Neural structures in the forebrain, especially the hippocampus, have a long established link to memory functions. Their exact roles are controversial and several new techniques are being used to address the neurophysiological patterns that are involved. One new line of inquiry is the study of oscillatory potentials that may contribute to the modification of neural pathways. Theta (3-7 Hz) and gamma (40-80 Hz) oscillations have been observed in the hippocampus and related structures, and have strong relationships to ongoing behavior. Several theories suggest that they may coordinate neural function in a way that facilitates the early detection of learned associations and the long term storage of memories. This project will employ a newly-developed brain-computer interface that controls the presence or absence of theta during training, and has been used to modify the rate of behavioral learning in animals. The project will utilize this interface while simultaneously recording electrical activity in order to explore the precise synchronized patterns of cellular activity during theta and their modification as a memory is formed. An important question is whether the presence of theta in the hippocampus can alter the cellular responses elsewhere in the brain during learning. Target structures such as the prefrontal cortex and septal region will be monitored. Preliminary data suggest that the coordination of neurons is optimal during theta and disorganized when theta is absent, producing rapid or delayed behavioral learning, respectively. Such findings will clarify potential mechanisms of learning and address important issues related to the coordination of memory circuits. In addition to improving the research climate at the university, the instrumentation and techniques employed by this project will be used by graduate and undergraduate students, affording them training in state of the art neuroscience and behavioral methods.
