The pathophysiology of traumatic brain injury (TBI) includes perturbations to energy metabolism. Improving our understanding of cerebral energy metabolism will lead to strategies that improve clinical outcomes. For the studies in my thesis I used microdialysis to deliver carbon-13 labelled substrates to the human brain. I combined this with nuclear magnetic resonance (NMR) spectroscopy of interstitial fluid sampled from the brain to interrogate glucose, lactate and tricarboxylic acid (TCA) cycle metabolism. Study I: I defined the optimal parameters for quantitative proton and carbon-13 NMR of cerebral microdialysates. Study II: I measured baseline microdialysate metabolite concentrations for brain and muscle and investigated the influence of muscle activity and cerebral catheter placement in grey or white matter on metabolite concentrations. Study III: I used 1,2-13C2 glucose to measure glycolysis and pentose phosphate pathway activity. Glycolysis is the dominant lactate-producing pathway but the pentose phosphate pathway also contributes and is increased in some TBI patients. Study IV: I used arterio-venous gradients to measure glucose and lactate delivery to the brain. There are periods after injury when lactate is imported from the circulation despite relatively high brain lactate levels suggesting up-regulation of lactate transport. Study V: I followed the metabolism of 3-13C lactate and demonstrated that lactate is metabolised by the TCA cycle. This occurs in both normal and injured brain but not in muscle. Study VI: I used 2,3-13C2 succinate to investigate the role of the TCA cycle in producing metabolites that are exported into the interstitium. The TCA cycle is found to be a source of lactate. Succinate delivered to the brain improves redox and enhances glutamate uptake into cells. The implications of the findings in my thesis on existing knowledge of cerebral metabolism are discussed. Strategies that might potentiate cerebral metabolism and improve clinical outcomes are suggested.

Traumatic Brain Injury (TBI) is a leading cause of death and disability in the United States for which there are no federally approved pharmacological treatments. Preclinical trials with nicotinamide (NAM) and progesterone (Prog) treatment demonstrate beneficial neuroprotection and recovery of function following TBI. The primary goal of this study was to assess both neuroprotection and recovery of function in an animal model of TBI after combination treatment of both NAM and Prog. Animals received a cortical contusion injury over the sensorimotor cortex and were treated with either nicotinamide (75 mg/kg, i.p. NAM loading dose, 12 mg/kg/hr NAM, s.c. over 72 hrs), Prog (10 mg/kg Prog, i.p. over 72 hrs), NAM and Prog(75 mg/kg, i.p. NAM loading dose, followed by continuous infusion of 12 mg/kg/hr NAM, s.c. over 72 hrs; 10 mg/kg Prog, i.p. over 72 hrs) or Vehicle (75 mg/kg, i.p. sterile saline loading dose, followed by continuous infusion 12 mg/kg/hr sterile saline, s.c. over 72 hrs; 10 mg/kg peanut oil, i.p. over 72 hrs), and compared to a craniotomy only (Sham) group. Following this regimen they were assessed in a battery of behavioral (fine and gross motor, sensory, and cognitive) tasks or a histological assessment at 24 hrs post-injury assessing lesion cavity size, degenerating neurons, and reactive astrocytes. Our results replicate the beneficial effects of treatment with either NAM or Prog demonstrating significant improvements in recovery of function, and a reduction in lesion cavitation, degenerating neurons and reactive astrocytes 24 hours post-injury. The combination treatment of NAM and Prog led to a significant improvement in both neuroprotection at 24 hrs post-injury and recovery of function in sensorimotor related tasks when compared to each individual treatment (NAM or Prog). It is suggested here that further preclinical trials using NAM and Prog as a combination treatment should be done to identify any drug interactions, pharmacokinetics, and a new window of opportunity and proper dosing of this combination treatment.

