Hippocampal involvement in contextual modulation of fear extinction

Extinction of fear conditioning in animals is an excellent model for the study of fear inhibition in humans. Substantial evidence has shown that extinction is a new learning process that is highly context-dependent. Several recovery effects (renewal, spontaneous recovery, and reinstatement) after extinction suggest that the contextual modulation of extinction is a critical behavioral mechanism underlying fear extinction. In addition, recent studies demonstrate a critical role for hippocampus in the context control of extinction. A growing body of evidence suggests that the hippocampus not only plays a role in contextual encoding and retrieval of fear extinction memories, but also interacts with other brain structures to regulate context-specificity of fear extinction. In this article, the authors will first discuss the fundamental behavioral features of the context effects of extinction and its underlying behavioral mechanisms. In the second part, the review will focus on the brain mechanisms for the contextual control of extinction. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56147/1/20331_ftp.pd

Comparison of delayed matching-to-sample performance in monkeys and children

Although research has consistently demonstrated that accuracy on a variety of memory tasks decreases as delay increases, relatively little research has been conducted to quantify this relationship across development in humans or directly compare rates of forgetting between humans and monkeys. This study utilized a delayed matching-to-sample (DMTS) task to compare the relative contributions of proactive interference and attention on the rate of forgetting in monkeys and children. The performance of 1125 children from four to fourteen years of age and 10 adult rhesus monkeys was compared. For this DMTS task, a shape was displayed on the center one of three press-plates. After a delay, the subjects were required to match the original shape with one of three choice shapes to receive a banana-flavored food pellet for monkeys, or a nickel for children. A modified power function provided an excellent fit for the data for monkeys and children. The forgetting rates in children decreased with age, and the forgetting rates for monkeys were most comparable to those of younger children. The data also suggest that proactive interference did not significantly contribute to the forgetting rates for monkeys or younger children. Further, the monkeys appeared to attend to the task at a level similar to that of younger children as evidenced by the similarities in response latencies. The results from this study indicate that the rate of forgetting in monkeys, as well as the mechanisms underlying this rate, appears to share more similarities with that of younger children than of older children

Costs and benefits linked to developments in cognitive control

Developing cognitive control over one’s thoughts, emotions, and actions is a fundamental process that predicts important life outcomes. Such control begins in infancy, and shifts during development from a predominantly reactive form (e.g. retrieving task-relevant information when needed) to an increasingly proactive form (e.g. maintaining task-relevant information in anticipation of needing it). While such developments are generally viewed as adaptive, cognitive abilities can also involve tradeoffs, such that the benefits of developing increasingly proactive control may come with associated costs. In two experiments, we test for such cognitive trade-offs in children who are transitioning to proactive control. We find that proactive control predicts expected benefits in children’s working memory, but is also associated with predicted costs in disproportionately slowing children under conditions of distraction. These findings highlight unique advantages and disadvantages of proactive and reactive control, and suggest caution in attempting to alter their balance during development