Attempted Encoding vs. Fixation. Activation maps for each of the attempted encoding conditions compared to visual fixation (color bar represents T scores): Face-Name pairs that were subsequently forgotten (Incorrect), Remembered with Low Confidence (LC-Correct), and Remembered with High Confidence (HC-Correct). Within the hippocampal formation, Incorrect (top left) and LC-Correct (top middle) demonstrated significant activation in mid-posterior hippocampus only, while HC-Correct (top right) demonstrated activation along the entire longitudinal axis of the hippocampus, including the anterior hippocampus. MR signal time courses were extracted for a three-dimensional region of interest (4-mm radius) for the posterior hippocampus (bottom left, A: centered at 21, −30, −3) and the anterior hippocampus (bottom right, B: centered at 24, −12, −15). The percent MR signal modulation for each condition is indicated on the y-axis and time in seconds is indicated on the x-axis. All encoding conditions (HC-Correct, LC-Correct, and Incorrect) showed similar response in mid- to posterior hippocampus, while HC-Correct responses were significantly higher (P < 0.00001) than LC-Correct and Incorrect in the anterior hippocampus.

Successful vs. Failed Encoding. Statistical activation maps demonstrating greater response during encoding of Face-Name pairs that were subsequently successfully remembered (High Confidence Correct) compared to Face-Name Pairs that were forgotten (Incorrect). Activation within the hippocampal formation is shown in three image planes: coronal (top), sagittal (middle), and transaxial (bottom), and was located in the anterior hippocampus bilaterally, and the right entorhinal cortex. Analyses performed with SPM99, and statistical activation maps (color bar represents T scores) of the event-related data averaged across subjects are displayed on an anatomic T1 image template.

Analysis of confidence and accuracy. Activation maps for HC-Correct vs. LC-Correct (yellow) and HC-Incorrect vs. LC-Incorrect (red) are displayed on coronal slices: prefrontal regions shown on left at y = 27, and hippocampal regions shown on the right at y = −12). No significant overlap was found using a conjunction analysis at the threshold of P < 0.001, but at the lower threshold atP < 0.01 (shown in figure), the only region showing overlap between confidence and accuracy was found in the left inferior prefrontal cortex. There was bilateral activation in the anterior hippocampal formation for the HC-correct vs. LC-correct contrast, but no activation within the hippocampal formation for the HC-Incorrect vs. LC-Incorrect even at the lower threshold of P < 0.01.