Traumatic brain injury (TBI) is a serious problem facing the medical community. Every year, over 1.7 million TBIs occur in the United States alone (CDC, 2010). Over 25 years of research and 21 major clinical trials have failed to yield a pharmaceutical treatment for this complicated injury (Maas et al., 2007). One of the possible reasons for the many clinical failures is a lack of behavioral assessment at the level of animal models. In particular, there is typically only one type of cognitive measure employed in most studies, usually a measure of spatial learning (e.g. Morris water maze). In other fields, alternative measures have been utilized for many years, including non-spatial discriminations. The primary goal of this study was to evaluate the use of a visual discrimination in a model of frontal TBI and determine whether or not administering a neuroprotectant could alleviate deficits in discrimination. Long-Evans rats were trained on a simple visual discrimination task and a progressive ratio schedule of reinforcement (PR). After assessing their baseline discrimination performance, motor ability and PR performance, they were advanced to surgery and given either a bilateral frontal controlled cortical impact TBI or sham procedure. Following TBI, injured rats were given either doses of the neuroprotectant nicotinamide (NAM; 150 mg/kg, i.p.) or a saline solution (1 ml/kg, i.p.). They were then assessed for 35 days on the discrimination and progressive ratio. On days 7, 14 and 27, motor abilities were assessed in automated motor activity monitors. On days 15-18 and 21-23 post-surgery, rats were also assessed on the Morris water maze (MWM). On day 43 post-surgery, rats were transcardially perfused and brains extracted. Brains were briefly post-fixed and then sliced on a sliding microtome at 40 µm. These slices were then mounted to slides and stained with cresyl violet to examine the extent of the lesion. Brain injury impaired performance on the discrimination task and PR task. In the discrimination task, deficits were primarily driven by an inability to complete chains of responses. On the PR task, deficits were characterized by reduced break points and low rates of responding. Administration of NAM reduced deficits in discrimination and PR performance. There were no gross motor deficits as a result of the injury. On the MWM task and measures of lesion size, there were no improvements due to NAM administration. Based on the outcome of this study, operant measures such as discrimination or progressive ratio could be incorporated into the testing battery for experimental TBI. Despite some of the challenges of adapting tasks designed for single-subject analysis, it is well worth the time spent due to the robust ability to detect deficits. Additionally, this study showed that nicotinamide administration was neuroprotective across multiple tasks, suggesting that these tasks are indeed well suited for the assessment of pharmacological agents and that nicotinamide has treatment potential for clinical populations.

After sustaining a traumatic brain injury (TBI), a person’s ability to make daily decisions can be affected. Simple tasks such as, deciding what to wear are no longer effortless choices, but are instead difficult decisions. Incorporating behavioral assays that address decision-making skills after TBI can help a pharmacological treatment become easily translatable, as it is specifically assessing a certain aspect of cognitive functioning. Magnesium is a multimodal treatment that can decrease apoptosis, decrease breakdown of the blood brain barrier, and lessen brain edema after a TBI, which can affect the recovery of a patient. A discrimination task was used in conjunction with a magnesium treatment in order to examine how decision-making is affected after TBI and if the treatment helps to attenuate cognitive and motor deficits. Thirty-one male Sprague-Dawley rats (Harlan, Indianapolis, IN) were used and separated into MAG/TBI, VEH/TBI, or VEH/Sham groups. Before induction of a bilateral frontal injury, rats were shaped to learn to dig in the sand for a reinforcer and then pre-trained on the dig task. After surgery, rats received either an i.p. injection of 2 mmol/kg magnesium chloride or 0.1% phosphate buffer solution (PBS). Magnesium injections occurred 4 hours post-surgery, then at 24 hours and at 72 hours. Dig task testing began 7 days post-injury, lasting for 4 weeks. The discriminations included two scent pairings; basil (baited) versus coffee then the reversal and then cocoa (baited) versus cumin then the reversal. The locomotor placing task was conducted in order to assess for the recovery of motor function after TBI. Fear conditioning was also conducted to examine the role of extinction after TBI. The results indicated that the magnesium treatment was successful at attenuating cognitive and motor deficits after TBI. The results also indicated that the dig task is a sufficient operant conditioning task in the assessment of frontal functioning after TBI. The fear conditioning procedures, however, failed to produce significant results. Discrimination testing and a magnesium treatment both have the potential to positively impact the millions of people suffering from a TBI.

Cognitive rehabilitation has been shown to have beneficial effects on functional recovery following traumatic brain injury. In the present study, the rehabilitative effects of cognitive training in the T-maze on functional recovery of behavior and cortical sparing following a cortical impact injury (CCI) were examined. T-maze alternation has a widespread application in detecting cognitive dysfunction, and alternation in particular utilizes working memory. 47 male Sprague-Dawley rats were divided into six groups (sham trained, sham yoked, sham control, injured trained, injured yoked, injured control). Injured animals received a bilateral frontal craniotomy (1.0 A/P, 0.0 M/L from Bregma). The cortices were depressed at a depth of 2.5 mm at a velocity of 3 m/s. T-maze training began on post surgery day 2 and continued daily through post surgery day 19. Following this rehabilitative T-maze training, cognition was assessed using two different memory tasks in the Morris water maze (MWM).

