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Posttraumatic stress disorder (PTSD) is a heterogeneous disorder, and symptom severity varies over time. Neurobiological factors that predict PTSD symptoms and their chronicity remain unclear. This study investigated whether the volume of the hippocampus and its subfields, particularly cornu ammonis (CA) 1, CA3, and dentate gyrus, are associated with current PTSD symptoms and whether they predict PTSD symptom changes over 2 years. We examined clinical and structural magnetic resonance imaging measures from 252 trauma-exposed post-9/11 veterans (159 with Time 1 PTSD diagnosis) during assessments approximately 2 years apart. Automated hippocampal subfield segmentation was performed with FreeSurfer Version 7.1, producing 19 bilateral subfields. PTSD symptoms were measured at each assessment using the Clinician-Administered PTSD Scale-IV (CAPS). All models included total intracranial volume as a covariate. First, similar to previous reports, we showed that smaller overall hippocampal volume was associated with greater PTSD symptom severity at Time 1. Notably, when examining regions of interest (CA1, CA3, dentate gyrus), we found that smaller Time 1 hippocampal volumes in the bilateral CA1-body and CA2/3-body predicted decreased PTSD symptom severity at Time 2. These findings were not accounted for by combat exposure or treatment history. Additionally, both Time 1 CA1-body and CA2/3-body volume showed unique associations with changes in avoidance/numbing, but not with changes in reexperiencing or hyperarousal symptoms. This supports a more complex and nuanced relationship between hippocampal structure and PTSD symptoms, where during the posttrauma years bigger may not always mean better, and suggests that the CA1-body and CA2/3-body are important factors in the maintenance of PTSD symptoms. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Objective: Although loss of consciousness associated with moderate or severe traumatic brain injury (TBI) is thought to interfere with encoding of the TBI event, little is known about the effects of mild TBI (mTBI), which typically involves only transient disruption in consciousness., Method: Blast-exposed Afghanistan and Iraq War veterans were asked to recall the blast event. Participants were stratified based on whether the blast was associated with probable mTBI (n = 50) or not (n = 25). Narratives were scored for organizational structure (i.e., coherence) using the Narrative Coherence Coding Scheme (Reese et al., 2011) and episodic recollection using the Autobiographical Interview Coding Procedures (Levine et al., 2002)., Results: The mTBI group produced narratives that were less coherent but contained more episodic details than those of the no-TBI group., Conclusion: These results suggest that mTBI interferes with the organizational quality of memory in a manner that is independent of episodic detail generation., ((c) 2015 APA, all rights reserved).)

Objective: To examine neuropsychological outcomes in veterans of Operations Enduring and Iraqi Freedom (OEF/OIF) with self-reported histories of blast exposure and determine the contribution of deployment-related mild traumatic brain injury (mTBI), and posttraumatic stress disorder (PTSD) and depression to performance. The effect of number of blast exposures and distance from the blast was also assessed., Method: OEF/OIF veterans who reported exposure to blast underwent structured interviews and were assigned to no-TBI (n = 39), mTBI without loss of consciousness (LOC; n = 53), or mTBI with LOC (n = 35) groups. They were administered tests of executive function, memory, and motor function at least 6 months after the index event., Results: Neuropsychological outcomes did not differ as a function of mTBI group. Blast load and distance from the blast also did not affect neuropsychological performance. Both PTSD and depression symptoms were significantly associated with neuropsychological outcomes., Conclusions: A history of mTBI with or without LOC during deployment does not contribute to objective cognitive impairment in the chronic phase post injury. In contrast, PTSD and depression symptoms are associated with cognitive performance decrements. This finding is thought to reflect at least in part the impact of psychiatric distress on neuropsychological performance.

Objective: This study aimed to resolve discrepant findings in the literature regarding the effects of massed repetition and a single long study presentation on memory in amnesia., Method: Experiment 1 assessed recognition memory in 9 amnesic patients and 18 controls following presentation of a study list that contained items shown for a single short study presentation, a single long study presentation, and three massed repetitions. In Experiment 2, the same encoding conditions were presented in a blocked rather than intermixed format to all participants from Experiment 1., Results: In Experiment 1, control participants showed benefits associated with both types of extended exposure, and massed repetition was more beneficial than long study presentation, F(2, 34) = 14.03, p < .001, partial eta(2) = .45. In contrast, amnesic participants failed to show benefits of either type of extended exposure, F < 1. In Experiment 2, both groups benefited from repetition, but did so in different ways, F(2, 50) = 4.80, p = .012, partial eta(2) = .16. Amnesic patients showed significant and equivalent benefit associated with both types of extended exposure, F(2, 16) = 5.58, p = .015, partial eta(2) = .41, but control participants again benefited more from massed repetition than from long study presentation, F(2, 34) = 23.74, p < .001, partial eta(2) = .58., Conclusions: The findings suggest that previous inconsistencies in the literature were due to procedural differences across studies. We discuss group differences in terms of the mechanisms by which both forms of extended exposure facilitate performance in each group.

