Despite its high frequency of occurrence, mild traumatic brain injury (mTBI), or concussion, is difficult to recognize and diagnose, particularly in pediatric populations. Conventional methods to diagnose mTBI primarily rely on clinical questionnaires and sometimes include imaging such as computed tomography (CT) or pencil and paper neuropsychological testing. However, these methods are time consuming, require administration/interpretation from health professionals, and lack adequate test sensitivity and specificity. We explore the use of BrainCheck, a computerized neurocognitive test that is available on iPad, iPhone or computer desktop, for mTBI assessment. The BrainCheck battery consists of 6 gamified traditional neurocognitive tests that assess areas of cognition vulnerable to mTBI such as attention, processing speed, executing functioning, and coordination. We administered BrainCheck to 25 participants diagnosed with mTBI at the emergency department (ED) of Children’s hospital within 96 hours of admittance to the ED, and 153 normal controls at a local high school. Statistical analysis included Chi-Square tests, Analysis of Variance (ANOVA), independent sample t-tests, and Hochberg tests to examine differences between mTBI, diagnoses by current gold standard clinical exam, and control groups on each assessment in the battery. Significant metrics from these assessments were used to build a logistic regression model that distinguishes mTBI from non-mTBI participants. Receiver operator score (ROC) analysis of our logistic regression model found a sensitivity of 84% and specificity of 80%. BrainCheck has potential in distinguishing mTBI from non-mTBI participants, by providing a shorter, gamified test battery to assess cognitive function after brain injury, while also providing a method for tracking recovery with the opportunity to do so remotely from a patient’s home.

Leigh syndrome (LS) is a pediatric form of mitochondrial disease which affects the central nervous system (CNS). LS is partly characterized by symmetric necrotizing lesions in the brainstem and cerebellum. Our laboratory utilizes the Ndufs4 (KO) mouse model of LS, as it closely resembles human LS, including the characteristic CNS lesions and the age of onset of disease. Ndufs4, which is also a causal LS gene in humans, is deleted in these mice. In addition to progressive CNS lesions, the Ndufs4 (KO) mice show ataxia and weight loss, and death occurs at a median of 55 postnatal days of age. Information regarding the temporal specificity and mechanisms underlying the pathogenesis of CNS lesions are unknown. Previously, our laboratory has discovered that the loss of Ndufs4 in the VGlut2 expressing glutamatergic neurons drives the CNS lesions and the aforementioned phenotypes of the KO mice. In order to characterize the early events in lesion formation in the CNS, we assess necrosis in the major cell types including VGlut2, GFAP, and Gad2 using GFP reporter lines. This is done by staining and imaging by confocal microscopy of the brain tissue of both the Ndufs4 (KO) and control mice from the cell-type specific GFP reporter lines at postnatal days 30 and 55, corresponding to pre- and post- disease respectively. Additionally, we will be collecting data from mice in more age groups, including at 25, 35, and 45 postnatal days of age. We expect that this will allow us to determine how defects in mitochondrial function lead to diseases such as Leigh Syndrome with tissue, region, and temporal specificity, and in turn, may allow a proposal for Leigh Syndrome treatment.

Traumatic brain injury (TBI) refers to brain damage resulting from an external force resulting in temporary or permanent impairment of cognitive, physical, and psychosocial functions. Following TBI, widespread neuronal loss occurs, and ischemic and inflammatory processes can greatly increase the extent of neural injury beyond the initial mechanical injury. Microglia are specialized immune cells in the brain that constantly surveil the extracellular environment and respond rapidly to damage by proliferating, phagocytosing debris, and releasing cytokines and chemokines that orchestrate recruitment and regulation of peripheral immune cells to the injured brain post-TBI. With the emergence of chemogenetics, a method by which engineered proteins interact with previously unrecognized chemical activators, inhibitory control can be exerted over microglia activation in a highly specific fashion allowing for precise targeting of brain regions and fewer off-target effects relative to traditional pharmacological approaches. The Weinstein lab aims to examine the effects of targeted inhibition of microglia activation using G-protein coupled receptors called Designer Receptors Exclusively Activated by Designer Drugs (DREADDs). Normally, following traumatic brain injury, the CD68 promoter region is upregulated, resulting in increased microglia expression. However, the inserted HM4Di DREADD gene utilizes this promoter to express the DREADD receptor, and the downstream effects result in neural inflammatory response inhibition. We hypothesize that microglial inhibition will reduce proliferation and local cytokine levels after TBI, thus modulating the inflammatory microenvironment, especially when inhibition is initiated early after TBI. To determine efficacy of DREADDs, we quantify microglia number and proliferation using immunohistochemistry and stereology. We use computer software to capture multi-channel fluorescent images and montages for use in cell counting following stereological methods for random, unbiased sampling of cortical tissue across the TBI epicenter and penumbra. We anticipate that regions expressing activated DREADDs, which should inhibit microglial activation, will have reduced microglia post-TBI relative to controls.