Beyond the N400: complementary access to early neural correlates of novel metaphor comprehension using combined electrophysiological and haemodynamic measurements

Sabrina Schneider; Alexander M Rapp; Florian B Haeußinger; Lena H Ernst; Friedrich Hamm; Andreas J Fallgatter; Ann-Christine Ehlis

doi:10.1016/j.cortex.2014.01.008

Beyond the N400: complementary access to early neural correlates of novel metaphor comprehension using combined electrophysiological and haemodynamic measurements

Cortex. 2014 Apr:53:45-59. doi: 10.1016/j.cortex.2014.01.008. Epub 2014 Jan 28.

Authors

Sabrina Schneider¹, Alexander M Rapp², Florian B Haeußinger², Lena H Ernst², Friedrich Hamm³, Andreas J Fallgatter², Ann-Christine Ehlis²

Affiliations

¹ Department of Psychiatry and Psychotherapy, University of Tuebingen, Germany. Electronic address: S.Schneider@med.uni-tuebingen.de.
² Department of Psychiatry and Psychotherapy, University of Tuebingen, Germany.
³ Department of Linguistics, University of Tuebingen, Germany.

PMID: 24566043
DOI: 10.1016/j.cortex.2014.01.008

Abstract

The simultaneous application of different neuroimaging methods combining high temporal and spatial resolution can uniquely contribute to current issues and open questions in the field of pragmatic language perception. In the present study, comprehension of novel metaphors was investigated using near-infrared spectroscopy (NIRS) combined with the simultaneous acquisition of electroencephalography (EEG)/event-related potentials (ERPs). For the first time, we investigated the effects of figurative language on early electrophysiological markers (P200, N400) and their functional relationship to cortical haemodynamic responses within the language network (Broca's area, Wernicke's area). To this end, 20 healthy subjects judged 120 sentences with respect to their meaningfulness, whereby phrases were either literal, metaphoric, or meaningless. Our results indicated a metaphor-specific P200 reduction and a linear increase of N400 amplitudes from literal over metaphoric to meaningless sentences. Moreover, there were metaphor related effects on haemodynamic responses accessed with NIRS, especially within the left lateral frontal cortex (Broca's area). Significant correlations between electrophysiological and haemodynamic responses indicated that P200 reductions during metaphor comprehension were associated with an increased recruitment of neural activity within left Wernicke's area, indicating a link between variations in neural activity and haemodynamic changes within Wernicke's area. This link may reflect processes related to interindividual differences regarding the ability to classify novel metaphors. The present study underlines the usefulness of simultaneous NIRS measurements in language paradigms - especially for investigating the functional significance of neurophysiological markers that have so far been rarely examined - as these measurements are easily and efficiently realizable and allow for a complementary examination of neural activity and associated metabolic changes in cortical areas.

Keywords: Broca's area; Event-related potentials; Figurative language; N400; Near-infrared spectroscopy.

MeSH terms

Adolescent
Adult
Cerebrovascular Circulation / physiology*
Comprehension / physiology*
Electroencephalography*
Evoked Potentials / physiology*
Female
Humans
Language
Male
Metaphor*
Middle Aged
Neuroimaging
Psychomotor Performance / physiology
Spectroscopy, Near-Infrared
Wechsler Scales
Young Adult