Performance of patients with Korsakoff's syndrome and herpes encephalitis was compared on a retrograde amnesia (RA) test, asking subjects to recall and recognize the definitions of words that had come into the language at different time periods. Performance was also compared on a related test in which participants were asked to produce the words to definitions they were given in free recall and cued recall versions. It was hypothesized that, if the temporal gradient in remote memory results from a shift of information from episodic to semantic memory, then there should be a temporal gradient on these tasks, possibly steeper (i.e., greater relative sparing of early memories) in the patients in the Korsakoff group than in the herpes encephalitis group, who have widespread temporal lobe damage. Furthermore, in comparing semantic and episodic remote memory tests, consolidation theory would predict uniform temporal gradients across such tasks, whereas multiple trace theory would predict a differential pattern. The results showed that patients with Korsakoff's syndrome and patients with herpes encephalitis were significantly impaired across all time periods on the vocabulary tests, with only minimal evidence of temporal gradients, relative to healthy participants, and there was no evidence of a differential pattern of impairment between the two patient groups. Comparison with performance on measures of episodic retrograde amnesia, in which there was a differential pattern of temporal gradient, suggests that the relative preservation of early episodic remote memories in patients with Korsakoff's syndrome does not result from an episodic-to-semantic shift in the quality with which memories are stored. These findings are discussed in relation to existing theories of RA and to the patients' underlying patterns of neuropathology.

Source memory involves recognizing or recalling particular features that cause us to think of a mental experience as representing a particular past event. Research directed at understanding source memory comes from many domains, including cognitive-behavioral psychology, neuroscience, lifespan psychology, clinical psychology, and psychiatry. The authors believe that integrating multiple approaches to investigating source memory--most notably here, cognitive-behavioral and cognitive neuroscience--provides productive cross-fertilization of theory, methods, and analyses that in turn will yield unique constraints to our understanding of human memory. The investigations in this special section demonstrate the promise of such an integrative approach for advancing theories of source memory., ((c) 2008 APA)

In 2 experiments using a converging associates paradigm, the authors evaluated implicit memory for gist information in amnesic patients. In Experiment 1, participants saw multiple sets of associates, each converging on a nonpresented theme word, and were then tested using an implicit word stem completion test and an explicit cued recall test. Amnesic patients showed intact implicit and impaired explicit memory for studied words, but memory for nonpresented lures was impaired, regardless of retrieval instructions. To evaluate whether impaired implicit memory for lures was due to accelerated forgetting of gist information, short study lists were used in Experiment 2, each consisting of a single set of associates. Amnesics' implicit memory for lures was again impaired. These results point to an inability to encode robust gist representations as the cause of impaired gist memory in amnesia., (Copyright (c) 2005 APA, all rights reserved.)

In 2 experiments involving patients with semantic dementia, the authors investigated the impact of semantic memory loss on both true and false recognition. Experiment 1 involved recognition memory for categories of everyday objects that shared a predominantly semantic relationship. The patients showed preserved item-specific recollection for the pictorial stimuli but, compared with control participants, exhibited significantly reduced utilization of gist information regarding the categories of objects. The latter result is consistent with the patients' degraded semantic knowledge. Experiment 2 involved categories of abstract objects that were related to one another perceptually rather than semantically. Patients with semantic dementia obtained item-specific recollection and gist memory scores that were indistinguishable from those of control participants. These results suggest that the reduction in gist memory in semantic dementia is largely specific to semantic representations and cannot be attributed to general difficulty with abstracting and/or utilizing gistlike commonalities between stimuli., (Copyright (c) 2005 APA, all rights reserved.)

