RUI: Frequency-Dependent Modulation of Hippocampal Neural Circuit in Freely Moving Rats

Trinity College, Hartford CT

Investigators

Abstract

0451285 Bronzino This investigation will contribute to developing a clear understanding of how local neural circuits respond to various inputs in determining how information is processed globally in the brain. The hippocampal formation, a brain structure intimately involved in learning and memory processes, is involved and the proposed studies are designed to quantify the modulation of a specific neuronal circuit within the hippocampal formation when it is subjected to different inputs (i.e., tetanization paradigms with varying burst frequencies). The investigators hypothesis is that modulation of the dentate cellular response is dependent upon the "burst frequency" of the tetanization paradigm activating this neuronal circuit. This is important as the pattern of firing in the perforant path consists of trains of 4-6 action potentials occurring every 25 ms, thereby sending a bursting pattern of activation to the dentate granule cells of the hippocampal formation. Tetanization of the medial perforant path (one of the major input pathways to the hippocampal formation) has been shown to induce long-term potentiation (LTP) in the dentate granule cell layer. This neural circuit serves as the first leg in the hippocampal trisynaptic circuit and such modulation influences the gating of neuronal transmission into and through the hippocampal formation; it therefore may play an important role in the development of learning and memory both in early life and throughout adulthood. The investigation is a unique partnership of the fields of biomedical engineering and neurobiology, melding the approaches and techniques of both disciplines to provide important insights regarding the performance of neural circuits capable of modifying their responses as they mature. Results obtained from the experiments to be conducted are expected to have benefits beyond the immediate studies. First, the miniaturized stimulation and recording methodologies that are to be developed to record bioelectric data in the freely moving pre-weaning animal can be used by others in a wide variety of applications. Second, the data acquired can be utilized to extend this line of research in the future.