Externally induced frontoparietal synchronization modulates network dynamics and enhances working memory performance

摘要

Like an orchestra that relies on the coordinated efforts of its members, the brain depends on its many regions working together to perform tasks such as memorizing a phone number or the name of someone we recently met. Many areas in the brain that are involved in these processes are located far apart, and so performing these tasks efficiently depends on the regions being able to communicate and coordinate information. Rhythmic waves of electrical activity in the brain are considered to be essential to maintain the flow of information. These brain waves occur when many brain cells repeatedly send signals at the same time, and the precise ‘beat’ of the signals might be especially important when performing more complex tasks. In recent years, cheap and safe electrical stimulation has shown promise in being able to influence brain waves. This technique can be used to investigate the importance of precise timing between brain waves and its impact on performing tasks, as well as changes in brain activity that occur when tasks are more complex. For example, is a person’s behaviour affected if electrical stimulation is used to make their brain waves more or less synchronized? Violante et al. stimulated distant regions of the brain of volunteers and monitored how they performed in tasks with varying difficulty. When these regions were stimulated with the same ‘beat’ to make the brain waves more synchronized, the person performed better in the more difficult tasks. In these tasks, participants had to monitor number sequences, and spot repeated patterns in the remembered information. To better understand this effect Violante et al. performed brain stimulation while collecting brain scans. The scans showed that stimulation at the same ‘beat’ increases brain activity in the regions involved in task performance and changes the pattern of how regions communicate in the brain. This finding suggests that the ‘beat’ of brain waves is important for task performance, and that stimulating the brain externally can alter how regions in the brain communicate. Future studies could extend these findings to patients, particularly those with the kind of damage to their brain that slows the communication between its distant regions. Stimulating these patients’ brains could help bypass the internal delays, and help them to complete everyday tasks more efficiently.