Spike's firing rate of specific regions visualization

Hi, recently I am doing some simulations of some animals like macaque. What I have now is an x3d file, a nii.gz file(with this two we could plot ROI), and the number of how many neurons spiking at each time point.
What I want to do is to visualize the firing rate during a specific time range of the ROI using colors. To be more detailed, if I simulated the brain’s firing rate for 3 seconds, and I have the firing rate of some regions during this time range, I set a threshold, if the number is bigger than this I’ll see it as an activation, so the concerned region(s) would be highlighted, more like an fMRI activation on a brain surface. What I have is x3d(brai template), a nii.gz file(ROI), and this spiking information. Are there any APIs of MNE could help me finish this task? I suppose the fMRI’s activation would be a good reference?

Thank you

To me it sounds like this would best be accomplished by fMRI-specific viz tools. You could try to use mne.viz.Brain plus brain.add_volume_data etc., but it’s going to be difficult and slow I think.