Understanding how neurones communicate with each other requires a detailed knowledge not only of the anatomical arrangement of the neuronal networks but knowledge of the events at the points of contact (synaptic transmission) and how this can be modulated by prior or concurrent activity.
Our group is working at the level of single neuronal cells in acute slices of rodent brain tissue. We are set-up to visualise and record from living cells within a slice of tissue. We can also inject biochemical markers to help identify the cells for subsequent morphological analysis. In our experiments, we can determine the strength of connections (synapses) between cells as well as the cellular properties of the receiving cell which determine the processing of afferent information.
We work in three different areas, each addressing a particular cellular property of transmission between cells. We record from cell pairs in various layers of cerebral cortex and investigate the characteristics of communication between cells. The goal is to determine the efficacy of the contacts between the cells, the mechanisms underlying its modulation, as well as the efficiency of information transfer between cells.
The efficacy of intercellular communication can change over time, i.e. the synapses are plastic. This is an important feature allowing the brain to adjust efficiently to changes in the environment. It is the basis of learning and memory. We are investigating aspects of both short- and long-term plasticity in the cortex. We are also interested in how different neuronal networks show specific forms of plasticity.
Using Two-Photon Laser Scanning Microscopy (TPLSM) we can image changes in calcium concentration within nerve terminals. Our aim is to investigate the sources of calcium that contribute to spontaneous and evoked synaptic transmission as well as calcium dynamics during short-term plasticity.
The electrical activity of presynaptic neurones is communicated via a chemical signal at the synapse to the postsynaptic cells where it is again converted to an electrical response. The postsynaptic specialisation of the synapse distant from the cell body on long processes (dendrites). This allows interaction between numerous cells (because of the large surface area for contacts) but has the disadvantage that much of the current initiated at the synapse is lost over the surface area of the cell. In most instances, only the current arriving at the cell body contributes to the discharge of the cell. We can build synthetic synapses on the living dendrite, inject a known current at this location, and quantify the amount of current that arrives at the cell body. Using this technique we can measure the interaction between specific synaptic sites and the cell body.
Our investigations will lead to a detailed and quantitative understanding of how neuronal microcircuits are built in our brain.
If you are interested in doing a PhD or Honours project in our laboratory, we are interested in talking with you.