Traumatic brain injury produces impairments in long-term and recent memory

Traumatic brain injury (TBI) in humans typically produces neurological suppression and a longer lasting impairment of memory clinically defined as post-traumatic amnesia. An animal model that reliably reproduces the physiological changes associated with TBI was used to assess the memory deficits following brain injury. Prior to TBI, rats were trained to perform one of four tasks that assessed either motor performance, long-term or recent memory. Rats were randomly assigned to one of three groups (anesthesia only, sham operation or fluid percussion). Following fluid percussion, used to produce TBI, rats were tested for 6 test sessions. The first session occurred 1-2 min after the experimental manipulation. The next 5 sessions followed the training schedule maintained prior to experimental manipulation. Differences in long-term memory occurred only in the first post-operative test session. Differences in recent memory performance were found across all 6 test sessions. The memory deficits were clearly dissociated from motor deficits. The similar memory deficits observed following human head injury and the experimentally produced TBI injury demonstrate that fluid percussion is a useful approach to examine underlying neurobiological mechanisms involved in head injury and possible clinical interventions.