There’s more to practical reasoning than just the VPC.
Let’s sum up what we’ve learned so far: if you suffer severe damage to your VPC, you lose your ability to engage in practical reasoning. The one therefore depends on the other, right?
Yes. In fact, the correlation between the two things has been firmly established. The author and his colleagues have studied 12 other patients who exhibit the same type of brain damage and cognitive symptoms. But as the old saying goes, correlation does not equal causation, so we need to be careful in drawing conclusions here.
To begin with, we can’t just draw a one-to-one correspondence between a particular part of the brain and a particular function. As we’ll see in more detail later, any given brain function is carried out by multiple parts of the brain working together. It’s their coordinated activity that enables the brain to do any of the things it does, like practical reasoning. We can assign different jobs to different parts of the brain – but we need to remember that no single part can do its job in isolation.
This brings us to the next caveat, which is that two other types of brain damage can lead to symptoms similar to those of Gage and Elliot. The first is damage to the amygdala and the anterior cingulate, which are both parts of the limbic system. These parts of the brain are known to play an important role in processing emotions.
The second is damage to the right side of the somatosensory cortex. This part of the brain is known to play an important role in our ability to experience physical sensations of touch, temperature, pain, joint position, and so-called “visceral states.” The latter includes all of the sensations we feel inside our organs, such as the heart, lungs, gut, blood vessels, and skin.
Alright, but can’t we just expand the equation? Practical reasoning = the VPC + the limbic system + the somatosensory cortex. Simple. Case closed.
Well, not quite, because at this point, we still have no idea how these three parts of the brain actually add up to something that can carry out practical reasoning. How do they work together to perform this cognitive function? Plus, we now have another puzzle to solve: what the heck do emotions and physical sensations have to do with practical reasoning? After all, that’s all the limbic system and the somatosensory cortex seem to be adding to the equation.
So what’s going on here? What’s the relationship between these three seemingly disparate parts of the brain?
