DESCRIPTION: (Adapted from applicant?s abstract): Theta oscillations (rhythmic, slow-wave activity) have long been studied in rodents and are thought to be important in spatial cognition and memory. Only recently have they been observed in humans. Recording intracranial electroencaphalographic (iEEG) signal from epileptic patients (who were undergoing long-term monitoring for subsequent resection surgery) established that theta was specifically related to a spatial navigation task and to a non-spatial working memory task. Theta was shown to covary with two variables that reflect learning. However, the specific roles of human theta remain unknown. The proposed research will extend the previous findings, analyzing the intracranially recorded neural signal during three tasks to test the effects of cognitively relevant task variables and subject performance on theta activity. Possible roles for theta in spatial cognition, memory and the perceptual characteristics of spatial cognitive tasks will be evaluated. A deeper understanding of human theta oscillations, how they relate to cognition and how they compare with rodent theta will help us to better understand the neurophysiology of cognition and memory, potentially leading to insights on the nature of cognitive disorders, both spatial and memory-related.