I spent my time this summer researching a fascinating subject in neuroscience called “adult neurogenesis.” In the Ming lab in the Department of Neuroscience at the University of Pennsylvania, we were interested in researching the properties and roles that adult-born cells in the brain’s memory center, the hippocampus, played in the process of memory consolidation during sleep. This is an especially enticing area of research since the hippocampus is one of only two areas in the brain where adult neurogenesis occurs. We used mice as our animal model to study the behavior of these cells during different states of sleep and during laser-induced activation. The goals of my project were to isolate these adult-born cells, gather data on their activity during different states, and conduct a control study on the lasers we used to stimulate these cells.
Many challenges were presented when attempting to research these adult-born neurons. In order to isolate the adult-born cells, we utilized genetic markers that are expressed at high levels only during the early stages of cell development to our advantage to tag the neurons. Our team inserted genes for a light-sensitive protein exclusively to the adult-born neurons using those developmental genetic markers. This light-sensitive protein would stimulate the neuron upon the shining of a laser inside the brain. We surgically implanted a specially designed microdrive, which we built ourselves in the lab, that housed an array of wires that recorded electrical activity and shined a light in the mouse brain during our experiments. The microdrives allowed us to record cell activity in the hippocampus through tetrodes; EEG (electroencephalogram) data was also gathered to record brain waves associated with different sleep states. As for measurement of the adult-born neurons, the process for identifying the individual cells involved using electrophysiological recordings during sleep, and then measuring the latency at which the cells fired after shining the laser. We typically looked for consistent, short latency firing, which would indicate that the cells were, indeed, being stimulated by the light-sensitive protein itself and not through a secondary pathway.
I was led by an incredible team of postdoctoral researchers who taught me the fundamental principles of research, the complex nature of studying the brain, and the fascinating experience of actually working in the field of neuroscience rather than just learning about it through a textbook. PURM allowed me to gain a newfound appreciation for the commitment and planning that goes into research studies, and just how exciting new discoveries can prove to be. The staff at the lab also helped me develop concrete skills such as reading scientific literature, presenting research findings during lab meetings, and a plethora of lab techniques. The lab staff was incredibly friendly and created a very welcoming environment to all undergraduates in the lab. I look forward to continuing the independent projects I began this summer, such as testing the damage that lasers on their own have on the brain, and eventually being able to publish my own findings.