Article

Where Is the Semantic System? A Critical Review and Meta-Analysis of 120 Functional Neuroimaging Studies

Language Imaging Laboratory, Department of Neurology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Cerebral Cortex (Impact Factor: 8.67). 04/2009; 19(12):2767-96. DOI: 10.1093/cercor/bhp055
Source: PubMed

ABSTRACT

Semantic memory refers to knowledge about people, objects, actions, relations, self, and culture acquired through experience. The neural systems that store and retrieve this information have been studied for many years, but a consensus regarding their identity has not been reached. Using strict inclusion criteria, we analyzed 120 functional neuroimaging studies focusing on semantic processing. Reliable areas of activation in these studies were identified using the activation likelihood estimate (ALE) technique. These activations formed a distinct, left-lateralized network comprised of 7 regions: posterior inferior parietal lobe, middle temporal gyrus, fusiform and parahippocampal gyri, dorsomedial prefrontal cortex, inferior frontal gyrus, ventromedial prefrontal cortex, and posterior cingulate gyrus. Secondary analyses showed specific subregions of this network associated with knowledge of actions, manipulable artifacts, abstract concepts, and concrete concepts. The cortical regions involved in semantic processing can be grouped into 3 broad categories: posterior multimodal and heteromodal association cortex, heteromodal prefrontal cortex, and medial limbic regions. The expansion of these regions in the human relative to the nonhuman primate brain may explain uniquely human capacities to use language productively, plan, solve problems, and create cultural and technological artifacts, all of which depend on the fluid and efficient retrieval and manipulation of semantic knowledge.

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    • "Functional connectivity analyses further showed that these prefrontal and more posterior regions were coupled together during the processing of event clusters. More specifically, the rostrolateral PFC was functionally connected to regions that have been associated with the controlled activation/selection and representation of semantic information (inferior frontal gyrus, lateral temporal cortex, inferior parietal cortex;Binder et al., 2009;Jefferies, 2013), as well as regions that might represent episodic details of specific events (hippocampus, retrosplenial cortex, precuneus, and visual cortex;Addis et al., 2004b;Daselaar et al., 2008;Martinelli et al., 2013). This functional coupling is consistent with the view that the rostrolateral PFC might support the joint consideration and integration of multiple sources of information to determine the relational dimensions that link events in clusters. "
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