Brain Injury: New Hope From a Study

An Italian study, funded by the EU, sheds new light on what happens after a brain injury: part of the brain goes to sleepso being able to ‘awaken’ dormant areas would improve the effectiveness of rehabilitation interventions. The work, published in ‘Nature Communications’, is signed by international doctors and scientists coordinated by Marcello Massimini, professor of Physiology at the University of Milan, and integrates literature data with the first evidence emerging from the Nemesis project (Neurological Mechanisms of Injury and Sleep-like cellular dynamics), winner in 2022 of a Synergy Grant worth over 10 million euros from the European Research Council (ERC).

The study suggests that part of the functional deficits resulting from structural damage to the brain, whether ischemic, hemorrhagic or traumatic, is due to the fact that areas of the cerebral cortex adjacent to or connected to the lesion they fall into a sleep-like statewhile the patient is awake. “The consequences of focal brain lesions go well beyond the damage caused directly by the loss of neurons,” explains Massimini. “Already in 1914,” he recalls, “the neurologist Constantin Von Monakow had intuited how neurological symptoms could depend to a large extent on a remote effect of local damage on the activity of distant brain areas. This is a significant fact,” the professor emphasizes, “because while it is difficult to repair structural damage, functional alterations of brain networks can in principle be corrected.” After a century, Von Monakow’s hypothesis was confirmed by recordings made with modern neuroimaging techniques: a focal lesion to the brain is associated with widespread alterations of brain networks and these functional alterations explain the symptoms. However, the neuronal mechanisms of these alterations were not known.

In the new study – they report from UniMi – the authors started from an ancient and somewhat forgotten notion, that of the presence of slow electroencephalographic waves, similar to those of sleep, in the area of ​​the lesion. Reviewing this observation in the light of recent electrophysiological investigations, it clearly emerges that these waves reflect the intrusion of cortical dynamics similar to those of sleep during wakefulness. In their work the researchers illustrate how these dynamics are generated and how they can lead to a disintegration of brain networks and behavioral deficits. Finally, they outline a scenario in which “post-lesion slow waves can be modulated to ‘wake up’ parts of the brain that have fallen ‘asleep’thus optimizing rehabilitation strategies and promoting recovery.”