Exploring Brain Activity In Information Integration During Working Memory

People need to continuously integrate all kinds of information received.This process mainly occurs in the working memory system.Working memory requires integrating information from different sensory systems such as the visual system and tactile system,and also integrating information of different features such as the color and shape.This study attempts to explore the neural mechanisms in the process of paired-associate learning(PAL)and the process of feature binding,which belong to the category of information integration in working memory.Many previous studies have shown that the sensory system plays an important role in both unimodal and crossmodal PAL.However,the neural dynamics of feedback processing of crossmodal PAL remain unclear.In order to explore the brain neural mechanism in this process,we recorded event-related scalp electrical potentials when human subjects performed the visuo-visual unimodal or visuo-tactile crossmodal PAL task.After analyzing the data in feedback processing,the results we obtained were as follows:(1)the feedback type effect: the amplitude of P300 decreased with incorrect trials and the P400/N400 complex was only present in incorrect trials;(2)the learning effect: progressive positive voltage shifts in frontal recording sites and negative voltage shifts in central and posterior recording sites were identified as learning proceeded;and(3)the task modality effect: compared with the unimodal PAL task,positive voltage shifts in frontal sites and negative voltage shifts in posterior sites were found in the crossmodal PAL task.These results provide relevant evidence for the neural mechanisms of crossmodal PAL in feedback processing.In working memory,the process of integrating feature information of an object is called feature binding.After exploring the paired-associate learning using EEG,we studied the neural mechanisms of feature binding using functional near-infrared spectroscopy(fNIRS)which has been known to have higher spatial resolution than EEG in locating cortical activity.Thus,we detected the brain activity of the participants using fNIRS while they performing the feature(color and shape)binding task.Results showed that specific activities were present in the frontal and parietal regions during the feature binding process.This indicated that these brain regions were likely to be involved in the process of feature binding.The two studies explored the brain activities related with the information integration in working memory,respectively from the temporal and spatial aspects.This research clarifies the ERP components in the feedback phase associated with the establishment of paired-associate memory,as well as the brain regions associated with color-shape feature binding.These findings will help understanding the brain mechanisms underlying information integration in working memory.