I am at the verge of submitting a paper on 'scientific explanation of reality' to an international philosophy body. First submitted draft was returned by the evaluation expert, asking me to re-submit it, after re-checking the validity of my assertion that 'science (biology) believes that neuron firing always precedes thought'. Can any one provide answer on biology's clear stand on above question ?
I think the only way to interpret these kinds of questions biologically is to assume that "thought" means "the perception of a thought occurring." The perception of a thought, like all perception, arises from neuronal firing.
The interesting biological (rather than philosophical) questions arise when we look at the relationship between the neural firing that gives rise to the perception of intent to act and neural firing that carries out the "intended" actions.
This paper is relevant. The authors are trying to argue that the initiation of a motor action comes before the perception of intent for that action. I'm not a cognitive neuroscience person, though, so I'm not very familiar with their techniques and personally have a hard time determining if they draw valid conclusions.
You've stumbled on an old and unanswered question that is still debated--- bordering on the issue of Free Will. The reason it is still in the realm of philosophy is because current experiments don't allow direct testing of which neurons give rise to specific thoughts. This area of consciousness is fraught with difficulties and we just can't get at an answer.
Now for a more philosophical answer. All consciousness is generated by the brain so every thought must come from neuronal firing necessarily. The difficulty lies in the fact that thoughts themselves cause neurons to fire and one is never thoughtless so we are reduced to the chicken and the egg problem if we continue down this path. However, assuming we come from a thought free state- for example deep coma-- the first thoughts we have are indeed generated by neuronal firing so your assertion is correct.