Figure 4.

Effects of lateral and feedforward inhibition on MSN spiking in the model. (A) Left, with lateral inhibition active (red line), the mean firing rate of MSNs in the network is significantly reduced compared to the case when lateral inhibition is inactive (black line). Right, with lateral inhibition active (red histograms), the standard deviation of the distribution of MSN firing rates in the network is increased compared to the case when lateral inhibition is inactive (black histograms). These effects become more pronounced at higher MSN spike rates. (B) Feedforward inhibition only slightly suppresses MSN spike firing in the model (black line), even at high FSI spike frequencies (red line). Unlike lateral inhibition, feedforward inhibition does not affect the distribution of MSN firing rates in the network (data not shown). These results indicate that lateral inhibition has a powerful effect on MSN spiking in the model relative to feedforward inhibition, despite the fact that cell-to-cell connections are weaker for lateral inhibition.