It depends on what you mean by 'thinking', but I think the view is pretty widespread that rational relations (like the relation of justification between premises and a conclusion) are not reducible to any physical relation in such a way that explains or even preserves the rational relation.

I'm thinking of Donald Davidson's 'Mental Events' as an example at the moment, just to illustrate the point. He would say that while every token mental state is identical to a token physical state, and every token mental causal relation (like a relation of inference or justification) is identical to a token physical causal relation...

...nevertheless, types of mental states, like the thought that it is raining, and types of mental causal relations, like the inference that if it is raining, and I don't want to get wet, then I should bring an umbrella, are not identical to types of physical states or types of physical causal relations.

This has the result that 1) we can be assured that the mind supervenes on the brain in some way, and that there's nothing immaterial or non-physical going on, but 2) there are in principle no explanations of brain states and relations which suffice as explanations of anything like thinking, reasoning, inferring etc..