title: Multiple head injuries in rats: effects on behavior.
abstract: BACKGROUND
  Evidence suggests that mild head injuries in humans can result in cumulative damage. No investigation to date has considered the effects of multiple subacute mild head injuries in an animal model.
  
  
  METHODS
  Forty-one male Long-Evans hooded rats were trained in a Morris water maze. All animals were fitted with a hollow intracranial screw. Concussions were generated using a fluid percussion device. Animals were then evaluated in the water maze until performance returned to baseline. Control animals received no concussions. The remaining animals were randomized to receive one, two, or three concussions. Animals were allowed to return to baseline after each concussion and were then killed. Motor performance was evaluated on a balance beam both before and after concussions.
  
  
  RESULTS
  After one concussion, 85% of animals showed performance deviation from baseline as measured by time to reach the platform, returning to baseline within a mean of 14.0 trials. After two concussions, 48% of animals showed deviation, with a mean return to baseline of 6.8 trials. After three concussions, 25% of animals showed deviation, with a mean return to baseline of 2.3 trials. Of postconcussive animals, 42% developed new inconsistent baseline levels of performance. Balance beam performance was unaffected.
  
  
  CONCLUSIONS
  Multiple concussions cause immediate transient impairment in spatial recognition and have extended effects on baseline performance in rats. Motor performance is not affected.
authors.affiliation: Department of Surgery, University of Vermont, Burlington, Vermont, USA.
authors.forename: Anthony L
authors.initials: AL
authors.lastname: DeRoss
authors.forename: Julie E
authors.initials: JE
authors.lastname: Adams
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Vane
authors.forename: Sheila J
authors.initials: SJ
authors.lastname: Russell
authors.forename: Adam M
authors.initials: AM
authors.lastname: Terella
authors.forename: Steven L
authors.initials: SL
authors.lastname: Wald
mesh_terms: D000818:Animals; D001924:Brain Concussion / Q000523:psychology*; D008297:Male; D023421:Models, Animal; D009043:Motor Activity / Q000502:physiology*; D009104:Multiple Trauma / Q000523:psychology*; D011897:Random Allocation; D051381:Rats; D020318:Rats, Long-Evans; D013037:Spatial Behavior / Q000502:physiology*; D013550:Swimming