Cortical mid-line structures In the past 20 years plus there has been an increase in
cognitive neuroscience studies that focus on the concept of the
self. These studies were developed in hopes of determining if there are certain brain regions that can account for the
encoding advantages involved in the self-reference effect. A great deal of research has been focused on several regions of the brain collectively identified as the cortical midline region. Brain imaging studies have raised the question of whether neural activity in cortical midline regions is self-specific. A
quantitative meta-analysis that included 87 studies, representing 1433 participants, was conducted to discuss these questions. The
analysis uncovered activity within several cortical midline structures in activities in which participants performed tasks involving the concept of self. Most studies that report such midline activations use tasks that are geared towards uncovering
neural processes that are related to social or psychological aspects of the self, such as self-referential judgments,
self-appraisal, and judgments of
personality traits. Also, in addition to their perceived role in several forms of self-representation, cortical midline structures are also involved in the processing of
social relationships and recognizing personally familiar others. Studies that show midline activations during understanding of social interactions between others or ascribing social traits to others (
impression formation) typically require subjects to reference the
mental state of others.
Prefrontal cortex There are several areas within the cortical midline structure that are believed to be associated with the self-reference effect. One of the more active regions involved in the self-reference effect appears to be the
medial prefrontal cortex (mPFC). The
prefrontal cortex (PFC) is the area of the brain that is believed to be involved in the planning of complex
behavior and the expression and regulation of personality characteristics in social situations. The implication that the prefrontal cortex is involved in the regulation of unique internal personality characteristics illustrates how it may be an important component of the self-reference effect. The medial prefrontal cortex in both
hemispheres has been proposed as a site of the "
self model" which is a theoretical construct made of essential features such as feelings of continuity and unity as well as
experience of agency. The idea of the self-reference effect being linked to the medial prefrontal cortex stems from several experiments attempting to locate the
mechanisms involved in the self-referencing process. Experiments in which participants were assigned tasks that required them to reflect on, or
introspect about their own mental states showed activity in the medial prefrontal cortex. For example, activity in the
ventromedial prefrontal cortex has been observed in tasks in which participants report on their own personalities or preferences, adopt a first person perspective, or reflect on their current
affective state. Similar activity in the ventromedial prefrontal cortex is displayed in cases where participants show the memory advantage that emerges when items are encoded in a self-relevant manner. During various
functional magnetic resonance imaging (fMRI) tests conducted while participants were performing self-referential tasks, there was a consistent showing of increases in
blood-oxygen-level dependent (BOLD) signals in the ventral medial and dorsal medial prefrontal cortex. Measuring BOLD signals is necessary for a sound interpretation of fMRI signals, as BOLD fMRI reflects a complex monitoring of changes in
cerebral blood flow, cerebral
blood volume and
blood oxygenation. ==Development over the lifespan==