In our research, we seek to understand how brain cells form the complex networks in the brain that underlie all thought and action. How brain cells will form connections with each other over development is largely determined by our genes. Many of the genetic changes identified in different causes of autism and Rett syndrome affect the communication between brain cells. Our research is focused on understanding how the genetic changes in Rett syndrome and some causes of autism affect brain function. For this project, we employed state-of-the-art techniques for collecting single brain cells from mice that have the genetic change found in Rett syndrome and some causes of autism. We used single-cell RNA sequencing to compare which genes are turned on and off in two types of brain cells and how this is altered by the genetic change in Rett syndrome. This results will help us understand understand how the genetic change in Rett syndrome causes problems with brain function and identify new avenues for treatments. To determine how the genetic changes in Rett syndrome alter the communication in brain cells, we also grew brain cells in a dish from mice with and without the genetic change in Rett syndrome. We applied two techniques for monitoring how neurons form functional connections with each other. In the first method, we grew the cells directly on a grid of recording electrodes. This allows us to observe spontaneous activity in the network of cells at multiple time points over early development. We found that the activity in the network of brain cells increases over development and becomes more organised in brain cells. We developed new methods with other scientists from math, engineering and computer science to understand the complex dynamics of network function and how these processes are disturbed during development by the genetic changes in Rett syndrome. We also applied a technique called two-photon calcium imaging in which a fluorescent dye is applied to the brain cells that changes its brightness in relation to the level of brain cell activity. Using this technique, we also saw that network activity increases over development in the brain cells and how brain cells synchronise their responses to form clusters within the larger network of brain cells. With this research, we are identifying how the genetic changes in Rett syndrome and some causes of autism impact network development. Our ultimate goal is to combine these two parts of the research to test new drugs--targeting genes identified from the single cell RNA sequencing--on the developing brain cell networks to improve function. This may provide new treatment strategies for improving the lives of people with Rett syndrome and some causes of autism.
