Impact of social knowledge about the speaker on irony understanding: Evidence from neural oscillations.

The aim of the present study was to explore neuronal oscillatory activity during a task of irony understanding. In this task, we manipulated implicit information about the speaker such as occupation stereotypes (i.e., sarcastic versus non-sarcastic). These stereotypes are social knowledge that influence the extent to which the speaker's ironic intent is understood. Time-frequency analyses revealed an early effect of speaker occupation stereotypes, as evidenced by greater synchronization in the upper gamma band (in the 150-250 ms time window) when the speaker had a sarcastic occupation, by a greater desynchronization for ironic context compared to literal context in the alpha1 band and by a greater synchronization in the theta band when the speaker had a non-sarcastic occupation. When the speaker occupation did not constrain the ironic interpretation, the interpretation of the sentence as ironic was revealed as resource-demanding and requiring pragmatic reanalysis, as shown mainly by the synchronization in the theta band and the desynchronization in the alpha1 band (in the 500-800 ms time window). These results support predictions of the constraint satisfaction model suggesting that during irony understanding, extra-linguistic information such as information on the speaker is used as soon as it is available, in the early stage of processing.

Effective connectivity of the left-ventral occipito-temporal cortex during visual word processing: Direct causal evidence from TMS-EEG co-registration.

As an interface between the visual and language system, the left ventral occipito-temporal cortex (left-vOT) plays a key role in reading. This functional role is supported by anatomical and functional connections between the area and other brain regions within and outside the language network. Nevertheless, only a few studies have investigated how the functional state of this area, which is dependent upon the nature of the task demand and the stimulus being processed, could influence the activity of the connected brain regions. In the present combined TMS-EEG study, we studied the left-vOT effective connectivity by adopting a direct, causal intervention approach. Using TMS, we probed left-vOT activation in different processing contexts and measured the neural propagation of activity from this area to other brain regions. A comparison of neural propagation measured during low-level visual detection of language versus non-language stimuli showed that processing language stimuli reduced neural propagation from the left-vOT to the right occipital cortex. Additionally, compared to the low-level visual detection of language stimuli, performing semantic judgments on the same stimuli further reduced neural propagation to the posterior part of the corpus callosum, right superior parietal lobule and the right anterior temporal lobe. This reduction of cross-hemispheric neural propagation was accompanied by an increase in the collaboration between areas within the left-hemisphere language network. Together, this first evidence from a direct causal intervention approach suggests that processing language stimuli and performing a high-level language task reduce effective connectivity from the left-vOT to the right hemisphere, and may contribute to the left-hemisphere lateralization typically observed during language processing.

Motor resonance during linguistic processing as shown by EEG in a naturalistic VR environment.

Embodied cognition studies have shown motor resonance during action language processing, indicating that linguistic representations are at least partially multimodal. However, constraints of this activation linked to linguistic and extra-linguistic context, function and timing have not yet been fully explored. Importantly, embodied cognition binds social and physical contexts to cognition, suggesting that more ecologically valid contexts will yield more valid measures of cognitive processing. Herein, we measured cortical motor activation during language processing in a fully immersive Cave automatic virtual environment (CAVE). EEG was recorded while participants engaged in a Go/No-Go task. They heard action verbs and, for Go trials, performed a corresponding action on a virtual object. ERSP (event-related spectral perturbation) was calculated during verb processing, corresponding to the pattern of power suppression (event-related desynchronization - ERD) and enhancement (event-related synchronization - ERS) relative to the reference interval. Significant ERD emerged during verb processing in both the µ (8-13 Hz) and beta band (20-30 Hz) for both Go and No-Go trials. µ ERD emerged in the 400-500 msec time window, associated with lexical-semantic processing. Greater µ ERD emerged for Go compared to No-Go trials. The present results provide compelling evidence in a naturalistic setting of how motor and linguistic processes interact.

Morphological processing without semantics: An ERP study with spoken words.

