Article Figures & Data
Figures
- Figure 1.
Experimental conditions, behavior, and time-frequency responses. A, The experimental design. After a 1000 ms interstimulus interval, a visual array is presented for 3000 ms. When the target is detected, subjects press a button to indicate in which quadrant of the array (upper or lower) it is located. In the inefficient search condition (in red), target and distractors have the same color. In the efficient search condition (in blue), the target has a different contrast than the distractors. B, Reaction time distribution for efficient (blue) and inefficient visual search (red). C, Statistical time-frequency maps (Wilcoxon Z, FDR corrected) for efficient (left) and inefficient (right) visual search from a recording site (patient 10; Talairach coordinates: [−43 −3 34]), located in dorsolateral prefrontal cortex.
- Figure 2.
Broadband gamma activity response patterns during visual search. A, Grand average broadband gamma response topography across all recording sites and all patients, plotted on a “glass brain” in MNI coordinates. B, Top, Single-trial BGA responses recorded from DLPFC (left, Talairach coordinates [−37 17 27]) and primary motor cortex (right, Talairach coordinates [−57 −28 48]) from patient 23 in the inefficient search condition. Middle, Scatter plot of single-trial BGA quanta versus reaction times. A BGA quantum is a significant time-sample of BGA response versus baseline power evaluated between stimulus onset and offset (Wilcoxon test, FDR corrected). Left and right panels correspond to upper BGA responses. C, Average BGA responses aligned to the response (button-press). Left and right panels correspond to top panel BGA responses.
- Figure 3.
Single-trial gamma-band responses to efficient and inefficient visual search from frontal-parietal recording sites. A, All recording sites with a transient gamma-band response (see Materials and Methods) located in glass brain (Talairach). B, Four illustrative examples (MRI, right) of single-trial gamma-band responses to efficient (eff) and inefficient (ineff) visual search (left) recorded within 4 regions of interest of the frontal-parietal network: DLPFC (patient 5, Talairach coordinates [−58 −1 34]), dACC (patient 10, Talairach coordinates [−12 11 47]), PrCS/MFG putative FEF (patient 10, Talairach coordinates [−46 −2 34]), and IPS (patient 23, Talairach coordinates [−52 −42 46]).
- Figure 4.
Single-trial gamma-band responses (Transient,Type 1) during efficient and inefficient visual search. A, Recording sites located in glass brain (Talairach). In blue: contacts with a stronger response during efficient vs inefficient search (Kruskal-Wallis, FDR corrected). B, Two illustrative examples of single-trial gamma-band responses during efficient (eff) and inefficient (ineff) search in the right and left fusiform gyrus: (patient 6, Talairach coordinates [36 −52 −12] and patient 20 [−30 −41 −16]). Bottom, Profile of gamma-band responses aligned to stimuli onset. Left and right panels correspond to top panel responses.
