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Item parameters dissociate between expectation formats: a regression analysis of time-frequency decomposed EEG data.

Monsalve IF, Pérez A, Molinaro N - Front Psychol (2014)

Bottom Line: During language comprehension, semantic contextual information is used to generate expectations about upcoming items.This has been commonly studied through the N400 event-related potential (ERP), as a measure of facilitated lexical retrieval.On the other hand, gamma-power (~50-70 Hz) was also modulated by predictability of the item in all conditions, which is interpreted as an index of a similar "matching" sub-step for both types of contexts, binding an expected representation and the external input.

View Article: PubMed Central - PubMed

Affiliation: BCBL. Basque Center on Cognition, Brain and Language Donostia, Spain.

ABSTRACT
During language comprehension, semantic contextual information is used to generate expectations about upcoming items. This has been commonly studied through the N400 event-related potential (ERP), as a measure of facilitated lexical retrieval. However, the associative relationships in multi-word expressions (MWE) may enable the generation of a categorical expectation, leading to lexical retrieval before target word onset. Processing of the target word would thus reflect a target-identification mechanism, possibly indexed by a P3 ERP component. However, given their time overlap (200-500 ms post-stimulus onset), differentiating between N400/P3 ERP responses (averaged over multiple linguistically variable trials) is problematic. In the present study, we analyzed EEG data from a previous experiment, which compared ERP responses to highly expected words that were placed either in a MWE or a regular non-fixed compositional context, and to low predictability controls. We focused on oscillatory dynamics and regression analyses, in order to dissociate between the two contexts by modeling the electrophysiological response as a function of item-level parameters. A significant interaction between word position and condition was found in the regression model for power in a theta range (~7-9 Hz), providing evidence for the presence of qualitative differences between conditions. Power levels within this band were lower for MWE than compositional contexts when the target word appeared later on in the sentence, confirming that in the former lexical retrieval would have taken place before word onset. On the other hand, gamma-power (~50-70 Hz) was also modulated by predictability of the item in all conditions, which is interpreted as an index of a similar "matching" sub-step for both types of contexts, binding an expected representation and the external input.

No MeSH data available.


Related in: MedlinePlus

Word-position by condition interaction for Alpha/Theta band model (6–9 Hz). Axis show transformed values for the dependent and independent variable: logarithm for the relative power values, and centered values for word position.
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Figure 3: Word-position by condition interaction for Alpha/Theta band model (6–9 Hz). Axis show transformed values for the dependent and independent variable: logarithm for the relative power values, and centered values for word position.

Mentions: Following the two-way contrast between the semantically constraining sentences and those containing fixed expressions, a cluster at the theta/alpha boundary (6–9 Hz) from 260 to 420 ms over frontal and temporal electrodes in the left hemisphere was selected for further analysis. Overall mean power within this window was lower for MWEs than for compositional contexts (mean: 0.97; SE: 0.03 vs mean: 1.08; SE: 0.04). However, the regression analysis revealed a condition-by-word-position interaction showing that the differences in power between the two conditions were not constant across the sentence. Theta power was negatively correlated with word position only in the case of fixed strings, and seems to be lower than for compositional contexts only when the target word occurs later on in the sentence, where differences between conditions are maximal (see Figure 3).


Item parameters dissociate between expectation formats: a regression analysis of time-frequency decomposed EEG data.

Monsalve IF, Pérez A, Molinaro N - Front Psychol (2014)

Word-position by condition interaction for Alpha/Theta band model (6–9 Hz). Axis show transformed values for the dependent and independent variable: logarithm for the relative power values, and centered values for word position.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4129372&req=5

Figure 3: Word-position by condition interaction for Alpha/Theta band model (6–9 Hz). Axis show transformed values for the dependent and independent variable: logarithm for the relative power values, and centered values for word position.
Mentions: Following the two-way contrast between the semantically constraining sentences and those containing fixed expressions, a cluster at the theta/alpha boundary (6–9 Hz) from 260 to 420 ms over frontal and temporal electrodes in the left hemisphere was selected for further analysis. Overall mean power within this window was lower for MWEs than for compositional contexts (mean: 0.97; SE: 0.03 vs mean: 1.08; SE: 0.04). However, the regression analysis revealed a condition-by-word-position interaction showing that the differences in power between the two conditions were not constant across the sentence. Theta power was negatively correlated with word position only in the case of fixed strings, and seems to be lower than for compositional contexts only when the target word occurs later on in the sentence, where differences between conditions are maximal (see Figure 3).

Bottom Line: During language comprehension, semantic contextual information is used to generate expectations about upcoming items.This has been commonly studied through the N400 event-related potential (ERP), as a measure of facilitated lexical retrieval.On the other hand, gamma-power (~50-70 Hz) was also modulated by predictability of the item in all conditions, which is interpreted as an index of a similar "matching" sub-step for both types of contexts, binding an expected representation and the external input.

View Article: PubMed Central - PubMed

Affiliation: BCBL. Basque Center on Cognition, Brain and Language Donostia, Spain.

ABSTRACT
During language comprehension, semantic contextual information is used to generate expectations about upcoming items. This has been commonly studied through the N400 event-related potential (ERP), as a measure of facilitated lexical retrieval. However, the associative relationships in multi-word expressions (MWE) may enable the generation of a categorical expectation, leading to lexical retrieval before target word onset. Processing of the target word would thus reflect a target-identification mechanism, possibly indexed by a P3 ERP component. However, given their time overlap (200-500 ms post-stimulus onset), differentiating between N400/P3 ERP responses (averaged over multiple linguistically variable trials) is problematic. In the present study, we analyzed EEG data from a previous experiment, which compared ERP responses to highly expected words that were placed either in a MWE or a regular non-fixed compositional context, and to low predictability controls. We focused on oscillatory dynamics and regression analyses, in order to dissociate between the two contexts by modeling the electrophysiological response as a function of item-level parameters. A significant interaction between word position and condition was found in the regression model for power in a theta range (~7-9 Hz), providing evidence for the presence of qualitative differences between conditions. Power levels within this band were lower for MWE than compositional contexts when the target word appeared later on in the sentence, confirming that in the former lexical retrieval would have taken place before word onset. On the other hand, gamma-power (~50-70 Hz) was also modulated by predictability of the item in all conditions, which is interpreted as an index of a similar "matching" sub-step for both types of contexts, binding an expected representation and the external input.

No MeSH data available.


Related in: MedlinePlus