The time-course of morphological processing during spoken word recognition was investigated using event-related brain potentials (ERPs) in an auditory lexical decision task. We compared three different types of French words: truly suffixed (e.g., pochette 'little pocket' = poche 'pocket' + diminutive suffix -ette), pseudo-suffixed (e.g., mouette 'seagull' = mou 'soft' + pseudo-suffix -ette) and non-suffixed target words (e.g., fortune 'fortune' = fort 'strong' + non-suffix -une). Suffixed (e.g., mouesse = mou + suffix -esse) and non-suffixed nonwords (e.g., mouipe = mou + non-suffix -ipe) were also tested. The behavioural results showed that participants responded more slowly to non-suffixed words than to truly suffixed and pseudo-suffixed words, but there was no difference between the two suffixed conditions. Moreover, participants made more errors rejecting pseudo-suffixed nonwords than non-suffixed nonwords. In the ERP analyses, T0 was shifted to the end of the embedded stem or pseudo-stem. The ERP results revealed enhanced N400 amplitudes for non-suffixed words compared to truly suffixed and pseudo-suffixed words. Again, there was no difference between the truly and pseudo-suffixed conditions. In addition, we found an increased N400 amplitude for both pseudo-suffixed and non-suffixed nonwords than for words. The latency of the onset of this N400 effect varied between the three experimental conditions: the word-nonword difference occurred earliest in the truly suffixed condition, slightly later in the pseudo-suffixed condition and latest in the non-suffixed condition. Both behavioural and EEG data jointly suggest that spoken words with a genuine morphological structure and words with a pseudo-morphological structure are decomposed into morphemic sub-units. Moreover, the earlier appearance of the N400 effects in the truly suffixed condition indicates that morphological information is more readily available in words with a semantically transparent morphological structure.

Metrical rhythm implicitly orients attention in time as indexed by improved target detection and left inferior parietal activation.

When we direct attentional resources to a certain point in time, expectation and preparedness is heightened and behavior is, as a result, more efficient. This future-oriented attending can be guided either voluntarily, by externally defined cues, or implicitly, by perceived temporal regularities. Inspired by dynamic attending theory, our aim was to study the extent to which metrical structure, with its beats of greater or lesser relative strength, modulates attention implicitly over time and to uncover the neural circuits underlying this process of dynamic attending. We used fMRI to investigate whether auditory meter generated temporal expectancies and, consequently, how it affected processing of auditory and visual targets. Participants listened to a continuous auditory metrical sequence and pressed a button whenever an auditory or visual target was presented. The independent variable was the time of target presentation with respect to the metrical structure of the sequence. Participants' RTs to targets occurring on strong metrical positions were significantly faster than responses to events falling on weak metrical positions. Events falling on strong beats were accompanied by increased activation of the left inferior parietal cortex, a region crucial for orienting attention in time, and, by greater functional connectivity between the left inferior parietal cortex and the visual and auditory cortices, the SMA and the cerebellum. These results support the predictions of the dynamic attending theory that metrical structure with its relative strong and weak beats modulates attentional resources over time and, in turn, affects the functioning of both perceptual and motor preparatory systems.

Rhythm implicitly affects temporal orienting of attention across modalities.

Here we present two experiments investigating the implicit orienting of attention over time by entrainment to an auditory rhythmic stimulus. In the first experiment, participants carried out a detection and discrimination tasks with auditory and visual targets while listening to an isochronous, auditory sequence, which acted as the entraining stimulus. For the second experiment, we used musical extracts as entraining stimulus, and tested the resulting strength of entrainment with a visual discrimination task. Both experiments used reaction times as a dependent variable. By manipulating the appearance of targets across four selected metrical positions of the auditory entraining stimulus we were able to observe how entraining to a rhythm modulates behavioural responses. That our results were independent of modality gives a new insight into cross-modal interactions between auditory and visual modalities in the context of dynamic attending to auditory temporal structure.