Identifying rate-limiting nodes in large-scale cortical networks for visuospatial processing: an illustration using fMRI

With the advent of functional neuroimaging techniques, in particular functional magnetic resonance imaging (fMRI), we have gained greater insight into the neural correlates of visuospatial function. However, it may not always be easy to identify the cerebral regions most specifically associated with performance on a given task. One approach is to examine the quantitative relationships between regional activation and behavioral performance measures. In the present study, we investigated the functional neuroanatomy of two different visuospatial processing tasks, judgement of line orientation and mental rotation. Twenty-four normal participants were scanned with fMRI using blocked periodic designs for experimental task presentation. Accuracy and reaction time (RT) to each trial of both activation and baseline conditions in each experiment was recorded. Both experiments activated dorsal and ventral visual cortical areas as well as dorsolateral prefrontal cortex. More regionally specific associations with task performance were identified by estimating the association between (sinusoidal) power of functional response and mean RT to the activation condition; a permutation test based on spatial statistics was used for inference. There was significant behavioral-physiological association in right ventral extrastriate cortex for the line orientation task and in bilateral (predominantly right) superior parietal lobule for the mental rotation task. Comparable associations were not found between power of response and RT to the baseline conditions of the tasks. These data suggest that one region in a neurocognitive network may be most strongly associated with behavioral performance and this may be regarded as the computationally least efficient or rate-limiting node of the network.     

The relationship between substance use and posttraumatic stress disorder in a methadone maintenance treatment program

Introduction and Aims

Posttraumatic stress disorder (PTSD) is frequently linked with substance abuse. The self-medication hypothesis suggests that some people may use illicit substances in an attempt to self-treat psychiatric symptoms. This study explores the relationship between substance abuse and PTSD symptom clusters in a methadone maintenance population.

Design and Methods

Clients of a methadone maintenance program at a public Drug and Alcohol Service were invited to complete the PTSD Checklist–Civilian Version, a screening tool for PTSD. Information about their history of substance use was also collected.

Results

Eighty clients (43 female, 37 male), aged 35 ± 8.0 years (mean ± SD), participated in the study, of which 52.7% screened positive for PTSD. Severity of marijuana use was significantly associated with a number of reexperiencing and hyperarousal symptoms and with overall severity of PTSD symptoms. Opiate, amphetamine, and benzodiazepine use did not appear to be related to PTSD symptoms.

Discussion and Conclusions

In this sample, marijuana may be used to self-treat certain PTSD symptoms, supporting the self-medication hypothesis. Further research is required to confirm the association between a diagnosis of PTSD and substance use. Given the high prevalence of PTSD in the substance-using population, routine PTSD screening in the substance abuse treatment setting may be justified.     

Reduction of self-injurious behavior in an autistic girl using a multifaceted treatment program

Self-injurious hand biting was reduced in an autistic girl by using fine water mist combined with a loud statement of “No!” following the behavior, and verbal praise for appropriate behavior. The subject was 6 years old when the interventions were implemented, and she had been in arm and head restraints since infancy. A fading procedure that moved from a large to smaller bottles allowed generalization across settings and people. Treatment was effective at a 6-month follow-up in both structured and unstructured settings.     

Measuring tobacco dependence treatment outcomes: A perspective from the behavior change consortium

The Behavior Change Consortium (BCC) served as a consortium of 15 National Institutes of Health-funded trials intended to link theories of health behavior change to outcomes related to improved diet, exercise, and/or tobacco cessation. Five sites developed and tested interventions aimed at changing tobacco use behaviors, and the remaining 10 focused on changing diet and/or physical activity. The BCC’s tobacco dependence workgroup functioned to identify measures of tobacco use and dependence for use across the 15 BCC trials. The BCC tobacco intervention trials described herein were categorized by type of trial; theory(ies) on which each was based; and the “thickness,” or intensity, of the intervention. Between-site differences across these parameters posed conceptual and analytic challenges for combining data for cross-site analyses, which were integral to the BCC mission of identifying mechanisms of health behavior change. The lessons learned by the BCC tobacco dependence workgroup regarding the measurement and analysis of tobacco outcomes among BCC trials are discussed, including the challenges and the opportunities regarding the preparation for cross-site analyses. The workgroup concludes that trials should report both assessment of a prolonged period of abstinence of 6 months or longer, in addition to the traditional 7-day point prevalence outcome. This project was supported in part by Grants R01-MH5954 (Geoffrey Williams), cofunded by the National Institute of Mental Health and National Cancer Institute (NCI); R01-CA8069601 (Victor Strecher), funded by NCI; and R01-62165 (Belinda Borrelli), funded by the National Heart, Lung, and Blood Institute.     

CASIG: a consumer-centered assessment for planning individualized treatment and evaluating program outcomes

This paper reports the psychometric characteristics of a measure that assesses the treatment outcomes of individuals with serious and persistent mental illness. Unlike other outcome measures, this one is designed to be embedded in the clinical process of planning and evaluating treatment. It collects individualized data, structures how the data are used to plan and evaluate a client's treatment, and produces aggregate information relevant for research and program purposes. Two parallel versions were developed: one for the client's self-report, and one for an informant's report.The self-report measure was administered by peer-interviewers to 244 community interviewees, and by inpatient peer-interviewers to 93 inpatient interviewees. The community interviewees also completed the BASIS-32 and SF-36. Informants for 103 of the community interviewees completed the informant version of the measure, and the CCAR. Inpatient staff completed the informant version for 161 inpatient residents without regard for matching the 93 inpatient interviewees.The two versions had acceptable internal consistency, test--retest, and interrater reliabilities. Correlations of the community interviewees' and informants' results with the BASIS-32, SF-36, and CCAR provided evidence of convergent and discriminant validity, as did contrasts between community and inpatients interviewees.The usefulness of the instrument for clinical, program and research purposes is discussed, with emphasis on the characteristics that enhance its value in clinical practice --- assessment of meaningful outcomes, operationalization of client empowerment, comprehensiveness, easy administration, and continuity across time and provider. Also discussed is a computer-based program to summarize and present the results in a rapid, clinically meaningful manner.     

Assessing readmission to substance abuse treatment as an indicator of outcome and program performance

Managed health care systems often use treatment readmission data as an indicator of psychiatric patient outcome and program performance. This study of 3,018 inpatients being treated for substance abuse in Department of Veterans Affairs medical centers found that across a range of measures and patient subpopulations, patient outcomes and program performance were virtually independent of treatment readmission. These findings suggest that even though readmission for substance abuse treatment may have value as an easily obtainable measure of health care utilization and cost, it cannot serve as a valid substitute for direct assessment of patient outcome or program performance.     

Mortality in heroin addiction: impact of methadone treatment

The mortality within a cohort of 115 street heroin addicts was studied for 5-8 years using the Kaplan-Meier survival estimate technique. This differed markedly from the relatively low mortality of 166 comparable heroin addicts given methadone maintenance treatment (MT). The street addicts' mortality rate was 63 times that expected, compared with official statistics for a group of this age and sex distribution. When 53 patients in MT were involuntarily expelled from treatment, due to violation of programme rules, they returned to the high mortality of street addicts (55 times that expected). A group of 34 rehabilitated patients who left MT with medical consent retained the low mortality of MT patients (their mortality rate was 4 times that expected). Despite this great improvement in survival, even patients in MT showed a moderately elevated mortality (8 times that expected), mainly due to diseases acquired before entering the treatment programme. It is concluded that MT exerts a major improvement in the survival of heroin addicts.     

Enhancing power while controlling family-wise error: an illustration of the issues using electrocortical studies

This study examined the relative family-wise error (FWE) rate and statistical power of multivariate permutation tests (MPTs), Bonferroni-adjusted alpha, and uncorrected-alpha tests of significance for bivariate associations. Although there are many previous applications of MPTs, this is the first to apply it to testing bivariate associations. Electrocortical studies were selected as an example class because the sample sizes that are typical of electrocortical studies published in 2001 and 2002 are small and their multiple significance tests are typically nonindependent. Because Bonferroni adjustments assume independent predictors, we expected that MPTs would be more powerful than the Bonferroni adjustment. Results support the following conclusions: (a) failure to control for multiple significance testing results in unacceptable FWE rates, (b) the FWE rate for the MPTs approximated the alpha set for the analyses, and (c) the statistical power advantage that MPTs provide over Bonferroni adjustments is important when using small sample sizes such as those that are typical of recent electrocortical studies.