Figure 4.

Left MTG pyramidal neurons in L2/L3 from subjects with higher VIQ scores are able to sustain fast action potential (AP) rise speed during high frequency firing. (a) AP firing in pyramidal neurons in L2/L3. AP rise speed was defined as the maximum speed of the rising phase of the AP (red dotted line). (b) Example AP traces at 30 Hz from two subjects with low and high VIQ. (c) At higher frequencies, the AP rise speed is faster in neurons from subjects with higher VIQ (red), and slower in subjects with lower VIQ (blue) only in the left MTG. Shaded area represents SEM. Each data point represents an average of APs from several per subject (Left MTG, Low VIQ Median (IQR) = 224.61(174.41–255.27) mV/ms, n subjects = 4, n cells = 15, High VIQ = 300.52(284.87–372.79) mV/ms, n subjects = 6, n cells = 16 Mann Whitney U test: U = 10, P = 0.0095. Right MTG, Low VIQ = 293.79(239.81–322.17) mV/msn subjects = 8, n cells = 36, High VIQ = 284.80(270.60–315.65) mV/ms, n subjects = 8, n cells = 29, U = 67, P = 0.96). (d) AP rise speeds at higher frequencies correlate with VIQ scores only in the left MTG (n subjects =10, n cells = 31, F(1,8) = 11.9), but not in the right MTG (n subjects =16, n cells = 65, F(1,14) = 3.42). After removal of the outlier (marked in red) from the analysis, the correlation remained significant (R² = 0.67, P = 0.007, F(1,7) = 14.3).