Fig. 3: Sites with short-onset latencies in frontal cortex encode the same spectrotemporal information as STG.
From: Parallel encoding of speech in human frontal and temporal lobes
A Example middle precentral gyrus STRF with the predicted and actual response to a single sentence. Predicted responses are obtained by convolving the spectrogram with the STRF and are proportional to the similarity between the stimulus’s spectrotemporal content and the STRF structure. B STRF prediction value distributions for all short-latency electrodes with a significant response to speech in mPreCG, VSMC, and IFG (suprasylvian cortex global mean Pearson correlation coefficient 0.39 ± 0.24; tested on held-out data). STRFs, which are predictive of neural responses, characterize spectrotemporal encoding at each site and are consistent with the presence of spectrotemporal representations in these areas. All box plots show the median, 25th and 75th percentiles. Notches approximate the 95% confidence interval of the median. n site prediction values = 46 IFG, 115 mPreCG, 110 vSMC, and 389 for STG. C Examples showing the high degree of STRF similarity between frontal lobe areas and STG. D There is no significant difference in short-onset (<200 ms) STRF tuning parameters across frontal lobe sites and STG, including: best frequency tuning (p > 0.05 Kruskal–Wallis test), spectral, or temporal tuning (p > 0.05 cosine similarity permutation test of mean spectral and temporal tuning vectors). Spectral and temporal tuning plots show the mean ± s.e.m for each area in each hemisphere; the total contralateral hemisphere mean tuning is plotted as a dotted line for reference. E Ensemble modulation transfer functions by area. The average modulation tuning for each area has a high degree of similarity. F There is no significant difference in temporal or spectral modulation tuning between frontal lobe areas and STG (p > 0.05, cosine similarity permutation test of mean spectral and temporal modulation tuning vectors26). BF best frequency; CC Pearson correlation coefficient; c/o cycles per octave; Hem. hemisphere; IFG inferior frontal gyrus; mPreCG middle precentral gyrus; Spec. Mod. spectral modulation; STRF spectrotemporal receptive field; Temp. Mod. Temporal Modulation; vSMC ventral sensorimotor cortex.
