Acquired Equivalence in U.S. Veterans With Symptoms of Posttraumatic Stress: Reexperiencing Symptoms Are Associated With Greater Generalization

Kostek, John A.; Beck, Kevin D.; Gilbertson, Mark W.; Orr, Scott P.; Pang, Kevin; Servatius, Richard J.; Myers, Catherine E.

doi:10.1002/jts.21974

Cited by 23 publications

(20 citation statements)

References 7 publications

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“…Consistent with these observations, we have found that genetically enhancing integration of adult-born DGCs is sufficient to enhance Consistent with these ideas, a recent study found a positive correlation between re-experiencing the traumatic event and the degree of fear overgeneralization in individuals with PTSD (Kostek et al, 2014).…”

Section: Adult Hippocampal Neurogenesis and Maintenance Of Memory Presupporting

confidence: 88%

Adult Hippocampal Neurogenesis, Fear Generalization, and Stress

Besnard

Sahay

2015

Neuropsychopharmacol

192

159

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The generalization of fear is an adaptive, behavioral, and physiological response to the likelihood of threat in the environment. In contrast, the overgeneralization of fear, a cardinal feature of posttraumatic stress disorder (PTSD), manifests as inappropriate, uncontrollable expression of fear in neutral and safe environments. Overgeneralization of fear stems from impaired discrimination of safe from aversive environments or discernment of unlikely threats from those that are highly probable. In addition, the time-dependent erosion of episodic details of traumatic memories might contribute to their generalization. Understanding the neural mechanisms underlying the overgeneralization of fear will guide development of novel therapeutic strategies to combat PTSD. Here, we conceptualize generalization of fear in terms of resolution of interference between similar memories. We propose a role for a fundamental encoding mechanism, pattern separation, in the dentate gyrus (DG)-CA3 circuit in resolving interference between ambiguous or uncertain threats and in preserving episodic content of remote aversive memories in hippocampal-cortical networks. We invoke cellular-, circuit-, and systems-based mechanisms by which adult-born dentate granule cells (DGCs) modulate pattern separation to influence resolution of interference and maintain precision of remote aversive memories. We discuss evidence for how these mechanisms are affected by stress, a risk factor for PTSD, to increase memory interference and decrease precision. Using this scaffold we ideate strategies to curb overgeneralization of fear in PTSD.

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Section: Adult Hippocampal Neurogenesis and Maintenance Of Memory Presupporting

confidence: 88%

Adult Hippocampal Neurogenesis, Fear Generalization, and Stress

Besnard

Sahay

2015

Neuropsychopharmacol

192

159

View full text Add to dashboard Cite

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“…Increased generalization has now been observed in three different studies of PTSD: in the first study, participants recruited from the same Veteran population as the current study were assessed on an acquired equivalence task (Kostek et al, 2014), and in the second, trauma-exposed individuals from a very different population (individuals with clinically-diagnosed PTSD and a single exposure to trauma) were assessed on a contextual processing task (Levy-Gigi et al, 2015). The current study assessed a different type of generalization: the ability to transfer learning when relevant stimulus features remain stable and irrelevant stimulus features are altered.…”

Section: Discussionmentioning

confidence: 85%

“…Participants were 60 Veterans from VA New Jersey Health Care System in East Orange, NJ (11.2% female, mean age 54.0 years, SD 10.3, mean education 14.4 years, SD 2.6) and from the same population used in our prior acquired equivalence study (Kostek et al, 2014). Thirty-eight Veterans (63.3%) self-identified as African-American, 18 (30.0%) as Caucasian, and the remaining 4 (6.7%) as Other or Mixed-race; 7 (13.7%) self-identified ethnicity as Hispanic.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, for example, when given specific cue words and asked to retrieve specific autobiographical memories, those with PTSD typically recall fewer specific episodes and the retrieved memories have fewer details (e.g., Brown, Williams, Bray, & Hourani, 2012; McNally, Lasko, Macklin, & Pitman, 1995). Increased generalization is also observed in associative learning tasks involving purely cognitive, impersonal information (Kostek et al, 2014; Levy-Gigi, Szabo, Richter-Levin, & Kéri, 2015). For example, a contextual processing task with positive and negative outcomes showed increased generalization of negative context in individuals with clinically diagnosed PTSD.…”

