Figure 4.
Phoneme selectivity and modulatory effects of phonotactics on cortical responses. A, Mean (± SEM) HG cortical responses to all CVC combinations in two example STG electrodes. Each electrode shows preferential responses to specific speech sounds (see color grid); however, contextual effects are apparent (e.g., e199-4 is most active when /n/ is the first phoneme). Dashed vertical lines indicate average V and C2 phoneme onsets. B, Linear STRFs, modeling each electrode's preferred acoustic frequencies, demonstrate that selectivity is driven by phoneme acoustics. C, Pfwd and Pbkw transition probabilities modulate neural activity not explained by the linear STRF in electrodes from A, B. Time courses of linear weights (red and blue lines ±95% CI) show significant effects during CV transition, vowel, and word offset time periods (p < 0.05; gray shading).