Aneta Dimoska

Inhibitory motor control in children with attention-deficit/hyperactivity disorder: event-related potentials in the stop-signal paradigm

BACKGROUND The aim of the study was to investigate the inhibitory control of an ongoing motor response and to identify underlying neural deficiencies, manifested in event-related potentials, that cause poorer inhibitory performance in children with attention-deficit/hyperactivity disorder. METHODS A stop-signal paradigm with a primary visual task and auditory stop signal was used to compare performance in 13 children with attention-deficit/hyperactivity disorder and 13 control children, while event-related potentials were recorded simultaneously. RESULTS Children with attention-deficit/hyperactivity disorder showed poorer inhibitory performance through a slower inhibitory process. Inhibitory processing of auditory stop signals was marked by a frontal N2 component that was reduced in the attention-deficit/hyperactivity disorder group relative to controls. A central positive component (P3) was associated with the success of inhibiting a response, but there were no group differences in its amplitude or latency. CONCLUSIONS Findings support the hypothesis of deficient inhibitory control in children with attention-deficit/hyperactivity disorder. Slower inhibitory processing appears to be due to a specific neural deficiency that manifests in the processing of the stop signal as attenuated negativity in the N2 latency range.

The auditory-evoked N2 and P3 components in the stop-signal task: Indices of inhibition, response-conflict or error-detection?

The N2 and P3 components have been separately associated with response inhibition in the stop-signal task, and more recently, the N2 has been implicated in the detection of response-conflict. To isolate response inhibition activity from early sensory processing, the present study compared processing of the stop-signal with that of a task-irrelevant tone, which subjects were instructed to ignore. Stop-signals elicited a larger N2 on failed-stop trials and a larger P3 on successful-stop trials, relative to ignore-signal trials, likely reflecting activity related to failed and successful stopping, respectively. ERPs between fast and slow reaction-time (RT) groups were also examined as it was hypothesised that greater inhibitory activation to stop faster responses would manifest in the component reflecting this process. Successful-stop P3 showed the anticipated effect (globally larger amplitude in the fast than slow RT group), supporting its association with the stopping of an ongoing response. In contrast, N2 was larger in the slow than fast RT group, and in contrast to the predictions of the response-conflict hypothesis, successful-stop N2 and the response-locked error-negativity (Ne) differed in scalp distribution. These findings indicate that the successful-stop N2 may be better explained as a deliberate form of response control or selection, which the slow RT group employed as a means of increasing the likelihood of a successful-stop. Finally, a comparison of stimulus and response-locked ERPs revealed that the failed-stop N2 and P3 appeared to reflect error-related activity, best observed in the response-locked Ne and error-positivity (Pe). Together these findings indicate that the successful-stop N2 and P3 reflect functionally distinct aspects of response control that are dependent upon performance strategies, while failed-stop N2 and P3 reflect error-related activity.

Can a "prompt list" empower cancer patients to ask relevant questions?

Abstracts and unpublished stu-dies were excluded. 36 Studies were included if a QPLwas provided to patients as part of a larger commu-nication intervention (eg, decision aids, informationbooklets, or coaching). Measures Because of the small number of RCT studies and thelarge variation in outcome measures between thema meta-analysis could not be performed. Objective,subjective, and psychometric measures were assessedseparately. Communication-related measures inclu-ded frequency and likelihood of patient questionasking coded from recorded consultations, patientself-report of questions asked, whether the QPLaided communication with the physician, perceivedhelpfulness or usefulness, and match between pre-ferred and perceived participation roles in the con-sultation. Patient psychological outcomes derivedfrom psychometric measures included anxiety, satis-faction with the consultation, depression, and psy-chological adjustment. Patient recall of medicalinformation postconsultation was also reported.226 CANCER July 15, 2008 / Volume 113 / Number 2

Response inhibition and interference control in children with AD/HD: a visual ERP investigation.

