Jeremy M Trott, Franklin B Krasne, Michael S Fanselow
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引用次数: 2
Abstract
There are sex differences in anxiety disorders with regard to occurrence and severity of episodes such that females tend to experience more frequent and more severe episodes. Contextual fear learning and generalization are especially relevant to anxiety disorders, which are often defined by expressing fear and/or anxiety in safe contexts. In contextual fear conditioning, a representation of the context must first be created, and then that representation must be paired with an aversive consequence. With some variation, the experiments presented here use a 3-d procedure in which day 1 consists of pre-exposure to the to-be-shocked context, day 2 consists of a single context-shock pairing after some placement-to-shock interval (PSI), and day 3 consists of testing in either the same or a novel context. With shorter pre-exposure periods, male rats showed more contextual fear, consistent with previous literature; however, after longer pre-exposure periods, female rats showed greater contextual fear. Additionally, while pre-exposure and PSI are both periods of time prior to the shock, it was found that they were not equivalent to each other. Animals with 120 sec of pre-exposure and a 30-sec PSI show a differential level and time course of fear expression than animals who received no pre-exposure and a 150-sec PSI, and this further depended on sex of the rat. Additionally, an experiment comparing recently versus remotely acquired contextual fear was run. Males were again shown to have greater contextual fear at both time points, and this contextual fear incubated/increased over time in males but not females. To facilitate identification of what processes caused sex differences, we used BaconX, a conceptual and computational model of hippocampal contextual learning. Computational simulations using this model predicted many of our key findings. Furthermore, these simulations suggest potential mechanisms with regard to hippocampal computation; namely, an increased feature sampling rate in males, which may account for the sex differences presented here and in prior literature.
期刊介绍:
The neurobiology of learning and memory is entering a new interdisciplinary era. Advances in neuropsychology have identified regions of brain tissue that are critical for certain types of function. Electrophysiological techniques have revealed behavioral correlates of neuronal activity. Studies of synaptic plasticity suggest that some mechanisms of memory formation may resemble those of neural development. And molecular approaches have identified genes with patterns of expression that influence behavior. It is clear that future progress depends on interdisciplinary investigations. The current literature of learning and memory is large but fragmented. Until now, there has been no single journal devoted to this area of study and no dominant journal that demands attention by serious workers in the area, regardless of specialty. Learning & Memory provides a forum for these investigations in the form of research papers and review articles.