Recording place cells from multiple sub-regions of the rat hippocampus with a customized micro-electrode array

The hippocampus is a subcortical structure which is involved in memory function. There is a considerable amount of evidence available which indicates that the hippocampal system is necessary for effective spatial learning in rodents and short-term topographical memory in human. Recordings of neural activities from the hippocampus of behaving animals can help us to understand how spatial information is encoded and processed by the hippocampus. In this work, we designed a triple-region microelectrode array (MEA) which took into concern the anatomical structures of the rat hippocampus. The array was composed of 16 stainless steel wires which were arranged into three groups that differed in length. Each group targeted one subregion of the hippocampus. The array was chronically implanted into the rat hippocampus through craniotomy. Neural activities were monitored both during the implantation and after recovery. The triple-region MEA was capable of recording unitary activities from multiple subregions of the rat hippocampus and the spatial distribution of firing rates were analyzed while the animal freely explored in the environment.