Children with Attention-deficit Hyperactivity Disorder (AD/HD) show deficits in executive inhibitory functions such as behavioral inhibition and interference control, but investigations of both of these domains in the same groups of children is scarce, especially with concurrent consideration of ERP indices of inhibitory processes. Twenty children with AD/HD and 20 matched controls aged between 8 and 14 years performed visual Go-Nogo (30% Nogo) and Flanker tasks while EEG was recorded. Results indicated that children with AD/HD traded off speed for accuracy in the Go-Nogo task, resulting in similar levels of response inhibition accuracy; in the Flanker task response speed and errors were at control levels, while misses were increased and showed an enhanced interference effect. In the Go-Nogo task, the AD/HD group showed reduced Go/Nogo P2, a reduced central N2 Nogo>Go effect, and a more anterior Go/Nogo P3 compared to controls. For the Flanker task, the AD/HD group showed delayed N1 and P2, dramatically reduced N2 to Incongruent stimuli, enhanced N2 to Neutral stimuli, as well as increased P3 to Incongruent stimuli, compared to controls. These results indicate that Go-Nogo behavioral inhibition and Flanker interference control were not equally impaired in children with AD/HD, and that factors such as effort, arousal and motivation require further investigation.

Suppression of P50 evoked potential component, schizotypal beliefs and smoking

Suppression of the P50 component of the evoked potential is an electrophysiological index of sensory gating that is blunted in schizophrenia spectrum disorders. Although P50 suppression is thought to be related to symptomatology, this is yet to be shown. The failure to demonstrate this relation has led some to argue that P50 suppression and symptomatology are not related. However, a possible confound has recently been corroborated [i.e., chronic smoking is related to superior P50 suppression [Crawford et al., Neuroscience Letters 317 (2002) 151]], and a relation has been found in questionnaire-defined individuals with indications of schizotypy [i.e., psychometric schizotypy is related to poor P50 suppression [Croft et al., Biological Psychiatry 50 (2001) 441]]. The present study attempted to replicate and extend both studies by examining P50 suppression, smoking histories, psychometric schizotypy and NEO Five-Factor Inventory (NEO-V) scores in 37 healthy participants. Replicating Crawford et al., P50 suppression was better in the heavier smokers. Providing a partial replication of Croft et al., P50 suppression was inversely related to schizotypy scores in participants who smoked little or not at all; however, P50 suppression was positively related to schizotypy in heavier smokers. Covarying for age and NEO-V scale scores had little effect on these relations. The findings provide evidence of important confounds that would limit our ability to detect P50 suppression/symptom relations in schizophrenia.

Implementing patient question-prompt lists into routine cancer care.

OBJECTIVE To examine the feasibility and acceptability of routine provision of patient question prompt lists (QPLs) to promote patient participation and patient-clinician communication in medical consultations. METHODS Four cancer centres across NSW, Australia (two rural, two urban) were invited to participate, involving distribution of QPLs to patients seeing a medical or radiation oncologist, or palliative care clinician. Patients rated their satisfaction after their next consultation. Cancer specialists provided their views at the end of the study. RESULTS Sixty-four percent (389/606) of patients attending consultations received a QPL. Of patients offered a QPL (426), 91% accepted. Of 139 patients surveyed post-consultation, 89% reported reading the QPL and, of these, 44% referred to the QPL during the consultation at least once. All of 10 cancer specialists providing their views post-implementation reported that QPL implementation in routine practice was feasible and did not strain resources. CONCLUSIONS Cancer patients and cancer specialists showed support for routine dissemination of the QPL. PRACTICE IMPLICATIONS For successful implementation of evidence-based tools we recommend promotion by local clinical champions, negotiation with clinic staff about dissemination methods, raised patient awareness through on-site project facilitators, media, consumer and support groups, and availability of resources in hard copy and via online sources.

An examination of the initial cancer consultation of medical and radiation oncologists using the Cancode interaction analysis system

This study provides an analysis of the structure of the initial cancer consultation, the consultation styles of medical and radiation oncologists, and their effect on patient outcomes. One hundred and fifty-five cancer patients attending their first consultation with either a medical or radiation oncologist were audiotaped and the transcripts were analysed using the Cancode computer interaction analysis system. Findings revealed that medical oncologists allowed patients and their families more input into the consultation and were rated as warmer and more patient-centred compared with radiation oncologists. However, radiation oncologists spent a longer period discussing, and were more likely to bring up, social support issues with patients. Both medical and radiation oncologists varied their consultation style according to the patients gender, age, anxiety levels, prognosis, and education. Patients seeing an oncologist who was rated as warmer and discussed a greater number of psychosocial issues had better psychological adjustment and reduced anxiety after consultation. These findings provide current evidence that may be used to inform improvements of communication skills training for oncologists and highlight the need for future communication research to separately consider oncologists from different disciplines.

