Human theta oscillations exhibit task dependence during virtual maze navigation

Theta oscillations (electroencephalographic activity with a frequency of 4- 8 Hz) have long been implicated in spatial navigation in rodents(1-3); howe ver, the role of theta oscillators in human spatial navigation has not been explored. Here we describe subdural recordings from epileptic patients lea rning to navigate computer-generated mazes. Visual inspection of the raw in tracranial signal revealed striking episodes of high-amplitude slow-wave os cillations at a number of areas of the cortex, including temporal cortex. S pectral analysis showed that these oscillations were in the theta band. The se episodes of theta activity, which typically last several cycles, are dep endent on task characteristics. Theta oscillations occur more frequently in more complex mazes; they are also more frequent during recall trials than during learning trials.