Interconnected brain regions – an end to the GCS?


Traumatic Brain Injury (TBI) can often lead to problems with a person’s cognitive control, affecting their attention, memory, thought, behaviour and emotion. Cognitive control is our ability to modify our behaviour and actions to adapt to the situation we are in. It provides the basis for planning, problem solving and adaptive behaviour (our ability to be self sufficient and independant, based on our age group).

person in MRI machine
photo credit: P4250960 via photopin (license)

Accumulating neuroscience evidence suggests that cognitive control functions are carried out within a network of highly interconnected brain regions. These networks allow for
communication across long distances within the brain and enable us to direct attention to important information in our internal and external environments, to plan and to problem solve. Three such networks have been identified: the salience network, the default-mode network (DMN) and the central-executive network (CEN).

Traumatic brain injury often leads to deficits in cognitive control. The salience network plays a vital role in controlling our emotions and our awareness to the physiological state of our body. Damage to the salience network produces deficits in awareness, such as difficulty with focusing and attention span.

The DMN allows for an internal focus of attention during self-reflective cognitive activity, and is responsible for our autobiographical memory (recalling events that happened to us, as well as facts about the time and place where the event occured), and social cognition (how people process social information). Damage to the DMN results in difficulties with remembering our personal histories, problems understanding time and space, and imagining the perspective of others.

The CEN supports an external focus of attention during goal directed, cognitively demanding tasks. Damage to this network results in impairment to flexibility of thought, working memory, and problem solving.

The different brain areas which comprise these networks communicate with each other via axons, the part of the cell which allows neurons to send electrical impulses to each other. Recent advances in neuroimaging techniques have shown that TBI results in damage to axons, and depending on where in the brain the damaged axons lie, damage to one of these networks, which, in turn, will result in specific deficits.

photo credit: Brain Animation via photopin (license)
photo credit: Brain Animation via photopin (license)
A New Approach to Diagnosing TBI

Since the mid-1970’s the severity of TBI has been diagnosed using The Glasgow Coma Scale (GCS). The GCS measures eye opening, verbal response, and motor response. The test is objective and correlates well with outcomes following severe TBI. It does not, however, predict the specific deficits that will develop in a brain injury survivor. In one recent study, researchers  propose moving away from using the GCS to indentifying the structural and functional integrity of each of the interconnected brain region. If damage is seen in a specific integrated brain region, then treatment can be better targeted and started earlier to deal with the specific deficits that will arise because of the location of the damage.

In a future post we will discuss new neuroscience research on interconnected brain regions and how this can be translated into effective interventions for TBI.

Since acquiring her traumatic brain injury in 2011, Sophia has educated herself about TBI. She is interested in making research accessible to other survivors.