Figure 1.
At the beginning of each trial, an auditory instruction was given regarding the formation of task sets (Memory task set or No memory task set condition), followed by a 6-sec delay (Preparation period). Then the task execution period began with stimulus faces presented for 3-sec, followed by a 3-sec delay. During this 6-sec period, four single-digits were presented one at a time for 1.5-sec each, and the participants were asked to add them and remember the final answer. After the delay, a probe face was presented for 1-sec and the participants were given 3-sec to judge whether or not the probe face was among the three faces for the Memory task set condition. For the No memory task set condition, they did not have to respond to the faces. Then a two-digit number was presented for 1-sec and they were asked to decide whether or not the number was the answer to the addition.
Table 1.
Areas of activation for the preparation and execution periods between the Face memory and No face memory conditions.
Figure 2.
Brain activation for the task preparation and task execution periods.
(a) Regions that showed activation during the preparation period in the contrast of Face Memory condition>No Face memory condition, including the left frontal pole (FP), left rostral anterior cingulate (ACCr), right orbital frontal cortex (OFC), and left inferior extrastriate (IES). No brain regions showed activation in the contrast of No Face Memory condition>Face memory condition for the preparation period. (b) Regions that showed activation during the execution period, in the contrast of Face Memory condition>No Face memory condition, including the lateral prefrontal cortex (LPFC), intraparietal sulcus (IPS), and IES. (c) Regions that showed activation during the execution period in the contrast of No Face Memory condition>Face memory condition, including bilateral FP. An uncorrected height threshold (p = 0.001) and an extent threshold (10 voxels) were used.
Figure 3.
Signal change (%) across the time course.
(a) Frontal pole (FP) showed activation for the Memory condition during the preparation period (6 seconds after the onset of a cue at 0 second) and deactivation during the execution period. (b) Rostral Anterior Cingulate Cortex (ACCr) exhibited activation during preparation but not during execution. (c) Lateral prefrontal cortex (LPFC) showed activation during execution. (d) Inferior extrastriate (IES) exhibited activation during execution. Inside the parentheses after each region name are the coordinates of the centre of the ROI. Error bars denote s.e.m. The filled data points indicate the points that the 99% confidence interval did not include zero. The blank data points indicate those points that the 99% confidence interval included zero. The central coordinates for each ROI is shown inside the parentheses.
Figure 4.
Signal change (%) across the time course.
(a) Orbitofrontal cortex (OFC) showed activation during preparation and deactivation during execution. (b) Left Caudal Anterior Cingulate Cortex (ACCc) exhibited activation during preparation and execution. (c) Intraparietal sulcus (IPS) showed activation during execution. (d) Inferior Temporal cortex (IT) showed activation during execution. Inside the parentheses after each region name are the coordinates of the centre of the ROI. Error bars denote s.e.m. The filled data points indicate the points that the 99% confidence interval did not include zero. The blank data points indicate those points that the 99% confidence interval included zero. The central coordinates for each ROI is shown inside the parentheses.