Cognitive evaluation of traumatically brain-injured rats using serial testing in the Morris water maze.
OBJECTIVE
As deficits in memory and cognition are commonly observed in survivors of traumatic brain injury (TBI), causing reduced quality of life for the patient, a major goal in experimental TBI research is to identify and evaluate cognitive dysfunction. The present study assessed the applicability of the serial Morris water maze (MWM) test to determine cognitive function following experimental TBI in the same group of rats which is particularly important for long-term studies and increasingly valuable for the evaluation of novel treatment strategies.


METHODS
Male Sprague-Dawley rats (n = 27) were anesthetized and subjected to either sham injury (n = 9) or lateral fluid percussion (FP) brain injury of moderate severity (n = 18). At 4 weeks post-injury, animals were trained in a water maze over 3 days (acquisition/learning phase) to find a submerged platform. At 8 weeks post-injury the hidden platform was then moved to the opposite quadrant, and animals were trained to find the new position of the platform over 3 days. Forty-eight hours later, animals were tested for memory retention in a probe trial in which the platform was not present.


RESULTS
Brain-injured animals had significant learning impairment (p < 0.0001), shifted-learning impairment (p < 0.001) and memory retention deficits (p < 0.01) in comparison to their sham-injured counterparts over the 8 week testing period. Swim speed and distance were not significantly altered by brain injury at any time point.


CONCLUSIONS
The validation of this testing paradigm using a clinically relevant experimental brain injury model is an important addition to behavioral outcome testing.
Thompson
Hilaire J
HJ
Traumatic Brain Injury Laboratory, Department of Neurosurgery, The University of Pennsylvania, Philadelphia, PA, USA. hilairet@u.washington.edu
LeBold
David G
DG
Marklund
Niklas
N
Morales
Diego M
DM
Hagner
Andrew P
AP
McIntosh
Tracy K
TK
D000818:Animals; D001522:Behavior, Animal; D001930:Brain Injuries / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology*; D004195:Disease Models, Animal; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors