The precuneus is tuned to words that refer to time, not to space, whereas the IPS has no preferences

Quantitative, temporal and spatial processes are proposed to be part of a magnitude system sharing the right intraparietal sulcus (r-IPS) as a common neural substrate (Walsh et al., 2003). Specificities for time and space are reported, identifying a role of the right Precuneus (r-Precuneus) in temporal estimations (Skye et al., 2023). Translating this evidence to the language domain, in line with the extended embodied knowledge framework, studies associated the IPS with the processing of quantity-related concepts (Catricalà et al., 2020). No evidence is available for time- and space-related concepts. Here we investigated the causal role of r-IPS and r-Precuneus in representing time- and space-related concepts using TMS.

Fifty-six time- and space-related nouns, matched for frequency, length, age-of-acquisition, emotional valence, and mean priming effect were selected. Priming to a category label (TIME or SPACE) modulated the neural activation prior to TMS and target presentation. Subjects had to indicate the target’s category. Fifty-six congruent and 56 incongruent trials were presented for r-IPS, r-Precuneus, and sham-baseline (Vertex) sites. Twenty-two healthy subjects participated. We performed a repeated measure ANOVA on the priming effect with TMS site as within-subject factor.

For both time- and space-related concepts the r-IPS stimulation abolished the priming effect reported for the Vertex (p=0.016), whereas r-Precuneus (p<0.006) stimulation was effective only for time-related concepts.

In line with the Magnitude theory (Walsh et al., 2003), results highlight the r-IPS as the shared substrate for linguistic stimuli connected to space and time. Instead, the r-Precuneus was tuned only for time concepts, which supports its role in temporal judgements.