Activity Subspaces in Medial Prefrontal Cortex Distinguish States of the World.
Activity Subspaces in Medial Prefrontal Cortex Distinguish States of the World.
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DOI：
10.1523/jneurosci.1412-21.2022
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发表时间：
2022-05-18
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内侧前额叶皮层（mPfC）的活动代表了关于世界状态的信息，包括现在的行为，如决策，以及最近的过去，如短期记忆。未知的是，关于世界不同状态的信息是否在相同的mPfC神经群体中表示，如果是这样，它们是如何保持不同的。为了解决这个问题，我们在这里分析mPfC的人口活动的雄性大鼠学习规则在Y型迷宫，与自我发起的选择试验，以臂端，然后由一个自我节奏的回报在试验间隔（ITI）。我们发现，审判和ITI人口活动从同一人口落入不同的低维子空间。这些子空间对世界的不同状态进行编码：任务的多个特征可以从试验和ITI活动中解码，但同一特征的解码轴在两个任务阶段之间大致正交，并且解码主要是试验期间当前的特征，但ITI期间先前试验的特征。这些子空间的区别被带入睡眠，其中群体活动在训练后睡眠中优先被重新激活，但与试验和ITI子空间的活动不同。我们的研究结果表明，在mPfC中，代表世界不同状态时的干扰问题通过占据世界状态的不同子空间的人口活动来解决，这些子空间可以由下游目标独立解码，并由上游输入独立解决。重要性陈述内侧前额叶皮层的活动在代表世界的当前和过去状态方面发挥着作用。我们发现，在迷宫任务中，内侧前额叶皮层中的单个群体的活动代表了至少两种不同的世界状态。这些表示是连续的，并且足够明显，下游种群可以从该活动中单独读出任何一种状态。此外，代表不同状态的活动在睡眠中被不同地重新激活。因此，不同的世界状态可以在同一个内侧前额叶皮层群体中表现出来，但这种表现方式避免了它们之间潜在的灾难性干扰。
Medial prefrontal cortex (mPfC) activity represents information about the state of the world, including present behavior, such as decisions, and the immediate past, such as short-term memory. Unknown is whether information about different states of the world are represented in the same mPfC neural population and, if so, how they are kept distinct. To address this, we analyze here mPfC population activity of male rats learning rules in a Y-maze, with self-initiated choice trials to an arm end followed by a self-paced return during the intertrial interval (ITI). We find that trial and ITI population activity from the same population fall into different low-dimensional subspaces. These subspaces encode different states of the world: multiple features of the task can be decoded from both trial and ITI activity, but the decoding axes for the same feature are roughly orthogonal between the two task phases, and the decodings are predominantly of features of the present during the trial but features of the preceding trial during the ITI. These subspace distinctions are carried forward into sleep, where population activity is preferentially reactivated in post-training sleep but differently for activity from the trial and ITI subspaces. Our results suggest that the problem of interference when representing different states of the world is solved in mPfC by population activity occupying different subspaces for the world states, which can be independently decoded by downstream targets and independently addressed by upstream inputs. SIGNIFICANCE STATEMENT Activity in the medial prefrontal cortex plays a role in representing the current and past states of the world. We show that during a maze task, the activity of a single population in medial prefrontal cortex represents at least two different states of the world. These representations were sequential and sufficiently distinct that a downstream population could separately read out either state from that activity. Moreover, the activity representing different states is differently reactivated in sleep. Different world states can thus be represented in the same medial prefrontal cortex population but in such a way that prevents potentially catastrophic interference between them.