Neuronal Network Laboratory

		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.
Christian Stricker	Anna Cowan
Assoc. Prof. ANUMS	Research Fellow JCSMR

Potential Projects

If you are interested in doing a PhD or Honours project in our laboratory, we are interested in talking with you. Potential projects are available in the following areas:

• Determine synaptic properties in small networks of neurones in rat brain slices. Our laboratory uses electrophysiological recording of synaptically connected pairs of neurones to investigate properties of synaptic transmission as well as short and long-term plasticity.

• Calcium imaging of presynaptic terminals. We investigate the role of intracellular calcium stores in synaptic transmission and short-term plasticity.

• Modelling of synaptic depression/facilitation/augmentation at cortical synapses.

• Modelling of presynaptic calcium dynamics during synaptic depression.

• Mathematical models of non-random features of synaptic transmission.
• Electrophysiology and quantal analysis of synaptic transmission combined with histological processing and computer-assisted reconstruction of connected cell pairs and their release sites.

Scientific Goals 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 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.

Recent Publications

• Fuhrmann, G., A.I. Cowan, I. Segev, M. V. Tsodyks, and C. Stricker, 2004, Multiple Mechanisms Govern Synaptic Dynamics at Neocortical Synapses: J Physiol, (in press).

• Cowan, A. I., and C. Stricker, 2003, Functional Connectivity in Layer IV Local Circuits of Rat Somatosensory Cortex: J Neurophysiol, (submitted).

• Simkus, C. R. L., and C. Stricker, 2002, Analysis of mEPSCs Recorded in Layer II Neurons of Rat Barrel Cortex: J Physiol, 545:509-520.

• Simkus, C. R. L., and C. Stricker, 2002, The Contribution of Intracellular Calcium Stores to mEPSCs Recorded in Layer II Neurons of Rat Barrel Cortex: J Physiol, 545:521-535.

• Gao, B.-X., C. Stricker, and L. Ziskind-Conhaim, 2001, Transition from GABAergic to Glycinergic Synaptic Transmission in Newly Formed Spinal Networks: J Neurophysiol, 86:492-502.

• Stricker, C., A. I. Cowan, A. C. Field, and S. J. Redman, 1999, Quantal Analysis of NMDA- Independent Long-Term Potentiation of EPSCs in Rat CA1 Neurones in vitro: J Physiol, 520:513-525.

• Stricker, C., A. C. Field, and S. J. Redman, 1996, Statistical Analysis of Amplitude Fluctuations in EPSCs Evoked in Rat CA1 Pyramidal Neurones in Vitro: J Physiol, 490:419-441.

• Cowan, A. I., C. Stricker, L. J. Reece, and S. J. Redman, 1998, Long-Term Plasticity at Excitatory Synapses on Aspinous Interneurons in Area CA1 Lacks Synaptic Specificity: J Neurophysiol, 79:13-20.

• Buhl, E. H., G. Tamás, T. Szilágyi, C. Stricker, O. Paulsen, and P. Somogyi, 1997, Effect, Number and Location of Synapses Made by Single Pyramidal Cells onto Aspiny Interneurones of Cat Visual Cortex: J Physiol, 500:689-713.

• Stricker, C., A. C. Field, and S. J. Redman, 1996, Changes in Quantal Parameters of EPSCs in Rat CA1 Neurones in vitro After the Induction of Long-Term Potentiation: J Physiol, 490:443-454.

• Stricker, C., D. Daley, and S. J. Redman, 1994, Statistical Analysis of Synaptic Transmission: Model Discrimination and Confidence Limits: Biophys J, 67:532-547.

• Stricker, C., and S. J. Redman, 1994, Statistical Models of Synaptic Transmission Evaluated Using the Expectation-Maximization Algorithm: Biophys J, 67:656-670.