Laura Colgin, University of Texas at Austin
Abstract: Brain rhythms reflect periodically synchronized electrical activity across groups of neurons and are thought to facilitate neuronal communication across brain regions. Gamma is a particular rhythm type that occurs throughout many regions of the brain and has been linked to functions such as attention and memory. In the hippocampus, a key brain region for memory, two distinct subtypes of gamma rhythms, slow and fast gamma, occur at different times. During slow gamma (~40 Hz), hippocampal subfield CA1 is coupled with neighboring subfield CA3, an area that is involved in memory retrieval. During fast gamma (~80 Hz), CA1 is coupled with the medial entorhinal cortex, a region that transmits information about an animal’s current position in the environment. In this talk, new data will be presented that supports the hypothesis that slow and fast gamma rhythms serve different mnemonic functions in the hippocampal network. The results suggest that the principal neurons of the hippocampus, “place cells”, code spatial information differently depending on whether slow or fast gamma rhythms are present. The results also link slow and fast gamma to different memory operations. The implications of these findings with regard to memory disorders will also be discussed.