Simple pictures, tough problems.

[Peter J.B. Hancock]

I think Steve Lehar and Ken Laws are making essentially the same,
valid point: that there is time for quite a lot of very local analogue
processing, for instance within a hypercolumn, even within a 90mS
overall response time.  Thus indeed a cell may actually fire before
those that are driving it, provided the activation is transferred
without the need for action potentials.

The real time constraint comes when you want to start sending messages
between cortical areas, which requires action potentials with their
associated delays.  There are huge numbers of fibres going top-down:
they are obviously doing something, but within 90mS I don't believe
they can be contributing much to the immediate recognition process,
though they certainly might have something to do with priming.  In the
case of the monkey face-recognition work, it's unclear at the moment
to what extent the experimental setup may have primed them to expect
faces, but they were being shown all sorts of other things as well.

Peter Hancock