Article Figures & Data
Figures
- Figure 1.
Experimental design and behavioral performance. A, Experimental design. The top illustrates a “same” trial (S1 and S2 are the same) with a fixed onset time. The bottom illustrates a “different” trial (S1 and S2 are different) with jittered onset time. The actual durations of the variable delay phases are specified in B and D. The light gray box indicates the interval of the spectral analyses: −0.8 to −0.1 s time locked to S2. B, Memory performance in Experiment 1. The gray bars illustrate the six variable delay-phase durations from 0.6 to 7.0 s (i.e., values in each bar). The line graph displays averaged memory performance in Az (dotted lines) and the exponential fit (solid lines), both separately for fixed and jittered onset times; error bars indicate SEM of Az. The bar graphs show the average values for the estimated parameters “growth” and “decay,” as well as the asymptote, separately for fixed and jittered onset times. Error bars display the SEM. In all graphs, green refers to fixed and magenta to jittered onset times. The asterisk indicates the significant difference between fixed and jittered onset times. C, Single-participant exponential fits. Every single plot displays the exponential fit of one participant separately for fixed (green) and jittered (magenta) onset times. Dots display the actual performance data Az. D, Memory performance in Experiment 2. The gray bars illustrate the three variable delay phase durations from 1.0 to 4.0 s (i.e., values in each bar). The line graph displays averaged memory performance in Az (RAU-transformed percentage; dotted lines) and the linear fit (solid lines) both separately for fixed and jittered onset times; error bars indicate SEM of Az. The bar graph shows the average values for the estimated slope separately for fixed and jittered onset times. Error bars display the SEM. In all graphs, green refers to fixed and magenta to jittered onset times. The asterisk indicates the significant difference between fixed and jittered onset times. E, Single-participant linear fits. Every single plot displays the linear fit of one participant separately for fixed (green) and jittered (magenta) onset times. Note that the x-axis has been log-transformed and linear fits thus appear inflected. Dots display the actual performance data Az.
- Figure 2.
Time–frequency grand averages power and phase coherence. A, Top, Grand-average power 5–20 Hz averaged across all sensors. Gray arrows on top indicate stimulus occurrence times. S1 refers to the to-be-remembered stimulus. S2 refers to the second stimulus. The index indicates the corresponding delay-phase duration in seconds. Bottom, Grand average of intertrial phase coherence 5–20 Hz averaged across all sensors. B, Alpha power (8–13 Hz) grand-average across channels per delay-phase duration.
- Figure 3.
Condition effects in alpha power. A, Effect of memory decay (1, 2, and 4 s delay phase). Top, Topographies of the t-values of the linear fit of alpha power on delay-phase duration on the sensor level. Marked channels present the significant cluster. The line graph represents alpha power extracted from the displayed channels. Bottom, Source projected linear fit of alpha power on delay-phase duration. z-transformed t-values are displayed with a threshold of |z| ≥ 1.96. Line graphs display delay-phase activity drawn from and averaged across the vertices presenting peak activity around left STG and left V1. All error bars show within-subject SE. B, Impact of temporal expectation on memory decay. Top, Topographies of the t-values of the impact of onset-time condition on the linear fit of alpha power on delay-phase duration on the sensor level. Marked channels present significant cluster. Line graphs represent alpha power extracted from the displayed channels. Bottom, Source projected difference between fixed and jittered onset times of the linear fit of alpha power on delay-phase duration. z-transformed t-values are displayed with a threshold of |z| ≥ 1.96. Positive z-values indicate that jittered onset times have a steeper slope than fixed onset times. Line graphs display condition-wise activity drawn from and averaged across the vertices presenting peak activity around left SMG and right V1. All error bars display within-subject SE.
- Figure 4.
Correlation of sensitivity in memory performance (Az) and alpha power. A, Topography of the correlation of alpha power and Az (t-values). Black dots display channels that belong to the significant positive cluster. B, Alpha power emerging from highlighted brain areas correlates with Az. Positive z-values indicate a positive correlation of Az and alpha power. C, Relation of anterior cingulate cortex (ACC) alpha power to accuracy. The gray lines show the single-subject z-transformed raw data of alpha power in left ACC and Az. The black line indicates the grand average correlation. The blue line of the inlet displays the density of the correlation values across all participants.
- Figure 5.
Functional connectivity. A, Effect of memory decay (1, 2, and 4 s delay phase). Functional connectivity of left STG and highlighted brain areas is modulated by delay phase duration. z-transformed t-values are displayed with a threshold of |z| ≥ 1.96. Positive z-values describe an increase of the phase locking value with delay-phase duration; negative z-values indicate a decrease of phase locking with delay-phase duration. Line graphs display the phase locking value between left STG and right V1 and left IFG, respectively, for each delay-phase duration. Error bars represent within-subject SE. B, Effect of temporal expectation on memory decay. Differential impact of fixed and jittered onset times on phase locking of left STG and highlighted brain areas along different delay phases. z-transformed t -values are displayed with a threshold of |z| ≥ 1.96. Positive z-values indicate that the slope of the correlation of phase locking and delay-phase duration is greater after fixed onset times than after jittered onset times. Negative z-values indicate that this correlation has a greater slope after jittered than after fixed onset times. Line graphs display the phase-locking value between left STG and right SMG and right hippocampus, respectively, for each delay-phase duration and each onset time condition (green line displays fixed and red line displays jittered onset times). Error bars represent within-subject SE. The brain topography in the center illustrates the seed region (i.e., left STG) of the connectivity analysis. C, Effect of alpha connectivity on memory performance. Both plots show memory performance for low and high alpha connectivity (wPPC) between left STG and right V1 (left plot) and left IFG (right plot) for each delay-phase duration. Black lines represent performance after high connectivity; gray lines indicate performance after low connectivity. Error bars indicate SEM.
