Exploration of perceptual and motor inhibition in children with traumatic brain injury

Perceptual and motor inhibition were examined using conflict resolution tasks for 12 children with traumatic brain injury and 24 matched controls. Direct comparisons of inhibition performances between the two groups showed a specific and disproportionate impairment of motor inhibition (compared with perceptual inhibition) for the children with traumatic brain injury, which suggests that inhibition processes might be differentially impaired in children after traumatic brain injury.     

Regulatory focus and executive function after interracial interactions

Recent research finds that interracial interactions can negatively impact executive function. The present study examined whether regulatory focus may moderate this effect. Specifically, prior to an interracial interaction, 45 White female students were told either to try to have a positive interracial exchange (promotion focus), avoid prejudice (prevention focus), or given no instruction (control). After the interaction, participants completed the Stroop color-naming task, which assessed executive attentional task performance. Results revealed that participants in the prevention and the no instruction, control conditions performed worse on the Stroop than participants in the promotion condition. The findings suggest that promoting positive contact through active engagement rather than prejudice avoidance attenuates the previously documented negative effects of interracial contact on cognitive functioning.     

Virtual action planning in Parkinson's disease: a control study.

Cognitive planning deficits affect patients with Parkinson's disease (PD) and traditional psychometric tests meet difficulties to evaluate their impact on daily life activities. Virtual reality (VR) may provide a new means of assessment. The objective of this study was firstly to develop a virtual environment (VE) useful to explore planning and secondly to examine the effectiveness of using VR in the assessment of cognitive planning for patients with PD. A virtual supermarket (VS) was designed in which participants carried out a task close to daily activities: a test of shopping list. There were two preliminary sessions to familiarize the participants with the software and the supermarket's layout. Then, during the assessment session, participants completed the task, without any time limitation. Global intellectual efficiency was assessed in order to exclude patients with dementia. Data related to the performance in the VS were recorded. Five patients with PD and five age-matched healthy volunteers, meeting inclusion criteria, constituted our convenience sample. The patients did not perform as well as the control group. In particular, the session's duration and the distance covered were longer. The patients' path is specific with numerous stops, turning around, and hesitancies. Finally, their motivation for further training sessions is aroused. The results underline the potential of using VR in the assessment of cognitive planning in PD. A larger analysis is currently being carried out to confirm and to explore all the outcome measures.     

On the role of familiarity with units of measurement in categorical accentuation: Tajfel and Wilkes (1963) revisited and replicated

The present article provides evidence for the role of participants' familiarity with units of measurement in categorical accentuation with unidimensional physical estimates. Belgian and American participants estimated the lengths of lines varying in length. Depending on the condition, the lines were or were not systematically associated with categorical labels, and the estimates were made either in inches or in centimeters. Consistent with our predictions, (a) categorical accentuation was higher when the lines were systematically categorized than when they were not, and (b) this effect was stronger when participants reported their estimates in an unfamiliar measurement unit (i.e., Belgian participants using inches, and American participants using centimeters). These findings support the view that people's reliance on categorical information is more likely to emerge given uncertain contexts of judgment. Additionally, they may help explain why researchers have had difficulties replicating the categorical accentuation effect in the past.     

Noradrenergic action in prefrontal cortex in the late stage of memory consolidation

These experiments investigated the role of the noradrenergic system in the late stage of memory consolidation and in particular its action at beta receptors in the prelimbic region (PL) of the prefrontal cortex in the hours after training. Rats were trained in a rapidly acquired, appetitively motivated foraging task based on olfactory discrimination. They were injected with a beta adrenergic receptor antagonist into the PL 5 min or 2 h after training and tested 48 h later. Rats injected at 2 h showed amnesia, whereas those injected at 5 min had good retention, equivalent to saline-injected controls. Monitoring extracellular noradrenaline efflux in PL by in vivo microdialysis during the first hours after training revealed a significant increase shortly after training, with a rapid return to baseline, and then another increase around the 2-h posttraining time window. Pseudo-trained rats showed a smaller early efflux and did not show the second wave of efflux at 2 h. These results confirm earlier pharmacological and immunohistochemical studies suggesting a delayed role of noradrenaline in a late phase of long-term memory consolidation and the engagement of the PL during these consolidation processes.     

A positron emission tomography study of short- and long-term treatment effects on functional brain activation in adults who stutter

Previous studies have shown that fluency-inducing techniques, such as choral speech, result in changes in neural activation as measured by functional neuroimaging. In the present study, positron emission tomography was used to investigate the effects of intensive behavioural treatment, followed by a 1-year maintenance program, on the pattern of cortical and subcortical activation in stuttering adults during silent and oral reading of single words. The results indicate changes in activation lateralisation, as well as a general reduction in overactivation, especially in the motor cortex, following treatment. The results are discussed in light of previous functional imaging studies with stuttering adults.

Educational objectives: The reader will learn about and be able to describe the: (1) use of functional neuroimaging PET in the study of stuttering; (2) differences in neural activation between stuttering and non-stuttering adults; and (3) effects of behavioural fluency treatment on cortical and subcortical activations in stuttering speakers.     

Pervasive influence of semantics in letter and category fluency: a multidimensional approach

We used multidimensional statistical procedures to study semantic and lexical processes underlying word retrieval in verbal-fluency performance. Forty healthy participants were given a two-choice letter task (i.e., generate items beginning with the letter 'A' or 'F', in any order) and a two-choice category task (i.e., generate animal or fruit names, in any order). Using correspondence analysis (CoA) and hierarchical clustering (HC), we found evidence of prominent semantic organization in both letter and category fluency. For example, a striking categorical segregation between animate and inanimate entities emerged during the letter task. Analysis of inter-item times revealed strong sequential priming effects in both tasks. Taken together, these results indicate that semantic facilitation is pervasive in word retrieval processes, even in the letter-fluency task, and therefore suggest that the traditional view of letter fluency as a purely phonemically based task should be revised. Finally, our findings may help explain patterns of verbal-fluency measures obtained in focal brain lesion patients.     

Lexical competition in phonological priming: Assessing the role of phonological match and mismatch lengths between primes and targets

In five experiments, we examined lexical competition effects using the phonological priming paradigm in a shadowing task. Experiments 1A and 1B replicate and extend Slowiaczek and Hamburger's (1992) observation that inhibitory effects occur when the prime and the target share the first three phonemes (e.g., /bRiz/-/bRik/) but not when they share the first two phonemes (e.g., /bRepsilonz/-/bRik/). This observation suggests that lexical competition depends on the length of the phonological match between the prime and the target. However, Experiment 2 revealed that an overlap of two phonemes is sufficient to cause an inhibitory effect provided that the primes mismatched the targets only on the last phoneme (e.g., /b[symbol: see text]l/-/b[symbol: see text]t/). Conversely, with a three-phoneme overlap, no inhibition was observed in Experiment 3 when the primes mismatched the targets on the last two phonemes (e.g., /bagepsilont/-/baga3/). In Experiment 4, an inhibitory effect was again observed when the primes mismatched the targets on the last phoneme but not when they mismatched the targets on the last two phonemes when the time between the offset of overlapping segments in the primes and the onset of overlapping segments in the targets was controlled for. The data thus indicate that what essentially determines prime-target competition effects in word-form priming is the number of mismatching phonemes.