A neural model of hippocampal–striatal interactions in associative learning and transfer generalization in various neurological and psychiatric patients

Building on our previous neurocomputational models of basal ganglia and hippocampal region function (and their modulation by dopamine and acetylcholine, respectively), we show here how an integration of these models can inform our understanding of the interaction between the basal ganglia and hippocampal region in associative learning and transfer generalization across various patient populations. As a common test bed for exploring interactions between these brain regions and neuromodulators, we focus on the acquired equivalence task, an associative learning paradigm in which stimuli that have been associated with the same outcome acquire a functional similarity such that subsequent generalization between these stimuli increases. This task has been used to test cognitive dysfunction in various patient populations with damages to the hippocampal region and basal ganglia, including studies of patients with Parkinson’s disease (PD), schizophrenia, basal forebrain amnesia, and hippocampal atrophy. Simulation results show that damage to the hippocampal region—as in patients with hippocampal atrophy (HA), hypoxia, mild Alzheimer’s (AD), or schizophrenia—leads to intact associative learning but impaired transfer generalization performance. Moreover, the model demonstrates how PD and anterior communicating artery (ACoA) aneurysm—two very different brain disorders that affect different neural mechanisms—can have similar effects on acquired equivalence performance. In particular, the model shows that simulating a loss of dopamine function in the basal ganglia module (as in PD) leads to slow acquisition learning but intact transfer generalization. Similarly, the model shows that simulating the loss of acetylcholine in the hippocampal region (as in ACoA aneurysm) also results in slower acquisition learning. We argue from this that changes in associative learning of stimulus–action pathways (in the basal ganglia) or changes in the learning of stimulus representations (in the hippocampal region) can have similar functional effects.     

Predictors of Partner Engagement in PTSD Treatment

A telephone survey was conducted to identify predictors of treatment engagement in 83 cohabitating female partners of 83 Vietnam theater veterans with combat-related post-traumatic stress disorder (PTSD). The survey assessed veterans for their trauma history and PTSD symptoms. Partners were assessed for caregiver burden, patient–partner involvement, PTSD treatment engagement, self-efficacy relating to PTSD, beliefs about benefits of PTSD treatment, and PTSD treatment barriers. Significant predictors of partner PTSD treatment engagement were the couple’s income, patient–partner involvement, and partner caregiver burden. These findings have implications for family interventions that may increase partner PTSD treatment engagement and improve PTSD treatment outcome.     

Children of Incarcerated Mothers and Their Caregivers: Factors Affecting the Quality of Their Relationship

We examined the quality of the relationship between children of incarcerated mothers and their kinship caregivers, to investigate whether perceived levels of warmth and acceptance were related to assessments of the children's behaviors. The sample consisted of 69 children (6 to 12 years) with currently incarcerated mothers who attended a recreational summer camp, and 25 of their caregivers. Children who felt lower levels of warmth and acceptance from their caregivers self-reported greater internalizing and externalizing behaviors. Caregivers' warmth and acceptance toward the children was lower when they assessed the children's behavior as difficult and the caregivers' parenting stress was high.     

Stimulus exposure effects in human associative learning

Learning that one cue (CS) predicts a second, salient cue (US) can often be slowed by prior exposure to one or both stimuli. In animals, CS-US learning is more strongly retarded following uncorrelated exposure to both CS and US than following exposure to the US alone. In this paper we present several studies showing a similar effect in humans, using a computer-based task. Experiments 1 and 2 used a between-groups design and demonstrated a strong CS/US exposure effect, whether or not the US was signalled by a neutral cue during exposure. Experiment 3 demonstrated similar effects using a within-subjects design. Overall, these results are consistent with several theoretical interpretations and suggest that uncorrelated CS/US exposure leads to a robust retardation of subsequent CS-US learning in humans.     

Negative Emotions Felt During Trial: the Effect of Fear,Anger, and Sadness on Juror Decision Making

During trial, jurors may experience a variety of emotions, many of which are negative. The current study examined the effects the negative emotions anger, fear, and sadness had on jurors' sentencing decisions and explored whether the cognitive appraisal theory or the intuitive prosecutor model could explain these effects. Jurors viewed the sentencing phase of a capital murder trial and were asked to sentence the defendant. Results indicated that after viewing the trial, jurors reported increased anger and sadness, but not fear. However, only change in anger affected jurors' sentences. Jurors who reported a greater change in anger were more likely to sentence the defendant to death. This effect was mediated by the level of importance that jurors placed on the prosecution's evidence and argument. Consistent with the intuitive prosecutor model, increased anger led to higher ratings of the importance of the aggravating evidence and an increase in death sentences. Implications are discussed. Copyright © 2015 John Wiley & Sons, Ltd.