Page 89 - NNS 2014 Program & Abstract Book

via the Schaffer collateral (SC) pathway, using 100Hz tetanic con-
stant-current stimuli. Potentiation was calculated as the change in
average response over the last 10 minutes of post-LTP recordings
divided by the average response over the last 10 minutes of pre-LTP
recordings.
After blast injury, in response to mossy fiber (MF) pathway stimu-
lation, S/R activity was slightly decreased in CA1 and CA3 regions. No
changes were seen with SC stimulation. After moderate blast injury, PP
ratios at shorter ISIs were marginally increased. However, long-term
potentiation was completely disrupted after both mild (-8 – 3%) and
moderate blast (8 – 5%), when compared to sham exposure (53 – 9%).
In previous studies, mild blast exposure did not cause cell death
[Effgen GB, J.Neurotrauma, 2014]. We conclude that primary blast
injury eliminates LTP, even without cell death, while leaving other
measures of evoked activity largely unchanged. LTP deficits may
explain memory loss commonly observed in TBI patients. Future
research will elucidate the mechanisms responsible for the disruption
of LTP following primary blast injury.
Key words
blast, in vitro, TBI
B3-05
ELECTROPHYSIOLOGICAL EVIDENCE OF AUDITORY
AND COGNITIVE DYSFUNCTION IN VETERANS EXPOSED
TO HIGH-INTENSITY BLASTS
Folmer, R.L.1,2, Hutter, M.1 , Belding, H.1, Papesh, M.1, Grush, L.3,
Leek, M.4, Gallun, F.1,2
1NCRAR, Portland VA Medical Center, Portland, OR, USA
2Oregon Health & Science University, Department of Otolaryngology,
Portland, OR, USA
3University of Colorado, Boulder, CO, USA
4VA Loma Linda, Loma Linda, CA, USA
During the recent conflicts in Afghanistan and Iraq (Operation Iraqi
Freedom/Operation Enduring Freedom/Operation New Dawn [OIF/
OEF/OND]), many service members have been exposed to high-
intensity blasts, which often cause traumatic brain injuries (TBI). The
Department of Veterans Affairs estimates the prevalence of TBI in the
OIF/OEF/OND Veteran population to be 7.8 percent. Many of these
blast-exposed Veterans experience multiple post-injury deficits, in-
cluding auditory processing disorders and cognitive dysfunction. The
objective of this study is to use event-related potentials to assess
auditory and cognitive processing abilities in this population. Several
different types of auditory event-related potentials (AERPs) were used
to evaluate Veterans who were exposed to high-intensity blasts during
military service within the last 10 years. AERPs included auditory
brainstem responses (ABRs) to click stimuli and long-latency re-
sponses to tonal, dichotic and speech stimuli. Responses recorded
from blast-exposed Veterans were compared with responses from age-
matched and older control subjects who have not experienced neu-
rological injuries. ABRs from the subject population did not differ
significantly from those recorded from control subjects. This suggests
that auditory processing at the level of the brain stem was not affected
by blast exposure. However, long-latency AERPs recorded from blast-
exposed Veterans had greater latencies and smaller amplitudes com-
pared to those recorded from age-matched control subjects. These
electrophysiological results are consistent with behavioral deficits in
auditory and cognitive processing exhibited by the injured Veterans.
Abnormal long-latency AERPs recorded from blast-exposed Veterans
might indicate damage to cortical structures and networks responsible
for higher-level auditory and cognitive processing. Unfortunately,
these deficits persist for many years after the initial injury, which
could accelerate the aging process of some affected brains.
Key words
auditory brainstem response, auditory processing, event-related po-
tentials, N200, P300
B3-06
VISUAL PRIMING ENHANCES THE EFFECTS OF NON-
SPATIAL COGNITIVE REHABILITATION TRAINING ON
SPATIAL LEARNING AFTER EXPERIMENTAL TBI
Kumar, K.1, Brough, E.1, Koesarie, K.1, Zou, H.1,4, Brayer, S.1,4, Thiels,
E.2,5, Skidmore, E.3, Wagner, A.1,4,5
1Physical Medicine & Rehabilitation, Univ. Pittsburgh
2Neurobiology, Univ. Pittsburgh
3Occupational Therapy, Univ. Pittsburgh
4Safar Center for Resuscitation Research, Univ. Pittsburgh
5Center for Neuroscience, Univ. Pittsburgh
Our previous work shows spatial (explicit) and non-spatial (implicit)
elements involved with place learning in the Morris water maze
(MWM) task can be dissociated and examined in the context of ex-
perimental traumatic brain injury (TBI). Also, the provision of non-
spatial cognitive training (CT) post-TBI improves place learning
versus untrained injured controls. Visual priming strategies are known
clinically to facilitate implicit learning. Thus we hypothesized that a
non-contextualized, brief exposure to extra-maze cues, in conjunction
with non-spatial cognitive training, may further improve MWM per-
formance and extra-maze cue utilization compared to non-spatial
training (no extra-maze cues priming). Adult male Sprague-dawley
rats (n = 66) received controlled cortical impact (CCI) injury or sham
surgery. Beginning d8 post-surgery CCI and Sham rats were exposed
for 6d to no training (NT) or cognitive training with/without brief non-
contextualized exposure to extra-maze cues (CT versus BE). Acqui-
sition trials (D14-18), Visible Platform (VP) (D19), and carryover
[D20-26)] trials were performed. Platform latencies and time spent
swimming the pool peripheral zone were assessed. CCI-BE rats out-
performed CCI-NT (p < 0.001) and CCI-CT rats (p = 0.054) with ac-
quisition trial latencies. Major latency reductions for CCI-BE versus
CCI-CT occurred D14-D15 (p < 0.001 both comparisons). CT reduced
peripheral zone swimming for CCI rats, but BE did not further reduce
swimming beyond the effects of CT. No differences with VP or
carryover trials were identified for CCI-BE versus CCI-CT, though
CCI-NT rats performed similar to CCI-CT/BE rats during carryover
trials. These data suggest that visual priming may increase CT ef-
fectiveness for initial place learning performance in the MWM, and
suggest visual priming response as another translationally relevant
experimental rehabilitation construct from which to assess aging and
sex differences, as well as pharmacotherapies on cognition after TBI.
Key words
cognitive training, traumatic brain injury, visual priming
B3-07
DIFFERENCES IN SYMPTOM SEVERITY IN MTBI PA-
TIENTS WITH AND WITHOUT PTSD
DeGraba, T., Williams, K., Caban, J., Bleiberg, J., Grammer, G.,
Kelly, J.
National Intrepid Center of Excellence, Bethesda, USA
A-57