Fig. 2: Frontal lobe areas have short-onset latencies like the superior temporal gyrus.
From: Parallel encoding of speech in human frontal and temporal lobes
A Spatial map of response latencies show short-onset latencies in STG, IFG, mPreCG, and vSMC (onset defined as first 1-ms time bin in which the response p-value is <0.05 for 15 consecutive 1-ms bins19,20; Wilcoxon rank-sum test). B All responses across participants with onset latencies less than 200 ms. C Two example participants showing the electrode sites with shortest onset latency in the STG and frontal lobe. As shown, the earliest onset latencies within a subject are similar between the frontal lobe and STG. D Latency distribution by area for onset latencies less than 160 ms (the proportion y-axis is relative to the full distribution of latencies up to 1600 ms). This shows the earliest onset latencies are similar across areas and is consistent with low-latency parallel inputs to each area. E Latency distribution boxplots for all onset latencies up to the temporal cutoff specified on the x-axis (80–720 ms). There is no significant difference between STG and IFG, mPreCG, or vSMC up to 240 ms in the right hemisphere and 200 ms in the left hemisphere (* = p < 0.05, two-sample Kolmogorov–Smirnov test, Bonferroni corrected, n latencies for left/right hem. = 52/84 IFG, 120/180 mPreCG, 98/91 vSMC, 330/274 STG). All box plots show the median (circle), 25th and 75th percentiles (box). These indistinguishable short-onset latency times are consistent with a subset of parallel inputs to the frontal cortex and STG rather than strictly hierarchical inputs from STG to the frontal cortex. CS central sulcus; IFG inferior frontal gyrus; mPreCG middle precentral gyrus; STG superior temporal gyrus; vSMC ventral sensorimotor cortex.
