Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA.
University of Minnesota, Minneapolis, MN, 55455, USA.
Psychopharmacology (Berl). 2019 Aug;236(8):2513-2525. doi: 10.1007/s00213-019-05197-0. Epub 2019 Mar 12.
Whether fear or anxiety is expressed is thought to depend on an animal's proximity to threat. In general, fear is elicited when threat is proximal, while anxiety is a response to threat that is distal and uncertain. This threat gradient model suggests that fear and anxiety involve non-overlapping neural circuitry, yet few behavioral paradigms exist that elicit both states. We studied avoid-approach conflict in rats that were behaving in a predator-inhabited foraging arena task that involved tangible threat and reward incentives. In the task, rats exhibited a variety of both fearful and anxious behaviors corresponding to proximal and distal threat, respectively. We then administered ethanol or diazepam to the rats in order to study how anxiolytics affected these fear and anxiety behaviors. We discovered that both ethanol and diazepam attenuated proximal-threat fear-like behaviors. Furthermore, we found that diazepam, but not ethanol, increased distal-threat anxiety-like behavior but also made rats less risk-averse. Finally, we describe how decisional conflict can be modeled as a partially observable Markov decision process and characterize a potential relationship between anxious behavior, diazepam's ability to suppress hippocampal theta oscillations, and hippocampal representations of the future.
是否表现出恐惧或焦虑被认为取决于动物与威胁的接近程度。一般来说，当威胁临近时会引起恐惧，而焦虑是对遥远和不确定的威胁的反应。这种威胁梯度模型表明，恐惧和焦虑涉及不重叠的神经回路，但很少有行为范式可以同时引发这两种状态。我们研究了在涉及有形威胁和奖励激励的捕食者居住觅食竞技场任务中行为的大鼠的回避-接近冲突。在任务中，大鼠表现出各种与近端和远端威胁相对应的恐惧和焦虑行为。然后，我们给大鼠注射乙醇或地西泮，以研究抗焦虑药如何影响这些恐惧和焦虑行为。我们发现，乙醇和地西泮都能减弱对近端威胁的恐惧样行为。此外，我们发现地西泮而非乙醇增加了对远端威胁的焦虑样行为，但也使大鼠降低了风险偏好。最后，我们描述了决策冲突如何可以建模为部分可观察马尔可夫决策过程，并描述焦虑行为、地西泮抑制海马θ振荡的能力以及海马体对未来的表示之间的潜在关系。
