models of attention

[Christof Koch]

This is in response to P. Kube's question re. the recent Gazzaniga report on
split-brain patients possibly having two "searchlights" of attention.
The model Shimon Ullman and I proposed would accomodate such a finding,
by just cutting our Winner-Take-All pyramid in two, leading to two
maximally salient points out there in the visual field. The problem, though,
is in locating this control structure.
F. Crick proposed in 1984 the Reticular Nucleus of the thalamus as the
site of this mechanism. However, the NRT, as are all the other thalamic
nuclei, is NOT interconnected with the NRT on the contralateral sienuclei, is no

In fact, no thalamic nuclei, with the exception of the ventral lateral
geniculate nucleus (which is different from the better known dorsal
lateral geniculate nucleus relaying visual information to the cortex),
has interhemispheric connections.
This seems to imply that the structure controlling attention may reside
in neocortex proper (including the claustrum). One caveat, of course, is that
negative anatomical findings can always be overthrown one day with better
techniques.

F. Crick and I have a paper coming out where we discuss a lot of these
things in relation to iconic and short-term memory, awareness, attention
and neuronal oscillations.

Christof