Ultimately, the spells usually give you any exception to the rules, but personally I would rule using the “Rule of Common Sense”. For example, you cannot use Mind Link with non-sentient creatures like a Horse or a Dog, except maybe to pass on very simple messages and commands, because the intellect simply isn’t up to the same level. Similarly, you wouldn’t be able to use it on a mindless creature like a golem because there is nothing to connect to, and I would give you penalties for connecting with something with the Alien Mind Monstrous Trait.
