MTA, is the first multisite, cooperative agreement treatment study of children, and the largest psychiatric/psychological treatment trial ever conducted by the National Institute of Mental Health. It examines the effectiveness of Medication vs. Psychosocial treatment vs. their combination for treatment of ADHD and compares these experimental arms to each other and to routine community care. In a parallel group design, 579 (male and female) ADHD children, aged 7–9 years, 11 months, were randomly assigned to one of the four experimental arms, and then received 14 months of prescribed treatment (or community care) with periodic reassessments. After delineating the theoretical and empirical rationales for Psychosocial treatment of ADHD, we describe the MTA's Psychosocial Treatment strategy applied to all children in two of the four experimental arms (Psychosocial treatment alone; Combined treatment). Psychosocial treatment consisted of three major components: a Parent Training component, a two-part School Intervention component, and a child treatment component anchored in an intensive Summer Treatment Program. Components were selected based on evidence of treatment efficacy and because they address comprehensive symptom targets, settings, comorbidities, and functional domains. We delineate key conceptual and logistical issues faced by clinical researchers in design and implementation of Psychosocial research with examples of how these issues were addressed in the MTA study.Deceased     

Parenting and Family Stress Treatment Outcomes in Attention Deficit Hyperactivity Disorder (ADHD): An Empirical Analysis in the MTA Study

Parenting and family stress treatment outcomes in the MTA study were examined. Male and female (579), 7–9-year-old children with combined type Attention Deficit Hyperactivity Disorder (ADHD), were recruited at six sites around the United States and Canada, and randomly assigned to one of four groups: intensive, multi-faceted behavior therapy program alone (Beh); carefully titrated and monitored medication management strategy alone (MedMgt); a well-integrated combination of the two (Comb); or a community comparison group (CC). Treatment occurred over 14 months, and assessments were taken at baseline, 3, 9, and 14 months. Parenting behavior and family stress were assessed using parent-report and child-report inventories. Results showed that Beh alone, MedMgt alone, and Comb produced significantly greater decreases in a parent-rated measure of negative parenting, Negative/Ineffective Discipline, than did standard community treatment. The three MTA treatments did not differ significantly from each other on this domain. No differences were noted among the four groups on positive parenting or on family stress variables. Results are discussed in terms of the theoretical and empirically documented importance of negative parenting in the symptoms, comorbidities and long-term outcomes of ADHD.     

Task switching and the measurement of “switch costs”

The measurement of “switch costs” is held to be of interest because, as is widely believed, they may reflect the control processes that are engaged when subjects switch between two (or more) competing tasks. [In task-switching experiments, the reaction time (RT) switch cost is typically measured as the difference in RT between switch and non-switch (repeat) trials.] In this report we focus on the RT switch costs that remain even after the subject has had some time to prepare for the shift of task, when the switch cost may be approximately asymptotic (so-called residual switch costs). Three experiments are presented. All three experiments used Stroop colour/word, and neutral stimuli. Participants performed the two tasks of word-reading and colour-naming in a regular, double alternation, using the “alternating runs” paradigm (R. D. Rogers & S. Monsell, 1995). The experiments were designed to test the hypothesis that RT switch costs depend on a form of proactive interference (PI) arising from the performance of a prior, competing task. A. Allport, E. A. Styles and S. Hsieh (1994) suggested that these PI effects resulted from “task-set inertia”, that is, the persisting activation-suppression of competing task-sets, or competing task-processing pathways. The results confirmed the existence of long-lasting PI from the competing task as a major contributor to switch costs. Non-switch trials, used as the baseline in the measurement of switch costs, were also shown to be strongly affected by similar PI effects. However, task-set inertia was not sufficient to account for these results. The results appeared inconsistent also with all other previous models of task switching. A new hypothesis to explain these between-task interference effects was developed, based on the stimulus-triggered retrieval of competing stimulus-response (S-R) associations, acquired (or strengthened) in earlier trials. Consistent with this retrieval hypothesis, switch costs were shown to depend primarily on the S-R characteristics of the preceding task (the task that was switched from) rather than the upcoming task. Further, the effects of the other, competing task were found to persist over many successive switching trials, affecting switch costs long after the stimulus overlap (and hence the principal S-R competition) between the current tasks had been removed. Switch costs were also found to be affected by recent, item-specific experience with a given stimulus, in either the same or the competing task. Finally, the results showed that switch costs were massively affected by the ratio of the number of prior trials, in response to the same stimuli, that had implemented either the currently intended or the competing S-R mappings. None of these effects are predicted by current models of residual switch costs, which appeal to the differences in control processes assumed to be engaged in switch versus non-switch trials. Received: 31 March 1999 / Accepted: 23 July 1999