Slide Slam C7 Sandbox Series
Spatio-temporal dynamics of phonological neighborhood effects in a picture-naming task
Gabriela Meade1,2,3, Katherine Andrade2,3, Connor Sperling2, Carrie McDonald3, David Lee3, Leena Kansal3, June Yoshii-Contreras3, Jerry Shih3, Sharona Ben-Haim3, Eric Halgren3, Stephanie Ries2; 1KU Leuven, 2San Diego State University, 3University of California San Diego
Phonological neighborhood is typically defined as the number of words that can be obtained by manipulating a single phoneme. Words from high-density (HD) phonological neighborhoods (e.g., belt) have many phonological neighbors (e.g., melt, bell, built, belly), whereas words from low-density (LD) phonological neighborhoods (e.g., frog) do not. Taking phonological neighbors into account is important because they are co-activated during word processing. RT effects of phonological neighborhood in picture naming have been reported in both directions (e.g., Diaz et al., 2021; Sadat et al., 2014). Sadat and colleagues (2014) have proposed that the net behavioral effect is a summation of 1) inhibition due to increased lexical competition and 2) facilitation due to increased feedback from the co-activated lexical representations to shared sublexical representations. Consistent with increased lexico-semantic processing and potential competition, HD words elicit larger amplitude negativities in the EEG waveform than LD words (e.g., Winsler et al., 2018). Consistent with facilitated sublexical processing, Diaz et al. (2021) recently reported that HD words elicited a decreased BOLD signal relative to LD words in regions associated with phonology and articulation. Understanding these opposing dynamics of increasing phonological neighborhood would therefore benefit from a method that has both the temporal resolution to distinguish between sublexical and lexical processing and the spatial resolution to determine where in the brain processing is influenced. Intracranial electroencephalography (iEEG) offers such a solution. In an ongoing study, we are recording iEEG data from patients who are undergoing neurological treatment for refractory epilepsy as they name pictures that have either HD or LD names. The 17 patients (ages 21-55; 5 females) who have participated thus far named the pictures in the HD condition faster and more accurately than those in the LD condition overall. We have also identified significant high-frequency band activity in several regions of interest - including the superior temporal and precentral gyri - that were motivated by the fMRI study by Diaz and colleagues (2021). The next step will be to identify the electrodes where stimulus- and response-locked high-frequency band activity significantly differs between the pictures with HD versus LD names. Upon completion, the time course of the effect and the functional significance of the regions in which these electrodes are located will contribute to our understanding of how exactly phonological neighbors influence word production.