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A time and place for language comprehension: mapping the N400 and the P600 to a minimal cortical network.

Brouwer H, Hoeks JC - Front Hum Neurosci (2013)

Bottom Line: Models of language processing that have been proposed thus far do not agree on these interpretations, and present a variety of complicated functional architectures.The left Inferior Frontal Gyrus (BA 44/45/47), in turn, serves a network epicenter for the integration of this retrieved meaning with the word's preceding context, into a mental representation of what is being communicated; these semantic and pragmatic integrative processes are reflected in P600 amplitude.We propose that our mapping describes the core of the language comprehension network, a view that is parsimonious, has broad empirical coverage, and can serve as the starting point for a more focused investigation into the coupling of brain anatomy and electrophysiology.

View Article: PubMed Central - PubMed

Affiliation: Center for Language and Cognition/BCN Neuro-Imaging Center, University of Groningen Groningen, Netherlands.

ABSTRACT
We propose a new functional-anatomical mapping of the N400 and the P600 to a minimal cortical network for language comprehension. Our work is an example of a recent research strategy in cognitive neuroscience, where researchers attempt to align data regarding the nature and time-course of cognitive processing (from ERPs) with data on the cortical organization underlying it (from fMRI). The success of this "alignment" approach critically depends on the functional interpretation of relevant ERP components. Models of language processing that have been proposed thus far do not agree on these interpretations, and present a variety of complicated functional architectures. We put forward a very basic functional-anatomical mapping based on the recently developed Retrieval-Integration account of language comprehension (Brouwer et al., 2012). In this mapping, the left posterior part of the Middle Temporal Gyrus (BA 21) serves as an epicenter (or hub) in a neurocognitive network for the retrieval of word meaning, the ease of which is reflected in N400 amplitude. The left Inferior Frontal Gyrus (BA 44/45/47), in turn, serves a network epicenter for the integration of this retrieved meaning with the word's preceding context, into a mental representation of what is being communicated; these semantic and pragmatic integrative processes are reflected in P600 amplitude. We propose that our mapping describes the core of the language comprehension network, a view that is parsimonious, has broad empirical coverage, and can serve as the starting point for a more focused investigation into the coupling of brain anatomy and electrophysiology.

No MeSH data available.


Schematic illustration of a Retrieval-Integration cycle in the left hemisphere. Words reach the posterior Middle Temporal Gyrus (pMTG) via the auditory cortex (ac) or the visual cortex (vc), depending on whether the linguistic input is spoken or written. The pMTG retrieves the lexical information associated with a word from the association cortices (generating the N400). The retrieved information is then connected to the Inferior Frontal Gyrus (IFG) via one of the white matter tracts in either the dorsal pathway (dp) or the ventral pathway (vp). The IFG integrates this information with a representation of the prior context into an updated representation of what is being communicated (generating the P600). Finally, the representation constructed in the IFG feeds back to the pMTG via white matter tracts in the dorsal or ventral pathway, causing pre-activation of lexical features of possible upcoming words.
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Figure 1: Schematic illustration of a Retrieval-Integration cycle in the left hemisphere. Words reach the posterior Middle Temporal Gyrus (pMTG) via the auditory cortex (ac) or the visual cortex (vc), depending on whether the linguistic input is spoken or written. The pMTG retrieves the lexical information associated with a word from the association cortices (generating the N400). The retrieved information is then connected to the Inferior Frontal Gyrus (IFG) via one of the white matter tracts in either the dorsal pathway (dp) or the ventral pathway (vp). The IFG integrates this information with a representation of the prior context into an updated representation of what is being communicated (generating the P600). Finally, the representation constructed in the IFG feeds back to the pMTG via white matter tracts in the dorsal or ventral pathway, causing pre-activation of lexical features of possible upcoming words.

Mentions: Putting the parts together, we can implement the Retrieval-Integration account in a cortical network, and walk through a typical processing cycle. Depending on whether the linguistic input is spoken or written, an incoming word reaches the lpMTG from respectively the auditory or the visual cortex. The lpMTG then acts as an epicenter for the retrieval of the lexical information associated with this word from the association cortices, where it is supposed to be stored in a distributed manner. The onset of this retrieval process corresponds to the onset of the N400 component, and ease with which semantic information can be retrieved corresponds to N400 amplitude. Via one of the candidate white matter tracts, the retrieved lexical information is then connected to the lIFG, where it will be integrated with a representation of the prior context into a representation of what is being communicated. The extent of work required to construct this updated representation corresponds to P600 amplitude. Finally, the representation constructed in the lIFG is fed back to the lpMTG via a white matter pathway resulting in the pre-activation of syntactic and semantic features of possible upcoming words. This Retrieval-Integration cycle is repeated as soon as a new word comes in. Figure 1 provides a schematic illustration of a typical Retrieval-Integration cycle.


