Anticipation process of the human brain measured by stimulus-preceding negativity (SPN)

Abstract

The human brain is activated even before a stimulus occurs if a person knows the stimulus will happen within a few seconds. The neural basis for this cognitive function, termed anticipation, is the subject of this review. One method for investigating the brain mechanism of anticipation employs stimulus-preceding negativity (SPN), which is a type of event-related potential (ERP). A critical feature of SPN is that SPN amplitude is greater at the right than at the left hemisphere. This feature suggests that the right hemisphere plays a significant role in the anticipation process. Some neuroimaging studies identified the anterior insula as a physiological source of SPN. The anterior insula is a part of the salience network that detects stimulus salience. Furthermore, recent neuroimaging studies reveal that the right anterior insula is involved in processing the salience outcome, whereas the left anterior insula is related to behavioral adaptation. The SPN study combining functional magnetic resonance imaging (fMRI) and ERP revealed that the right anterior insula showed increased activity preceding a stimulus, while the left anterior insula was not activated. Such studies lead to the hypothesis that saliency of an anticipated stimulus evokes the salience network in advance of a stimulus, and that this network then pre-activates other brain regions in perception of an anticipated stimulus. These processes can be shown as SPN variations in amplitude and cortical distribution. In general, SPN studies suggest that the saliency of an anticipated stimulus is a key factor in evoking anticipatory brain activity.