Cortical oscillations

[Christof Koch]

Two interesting points re. the cortical 40 Hz oscillations.

1. At the moment, no good solid electrophysiological evidence exists for 40 Hz o
scillations in monkey, either in visual or in olfactory cortex.  Mainly because
people havenUt tried yet or are just working on it. There
is some anectodal evidence but nothing with statistics etc.  Given that a number
 of monkey researchers  have looked over the last year at their single cell  dat
a in light of the Singer and Gray results and didnUt see anything obvious is qui
te disconcerting to me... WeUll have to await more data.  It really would be wei
rd, though, it catUs would hum but not monkeys...

2.  However, binding as postulated by von der Malsburg and attention/
awareness as postulated by Crick and myself does not require oscillations but ph
ase-locking. Oscillations is just one way to achieve
phase-locked firing.  Thus, all these theories could perfectly well work with no
n-oscillatory phase-locking.  I havenUt seen any proof that phase-locking is mor
e difficult to achieve in non-oscillatory than in oscillatory systems. Thus, the
 crucial experiment for these theories is a multi-electrode experiment, showing
phase-locked firing on individual trials between cells in different cortical are
as in an awake monkey performing some task requiring focal-attention.



Christof Koch