Sooraj Shah ’24
The discussion of brain injury, particularly in contact sports such as boxing or football, has grown in importance as more and more former athletes speak out on the lingering effects years after retirement. The discovery of CTE (chronic traumatic encephalopathy) in 2002 marked the beginning of increased attention and research into traumatic brain injuries (TBI). While CTE was found to spread throughout layers of the cortex over time, short-term effects of brain function in reaction to injury had not yet been explored. A study led by Dr. Sima Mofakham, a professor in the Department of Surgery, and Dr. Charles Mikell, a professor in the Department of Neurosurgery at the Renaissance School of Medicine at Stony Brook University, focused on investigating the role of the thalamus in the brain as an activator of cortical neuron configurations.
For the study, 15 patients with TBI over the age of 18 were identified, all of which were assessed with the Glasgow Coma Scale (GCS). The GCS measures the level of a person’s consciousness after a brain injury. A score under 8 indicates TBI. Electroencephalography (EEG) readings of the scalp were taken as patients recovered for 40 minutes each. There were two outcomes considered: an outcome where patients were able to follow verbal directions within 2 months of the injury was positive, while a negative outcome included those who experienced death or unconsciousness for more than 2 months. Patients’ thalamo-prefrontal circuit integrity, or activity of the thalamus in the brain, was measured using fractional anisotropy (FA) which can detect microscopic changes in thalamic activity. Patients were then grouped based on FA values, where a low FA corresponded with poor thalamic activity while a high FA value corresponded with better activity.
The results showed that thalamic activity controls cortical assemblies – large populations of neurons – thereby controlling cognitive function and response. The absence or disruption of thalamic input results in these cortical assemblies to remain in an attractor state. The attractor state is defined as when the behaviors and different brain states are limited due to the cortical network being restricted to repetitive activity. This repetitive action results in predictable behavior, as repetitive cortical activity limits the patient’s cognitive ability to respond in a variety of ways. The presence of cortical attractors also reveals that the thalamocortical interactions may play a role in the unpredictable behaviors associated with the conscious state as well. The focus of future research will reveal the exact role the thalamus plays in conscious behavior, the applications of which may be in patients with a history of brain injury exhibiting unpredictable behavioral symptoms for treatment.
 S. Mofakham, et al. Injury to thalamocortical projections following traumatic brain injury results in attractor dynamics for cortical networks, Progress in Neurobiology, 210, (2022). doi: https://doi.org/10.1016/j.pneurobio.2022.102215.