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The Brain : Concussion
CHAPTER 5. DIAGNOSING CONCUSSION concussion, as well as in the following weeks and months. Specifically, she has been examining brain networks, which are the different patterns of activity associated with different brain functions. There are networks in the brain that are engaged during different activities, for example, during movement or emotional responses. The symptoms in diseases such as Alzheimer’s and schizophrenia result from disruption to these networks. For concussion, research is showing a similar brain network disruption, but one network in particular is affected. It’s known as the ‘default mode’ network and it’s the one that’s most active when our brain is in what could be called ‘idling mode’. We don’t yet understand why this network is so important, or why it is particularly badly affected by concussion. But, says Dr Nasrallah, changes to this network are apparent soon after concussion. For her work on brain networks she’s been using laboratory mice, which provide good clues to what’s going on in our brains because like us they’re mammals. Dr Nasrallah has also been gathering information about what happens inside the heads of military personnel exposed to blast injuries, when they’re not close enough to be knocked over but close enough to feel shock waves, which may shake the brain about inside the skull. PET Positron emission tomography (PET) is a form of imaging that uses a radioactive tracer to highlight certain types of material in the brain. For concussion, it’s being used to study the development of abnormal tau tangles. These are known to be a feature of chronic traumatic encephalopathy (CTE), which is a form of dementia associated with repeated concussions . A US study of former NFL players suspected of having CTE used PET to generate maps of how tau tangles were distributed through the brain. Firstly, these tangles were confirmed to be absent from the brains of people who hadn’t played football. In the ex-footballers the tangles were present and appeared to follow a particular pattern of formation. They appeared THE MESSAGE Brain imaging studies are helping us understand what is going on in the brain during concussion. It’s also hoped they might show characteristic changes with concussion or CTE that can be used to diagnose these conditions and monitor recovery. The reality is that what researchers are likely to find are a series of indicators that can be used by doctors in combination with clinical assessments to make a diagnosis of concussion and assess the recovery time required. That will enable doctors to predict who is more likely to suffer long- term consequences from concussion and allow them to intervene early to prevent or limit the damage. first in the midbrain region, then moved to subcortical areas and the part of the brain that controls anxiety and stress, and finally showed up in the cortex. This was in contrast to what is seen in Alzheimer’s patients, where tau tangles appear first in two areas: the hippocampus and the entorhinal cortex, which are both important in memory and navigation.
Learning and Memory