The cingulate cortex and limbic systems for action, emotion, and memory.

Different limbic structures including the hippocampal memory system and the amygdala/orbitofrontal emotion system have very different connectivity and functions, and it has been suggested that we should no longer think of a single limbic system. A framework is provided for understanding the connectivity and functions of different parts of the cingulate cortex in action, emotion, and memory, in the context of connections of different parts of the cingulate cortex with other limbic and neocortical structures. First, the anterior cingulate cortex receives information from the orbitofrontal cortex about reward and nonreward outcomes. The posterior cingulate cortex receives action-related and spatial information from parietal cortical areas. It is argued that these are inputs that allow the cingulate cortex to perform action-outcome learning, with outputs from the midcingulate motor area to premotor areas. Damage to the anterior cingulate cortex impairs action-outcome learning and emotion because of its reward-related representations. Second, the posterior cingulate cortex provides "action" and "spatial" information from the parietal cortex into the hippocampal memory system via the parahippocampal gyrus, and the anterior cingulate cortex (receiving from the orbitofrontal cortex) provides reward-related input into the hippocampal memory system via the posterior cingulate and parahippocampal gyrus. Thus posterior cingulate damage can impair hippocampal episodic memory and retrieval, especially the spatial component. These functions are related to the place of this proisocortical limbic region in brain connectivity.