• Mayuri Vaish

Balance of Inhibition and Excitation in the Auditory Cortex of Rats

Spike-Timing-Dependent-Plasticity (STDP) describes the time-dependent change in synaptic weight (i.e, strength between two neural connections). It suggests that synaptic strength increases when a pre-synaptic (input) spike occurs before a post-synaptic (output) one, and vice versa. Although prior computational functions have been created to describe STDP, the role of inhibitory (decreased chance of neural firing) STDP in regulating the usage of a specific neural signaling pathway involving excitatory (increased chance of firing) STDP is not fully understood.

Aim: This research aims to determine whether there is a balance in excitatory and inhibitory synaptic weights by utilizing a feedforward circuit model containing eSTDP and iSTDP parameters, as developed by Kleberg et al. (2014).

Method: Neural simulation software ‘Brian’ was used to develop a program in the Python programming language under the ‘Anaconda’ data science platform. Here, two excitatory and two inhibitory neuron groups of sizes 100 and 25 neurons per group were connected to one Leaky-Integrate-and-Fire (LIF) output neuron. The change in synaptic weight for each excitatory and inhibitory connection to the LIF was defined by their specific STDP equations, after which the spike times, conductances, and synaptic weights were recorded and plotted for simulation times ranging from 100 to 5,000 ms.

Results: Data showed that synaptic weight changes in a temporal-dependent manner, and that inhibitory STDP influenced the likelihood of firing in the LIF neuron.

Conclusion: This data can be used to explain ongoing data collected from whole cell measurements of spontaneous and sound-evoked excitation and inhibition in the auditory cortex of anesthetized rats.

[Code can be found here: bit.ly/STDPcode]