pooneilの脳科学論文コメント

■ Goodale and Milner

昨日からの続き。

また、"The visual brain in action"において著者は

"Visual phenomenology ... can arise only from processing in the ventral stream ..." "We have assumed ... that visual-processing modules in the dorsal stream ... are not normally available to awareness." ("The visual brain in action" p.200)

と書き、「意識に上る・上らない」というのとほとんど同じことを言っていますが、さらには哲学的に厳密な意味ではそのようにも言いきれないと書きます。

"Although D.F. in particular seems to have lost conscious perception of shape, it is perhaps debatable whether or not the dissociation between what she can and cannot do is best captured as 'conscious' versus 'unconscious'. ... In a strict philosophical sense, we are doubtless treading on thin ice in proposing that stimulus processing in the ventral stream is a necessary condition for visual awareness, though we are comfortable with defending the proposal that such processing is a necessary condition for visual perception and recognition. Likewise, we suspect that the visual processing that goes in the dorsal stream operates in the absence of awareness, all we can really defend is the contention that one is normally unable to report verbally on the contents of that processing and that it proceeds largely independently of processes of perception and recognition." ("The visual brain in action" p.200-201)

かなり気をつけて書いている様子が見えます。

というわけでmdsさんが言う通りではありますが、かなり近い線を行っていることをわかってもらえるかと思います。また、上の厳密な意味で膝状体視覚経路と膝状体外視覚経路に関しても吟味する必要はありそうです。

なお、Goodale and Milerの説に対する反論はいろいろあるようですが、とりあえず私が知っているのはJ. Kevin O’ReganとAlva NoëのBEHAVIORAL AND BRAIN SCIENCES '01 "A sensorimotor account of vision and visual consciousness."です。これのp.969において

The work of Milner and Goodale suggests that damage to the ventral stream disrupts non-visuo-motor aspects of seeing. This is an important finding. But it would be a mistake to infer from this that the ventral stream is therefore the place where visual awareness happens.

と書いていたりします。