Here's a talk from 2008 by Phiippe Goldin (now at Stanford) about the neuroscience of emotions, aimed at non-scientists, specifically Google employees:
We've not talked a lot about on the podcast so far about the differences in approach between current psychology and philosophy. In this lecture, we get references to specific studies of external behavior, of discussion of observable capacities in people, and attempts to correlate these to brain states: all methods that, according to the consensus on our philosophy of mind episode, are going to miss something essential about emotional experience and so not constitute a full account. Still, this method doesn't restrict the subject matter (he mentions re. the subject of empathy that ten years ago, scientists wouldn't touch it) and is geared towards providing not only clinical benefits, but insights to help people live their lives (i.e. what the humanities are supposed to address).
Relevant to our Spinoza discussion, I wanted to focus on his account of empathy, which comes about half way into the lecture. He states that the ability to perceive others and imitate their behaviors is a building block to empathy. As we watch others, our brains set up simulations to mirror others' behavior.
This claim augments Spinoza's account of our relations to others. Spinoza says that we identify with others like ourselves, and that we should be nice to people because people like ourselves are useful to us, but it turns out that this is not an abstract, implicit calculation we make about others' ability to serve our interest, but an immediate empathetic reaction.
But shouldn't Spinoza say that this is bad, in that this is surely a passion that's pulling at us; wouldn't it be more godly for him for it to be a cool calculation that motivates us to empathize with others?
I think the solution here lies in distinguishing between the justification for ethical action, which lies in reason (i.e. the calculation that others are a boon to us) and motivation to act ethically, which will inevitably involve some passion or other. For the most part, this is a useful (and hence good) passion; however, if our sympathy for someone in misery brings us down, then it's time to disengage and let some other passion like our innate lust for happiness and power, overrule our empathy.
Soon after this discussion, he starts talking about neurological measurements of "compassion meditation practice." We are like a fly stuck on sundew leaves! Neuroscience here meets New Agey sentiment. Neuroplasticity as it's discussed here could, I think, be the physical correlate for Spinoza of his associationist psychology: meditation is essentially dwelling on some connection of ideas, and so we should expect that corresponding physical concatinations will occur.