A time and place for language comprehension: mapping the N400 and the P600 to a minimal cortical network.

Brouwer H, Hoeks JC - Front Hum Neurosci (2013)

Schematic illustration of a Retrieval-Integration cycle in the left hemisphere. Words reach the posterior Middle Temporal Gyrus (pMTG) via the auditory cortex (ac) or the visual cortex (vc), depending on whether the linguistic input is spoken or written. The pMTG retrieves the lexical information associated with a word from the association cortices (generating the N400). The retrieved information is then connected to the Inferior Frontal Gyrus (IFG) via one of the white matter tracts in either the dorsal pathway (dp) or the ventral pathway (vp). The IFG integrates this information with a representation of the prior context into an updated representation of what is being communicated (generating the P600). Finally, the representation constructed in the IFG feeds back to the pMTG via white matter tracts in the dorsal or ventral pathway, causing pre-activation of lexical features of possible upcoming words.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3824103&req=5

Figure 1: Schematic illustration of a Retrieval-Integration cycle in the left hemisphere. Words reach the posterior Middle Temporal Gyrus (pMTG) via the auditory cortex (ac) or the visual cortex (vc), depending on whether the linguistic input is spoken or written. The pMTG retrieves the lexical information associated with a word from the association cortices (generating the N400). The retrieved information is then connected to the Inferior Frontal Gyrus (IFG) via one of the white matter tracts in either the dorsal pathway (dp) or the ventral pathway (vp). The IFG integrates this information with a representation of the prior context into an updated representation of what is being communicated (generating the P600). Finally, the representation constructed in the IFG feeds back to the pMTG via white matter tracts in the dorsal or ventral pathway, causing pre-activation of lexical features of possible upcoming words.
Mentions: Putting the parts together, we can implement the Retrieval-Integration account in a cortical network, and walk through a typical processing cycle. Depending on whether the linguistic input is spoken or written, an incoming word reaches the lpMTG from respectively the auditory or the visual cortex. The lpMTG then acts as an epicenter for the retrieval of the lexical information associated with this word from the association cortices, where it is supposed to be stored in a distributed manner. The onset of this retrieval process corresponds to the onset of the N400 component, and ease with which semantic information can be retrieved corresponds to N400 amplitude. Via one of the candidate white matter tracts, the retrieved lexical information is then connected to the lIFG, where it will be integrated with a representation of the prior context into a representation of what is being communicated. The extent of work required to construct this updated representation corresponds to P600 amplitude. Finally, the representation constructed in the lIFG is fed back to the lpMTG via a white matter pathway resulting in the pre-activation of syntactic and semantic features of possible upcoming words. This Retrieval-Integration cycle is repeated as soon as a new word comes in. Figure 1 provides a schematic illustration of a typical Retrieval-Integration cycle.

Bottom Line: Models of language processing that have been proposed thus far do not agree on these interpretations, and present a variety of complicated functional architectures.The left Inferior Frontal Gyrus (BA 44/45/47), in turn, serves a network epicenter for the integration of this retrieved meaning with the word's preceding context, into a mental representation of what is being communicated; these semantic and pragmatic integrative processes are reflected in P600 amplitude.We propose that our mapping describes the core of the language comprehension network, a view that is parsimonious, has broad empirical coverage, and can serve as the starting point for a more focused investigation into the coupling of brain anatomy and electrophysiology.

View Article: PubMed Central - PubMed

Affiliation: Center for Language and Cognition/BCN Neuro-Imaging Center, University of Groningen Groningen, Netherlands.

ABSTRACT
We propose a new functional-anatomical mapping of the N400 and the P600 to a minimal cortical network for language comprehension. Our work is an example of a recent research strategy in cognitive neuroscience, where researchers attempt to align data regarding the nature and time-course of cognitive processing (from ERPs) with data on the cortical organization underlying it (from fMRI). The success of this "alignment" approach critically depends on the functional interpretation of relevant ERP components. Models of language processing that have been proposed thus far do not agree on these interpretations, and present a variety of complicated functional architectures. We put forward a very basic functional-anatomical mapping based on the recently developed Retrieval-Integration account of language comprehension (Brouwer et al., 2012). In this mapping, the left posterior part of the Middle Temporal Gyrus (BA 21) serves as an epicenter (or hub) in a neurocognitive network for the retrieval of word meaning, the ease of which is reflected in N400 amplitude. The left Inferior Frontal Gyrus (BA 44/45/47), in turn, serves a network epicenter for the integration of this retrieved meaning with the word's preceding context, into a mental representation of what is being communicated; these semantic and pragmatic integrative processes are reflected in P600 amplitude. We propose that our mapping describes the core of the language comprehension network, a view that is parsimonious, has broad empirical coverage, and can serve as the starting point for a more focused investigation into the coupling of brain anatomy and electrophysiology.

No MeSH data available.