Impaired contextual modulation of memories in PTSD: an fMRI and psychophysiological study of extinction retention and fear renewal

Post-traumatic stress disorder (PTSD) patients display pervasive fear memories, expressed indiscriminately. Proposed mechanisms include enhanced fear learning and impaired extinction or extinction recall. Documented extinction recall deficits and failure to use safety signals could result from general failure to use contextual information, a hippocampus-dependent process. This can be probed by adding a renewal phase to standard conditioning and extinction paradigms. Human subjects with PTSD and combat controls were conditioned (skin conductance response), extinguished, and tested for extinction retention and renewal in a scanner (fMRI). Fear conditioning (light paired with shock) occurred in one context, followed by extinction in another, to create danger and safety contexts. The next day, the extinguished conditioned stimulus (CS+E) was re-presented to assess extinction recall (safety context) and fear renewal (danger context). PTSD patients showed impaired extinction recall, with increased skin conductance and heightened amygdala activity to the extinguished CS+ in the safety context. However, they also showed impaired fear renewal; in the danger context, they had less skin conductance response to CS+E and lower activity in amygdala and ventral-medial prefrontal cortex compared with combat controls. Control subjects displayed appropriate contextual modulation of memory recall, with extinction (safety) memory prevailing in the safety context, and fear memory prevailing in the danger context. PTSD patients could not use safety context to sustain suppression of extinguished fear memory, but they also less effectively used danger context to enhance fear. They did not display globally enhanced fear expression, but rather showed a globally diminished capacity to use contextual information to modulate fear expression

The neural correlates of intertemporal decision‐making: Contributions of subjective value, stimulus type, and trait impulsivity

Making choices between payoffs available at different points in time reliably engages a decision‐making brain circuit that includes medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), and ventral striatum (VS). Previous neuroimaging studies produced differing accounts of the functions of these regions, including that these regions: (1) are sensitive to the value of rewards discounted by a function of delay ('subjective value'); (2) are differentially sensitive to the availability of an immediate reward; and (3) are implicated in impulsive decision‐making. In this event‐related fMRI study of 20 volunteers, these hypotheses were investigated simultaneously using a delay discounting task in which magnitude of rewards and stimulus type, i.e., the presence or absence of an immediate option, were independently varied, and in which participants' trait impulsivity was assessed with the Barratt Impulsiveness Scale. Results showed that mPFC, PCC, and VS are sensitive to the subjective value of rewards, whereas mPFC and PCC, but not VS, are sensitive to the presence of an immediate reward in the choice option. Moderation by individual differences in trait impulsivity was specific to the mPFC. Conjunction analysis showed significant overlap in mPFC and PCC for the main effects of subjective value and stimulus type, indicating these regions may serve multiple distinct roles during intertemporal decision‐making. These findings significantly advance our understanding of the specificity and overlap of functions subserved by different regions involved in intertemporal decision‐making, and help to reconcile conflicting accounts in the literature. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86833/1/21136_ftp.pd

Aberrant Reward Center Response To Partner Reputation During A Social Exchange Game In Generalized Social Phobia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97533/1/da22091.pd

Mental Health Service Utilization before and after Receipt of a Service‐Connected Disability Award for PTSD: Findings from a National Sample

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146624/1/hesr12859.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146624/2/hesr12859-sup-0001-AppendixSA1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146624/3/hesr12859_am.pd

Determinants of National Guard Mental Health Service Utilization in VA versus Non‐VA Settings

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134155/1/hesr12446.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134155/2/hesr12446-sup-0001-AppendixSA1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134155/3/hesr12446_am.pd

Predictors of PTSD Symptom Change Among Outpatients in the U.S. Department of Veterans Affairs Health Care System

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136244/1/jts22156.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136244/2/jts22156_am.pd

On the age of the Deccan traps near Rajahmundry

It must be remembered, however, that practically all this palaeontological evidence in support of an eocene age for the Deccan trap comes from plant fossils; and the question naturally arises as to what dependence is to be placed upon fossil plants as a guide to geological age—how far they could be considered "absolute indicators of a geological horizon". Whenever there has been a possible difference of opinion on the age of a bed as determined by the evidence of terrestrial fossil plants as against fossil marine animals, it is true that the geologist will always prefer the evidence of the latter and fix the age accordingly. But in a case like the age of the inter-traps where the decisive evidence of fossil marine animals is not available, it seems only reasonable to accept an age based on the verdict of the plant fossils, unless such a conclusion can be shown to be definitely unacceptable from the geological side

Genetic structure, diversity, and allelic richness in composite collection and reference set in chickpea (Cicer arietinum L.)

<p>Abstract</p> <p>Background</p> <p>Plant genetic resources (PGR) are the basic raw materials for future genetic progress and an insurance against unforeseen threats to agricultural production. An extensive characterization of PGR provides an opportunity to dissect structure, mine allelic variations, and identify diverse accessions for crop improvement. The Generation Challenge Program <url>http://www.generationcp.org</url> conceptualized the development of "composite collections" and extraction of "reference sets" from these for more efficient tapping of global crop-related genetic resources. In this study, we report the genetic structure, diversity and allelic richness in a composite collection of chickpea using SSR markers, and formation of a reference set of 300 accessions.</p> <p>Results</p> <p>The 48 SSR markers detected 1683 alleles in 2915 accessions, of which, 935 were considered rare, 720 common and 28 most frequent. The alleles per locus ranged from 14 to 67, averaged 35, and the polymorphic information content was from 0.467 to 0.974, averaged 0.854. Marker polymorphism varied between groups of accessions in the composite collection and reference set. A number of group-specific alleles were detected: 104 in Kabuli, 297 in desi, and 69 in wild <it>Cicer</it>; 114 each in Mediterranean and West Asia (WA), 117 in South and South East Asia (SSEA), and 10 in African region accessions. Desi and kabuli shared 436 alleles, while wild <it>Cicer </it>shared 17 and 16 alleles with desi and kabuli, respectively. The accessions from SSEA and WA shared 74 alleles, while those from Mediterranean 38 and 33 alleles with WA and SSEA, respectively. Desi chickpea contained a higher proportion of rare alleles (53%) than kabuli (46%), while wild <it>Cicer </it>accessions were devoid of rare alleles. A genotype-based reference set captured 1315 (78%) of the 1683 composite collection alleles of which 463 were rare, 826 common, and 26 the most frequent alleles. The neighbour-joining tree diagram of this reference set represents diversity from all directions of the tree diagram of the composite collection.</p> <p>Conclusion</p> <p>The genotype-based reference set, reported here, is an ideal set of germplasm for allele mining, association genetics, mapping and cloning gene(s), and in applied breeding for the development of broad-based elite breeding lines/cultivars with superior yield and enhanced adaptation to diverse environments.</p

Mild Traumatic Brain Injury and Treatment Response in Prolonged Exposure for PTSD

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98185/1/jts21813.pd