Fig 7. Acoustic features are encoded differently between phrases and sentences in a phase locked manner (IMAGE)
Caption
Comparison between the real performance and the random performance of the STRF in each canonical frequency band. The results suggested that only the performance of the STRF in the Delta band (< 4 Hz) and Theta band (4-8 Hz) was statistically better than the random performance. The blue and red dots represent the real performance of the STRFs for the phrases and the sentences, respectively. The error bar represents two s.e.m centered on the mean. The gray dots represent the random performance drawn by permutations. (b) The performance of the low-frequency range (< 8 Hz) STRF averaged across all participants. The solid blue and red dot represent the averaged performance across all testing trials. The error bar represents two s.e.m across the mean. The transparent blue and red dots represent the model’s performance on each testing trial for the phrases and the sentences, respectively. The results indicate no performance difference on the kernel between the phrases and the sentences. (c) The comparison between the real neural response (dashed lines) and the model predicted response (solid blue for the phrase, solid red for the sentence) at a sample sensor Cz. The results suggest that the STRFs performed equally well for the phrases (r = 0.47, p<1e-5 ***, n=1024) and the sentences (r=0.41, p<1e-5 ***, n=1024). (d) The clustered STRF using the selected sensors showing the biggest activity (negative) on the ROI. The figure on the left and right side of the upper panel represents the clustered STRF for the phrases at the left and right hemisphere, respectively. The corresponding position of the lower panel represents the clustered kernel for the sentences. (e) The figure shows how the sensors were selected, in which the bigger the red circle represents the more times the sensor was selected across all participants. (f) The TRFs that were decomposed from the STRFs, in which the blue and red lines represent the phrases and the sentences, respectively. The solid and the dashed lines represent left and right hemisphere, respectively. (g) The comparison of the magnitude of the TRFs. The blue and the red bars represent the phrases and the sentences, respectively. The error bar shows 1 s.e.m across the mean on each side. A 3-way repeated measure ANOVA of the peak magnitude was conducted on the factors of Stimulus-type (phrase or sentence), Hemisphere (left or right) and Peak-type (~100 ms or ~300 ms). The results indicated a main effect of Stimulus-type and a 3-way interaction. The post hoc comparison on the main effect of Stimulus-type suggested that the amplitude (negative) was stronger for the phrase condition than the sentence condition (t (59) = 4.55, P < 2e-5 ***). To investigate the 3-way, Stimulus-type*Peak-type*Hemisphere, interaction, two 2-way repeated measure ANOVA with the Bonferroni correction were conducted on the factors of Hemisphere and Audio-type at each level of the Peak-type. The results indicated a main effect of Stimulus-type at the first peak (F (1, 14) = 8.19, p = 0.012 *) and a 2-way Hemisphere*Stimulus-type interaction at the second peak (F (1, 14) = 6.42, p = 0.023 *). At the first peak, a post hoc comparison on the main effect of Stimulus-type was conducted using a paired sample t tests, the results showed that the magnitude of the phrase condition was higher than the magnitude of the sentence condition (t (29) = 3.49, p = 0.001 ***). For the 2-way, Hemisphere*Stimulus-type, interaction at the second peak, the paired sample t tests with Bonferroni correction was conducted to compare the difference of the magnitude between the phrases and the sentences at each hemisphere. The results indicate that the magnitude at the second peak was stronger for the phrase condition than the sentence condition in the right hemisphere (t (14) = 3.21, p = 0.006 **), but not the left hemisphere (t (14) = 0.86, p = 0.40). (h) The comparison of the peak latency of TRFs, the blue and the red bars represent the phrases and the sentences, respectively. The error bar shows 1 s.e.m across the mean on each side. A 3-way repeated measure ANOVA of the peak latency was conducted on the factors of Stimulus-type (phrase or sentence), Hemisphere (left or right) and Peak-type (~100 ms or ~300 ms). The results indicated a main effect of Peak-type and a 3-way interaction. The post hoc comparison on the main effect of Peak-type suggested that the latency of the first peak was significantly faster than the second peak (t (59) = 38.89, p < 2e-16 ***). The post hoc comparison on the 3-way interaction with the Bonferroni correction on the factors of Hemisphere and Stimulus-type for each level of the Peak-type suggested a 2-way Hemisphere*Stimulus-type interaction at the first peak (F (1, 14) = 12.83, p = 0.002**). The post hoc comparison on this 2-way interaction using paired sample t tests with the Bonferroni correction indicated that the latency at the first peak was significantly longer for the sentences than the phrases at the right hemisphere (t (14) = 3.55, p = 0.003 **), but not the left hemisphere (t (14) = 0.58, p = 0.56). (i) The SRFs which were decomposed from the STRFs, in which the red and the blue lines represent the phrases and the sentences, respectively, the solid and the dashed lines represent the left and right hemisphere, respectively. (j) The comparison of the amplitude of the SRFs. The SRF was first separated into three bands, low (< 0.1 kHz), middle (0.1 to 0.8 kHz) and high (> 0.8 kHz) based on the averaged frequency response of the STRF, then a 3-way repeated measure ANOVA of the amplitude was conducted on the factors of Stimulus-type (phrase or sentence), Hemisphere (left or right) and Band-type (low, middle and high). The results indicated a main effect of Band-type (F (2, 28) = 119.67, p < 2e-14 ***) and a 2-way, Band-type*Stimulus-type, interaction (F (2, 28) = 27.61, p < 3e-7 ***). The post hoc comparison on the main effect of Band-type using paired sample t tests with Bonferroni correction showed that the magnitude of the middle frequency band was stronger than the low-frequency band (t (59) = 17.9, p < 4e-25 ***) and high frequency band (t (59) = 18.7, p < 5e-26 ***). The post hoc comparison using paired sample t tests with the Bonferroni correction on the, Band-type*Stimulus-type, interaction showed that the amplitude of the SRF was stronger for the phrases than the sentences only at middle frequency band (t (29) = 4.67, p < 6e-5 ***). The underlying data can be found in https://doi.org/10.5281/zenodo.6595789.
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Fan Bai, Antje S. Meyer and Andrea E. Martin
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