Right Frontal HD-tDCS Reveals Causal Involvement of Time perception Networks in Temporal Processing of Concepts

Abstract

Evidence suggests that perceptual and action related features of concepts are grounded in the corresponding sensory-motor networks in the human brain. However, less is known about temporal features of event concepts (e.g., a lecture) and whether they are grounded in time perception networks. We examined this question by stimulating the right dorsolateral prefrontal cortex (rDLPFC) —a part of time perception network — using HD-tDCS and subsequently recording EEG while participants performed semantic and time perception tasks. Semantic tasks were composed of event nouns duration judgment (EDur), object nouns size judgment (OSize), valence judgement of event (EVal) and object (OVal) nouns. In the time perception task, participants judged the durations of pure tones. Results showed that stimulation accelerated responses for time perception task and decreased the magnitude of global field power (GFP) compared to sham stimulation. Semantic task results revealed that cathodal, but not sham, stimulation significantly decreased GFP for EDur relative to OSize and to EVal. These findings provide first causal evidence that temporal features of event words are grounded in the rDLPFC and in the temporal cognition network, and shed light on the conceptual processing of time.