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Brain dynamics and patterns of activity signature of inner speech during recall and conceptual emergence in bilinguals

Final Report Summary - NINAME (Brain dynamics and patterns of activity signature of inner speech during recall and conceptual emergence in bilinguals.)

The influence of narrative processes on episodic autobiographical system is an inherent component present in recall processes that had never been studied so far. Life experiences are transformed into episodic autobiographical memory via the hippocampal region in interplay with ventromedial prefrontal cortex and retrosplenial cortex. In the two years we experimentally assessed the influence of narrative processes on the hippocampo-cortical system thanks to language manipulation in fluent bilinguals. We predicted that recall in the maternal language (L1) has a specific signature in the network, due to hypothesized self-relatedness to the language. To assess such a prediction, we tackled three main aims: to construct the dynamics of the life-events according to the language of event construction; to understand the importance of the realness and selfness aspect of the constructed events and finally investigate the inner speech of life-events in L1 compared to the inner speech of life events in the second language (L2) using a multimodal fMRI approach. The full experiment was carried out on 15 bilingual basque-spanish speakers. The language encoding was controlled via a person-related procedure. Taking into account that in ecological settings bilinguals adapt their language to the person they interact with, we selected participant specific persons that only spoke basque with the participant and persons who only speak spanish to the participant. The attachment level to the language-specific person was controlled and equivalent relatedness and emotional attachment was ensured with a semi-structured behavioral procedure preceding the fMRI acquisition. During fMRI acquisition, each participant constructed four type of events in each language (past life events, future life events, dreammed events, fictious events) and a standard control task (object viewing description). As in an ecological situation participants were asked to follow the flow of languages, and they were thus instructed to describe in their mind each life event in the language the event instruction. Eight runs with a block in each language was first assessed. One week later, a repetition procedure was given to assess the repetition effect in this process. The preliminary findings support an important influence of narrative processes on the episodic system during event construction. More precisely, language affection affects the ventromedial prefrontal cortex and the precuneus, with an enhanced activation for L1 inner speech. Also, differences related to the realness of the events in interaction with the used language would touch the temporo-parietal junction and the parahippocampal region. To further this proposal the project offered the investigator the opportunity to propose a theoretical model on the influence of inner speech on the episodic system.