Contextual encoding by ensembles of medial prefrontal cortex neurons
Contextual encoding by ensembles of medial prefrontal cortex neurons
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DOI：
10.1073/pnas.1114415109
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发表时间：
2012-03-27
影响因子：
11.1
通讯作者：
Seamans, Jeremy K.
中科院分区：
文献类型：
--
作者：
Hyman, James M.;Ma, Liya;Seamans, Jeremy K.
语境表征用于指导行为的许多方面，并影响刺激或行为的编码和解释方式。内侧前额叶皮质(MPFC)，包括扣带回前亚区，与语境编码有关，但mPFC形成的语境表征的性质尚不清楚。利用大鼠的多个单单位四极管记录，我们发现当动物在不同的环境背景之间移动时，mPFC集合中出现了不同的活动模式。这些活动模式的差异明显大于在海马区整体观察到的差异。虽然大约11%的mPFC细胞在多次暴露于相同的环境中时一致地偏好一个环境而不是另一个环境，但当考虑到大约50%的mPFC神经元的活动时，环境设置的最佳解码(预测)发生了。另一方面，反复暴露在完全相同的环境中，人口活动模式并不相同。这在一定程度上是因为mPFC系综的状态似乎随着时间系统地改变，这样我们有时可以根据在第一次曝光期间观察到的依赖时间的移位的线性外推来预测稍后重返一个环境时系综状态的变化。我们还观察到许多强烈的动作选择性mPFC神经元表现出显著程度的上下文依赖的调制。这些结果突出了mPFC和海马体在语境编码方案上的潜在差异，并表明mPFC形成了丰富的语境表征，不仅考虑到感觉线索，而且还考虑到动作和时间。
Contextual representations serve to guide many aspects of behavior and influence the way stimuli or actions are encoded and interpreted. The medial prefrontal cortex (mPFC), including the anterior cingulate subregion, has been implicated in contextual encoding, yet the nature of contextual representations formed by the mPFC is unclear. Using multiple single-unit tetrode recordings in rats, we found that different activity patterns emerged in mPFC ensembles when animals moved between different environmental contexts. These differences in activity patterns were significantly larger than those observed for hippocampal ensembles. Whereas approximate to 11% of mPFC cells consistently preferred one environment over the other across multiple exposures to the same environments, optimal decoding (prediction) of the environmental setting occurred when the activity of up to approximate to 50% of all mPFC neurons was taken into account. On the other hand, population activity patterns were not identical upon repeated exposures to the very same environment. This was partly because the state of mPFC ensembles seemed to systematically shift with time, such that we could sometimes predict the change in ensemble state upon later reentry into one environment according to linear extrapolation from the time-dependent shifts observed during the first exposure. We also observed that many strongly action-selective mPFC neurons exhibited a significant degree of context-dependent modulation. These results highlight potential differences in contextual encoding schemes by the mPFC and hippocampus and suggest that the mPFC forms rich contextual representations that take into account not only sensory cues but also actions and time.