Neuroscience can measure the transmission of nerve impulses within the brain. They can detect the reaction to thought provoking stimuli and the accompanying changes in brain chemistry. Our ability to think is explained largely by chemistry. No supernatural (or as you would call it, metaphysical) explanation required.
On what I know, I would not deny the first two statements. However, in no way do such facts (basic measurements/observations) begin to "explain" our ability to think - which is a very diverse and complex activity. Actually, compared to the two measurements/observations you cite there is a plethora of "non-scientific/non-chemistry" evidence regarding our ability to think. This thread, and this post, comprise some of that.
