Peter Jonas’ group at Freiburg made paired recordings from neurons in many different brain regions. They have determined the pre- and postsynaptic features of the GABA-A receptor mediated inhibitory synaptic responses that are characteristic features of certain classes of inhibitory neurons. One interesting brain subnetwork is composed of fast spiking interneurons that are theorized to underlie gamma frequency (40-80 Hz) oscillations, such as those identified by Wittington, et al. Bartos et al have modeled such networks, and studied the relationship between synaptic strength, delay, driving current etc on network activity. Peter Jonas has kindly provided us with the source code for their network model.
Run the netringorig.hoc simulation. The plot in the lower middle panel dynamically displays voltage records for two cells in the network, while the others will update after the simulation is complete.
Look at the source code, which is well documented, to determine how and when tonic drive is added. Does each cell receive the same drive? What happens as the drive is turned on? Similarly, what happens when the network synaptic connections are activated, which occurs later in the simulation? How does network inhibition affect synchrony? Explain.
Now run the simplified simulation netring.hoc. This runs for a shorter time. How robust are the oscillations? Do the inhibitory connections have to be hyperpolarizing? Are synchrony and frequency linked? Choose a metric for synchrony (there is not a single answer here, but justify your choice) to show your results.
Hypothesize on the origin(s) of the slow (relative to the fast channel kinetics) oscillatory frequency. (A strong argument will contain graphs of independent and dependent variables and it will contain various lines of evidence supporting your hypothesis).
Other reading: