The relationship between Hippocampal asymmetry and working memory processing in combat-related PTSD: a monozygotic twin study

BACKGROUND: PTSD is associated with reduction in hippocampal volume and abnormalities in hippocampal function. Hippocampal asymmetry has received less attention, but potentially could indicate lateralised differences in vulnerability to trauma. The P300 event-related potential component reflects the immediate processing of significant environmental stimuli and has generators in several brain regions including the hippocampus. P300 amplitude is generally reduced in people with PTSD. METHODS: Our study examined hippocampal volume asymmetry and the relationship between hippocampal asymmetry and P300 amplitude in male monozygotic twins discordant for Vietnam combat exposure. Lateralised hippocampal volume and P300 data were obtained from 70 male participants, of whom 12 had PTSD. We were able to compare (1) combat veterans with current PTSD; (2) their non-combat-exposed co-twins; (3) combat veterans without current PTSD and (4) their non-combat-exposed co-twins. RESULTS: There were no significant differences between groups in hippocampal asymmetry. There were no group differences in performance of an auditory oddball target detection task or in P300 amplitude. There was a significant positive correlation between P300 amplitude and the magnitude of hippocampal asymmetry in participants with PTSD. CONCLUSIONS: These findings suggest that greater hippocampal asymmetry in PTSD is associated with a need to allocate more attentional resources when processing significant environmental stimuli.Timothy Hall, Cherrie Galletly, C.R. Clark, Melinda Veltmeyer, Linda J. Metzger, Mark W. Gilbertson, Scott P. Orr, Roger K. Pitman and Alexander McFarlan

Whose Development? How Women Living Near the Yanacocha Mine, Peru, Envision Potential Futures

Among women opposing expansion of mining operations in Cajamarca, Peru, narratives of preferred alternatives diverge: from sustainable mining, to alternative economic development, to more radical alternatives to ‘development’. In these accounts, both their relative powerlessness and agency become apparent. This article critically explores women’s views of development and their imaginings of their region with or without mining. I argue that those who opposed mining show a continuing engagement with questions of development in the aftermath of conflict over natural resource extraction, highlighting a common thread of desires for bottom-up initiatives embracing local knowledge, practice and history

Event-related potential studies of post-traumatic stress disorder: a critical review and synthesis

Despite the sparseness of the currently available data, there is accumulating evidence of information processing impairment in post-traumatic stress disorder (PTSD). Studies of event-related potentials (ERPs) are the main tool in real time examination of information processing. In this paper, we sought to critically review the ERP evidence of information processing abnormalities in patients with PTSD. We also examined the evidence supporting the existence of a relationship between ERP abnormalities and symptom profiles or severity in PTSD patients. An extensive Medline search was performed. Keywords included PTSD or post-traumatic stress disorder, electrophysiology or EEG, electrophysiology, P50, P100, N100, P2, P200, P3, P300, sensory gating, CNV (contingent negative variation) and MMN (mismatch negativity). We limited the review to ERP adult human studies with control groups which were reported in the English language. After applying our inclusion-exclusion review criteria, 36 studies were included. Subjects exposed to wide ranges of military and civilian traumas were studied in these reports. Presented stimuli were both auditory and visual. The most widely studied components included P300, P50 gating, N100 and P200. Most of the studies reported increased P300 response to trauma-related stimuli in PTSD patients. A smaller group of studies reported dampening of responses or no change in responses to trauma-related and/or unrelated stimuli. P50 studies were strongly suggestive of impaired gating in patients with PTSD. In conclusion, the majority of reports support evidence of information processing abnormalities in patients with PTSD diagnosis. The predominance of evidence suggests presence of mid-latency and late ERP components differences in PTSD patients in comparison to healthy controls. Heterogeneity of assessment methods used contributes to difficulties in reaching firm conclusions regarding the nature of these differences. We suggest that future ERP-PTSD studies utilize standardized assessment scales that provide detailed information regarding the symptom clusters and the degree of symptom severity. This would allow assessment of electrophysiological indices-clinical symptoms relationships. Based on the available data, we suggest that ERP abnormalities in PTSD are possibly affected by the level of illness severity. If supported by future research, ERP studies may be used for both initial assessment and treatment follow-up

Relocating participation within a radical politics of development

In response to (and in sympathy with) many of the critical points that have been lodged against participatory approaches to development and governance within international development, this article seeks to relocate participation within a radical politics of development. We argue that participation needs to be theoretically and strategically informed by a notion of ‘citizenship’, and be located within the ‘critical modernist’ approach to development. Using empirical evidence drawn from a wide range of contemporary approaches to participation, the paper shows that participatory approaches are most likely to succeed where (i) they are pursued as part of a wider radical political project; (ii) where they are aimed specifically at securing citizenship rights and participation for marginal and subordinate groups; and (iii) when they seek to engage with development as an underlying process of social change rather than in the form of discrete technocratic interventions. However, we do not use these findings to argue against using participatory methods where these conditions are not met. Finally, the paper considers the implications of this relocation for participation in both theoretical and strategic terms

Mind the (yield) gap(s)

This paper explores the origin of the notion of “yield gap” and its use as a framing device for agricultural policy in sub-Saharan Africa. The argument is that while the yield gap of policy discourse provides a simple and powerful framing device, it is most often used without the discipline or caveats associated with the best examples of its use in crop production ecology and microeconomics. This argument is developed by examining how yield gap is used in a selection of recent and influential agricultural policy documents. The message for policy makers and others is clear: “mind the (yield) gap(s)”, for they are seldom what they appear

Integrative assessment of brain and cognitive function in post-traumatic stress disorder

Copyright © 2005 Imperial College PressThe present study combined neuropsychological and electrophysiological measures to obtain a comprehensive profile of the everyday attentional and memory dysfunction reported in PTSD. The event-related potential (ERP) literature has consistently found abnormalities in late components (N2, P3) reflecting working memory (WM) function. However, the neuropsychological profile reported in the literature has considerable variation. The present study examined ERP activity in 33 PTSD participants and matched controls during a standard two-tone auditory oddball task. Neuropsychological assessment was carried out using a task battery assessing a wide range of cognitive functions. Consistent with previous work, the PTSD group showed delayed N2 latency and reduced P3 target amplitude, together with slower and less accurate target detection. Scalp topography provided evidence of widespread abnormality during WM function, but with strongest effects broadly over the left hemisphere. Neuropsychological testing found concomitant difficulties on factorial measures of verbal memory retention/access and sustained attention but enhanced performance on measures of immediate recall. This integrative pattern of effects reflects a specific impairment in the operation of working memory systems that guide ongoing, planned behavior and that facilitate the acquisition and retention of new memories.Melinda D. Veltmeyer; C. Richard Clark; Alexander C. McFarlane; Kim L. Felmingham; Richard A. Bryant; Evian Gordo

Working memory function in post-traumatic stress disorder: An event-related potential study

Copyright © 2009 International Federation of Clinical Neurophysiology Published by Elsevier Ireland Ltd.Objective Previous studies using event-related potentials (ERPs) in post-traumatic stress disorder (PTSD) have demonstrated reduced P3 amplitude during target detection and working memory (WM) processes. This study investigated effects of psychotropic medication (primarily antidepressants) on these ERP components. Methods ERPs were recorded from 26 scalp sites in 34 PTSD patients (20 unmedicated, 14 medicated) with age- and gender-matched controls during a WM paradigm that involved detection of target letters on a visual display. Results As expected, PTSD patients showed a reduced amplitude P3wm component during WM updating and a reduced and delayed target P3 component. Contrary to expectation, these ERP effects were most apparent in the medicated subgroup of PTSD patients. The medicated PTSD subgroup showed a trend towards reduced P3wm amplitude compared with controls and a significant amplitude reduction and delay of target P3 component, while there was little difference between the non-medicated PTSD subgroup and controls. Neither ERP nor behavioural measures were related to Clinician Administered PTSD Scale (CAPS) symptom severity measures. Conclusions These results are consistent with research that suggests antidepressant medication may impair working memory performance. Significance The present study illustrates the importance of monitoring medication effects on cognitive performance during clinical efficacy studies.Melinda D. Veltmeyer, C. Richard Clark, Alexander C. McFarlane, Kathryn A. Moores, Richard A. Bryant and Evian Gordonhttp://www.elsevier.com/wps/find/journaldescription.cws_home/601528/description#descriptio