Research in Medicine

Background : Evidence indicates that the orbitofrontal cortex (OFC) in the brain is probably invoemotional learning. The aim of the present study is to evaluate the role of OFC on spatial memory in dark and light area in rotation arena in place avoidance learning model.

Material and methods : Long-Evans strain rats (280-300gr) were surgically implanted bilaterlved in ally with cannulae aimed at the OFC and were trained to avoid a 60 degree segment of the arena entering which was punished by mild foot shock. The punished sector was defined by room cues during rotation in the light and by the floor cues in the dark. Place avoidance training occurred in a single 30- min session and the avoidance memory was assessed during a 30-min extinction trial 24 h later. The time to the first entry and the number of entrances into the punished sector during extinction were used to measure the place avoidance memory. Bilateral injections of Tetrodotoxin (5 ng/ml per side) was used to inactivate the OFC 60 min prior to acquisition, immediately after training, or 60 min before the retrieval test. Control rats received saline with the same volume that was injected at the same time.

Results : The results indicated that acquisition and consolidation of spatial memory in dark and light area was impaired (p<0.01). But retrieval was not impaired in either task (p>0.05).

 Conclusion : We conclude that the OFC modulates spatial memories formed within representations of space that depend upon dark and light information.