I just returned from a vacation in London and Scotland, which is a fantastic way to clear your mind. Then I returned and asked people, what did I miss? Apparently this which instantly clouded my mind back up.
Here’s a suggestion: never trust an article called “Here’s Why Most Neuroscientists Are Wrong About the Brain”. Especially when the first sentence is flat-out wrong:
Most neuroscientists believe that the brain learns by rewiring itself—by changing the strength of connections between brain cells, or neurons
Okay maybe not wrong – that is one, though not the only, way that neuroscientists think the brain learns – but certainly misleading in the extreme. What are some of the non-synaptic mechanisms that contribute to plasticity?
- Homeostatic plasticity/intrinsic excitability
- eg. dopamine-related (all sorts of transcription changes)
- Developmental plasticity
- Attractor states (we can quibble about whether this counts)
- Dendritic excitability
That’s what I can come up with off top of my head; I am sure that there are more. I’ll just focus on one for a second – because I think it is pretty cool – the intrinsic excitability of a neuron. Neurons maintain a balance of hyperpolarizing and depolarizing ion channels in order to control how often they fire, as well as how responsive they are to input in general. Now a simple experiment is to simply block the ability of a neuron to fire for, say, a day. When you remove the blockade, the cell will now be firing much more rapidly. It is pretty easy to imagine that all sorts of things can happen to a network when a cell fundamentally changes how it is firing action potentials. [For more, I always think of Gina Turrigiano in connection to this literature.]
I also wonder about this quote in the article:
Neuroscientists have not come to terms with this truth. I have repeatedly asked roomfuls of my colleagues, first, whether they believe that the brain stores information by changing synaptic connections—they all say, yes—and then how the brain might store a number in an altered pattern of synaptic connections. They are stumped, or refuse to answer.
Perhaps he has was unclear when asking the question because this is a solved problem. Here is a whole chapter on encoding numbers with ‘synaptic’ weights. Is this how the brain does it? Probably not. But it is trivially easy to train a classic neural network to store numbers.
I do not mean to harp on the author of this piece, but these are interesting questions that he is raising! I love molecules. Neuroscience often enjoys forgetting about them for simplicity. But it is important that neuroscientists are clear on what we already know – and what we actually do not.
[note: sorry, I meant to post this late last week but my auto-posting got screwed up. I’m going to blame this on jet lag…]