Give up? Do something else (bee keeping, perhaps)?
There’s a popular complaint out there that FMRI/MEG/EEG are correlational techniques, and so the patterns of activation we see may be by-products or epiphenomena. As such, FMRI/EEG/EEG may not tell us anything of interest about how the brain accomplishes tasks. Let’s take this position as a given and that there is a very real possibility that these are epiphenomena and so they are of limited use (NB the NeuroRant collective will point out how fundamentally stupid the epiphenomenon idea at a later date).
So what’s the solution? Give up? Do something else (bee keeping, perhaps)?
No. Never. Not this time. The solution is transcranial magnetic stimulation (TMS). TMS disrupts neural processes and so tells us if a region is NECESSARY for a given task (unlike grubby old FMRI which only shows it’s correlated with a task). Now TMS fixes everything, doesn’t it? For example, we zap motor cortex and motor output is disrupted. Ipso facto, the motor cortical region is necessary for motor output (like ranting). Great. Solved. Now we can get somewhere, right? Cure some neurological and psychiatric conditions? Get some Pulltizer prize-winning popular science books written, right? Wrong.
NeuroRant says: ‘Big Whoop’. We have established that a certain bit of the brain, X, is ‘necessary’ for process Y, but what have we learnt? What does being necessary mean? Does it mean that region X contains the neural representations that allows process Y to work? Not necessarily. Does it mean X is an important way-point, necessary for relaying information from brain region A to brain region B or down the spinal tract to make the body do something? Again not necessarily. Does it mean that region X modulates what region A does to allow A to do something important? Again not necessarily.
In fact, TMS-ing region X and so disrupting process Y could mean very, very many things, some of which are deeply uninteresting. In fact, you could imagine a really long daisy chain of processes that all have contributions on each other. So disrupting region X, disrupts process Z1 which disrupts process Z2 which disrupts process Z3 which disrupts process Z4, ad nauseum… finally disrupting process Y. In fact this process could go on for ever, like might happen in a reductio ad absurdum. Oh, it is a reductio ad absurdum. Nice.
To illustrate, I might find that zapping my left medial-inferior-ventral-caudal-anterior-lateral-dorsal-parietal lobe increases the likelihood of me trolling strangers’ blog posts. This region is therefore necessary for stopping me irritating strangers. However, this may be deeply uninteresting. In actual fact (fact, in this thought experiment although unfortunately not in reality), this is because left medial-inferior-ventral-caudal-anterior-lateral-dorsal-parietal lobe actually is the part of the brain that allows bee-keeping thought processes to flourish. As everyone knows, bee-keeping, and thinking about such matters, is an intensely calming persuit. If you stop this relaxing brain process then all sort of chaos starts churning around the brain. One thing leads to another, and it’s stranger-trolling time. The ‘necessary’ bit of TMS hasn’t really bought us anything about understanding how the brain works.
NeuroRant does not want to dismiss TMS as a useful technique. In fact, some of NeuroRant’s best friends are TMS-ers. However, NeuroRant isn’t convinced that TMS adds something, IN PRINCIPLE, very different to FMRI/MEG/EEG. It’s not better. It’s just a different approach with a different emphasis. That is, TMS could, in principle, all be neurobollocks in the same way that FMRI/EEG/MEG could be. Although, completely, blindingly, obviously BOTH techniques aren’t neurobollocks.