abstract: Adults with a history of traumatic brain injury (TBI) often show deficits in executive functioning, which include the ability to inhibit, switch, and attend to task relevant information. These abilities are also essential for language processing in bilinguals, who constantly inhibit and switch between languages. Currently, there is no data regarding the effect of TBI on executive function and language processing in bilinguals. This study used behavioral and eye-tracking measures to examine the effect of mild traumatic brain injury (mTBI) on executive function and language processing in Spanish-English bilinguals. In Experiment 1, thirty-nine healthy bilinguals completed a variety of executive function and language processing tasks. The primary executive function and language processing tasks were paired with a cognitive load task intended to simulate mTBI. In Experiment 2, twenty-two bilinguals with a history of mTBI and twenty healthy control bilinguals completed the same executive function measures and language processing tasks. The results revealed that bilinguals with a history of mTBI show deficits in specific executive functions and have higher rates of language processing deficits than healthy control bilinguals. Additionally, behavioral and eye-tracking data suggest that these language processing deficits are related to underlying executive function abilities. This study also identified a subset of bilinguals who may be at the greater risk of language processing deficits following mTBI. The findings of this study have a direct impact on the identification of executive function deficits and language processing deficits in bilinguals with a history mTBI. / Dissertation/Thesis / Doctoral Dissertation Speech and Hearing Science 2015

abstract: Pediatric traumatic brain injury (TBI) is a leading cause of death and disability in children. When TBI occurs in children it often results in severe cognitive and behavioral deficits. Post-injury, the pediatric brain may be sensitive to the effects of TBI while undergoing a number of age-dependent physiological and neurobiological changes. Due to the nature of the developing cortex, it is important to understand how a pediatric brain recovers from a severe TBI (sTBI) compared to an adult. Investigating major cortical and cellular changes after sTBI in a pediatric model can elucidate why pediatrics go on to suffer more neurological damage than an adult after head trauma. To model pediatric sTBI, I use controlled cortical impact (CCI) in juvenile mice (P22). First, I show that by 14 days after injury, animals begin to show recurrent, non-injury induced, electrographic seizures. Also, using whole-cell patch clamp, layer V pyramidal neurons in the peri-injury area show no changes except single-cell excitatory and inhibitory synaptic bursts. These results demonstrate that CCI induces epileptiform activity and distinct synaptic bursting within 14 days of injury without altering the intrinsic properties of layer V pyramidal neurons. Second, I characterized changes to the cortical inhibitory network and how fast-spiking (FS) interneurons in the peri-injury region function after CCI. I found that there is no loss of interneurons in the injury zone, but a 70% loss of parvalbumin immunoreactivity (PV-IR). FS neurons received less inhibitory input and greater excitatory input. Finally, I show that the cortical interneuron network is also affected in the contralateral motor cortex. The contralateral motor cortex shows a loss of interneurons and loss of PV-IR. Contralateral FS neurons in the motor cortex synaptically showed greater excitatory input and less inhibitory input 14 days after injury. In summary, this work demonstrates that by 14 days after injury, the pediatric cortex develops epileptiform activity likely due to cortical inhibitory network dysfunction. These findings provide novel insight into how pediatric cortical networks function in the injured brain and suggest potential circuit level mechanisms that may contribute to neurological disorders as a result of TBI. / Dissertation/Thesis / Embargo / Doctoral Dissertation Biology 2015

Consequences of acquired brain injury (ABI) can be life long and complex. The majority of those who sustain an ABI are cared for by family members. Many are young adults who are cared for by parents. A systematic review highlighted that there is little in the way of research that focused on the experience of parent caregivers, particularly in the traumatic brain injury (TBI) population and in the early days of caregiving post discharge from hospital. Method A qualitative design using Interpretative Phenomenological Analysis (IPA) was used. Six participants were recruited; three from the NHS and three from Headway. Results Four superordinate themes emerged: carrying on with the parenting role; barriers to caregiving; factors that engender mastery; and the psychological, physical and social impact on parents. Conclusion The early weeks at home following discharge from hospital are exciting but exhausting and parents were ill-prepared to meet some of the challenges. Parents wanted more TBI specific services for their family members and themselves. Some experienced difficult emotions during the first few weeks at home and so there is a need for regular, on-going input that starts before discharge from hospital. This has relevance for professionals as parents should be involved in the care and decision making from the acute stage onwards as they will be the people assuming responsibility on discharge from hospital. They should be assessed early on to see what psychological or practical support must be in place before their family member leaves hospital.

