This criticism misses the mark, says Rafael Yuste from Columbia University, who works on developing new tools for studying the brain. We still don’t understand how the brain works, he says, “because we’re still ignorant about the middle ground between single neurons and behavior, which is the function of groups of neurons—of neural circuits.” And that’s because of “the methodological shackles that have prevented investigators from examining the activity of entire nervous system. This is probably futile, like watching TV by examining a single pixel at a time.” By developing better tools that can watch entire neural circuits in action, programs like the BRAIN Initiative are working against reductionism and will take us closer to capturing the emergent properties of the brain.
But Krakauer says that this viewpoint just swaps “neuron” for “neural circuit” and then makes the same conceptual mistake. “It’ll be interesting to see emergent properties at the level of the circuit, but it’s a fallacy to think that you get closer to the whole organism and understanding will automatically ensue,” he says.
He and his colleagues aren’t dismissing new technologies, either. They’re not neuro-Luddites. “These new tools are amazing; I’m using them right now in my lab,” says Asif Ghazanfar from Princeton University, who studies communication between pairs of marmoset monkeys. “But I spent seven years trying to understand their vocal behavior first. Now, I have some specific ideas about what the neural circuitry behind that might look like, and I’ll design careful experiments to test them. Often it seems that people do the reverse: They look at the cool tech and say, ‘What questions can I ask with that?’ And then you get these results that you can interpret in vague ways.”
This point is crucial. Unlike others who have levied charges of reductionism against neuroscience, Ghazanfar and his peers aren’t dualists—they aren’t saying there’s a mind that sits separate from the brain and resists explanation. They’re saying that explanations exist. It’s just that we’re looking for them in the wrong way. Worse, we’re arriving at the wrong explanations.
Consider mirror neurons. These cells, first discovered in monkeys, fire in the same way when an animal performs an action and when it sees another individual doing the same. To some scientists, these shared firing patterns imply understanding: Since the monkey knows its intentions when it moves its own body, based on the firing of the mirror neurons, it should be able to infer similar intentions upon whomever it watches. And so, these neurons have been mooted as the basis of empathy, language, autism, jazz, and even human civilization—not for nothing have they been called the “most hyped concept in neuroscience.”
Here’s the problem: In the monkey experiments, scientists almost never check the animals’ behavior to confirm that they genuinely actually understand what they’re seeing in their peers. As Krakauer and colleagues write, “An interpretation is being mistaken for a result; namely, that the mirror neurons understand the other individual.” As others have written, there’s little strong evidence for this—or even for the existence of mirror neurons in humans. This is the kind of logical trap that you fall into when you ignore behavior.