Brain network activity for spatial navigation
In the brain's medial entorhinal cortex (MEC), neurons called grid cells generate representations of location, which is crucial for memory and cognition. Moreover, grid cell spatial information code requires input from another structure, medial septum (MS), to be active. As little is known about how the MS cells connect with their targets in the MEC, the SEPTOENTOCIRCUITS (The influence of parvalbumin neurons from the medial septum and diagonal band complex on medial entorhinal cortex activity) project used optogenetic tools to investigate this connectivity. These connections were mapped through the use of electrophysiology and optogenetics, which was utilised to activate MS inputs to the MEC. Researchers tested if GABAergic neurons in the MS control the timing of network activity in the MEC through actions on specific neuronal populations. Results showed that MS GABAergic neurons specifically target GABAergic cells in the MEC. Moreover, GABAergic projections targeted interneurons in all layers in the MEC, while the glutamatergic projection was not as prevalent or specific. Using animals in a virtual reality environment, the researchers tested to see if specific activation of parvalbumin neurons in the MS modified network activity in the MEC. Research continues past project closure and the team are also investigating if modulation of MS projections affects navigation of mice through a virtual environment. SEPTOENTOCIRCUITS research has enhanced our understanding of how the healthy brain operates. Another key outcome, is that many epileptic seizures that are not treatable with drugs originated in the hippocampal formation, where the MEC is located, stimulating MS neurons may be a potential treatment for epilepsy. Data from SEPTOENTOCIRCUITS improved our overall knowledge of the nervous system. This data is suitable for implementation in computer simulations of neural circuitry. The data could also aid in the development of software to improve computer navigation. Results from SEPTOENTOCIRCUITS research have been published in the Journal of Neuroscience.
