Figure 2
Occipital cortical responses during the different phases of conditioning. (A) Changes in the grand average (N = 19) of visual electrocortical activity for each learning phase (habituation, acquisition, extinction, and day 2 delayed recall) and for each CS orientation. Regional means of the ssVEP spectral power current source density (CSD, Laplacian space), averaged across 3 occipital midline sensor locations (O1, Oz, O2), were used to estimate the occipital cortex surface potential. Values are signal-to-noise ratios (SNR), i.e., the power at the driving frequency was divided by the average power for the five frequency bins below and four frequency bins above the driving frequency (as the noise estimate). Supplementary Fig. S1 shows single subject data. (B) The same data after habituation correction for acquisition, extinction, and day 2 delayed recall. The insert shows a view of the back of the electrode array used, the sensor locations used for averaging are highlighted. Error bars show 1 standard error of the mean (SEM). Supplementary Fig. S2 shows single subject data. (C) Cortical regions responsive to fear conditioning: Topographical distributions (back views of the scalp) showing results (F-values with N = 19) of planned contrasts testing for lateral inhibition (top, black line, ‘Mexican hat’ contrast) versus fear generalization (bottom, blue line, quadratic contrast) of habituation-corrected electrocortical responses across orientations, averaged over all acquisition, extinction, and day 2 delayed recall trials. F-values exceeding ±4.41 indicate a reliable model fit. Fits matching the opposite pattern (i.e., inverted ‘Mexican hat’ or quadratic) are shown in blue. The numbers above the line-graphs on the left are the weights used for planned contrasts.
