And how we have used it to understand how we think about others.
The two assumptions of brain imaging are: the brain has discrete areas which do individual things, and those individual things are grouped together by function. With these in tact, and little evidence to disprove it currently, we use brain imaging to help learn how the brain works.
Brain imaging methods:
- CAT scans — computerized axial tomography
Essentially, lots of x-rays.
- fMRI — Functional Magnetic Resonance Imaging
Provides a consistent magnetic field. Hydrogen atoms align. It then gives a pulse of energy. It then tracks how the energy is released by the hydrogen atoms. Because they are all aligned, we can triangulate their location. If there is a lot of oxygenated blood, we see a difference in the energy released (according to BOLD). If there is more oxygenated blood, then that area of the brain is working harder. In short: More blood, more energy, more measurable, brighter dot.
- NIRS — Near InfraRed Spectroscopy
Non-invasive but non-deep brain imaging that relies on light. Essentially, the light is reflected differently when there is different levels of oxygenated blood.
- TMS — transcranial magnetic stimulation
Stick a big ol’ electromagnet on your head. Pulse it for a few seconds. See what stops working — “virtual brain lesions”.
In short: A big magnet that can stop things working temporarily.
So what have we found?
One interesting thing we have seen is that imagination triggers areas of real image processing. Thinking of a dog actually calls areas of the brain that would fire if you had actually seen a dog.
It has also proved that it is a uniquely-human thing to simulate other peoples minds. Only humans have been shown to reproduce mental states of others and process the, as if we are them.
In fact, when researchers left people to quietly stay in brain imaging devices, the non-tasked subjects brain activity died down, but the mind simulation activities grew — suggesting we have some predisposition to start imagining others thoughts when there is no stimulus, though I am sure this could be argued. This same over activity has been suggested as the reason we have a “tendency to anthropomorphize”.
Glad you think so. But we have also noticed other things. When the brain is tasked with other work that is non-human-thought-simulation tasks, it struggles. This behaviour doesn’t happen for other types of brain regions.
[Social thought regions] “tend to deactivate when a person thinks about something other than a mind”
The impact of this that when tasked with non-social thought challenges, our mind closes the ability to do social thought. This will be expanded further in another write up.
I hope this write up on a few different ways to do brain mapping was interesting!
Inspired by Jason P. Mitchell’s “Watching minds interact” from “What’s next? Dispatches on the future of science” 2009
Recently I began reading this book of science essays that were meant to assess the future. Seeming it is 10 years since the book was published, I thought it may be interesting to revisit these. Here the focus was on neurons and empathy.