On the behavioral significance of head direction cells: Neural and behavioral dynamics during spatial memory tasks

Current theories assume that rats use the directional information reflected by head direction (HD) cells when performing spatial tasks. This assumptio n was assessed by monitoring anterior thalamic HD cell activity and relatin g it to the subject's behavioral response on 2 spatial memory tasks that te sted either reference memory or working memory. In both tasks, there was a significant number of trials where there was not a tight coupling between t he preferred firing direction of HD cells and the direction of the behavior al response. In addition, it was possible to intentionally change the prefe rred direction of HD cells without affecting performance accuracy. An addit ional experiment showed that manipulations that affected internal. but not external, cues impaired performance on the reference memory task. These fin dings suggest that HD cell activity was not consistently guiding the subjec ts' behavior on these 2 spatial tasks.