Abstract.

• Theta oscillations (electroencephalographic activity with a frequency of 4-8 Hz) have long been implicated in spatial navigation in rodents; however, the role of theta oscillators in human spatial navigation has not been explored. Here we describe subdural recordings from epileptic patients learning to navigate computer-generated mazes.

• Visual inspection of the raw intracranial signal revealed striking episodes of high-amplitude slow-wave oscillations at a number of areas of the cortex, including temporal cortex. Spectral analysis showed that these oscillations were in the theta band.

• Episodes of theta activity, which typically last several cycles, are dependent on task characteristics. Theta oscillations occur more frequently in more complex mazes; they are also more frequent during recall trials than during learning trials.