Truly, I believe there are multiple architectures for information processing in the body, and not only in the brain/neurons. Think of the computing landscape where you have a salad bowl of ANN's implemented on TPU's, some GPU's, some specialized ASIC's, DSP's, some CPU's. There is no reason to believe efficient information encoding through evolution ends up with one architecture. It's going to turn out to be as varied as the differentiated cells in the body, though there may be some unification in foundational units at the equivalent level of transistors of something, maybe some molecular machinery that stores a bit or activates a switch. Presumably that's what Gallistel is looking for. It does seem wasteful for a whole neuron to be the basic unit of information processing, so I agree there should be something more atomic inside.