Important Brain Networks

By leveraging Connectomics to trace functional connectivity, seven large-scale brain networks have been identified. These networks have the most dominance over cortical function in the brain, and each serves an overarching common function. While some networks are familiar, many networks, and their constituents, are newly discovered¹.

These major networks control brain function both during task processing and while at rest. The brain’s neural networks have a hierarchy to their operation, and they integrate and synchronize to carry out 'complex functions'.

Most brain processes are considered complex functions because multiple brain networks (and thus multiple brain areas) fire and work together in unison to execute individual tasks.

Between the seven main networks there have been important interactions that have been observed that have answered age old mysteries about neurological function and dysfunction.

Of the seven main brain networks, the dominant control networks are the most active. The CEN focuses on external goals and is responsible for active synthesis of memory with external activities². The DMN, on the other hand, is the alternate network to the CEN. It is the most consistent network in the brain, and controls the brain’s passive, internal state for internal thinking and evaluating ideas².

These two networks represent the mind’s internal and external states, and they work in tandem with other networks, such as the visual, sensorimotor, limbic, and attention networks. Together, they process external sights and sounds, internal emotions, or other stimuli that can lead either to internal thought or external active tasks.

Though the CEN and DMN are always active because of their dominant roles, they are not supposed to operate at the same time. The brain continually switches between the CEN and DMN as needed for external or internal processing.

The salience network is solely responsible for regulating the switch between these two control networks, and it determines which network is in control at any given moment. Additionally, the SN is also responsible for regulating emotion and pain from the other main networks. The SN regulates these changes so quickly and effectively that the process is typically imperceptible to the human mind.

However, the SN can have negative implications for the brain when it becomes overactive and abnormally handles network switching or emotional regulation. These irregularities can lead to mental illness, such as schizophrenia, depression, anxiety, and post-traumatic stress disorder. Analyzing the brain's neural networks opens up a range of possibilities to diagnose and treat these neuropsychiatric disorders.

The subcomponents of the seven main networks further form highly specific subnetworks, both within and between main networks - each a process that describes a specific function of our brain. This is analogous to continents containing broadly similar countries and cultures, with individual countries and cultures forming highly specific relationships with themselves and others.

Listed below are some of the most important subnetworks discovered in recent years.