Section: Introductionmentioning

confidence: 92%

“…Another study used an acquired equivalence task where subjects learned to associate stimuli with outcomes (Kostek et al, 2014). Some stimuli were equivalent (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Increased generalization of learned associations is related to re-experiencing symptoms in veterans with symptoms of post-traumatic stress

Anastasides¹,

Beck²,

Pang³

et al. 2015

Stress

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One interpretation of re-experiencing symptoms in post-traumatic stress disorder (PTSD) is that memories related to emotional information are stored strongly, but with insufficient specificity, so that stimuli which are minimally related to the traumatic event are sufficient to trigger recall. If so, re-experiencing symptoms may reflect a general bias against encoding background information during a learning experience, and this tendency might not be limited to learning about traumatic or even autobiographical events. To test this possibility, we administered a discrimination-and-transfer task to 60 Veterans (11.2% female, mean age 54.0 years) self-assessed for PTSD symptoms in order to examine whether re-experiencing symptoms were associated with increased generalization following associative learning. The discrimination task involved learning to choose the rewarded object from each of six object pairs; each pair differed in colour or shape but not both. In the transfer phase, the irrelevant feature in each pair was altered. Regression analysis revealed no relationships between re-experiencing symptoms and initial discrimination learning. However, re-experiencing symptom scores contributed to the prediction of transfer performance. Other PTSD symptom clusters (avoidance/numbing, hyperarousal) did not account for significant additional variance. The results are consistent with an emerging interpretation of re-experiencing symptoms as reflecting a learning bias that favours generalization at the expense of specificity. Future studies will be needed to determine whether this learning bias may pre-date and confer risk for, re-experiencing symptoms in individuals subsequently exposed to trauma, or emerges only in the wake of trauma exposure and PTSD symptom development.

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Learning and generalization from reward and punishment in opioid addiction

Myers

Rego

Haber

et al. 2017

Behavioural Brain Research

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This study adapts a widely-used acquired equivalence paradigm to investigate how opioid-addicted individuals learn from positive and negative feedback, and how they generalize this learning. The opioid-addicted group consisted of 33 participants with a history of heroin dependency currently in a methadone maintenance program; the control group consisted of 32 healthy participants without a history of drug addiction. All participants performed a novel variant of the acquired equivalence task, where they learned to map some stimuli to correct outcomes in order to obtain reward, and to map other stimuli to correct outcomes in order to avoid punishment; some stimuli were implicitly “equivalent” in the sense of being paired with the same outcome. On the initial training phase, both groups performed similarly on learning to obtain reward, but as memory load grew, the control group outperformed the addicted group on learning to avoid punishment. On a subsequent testing phase, the addicted and control groups performed similarly on retention trials involving previously-trained stimulus-outcome pairs, as well as on generalization trials to assess acquired equivalence. Since prior work with acquired equivalence tasks has associated stimulus-outcome learning with the nigrostriatal dopamine system, and generalization with the hippocampal region, the current results are consistent with basal ganglia dysfunction in the opioid-addicted patients. Further, a selective deficit in learning from punishment could contribute to processes by which addicted individuals continue to pursue drug use even at the cost of negative consequences such as loss of income and the opportunity to engage in other life activities.

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Acquired Equivalence in U.S. Veterans With Symptoms of Posttraumatic Stress: Reexperiencing Symptoms Are Associated With Greater Generalization

Cited by 23 publications

References 7 publications

Adult Hippocampal Neurogenesis, Fear Generalization, and Stress

Adult Hippocampal Neurogenesis, Fear Generalization, and Stress

Increased generalization of learned associations is related to re-experiencing symptoms in veterans with symptoms of post-traumatic stress

Learning and generalization from reward and punishment in opioid addiction

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