Top neurologist in Boston area

My father has been losing his memory for the past 6 months. It has steadily been getting worse. Today he can't remember anything. Things he told me 5 minutes ago, he doesn't remember. I want to get him to a top neurologist in the Boston area to get evaluated. He has been to a local neurologist and had an MRI but it did not show anything unusual. This neurologist was not particularly helpful.

Does anyone know of a really good neurologist in the Boston area that you might be able to recommend? I think he needs to be looked at ASAP because his memory is really getting bad. It's actually getting a little scary.

Thanks for your help!