Extended Data Fig. 8: The Fano factor of EC neurons is periodic at the behaviourally relevant periodicity.
a, An example neuron (monkey A) showing a periodic Fano factor (bottom) but little or no periodicity in average spike count time series (top). b, ACG of Fano factor for the two example neurons (blue) and their corresponding (Poisson) null ACG (orange). c, Distribution of periodicity of the Fano factor for neurons with significant periodicity compared to their corresponding (Poisson) null data. Dotted lines denote the window within which significant difference was tested. We created a null distribution for each neuron by passing its mean firing rate through a Poisson process 100 times. We calculated the distribution of the true Fano factor by bootstrapping 100 times. We then computed the autocorrelation of the Fano factor and the corresponding PI for both distributions. We then estimated the periodicity of each neuron that had a significantly higher PI in the window of 300 to 900 ms lag, compared to its corresponding Poisson Null (two-sample t-test with p < (.0001/20), with Bonferroni correction). The periodicities of the neurons with significant periodic Fano factor were tightly clustered at the behaviourally relevant periodicity of 650 ms. d–f, Same as a–c for monkey M. Note that plots c, right and f, right are also shown in Fig. 4h. They are included here for completeness and clarity.
