Dr. Rose's piece is the only one I've seen that makes his particular claims. I'm sure he's a neuroscientist (I checked), but the article that seems to have caused all this fuss isn't a technical article, its a lay article. It really doesn't make any "technical claims" (its also the only one that shows up if you google the guy). It hedges a lot. And the logic is more than a little tautological.
It is (and must be) entirely true that fish cannot have a human experience of pain. To define some necessary component of pain as a psychological rather than as a neurological experience 1) predetermines the conclusion 2) moves us immediately outside of the good doctor's area of expertise.
There must be, somewhere between us and the starfish, a species that is 1) more primitive than us and 2) experiences pain in a manner similar to the way we experience it. This may be restricted to primates, it may be restricted to mammals, it may not. But there has to be a first instance. Dogs will yelp, they will sulk, they are social and appear to be both emotional and sentient to at least some degree. Do they experience pain? Is their neocortex sufficiently advanced?
Vision appears a good long way down the evolutionary tree, but it doesn't appear as a bright line. It appears as clusters of light sensitive cells. These clusters are in no way capable of anything we might term vision. Between that instance and the eagle there are a very wide range of developmental capacities. This sort of stuff doesn't happen overnight.
At some point, very early on in the game, nociceptors developed. At some point after that the mechanism by which we experience pain also
began to develop.
I have no idea at what stage of development this mechanism is in in fish. I haven't seen any evidence that Dr. Rose has either, unless he moonlights as an icthyologist.
It does seem to me that the most essential and unpleasant aspects of the experience of pain are very primitive and old brain mechanisms. Much of this stuff happens not in the neocortex but in the brainstem. For
instance :
Conclusion:
The anatomical and physiological studies thus provide complementary evidence of pain processing in the brainstem.
Q. Where does the information about pain go after the brainstem?
To answer this question anatomical studies have utilized retrograde transport of substances from the sites in the brain thought to be receive projections from the brainstem, ie. the thalamus. Electrophysiological evidence has been provided using the technique of antidromic activation following electrical stimulation in various parts of the thalamus. Caudalis neurones projecting out of the nucleus are found mainly in laminae I and III-VI but not in layer II, the substantia gelatinosa. Some layer II cells receive low threshold inputs, others nociceptive inputs and many can be modulated by inputs from higher centres. Thus these neurones are critical interneurones. Caudalis neurones in laminae I, V and VI project to;
1) the posterior thalamus,
2) cerebellum, periaqueductal grey (PAG), parabrachial area, brainstem reticular formation, spinal cord, areas of the trigeminal brainstem
Cerebrum anyone?
Fish clearly experience something and since I can't say with any sense of certainty what that might be I prefer to err on the side of caution. I think my own brand of anthropomorphism is kinder and gentler than Dr. Rose's. And I do think he is anthopomorphizing…
heh