Varying required effort during interference control in children with AD/HD: Task performance and ERPs

Prominent models of attention-deficit/hyperactivity disorder (AD/HD) contend that disinhibition is the core deficit, or that any inhibition deficits that exist are secondary to dysfunctional energetic regulation (i.e. effort and arousal). This study tested these models by investigating the influence of task-directed effort, as manipulated by stimulus degradation, on interference control deficits in children with AD/HD. Twenty children with AD/HD aged between 7 and 14years were matched in age to 20 controls and performed a modified visual Eriksen flanker task, while EEG and skin conductance level (SCL) were recorded. Participants completed the task under three conditions varying in stimulus degradation: none, 30% or 60%. Results revealed a quadratic effect with improved task performance in the 30% degradation condition, relative to the other conditions. Overall, children with AD/HD showed a tendency towards increased errors and more variable responding, although this did not differ between conditions. Importantly, children with AD/HD showed no deficits in interference control at a behavioural level. SCL revealed reduced activity in the AD/HD group during the non-degraded condition which normalised to control levels in the highest degradation condition. ERPs revealed two functionally distinct N2 components, one of which, along with the P3, was larger to incongruent stimuli, consistent with previous studies linking this component to inhibitory processing. Atypical activation of these components was evident in children with AD/HD and occurred as a function of degradation condition. Taken together these findings suggest the role of other factors such as state regulation as underlying deficits in AD/HD.

Event-related slow-wave activity in two subtypes of attention- deficit/hyperactivity disorder

OBJECTIVE Previous time-frequency studies have indicated that event-related low-frequency activity has important effects on component topography and developmental effects in auditory event-related potentials (ERPs) of children and adolescents. This study investigated the influence of event-related slow-wave (SW) (0.01-2 Hz) activity in the group differences seen between children with and without attention-deficit/hyperactivity disorder (AD/HD) of different subtypes. METHODS Time-frequency analysis techniques were applied to auditory ERP data derived from children with AD/HD predominantly inattentive type (n = 30), AD/HD combined type (n = 30) and age-matched control subjects (n = 30). RESULTS Event-related early frontal negative and late posterior positive SW components were reduced in the AD/HD combined type group, but not AD/HD inattentive type group, relative to controls. The RESIDUAL ERPs, which represented event-related 2-12 Hz activity, showed clinical vs. control group differences in components that were similar in both AD/HD subtype groups. CONCLUSIONS The time-frequency results showed that event-related SW (0.1-2 Hz) activity contributes importantly to group differences between AD/HD and control children, and the pattern of group differences from controls for each of the AD/HD subtype groups, which are evident in raw ERPs. These results emphasise both the clinical and developmental importance of this form of analysis. SIGNIFICANCE This novel approach revealed additional specific information about stimulus processing and regional inhibition/activation in two AD/HD subtypes, relative to control subjects.

A developmental investigation of stop-signal inhibition: Dissociating low- and higher-frequency activity in the event-related potential

Abstract. The present study examined the development of response inhibition in the stop-signal task across child (8-13 years), young-adult (18-22 years), and middle-aged adult (29-47 years) groups through a dissociation of low- and higher-frequency ERP activity. Fifty-one subjects (n = 17 in each group) performed the stop-signal task, which consisted of a visual choice reaction time (RT) task and auditory stop-signals, while EEG was recorded. The original EEG data (0.01-30 Hz) was subsequently filtered to separate slow-wave (0.01-2 Hz) and residual (2-30 Hz) activity. Performance findings revealed that stop-signal reaction time (SSRT) decreased from the child to young-adult group and then showed a small increase in the middle-aged adult group. Original ERPs revealed decreasing N1 and N2 amplitudes and increasing P2 and P3 amplitudes across the scalp with increasing age for successful-stop trials. These developmental effects did not occur in the residual waveforms after removal of slow-wave activity. For f...