Page 96 - NNS 2014 Program & Abstract Book

profile of functional deficits. These data highlight the vulnerability of the
adolescent brain to even a single concussive insult which does not
produce pathological hallmarks traditionally associated with brain in-
jury. Ongoing studies aim to evaluate whether reduced activity reflects
changes in depressive or anxiety-like behaviors. Support: Private donor.
Key words
adolescence, behavior, concussion, hypoactivity, mild brain injury
B4-14
PEDIATRIC POST-CONCUSSION SYMPTOMS ARE ASSO-
CIATED WITH REDUCED CORTICAL COMMUNICATION
AS DETECTED WITH NEAR-INFRARED SPECTROSCOPY
Urban, K.J., Barlow, K.M., Jimenez, J.J., Goodyear, B.G., Dunn, J.F.
University of Calgary, Department of Neuroscience, Calgary, Canada
Traumatic brain injury (TBI) is the leading cause of injury under the
age of 25. Its pathophysiology is poorly understood and it is difficult
to detect with standard imaging methods. Functional near-infrared
spectroscopy (fNIRS) is an inexpensive and portable technology with
high temporal resolution, and can detect changes in hemoglobin as-
sociated with cortical brain activity. This project aimed to determine if
fNIRS could detect reduction in functional coherence in pediatric
mTBI patients with chronic symptoms as a marker of impaired in-
terhemispheric communication associated with brain injury.
Twelve patients (age 15.2 – 1.9 years, six males) with chronic
mTBI symptoms (average time since injury = 179 days) and eight
healthy control subjects (age 14 – 2.2, five males) were recruited.
Using a continuous wave mapping system (CW5, TechEn, Inc.,
Milford, MA), fNIRS data were recorded from the motor cortices for
five minutes each of rest, and finger tapping task activation. Data from
the source-detector pair over the left hemisphere that exhibited the
greatest increase in oxyhemoglobin during finger tapping was taken as
a frequency reference for coherence analysis. Values were averaged
over each of the ipsilateral and contralateral hemispheres.
During finger tapping there was no difference in magnitude of ac-
tivation of total and oxy-hemoglobin. Resting-state coherence did not
differ between mTBI patients and controls. Coherence for mTBI was
initially lower in all parameters except in the ipsilateral side during
task activation. Coherence during finger tapping was significantly
reduced for mTBI patients in both the ipsilateral (p < 0.01) and con-
tralateral (p < 0.001) hemispheres, compared with controls.
Reduced coherence between the motor cortices is consistent with im-
paired communication and may reflect damage to communicating fiber
tracts. fNIRS provides a newnon-invasivemethod to study brain functional
impairment associated with mTBI. The study illustrates chronic functional
impairments following mTBI’s and further studies should investigate
whether coherence continues to be altered with symptom resolution.
Key words
brain connectivity, concussion, mild traumatic brain injury, near in-
frared spectroscopy
B4-15
MIDLINE FLUID PERCUSSION INJURY IN THE DEVELOP-
ING RODENT RESULTS IN DIFFUSE INJURY AND DEVIA-
TION OF THE NEUROVASCULAR UNIT
Ellis, T.W.1–3, Rowe, R.K.2–4, Harrison, J.L.2,3,5, Ziebell, J.M.2,3,
Adelson, P.D.2,3,5, Lifshitz, J.2–4
1Midwestern University, College of Health Sciences, Glendale, USA
2BARROW Neurological Institute at Phoenix Children’s Hospital,
Phoenix, USA
3University of Arizona College of Medicine Phoenix, Department of
Child Health, Phoenix, USA
4Phoenix Veteran Affairs Healthcare System, Phoenix, USA
5Arizona State University, Interdisciplinary Program in Neuroscience,
Phoenix, USA
Juvenile diffuse traumatic brain injury (jTBI) leaves survivors facing
a lifetime of potential neurological symptoms. Pathology across the
neurons, glia and vasculature of the neurovascular units (NVU)
likely underlie the symptomatology and serve as potential thera-
peutic targets. We hypothesize that diffuse jTBI in the rat (post-natal
day 17) results in a deviation of the NVU from the natural devel-
opment in uninjured animals over 28d post-injury and across brain
regions. Moderate jTBI was induced by midline fluid percussion
injury (1.4atm) and verified by the clinical endpoints of righting
reflex suppression, seizure and apnea. Unlike in older rats, righting
reflex was inconclusive in juveniles, but 87% experienced seizures
(72 – 9s), and 77% experienced apnea (31 – 7s). All brain-injured
animals presented with hematoma and herniation, followed by
stunted weight gain, evident through 28d post-injury. At 2 h, 1d, 7d,
and 28d post-injury, tissue was examined for components of the
NVU. Similar to MRI following clinical diffuse injury, H&E stain-
ing confirmed jTBI without overt damage or cavitation. IgG ex-
travasation showed vasculature damage in the cingulate and motor
cortices indicating permeability of the blood brain barrier at 2 h and
1d with resolution by 7d post-injury. Astrocyte (GFAP) and micro-
glia (Iba-1) activation were observed following injury in the same
regions as IgG and returning to sham-level by 28d post-injury. In
conclusion, we have developed a clinically relevant model of diffuse
jTBI to investigate neurological deficits associated with the cingu-
late and motor cortices, while screening therapeutic treatments as-
sociated with the NVU.
Funding: PCH Mission Support Funds
Key words
diffuse brain injury, midline fluid percussion injury
B4-16
ELECTROPHYSIOLOGICAL SIGNATURES OF JUVENILE
MILD TRAUMATIC BRAIN INJURY DURING NOVEL OB-
JECT RECOGNITION
Biswas, C. , Hokhikyan, V., Karkare, V.P., Segal, A., Giza, C.C.,
Markovic, D., Cai, Y., Hovda, D.A.
University of California, Los Angeles, Los Angeles, USA
Mild traumatic brain injury (mTBI) acquired through various ci-
vilian and military impacts affects *40% of 1 million juvenile
patients annually in the USA. Despite numerous studies on neu-
roplastic changes caused by a single incidence of mTBI, few have
attempted to directly correlate the longitudinal process of functional
recovery with repeat performance at a hippocampally-centered working
memory task. We studied concurrent behavior and electrophysiology in
juvenile, male Sprague-Dawley rats implanted with four hippocampal
electrodes and a miniature extra-cranial wireless transceiver system to
elicit cross-frequency coupling in local field potentials (LFPs) and thus
establish the signature of injury. We monitored untethered animals
demonstrating stereotypical behaviors during repeated assignments
of the stressor-free novel object recognition (NOR) task during
three weeks following fluid-percussion injury at PND35, compar-
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