No abstract

Choosing between two items involves deliberation and comparison of the features of each item and its value. Such decisions take more time when choosing between options of similar value, possibly because these decisions require more evidence, but the mechanisms involved are not clear. We propose that the hippocampus supports deliberation about value, given its well-known role in prospection and relational cognition. We assessed the role of the hippocampus in deliberation in two experiments. First, using fMRI in healthy participants, we found that BOLD activity in the hippocampus increased as a function of deliberation time. Second, we found that patients with hippocampal damage exhibited more stochastic choices and longer reaction times than controls, possibly due to their failure to construct value-based or internal evidence during deliberation. Both sets of results were stronger in value-based decisions compared to perceptual decisions.

No abstract

R. A. (2021). Altered white matter microstructural organization in posttraumatic stress disorder across 3047 adults: results from the PGC-ENIGMA PTSD consortium. Molecular Psychiatry,26,[4315][4316][4317][4318][4319][4320][4321][4322][4323][4324][4325][4326][4327][4328][4329][4330]

No abstract

Background: Previous studies using candidate gene and genome-wide approaches have identified epigenetic changes in DNA methylation (DNAm) associated with posttraumatic stress disorder (PTSD). Methods: In this study, we performed an EWAS of PTSD in a cohort of Veterans (n = 378 lifetime PTSD cases and 135 controls) from the Translational Research Center for TBI and Stress Disorders (TRACTS) cohort assessed using the Illumina EPIC Methylation BeadChip which assesses DNAm at more than 850,000 sites throughout the genome. Our model included covariates for ancestry, cell heterogeneity, sex, age, and a smoking score based on DNAm at 39 smoking-associated CpGs. We also examined in EPIC-based DNAm data generated from pre-frontal cortex (PFC) tissue from the National PTSD Brain Bank (n = 72).

This study examined the performance of patients with Korsakoff and non-Korsakotf amnesia on tests of picture priming. Both groups showed intact priming on a picture-naming task but impaired priming on a fragment-completion task when fragmented pictures were presented at study. When whole pictures were presented at study, patients with non-Korsakoff amnesia showed intact priming, but Korsakoff patients' priming remained impaired. Both groups performed equally poorly on a picture-recognition task. It is concluded that non-Korsakoff patients show intact picture priming when explicit memory does not contaminate fragment-completion performance. Korsakoff patients, in contrast, show a selective impairment in the perceptual processes that mediate picture-fragment completion priming.Recent neuropsychological investigations of patients with amnesia have demonstrated a compelling dissociation between implicit and explicit memory (for reviews, see Moscovitch, Vriezen, & Gottstein, 1993;Schacter, Chiu, & Ochsner, 1993). Although patients with amnesia are severely impaired on explicit tests of memory such as recall and recognition, they frequently demonstrate entirely preserved performance on implicit tests of memory that do not make reference to an earlier study episode. Implicit memory may be revealed by repetition priming, the bias or facilitation in processing a stimulus due to prior exposure. A major emphasis in neuropsychological studies of implicit memory has been the processing of verbal information. Having been exposed to a word in a study phase, patients with amnesia are more accurate at identifying this word at threshold exposure (Cermak, Talbot, Chandler, & Wolbarst, 1985), faster in judging it to be a real word (Verfaellie, Cermak, Letourneau, & Zuffante, 1991), and more likely to generate it in response to its initial letters (Graf,

This study examined the effects of repetition and spacing of repetitions on amnesia patients' recognition and recall of a list of words. Like controls, amnesia patients recognized items better when repetitions were spaced compared with when they were massed. This finding was attributed to the additional rehearsal that distributed presentations typically encourage. Amnesia patients also showed normal spacing effects in a recall task, suggesting that they were able to benefit from the variable encoding that spaced repetitions allow to establish additional retrieval cues. However, even though instructions to encode repeated items in a variable manner enhanced massed presentations to the point where spacing no longer produced an advantage for the normal controls, it did not have a similar effect for the amnesia patients. This led to the conclusion that amnesia patients cannot take advantage of strategically provided opportunities to enhance their variable encoding of interitem associations. Instead, it is suggested that the automatic activation of different aspects of items and interitem associations is responsible for the spacing effect in their recall.The ability of amnesia patients to demonstrate enhanced performance on the second occurrence of an item has been investigated extensively in the context of implicit memory tasks. Beneficial effects of repetition have been demonstrated on tasks of perceptual identification (Cermak, Talbot, Chandler,