Leon-Cabrera, P. | bioRxiv Science

bioRxiv2025

Alpha and beta desynchronization during consolidation of newly learned words

While a growing body of literature exists on initial word-to-meaning mapping and retrieval of fully lexicalized words, our understanding on the consolidation that occurs between these two stages remains limited. The current study investigated the neural correlates of retrieving newly learned word meanings using oscillatory brain dynamics. Participants learned to associate new words with unknown objects and performed overt and covert naming tasks during the first and last days of a five-day training period. Behavioral results showed improved overt naming on Day 5 compared to Day 1. Selecting only words that were successfully produced in the overt naming task, we examined oscillatory activity associated with word retrieval while participants produced new words covertly, both pre- (Day 1) and post (Day 5) learning. The results showed a robust alpha (8-12 Hz) and lower beta (13-25 Hz) power decrease during covert naming after learning. We hypothesize that this alpha-beta power decrease indexes successful word retrieval following consolidation.

neuroscience↗

bioRxiv2020

Neural signatures of predictive language processing in Parkinson's disease with and without mild cognitive impairment

Cognitive deficits are common in Parkinsons disease (PD), with some PD patients meeting criteria for mild cognitive impairment (MCI). An unaddressed question is whether linguistic prediction is preserved in PD. This ability is nowadays deemed crucial in achieving fast and efficient comprehension, and it may be negatively impacted by cognitive deterioration. To fill this gap of knowledge, we used event-related potentials (ERPs) to evaluate mechanisms of linguistic prediction in a sample of PD patients (on dopamine compensation) with and without MCI. To this end, participants read sentence contexts that were predictive or not about a sentence-final word. The final word appeared after 1 second, matching or mismatching the prediction. The introduction of the interval allowed to capture neural responses both before and after sentence-final words, reflecting semantic anticipation and processing. PD patients with normal cognition (N = 58) showed ERP responses comparable to those of matched controls. Specifically, in predictive contexts, a slow negative potential developed prior to sentence-final words, reflecting semantic anticipation. Later, expected words elicited reduced N400 responses (compared to unexpected words), indicating facilitated semantic processing. Besides, PD patients with MCI (N = 20) showed a prolongation of the N400 congruency effect (compared to matched PD patients without MCI), indicating that further cognitive decline impacts semantic processing. Finally, lower verbal fluency scores correlated with prolonged N400 congruency effects and with reduced pre-word differences in all PD patients (N = 78). This relevantly points to a role of deficits in temporal-dependent mechanisms in PD, besides prototypical frontal dysfunction, in altered semantic anticipation and semantic processing during sentence comprehension.

neuroscience↗