Autobiographic memory is essential to personal identity and is tightly coupled to spatial memory. Both processes are supported by a structure called the hippocampal formation. Damage to this area can cause severe memory deficits, as it is the case in Alzheimer’s patients. Especially the ability to retrieve and dissociate similar memories experienced in the same location can be dramatically impaired. Spatially identical memories are represented by the same neuronal population in the hippocampus. However, different experiences within the same space are encoded as different firing rates within the active population of neurons, a so-called ‘rate code’. It is also known that in slow wave sleep, recently experienced events are being replayed by reactivating the neurons in the same sequential order, as they have been active during the time of the event. In my PhD, I am interested in, whether, during sequence reactivation in the hippocampus, the rate code that allows the separation of similar experiences in the same place, is being preserved. In Dr. Bruce McNaughton’s laboratory, we use large-scale single unit recordings to monitor large populations in the hippocampus simultaneously during both behaviour and sleep.

As a visiting research scholar I had the opportunity to work closely with Dr. Bruce McNaughton, Dr. Fabian Kloosterman and Dr. Arno Aarts on developing and testing a new microdrive loaded with flexible silicon probes (provided by ATLAS Neuroengineering) to increase the numbers of neurons that can be recorded from simultaneously significantly.

As a research assistant in Dr. Stefan Leutgeb’s laboratory I investigated how the hippocampus separates similar memories experienced in distinct spatial locations. I assembled the implanted recording devices (‘hyperdrives’, with 12 independently movable recording tetrodes), conducted the behavioural testing and single-unit recordings, histological preparation of the tissue, as well as the data processing and analysis. I presented my work at Neuroscience seminars at UCSD and at the international Society for Neuroscience (SfN) meeting in Chicago, 2009.

Thesis title: "Hippocampal population coding to distinguish separate spatial memories"In Drs. May-Britt and Edvard Mosers' (Nobel prize in Medicine or Physiology, 2014) laboratory I investigated how the hippocampus in rodents distinguishes between similar memories acquired at different locations. Under Dr. Stefan Leutgeb's supervision I learned how to assemble microdrives, do in vivo electrophysiological recordings, behavioural testing, spike sorting of the recorded data, histology as well as data analysis in matlab.