Category: Executive Functions

Wöst­mann, Alavash and Obleser demon­strate that alpha oscil­la­tions in the human brain imple­ment dis­trac­tor sup­pres­sion inde­pen­dent of tar­get selection.

In the­o­ry, the abil­i­ty to selec­tive­ly focus on rel­e­vant objects in our envi­ron­ment bases on selec­tion of tar­gets and sup­pres­sion of dis­trac­tion. As it is unclear whether tar­get selec­tion and dis­trac­tor sup­pres­sion are inde­pen­dent, we designed an Elec­troen­cephalog­ra­phy (EEG) study to direct­ly con­trast these two processes.

Par­tic­i­pants per­formed a pitch dis­crim­i­na­tion task on a tone sequence pre­sent­ed at one loud­speak­er loca­tion while a dis­tract­ing tone sequence was pre­sent­ed at anoth­er loca­tion. When the dis­trac­tor was fixed in the front, atten­tion to upcom­ing tar­gets on the left ver­sus right side induced hemi­spher­ic lat­er­al­i­sa­tion of alpha pow­er with rel­a­tive­ly high­er pow­er ipsi- ver­sus con­tralat­er­al to the side of attention.

Crit­i­cal­ly, when the tar­get was fixed in front, sup­pres­sion of upcom­ing dis­trac­tors reversed the pat­tern of alpha lat­er­al­i­sa­tion, that is, alpha pow­er increased con­tralat­er­al to the dis­trac­tor and decreased ipsi­lat­er­al­ly. Since the two lat­er­al­ized alpha respons­es were uncor­re­lat­ed across par­tic­i­pants, they can be con­sid­ered large­ly inde­pen­dent cog­ni­tive mechanisms.

This was fur­ther sup­port­ed by the fact that alpha lat­er­al­i­sa­tion in response to dis­trac­tor sup­pres­sion orig­i­nat­ed in more ante­ri­or, frontal cor­ti­cal regions com­pared with tar­get selec­tion (see figure).

The paper is also avail­able as preprint here.