Churchland lab

Causal experiments are appealing. For example, perturbing neural activity in a particular brain area and seeing a change in behavior seems like good evidence that the brain area in question supports the behavior. Experiments that instead just correlate neural activity to behavior are criticized because the relationship between the two could be simply coincidental. But is this really fair? Cosyne workshop organizer Arash Afraz, a postdoc in Jim DiCarlo’s lab at MIT, brought together 6 of us to argue it out. The lineup included myself, Karel Svoboda, Rick Born, Chris Fetsch, Mehrdad Jazayeri and Daniel Yamins.

A number of interesting points were brought up. For instance, one problem with perturbation experiments that is not at first obvious is that they drive neural activity in such an unusual way that they actually expand the space of possible hypotheses rather than restrict it. On the other hand, the fact that neural activity during perturbations is unusual might be a strength: pushing the system into states it doesn’t normally occupy might offer key insights into what the area does.

In the end, we agreed that in some circumstances, assuming correlation implies causation is truly the optimal strategy. Well…  okay, only 1 circumstance, but its an important one: the correlation between the national rates of chocolate consumption and nobel prize frequency (right). There are a lot of alternative explanations for this relationship, but to be safe, we all decided to eat more chocolate anyway (hence the Lindt bars in the photo above).