This study examined verbal recognition memory in amnesic patients with frontal lesions (AF), nonamnesic patients with frontal lesions (NAF), and amnesic patients with medial temporal lesions (MT). To examine susceptibility to false alarms, the number of studied words drawn from various categories was varied. The AF and MT groups demonstrated reduced hits and increased false alarms. False alarms were especially elevated when item-specific recollection was strongest in control participants. The NAF group performed indistinguishably from control participants, but several patients showed excessive false alarms in the context of normal hit rates. These patients exhibited impaired monitoring and verification processes. The findings demonstrate that elevated false recognition is not characteristic of all frontal patients and may result from more than 1 underlying mechanism., (((c) 2004 APA, all rights reserved))

This study examined the status of recollection in amnesia when recollection is supported by perceptual rather than conceptual processes. Two experiments investigated the size congruency effect-the advantage in recognition of patterns presented in the same size, rather than in different sizes-at study and test. In Experiment 1, the authors used a remember-know paradigm in nonamnesic individuals and demonstrated that the size congruency effect was due to enhanced recollection. In Experiment 2, the authors examined whether amnesic patients would show a size congruency effect when their overall level of performance was matched to that of controls. Amnesic patients failed to show a size congruency effect. These findings provide evidence for a disproportionate disruption in recollection compared with familiarity in amnesia, even when recollection is supported by perceptual processes.

To examine the relationship between recall and recognition memory in amnesia, the authors conducted 2 experiments in which recognition memory was equated between patients with amnesia and control participants. It was then determined whether recall was also similar across groups. In Experiment 1, recognition was equated by providing amnesic patients with additional study exposures; in Experiment 2, recognition was equated by testing controls following a longer delay. These different methods of equating recognition across groups led to divergent results because amnesic patients' recall performance was lower than controls' recall performance in Experiment 1 but not in Experiment 2. These findings are accounted for by considering the differential contribution of recollection and familiarity to the performance of amnesic patients and controls in the 2 experiments.

Studies have shown lower false recognition of semantically related lure words in patients with global amnesia than in matched controls. This pattern has been interpreted as suggesting that medial temporal and diencephalic structures that are damaged in amnesia and that contribute to veridical memory also contribute to false recognition. It has been argued that whereas controls form and retain a well-organized representation of the semantic gist of studied items, patients with amnesia can retain only a degraded gist representation. However, these studies are subject to an alternative interpretation involving greater source confusions in controls. The authors used a categorized-pictures paradigm to test recognition under conditions in which source confusions were unlikely to occur. Relative to controls, patients with amnesia showed reduced false recognition of categorically related pictorial lures, thereby supporting the notion of degraded gist representations in amnesia.

This study investigated the extent to which amnesic patients use fluency of perceptual identification as a cue for recognition. Perceptual fluency was measured by having participants gradually unmask words before making recognition judgments. In Experiment 1, familiarity was the only possible basis for recognition because no words had been presented in the study phase. In Experiment 2, recollection provided an alternative basis for recognition because words had appeared in the study phase. Amnesic patients were as likely as normal controls to use perceptual fluency as a cue for recognition in Experiment 1 but were more likely than controls to do so in Experiment 2. For both groups, perceptual fluency affected judgments for studied and unstudied items to the same extent in Experiment 2. These findings suggest that amnesic patients do use perceptual fluency cues, but reliance on perceptual fluency does not necessarily elevate recognition accuracy.

Font-specificity in visual word-stem completion priming was examined in patients with global amnesia and Patient M.S., who had a right-occipital lobectomy. Word-stems appeared in the same or different font as study words. Amnesic patients showed normal font-specific priming (greater priming for words studied in the same than different font as test), despite impaired word-stem cued recall. Patient M.S. failed to exhibit font-specific priming, despite preserved declarative memory. Therefore, perceptual specificity in visual priming depends on visual processes mediated by the right-occipital lobe rather than medial temporal and diencephalic regions involved in declarative memory.

Little is known about the neuropsychology of false recognition. D.L. Schacter, M. Verfaellie, and D. Pradere (1996) induced false recognition in amnesic patients and normal controls by exposing them to numerous semantic associates of a nonstudied word and found that amnesics showed significantly reduced levels of false recognition. To determine whether this outcome is specific to the semantic domain, the authors examined false recognition after exposure to lists of conceptually and perceptually related words. In the control group, conceptual false recognition was associated with "remember" responses and perceptual false recognition was associated with "know" responses. Amnesic patients showed reduced levels of conceptual and perceptual false recognition that were approximately equally divided between remember and know responses.

Dual-process theories of recognition posit that a perceptual familiarity process contributes to both explicit recognition and implicit perceptual memory. This putative single familiarity process has been indexed by inclusion-exclusion, remember-know, and repetition priming measures. The present studies examined whether these measures identify a common familiarity process. Familiarity-based explicit recognition (as indexed by the inclusion-exclusion and the independence remember-know procedures) increased with conceptual processing. In contrast, implicit word-identification priming and familiarity-based word-stem completion (as indexed by inclusion-exclusion) increased with study-test perceptual similarity. These dissociations indicate that familiarity-based explicit recognition may be more sensitive to conceptual than to perceptual processing and is functionally distinct from the perceptual familiarity process mediating implicit perceptual memory.