Contralateral Delayed Activity Reflects The Focus Of Attention Storage In Working Memory

The visual working memory(VWM)system is a system with limited working space,which can save information online,also can be accessed and operated at any time for various cognitive processing.Recent years,neuroelectrophysiology is increasingly being used to study VWM.In the EEG study of visual working memory,an ERP indicator that is widely used to measure the number of items stored in working memory is the contralateral delay activity(CDA).This ERP component is considered to be the macroscopic manifestation of the continuous firing of neurons related to visual working memory,which can reflect the total number of items stored in working memory.But according to the "activity-rest" model recently proposed by researchers,the content of visual working memory can also be temporarily stored in an offline state without any neuron activation.Based on this model,we will be able to draw inferences that the content of visual working memory stored in the offline state will not induce the CDA component that reflects the continuous firing of neurons.Therefore,CDA may only reflect the content stored in the online state of working memory,and has nothing to do with the memory items stored in the offline state.The study uses an improved dual post-cue paradigm to detect the modulation of CDA amplitude by memory items stored in online and offline states.Experiment 1 uses the memory items presented in the middle of the field of vision that do not induce CDA of lateral neural activity to detect whether CDA reflects items in the focus of attention.If the CDA only reflects the items in the focus of attention,then when the lateral item is outside the focus of attention,that is,when the first clue is the middle item of the field of view,the lateral CDA waveform will not be generated.Experiment 2 used the double-detection change-aware paradigm to verify whether the opinions obtained in Experiment 1 are correct.Experiment 2uses the first detection of memory array 2 to ensure that memory array 2 is in the focus of attention,to explore whether CDA reflects the items in the focus of attention.If CDA does reflect the items in the focus of attention,then the CDA amplitude in the second delay period of the memory array should be similar to the CDA amplitude after the first memory array,because they all represent the memory items in the focus of attention.On the contrary,if the CDA amplitude during the delay period of memory array 2 is much greater than that of memory array 1,CDA reflects general memory items and has nothing to do with the focus of attention.The results of experiment 1 show that when working memory items are stored online according to the requirements of the task,they can induce significant CDA during the delay period,and when the memory item is stored offline because it is no longer needed by the current task,no significant CDA is generated during the delay period.The results of Experiment 2 show that when working memory items are stored in the focus of attention according to the requirements of the task,they can induce significant CDA during the delay period,while other memory items outside the focus of attention did not produce significant CDA.Based on the above research results,CDA can only track working memory items stored in online or focus of attention,and items that are off-line or out of focus may be stored in an activity-rest method.These evidences strongly challenge a classic hypothesis about CDA,that is,CDA components can reflect all the contents stored in visual working memory.