Connectivity of ensembles


I am new to Nengo but have some experience with other programs like Brian2 and Pytorch for modelling neural networks. I am building a model of a portion of the motor cortex and am trying to connect the groups of neurons up in a physiologically realistic way.

So, I have two questions about the connectivity between and within ensembles. When you define a connection between two ensembles, is that an all-to-all connection? Is there a way you can modify which neurons connect to which? Or ideally, is there a way to implement probabilistic connectivity? I.e., the probability a neuron in ensemble a connects to any other neuron in ensemble b is 0.8, or something like that? Similarly for the recurrent connectivity, can we implement some sort of probabilistic connectivity like I described?

Any help/advice greatly appreciated!

Update: I have read some other posts on the forum and it seems to create neuron-to-neuron connections you just use “.neuron” in your usual nengo.Connection, and can also define a weight matrix. However, I am still unsure of the probabilistic connectivity question I posed?