Class of 2015 Abstract / Objectives: Guidelines from the Brain Trauma Foundation recommend that after traumatic brain injury (TBI) patients should be given seizure prophylaxis for up to seven days. Currently, phenytoin is the first line therapy for this indication. However, levetiracetam is increasingly being used as an alternative because it does not require serum concentration monitoring and has a desirable safety profile. Studies evaluating levetiracetam have used a loading dose, followed by a maintenance dose of 1000 mg every 12 hours. The primary objective of this study was to evaluate the efficacy of low-dose (500 mg every 12 hours) levetiracetam for seizure prophylaxis after TBI. Methods: This was a retrospective cohort study conducted in a tertiary care, academic institution that is designated as a level 1 trauma center. Institutional review board approval was obtained prior to data collection. Consecutive patients with TBI between 2010 and 2012, who received levetiracetam for seizure prophylaxis, were included. Patients who met at least one of the following criteria were included: cortical contusion on computerized tomography scan, subdural hematoma, epidural hematoma, intracerebral hematoma, depressed skull fracture, penetrating head injury, or Glasgow Coma Scale (GCS) of 10 or less. Patients were excluded if they were less than 16 years of age, had a previous head injury, previous neurosurgery, history of seizure, or anti-seizure medication, or were given a loading dose of levetiracetam, or given a maintenance dose greater than 500 mg every 12 hours. The primary outcome was the occurrence of a seizure within seven days of TBI. A one-sample test of proportions was used to compare the rate of seizures while being treated with levetiracetam to a hypothesized value of 3.6 percent (from previous trials), using an a priori alpha for 0.05. Results: There were a total of 146 patients included in the study, who were treated with levetiracetam 500 mg every 12 hours. The median age was 51 years (interquartile range 31 to 65 years), 110 (75 percent) were male, and the median GCS on admission was 11 (interquartile range 5 to 14). The mechanisms of injury were fall (n equals 49), motor vehicle or motorcycle collisions (n equals 42), pedestrian or bicyclist (n equals19), assault (n equals16), suicide attempt (n equals 2), and other (n equals18). The median time to first dose of levetiracetam was 4 hours after injury (interquartile range 1 to 13 hours). After initiation of levetiracetam, there were 5 (3.4 percent) patients who had a seizure within seven days. This was not significantly different than the hypothesized population value (p equals 0.910). The median length of stay was 13 days (interquartile range 9 to 21) and 7 (4.8 percent) patients died during hospitalization. Conclusions: A low-dose of levetiracetam 500 mg every 12 hours after TBI was effective for early seizure prevention. This regimen may be an appropriate alternative to phenytoin or traditional dose levetiracetam for this indication. Future, prospective studies are needed to confirm these findings.

One of the serious public health problems is the Traumatic Brain Injury, also known as silent epidemic, affecting millions every year. Management of these patients essentially involves neuroimaging and noncontrast CT scans are the first choice amongst doctors. Significant anatomical changes identified on the neuroimages and volumetric assessment of haemorrhages and haematomas are of critical importance for assessing the patients’ condition for targeted therapeutic and/or surgical interventions. Manual demarcation and annotation by experts is still considered gold standard, however, the interpretation of neuroimages is fraught with inter-observer variability and is considered ’Achilles heel’ amongst radiologists. Errors and variability can be attributed to factors such as poor perception, inaccurate deduction, incomplete knowledge or the quality of the image and only a third of doctors confidently report the findings. The applicability of computer aided dianosis in segmenting the apposite regions and giving ’second opinion’ has been positively appraised to assist the radiologists, however, results of the approaches vary due to parameters of algorithms and manual intervention required from doctors and this presents a gap for automated segmentation and estimation of measurements of noncontrast brain CT scans. The Pattern Driven, Content Aware Active Contours (PDCAAC) Framework developed in this thesis provides robust and efficient segmentation of significant anatomical landmarks, estimations of their sizes and correlation to CT rating to assist the radiologists in establishing the diagnosis and prognosis more confidently. The integration of clinical profile of the patient into image segmentation algorithms has significantly improved their performance by highlighting characteristics of the region of interest. The modified active contour method in the PDCAAC framework achieves Jaccard Similarity Index (JI) of 0.87, which is a significant improvement over the existing methods of active contours achieving JI of 0.807 with Simple Linear Iterative Clustering and Distance Regularized Level Set Evolution. The Intraclass Correlation Coefficient of intracranial measurements is >0.97 compared with radiologists. Automatic seeding of the initial seed curve within the region of interest is incorporated into the method which is a novel approach and alleviates limitation of existing methods. The proposed PDCAAC framework can be construed as a contribution towards research to formulate correlations between image features and clinical variables encompassing normal development, ageing, pathological and traumatic cases propitious to improve management of such patients. Establishing prognosis usually entails survival but the focus can also be extended to functional outcomes, residual disability and quality of life issues.