Chapter
Four
Neuroscience
describing the areas identified in the neuroimaging studies as visual conscious-
ness areas (ffytche, 2000) or sites where consciousness is generated (Chalm-
ers, 2000), and the brain processes involved as those ‘that are qualia laden
as opposed to those that are not’ (Ramachandran and Hubbard, 2001, p. 24).
Meanwhile, Crick and Koch suggest that ‘it is the transient results of the com-
putations which correlate with qualia; most of the computations leading up to
those results are likely to be unconscious’ (Crick and Koch, 2000, p. 104, original
italics). Similarly, Ray Jackendoff (1987) and Jesse Prinz (2007) try to determine
what kind of information is encoded in different stages of the visual hierarchy
and how well it corresponds to the features of conscious visual experience. Prinz
asks ‘Where, in the flow of information, does consciousness arise?’, and con-
cludes that ‘Conscious states are attentionally modulated intermediate-level
representations’ (pp. 247, 258).
The idea of a place where consciousness happens is what Dennett characterises
using the metaphor of the Cartesian theatre (which we met in Chapter 1 and will
learn more about in the next chapter): the place where everything comes together
and consciousness happens. It is seen in extreme form in Descartes’s idea of the
pineal gland as the seat of the soul, and in the view that William James pilloried of
a single ‘pontifical neuron’ to which ‘our’ consciousness is attached. We know that
damage to almost any area of the brain has some effect on consciousness, and so
in some sense the whole brain is involved. This was certainly James’s view. He said
that ‘The consciousness, which is itself an integral thing not made of parts, “corre-
sponds” to the entire activity of the brain, whatever that may be, at the moment’
(1890, i, p. 177). But he was under no illusion that this solved the problems: ‘The
ultimate of ultimate problems, of course, in the study of the relations of thought
and brain, is to understand why and how such disparate things are connected at
all’ (1890, i, p. 177). This, his version of the hard problem, remains whichever areas
are favoured, and whether they are discrete or distributed.
The idea of a ‘bridge locus’ was proposed by vision researchers in the 1980s
as a locatable part of the brain to be a crossing point for the chasm between
inner and outer worlds, between matter and consciousness (Movshon, 2013).
Neural activity at the bridge locus would be necessary and sufficient for visual
consciousness: ‘The occurrence of a particular activity pattern in these bridge
locus neurons is necessary for the occurrence of a particular perceptual state;
neural activity elsewhere in the visual system is not necessary’ (Teller and Pugh,
1983, p. 581). Much neuroscientific work on visual consciousness, even if it has
not explicitly invoked the bridge locus, seems to assume that something like it
might be found. As vision scientist Anthony Movshon puts it: ‘In neuroscience, a
huge premium is now placed on localizing particular functions in the brain. No
conversation about perception, cognition, or action goes far without a consid-
eration of where in the brain the function under discussion is “located” ’ (2013,
p. 221).
We must remember here the difference between identifying brain areas involved
in specific cognitive functions and trying to find those responsible for conscious
experiences. While fMRI and other scanning methods find ever more locations
where activity correlates with particular experiences or actions, this is very differ-
ent from research on the NCCs, which tries to find those specifically responsible
for conscious experiences as opposed to unconscious processing.