40-Hz oscillations

X042 at HEC.CA X042 at HEC.CA
Thu May 27 09:07:29 EST 1993

Hi !
Some of you have certainly read the following article :
Llinas R.R., Ribary U. (1993) Coherent 40-Hz oscillation characterizes dream
state in humans. Proc.Natl.Acad.Sci.USA; 90:2078-2081, march 1993

In any case here is the abstract :
Magnetic recording from five normal human adults demonstrates large 40-Hz
coherent magnetic activity in the awake and in REM sleep states that is
very reduced during delta sleep. This 40-Hz magnetic oscillation have been
shown to be reset by sensory stimuli in the awake state. Such resetting is
not observed during REM or delta sleep. The 40-Hz in REM sleep is characte-
rized, as is that in the awake state, by a fronto-occipital phase shift
over the head. This phase shift has a maximum duration of 12-13 msec.
Because 40-Hz oscillations is seen in wakefulness and in dreaming, we
propose it to be correlate of cognition, probably resultant from coherent
40-Hz resonance between thalamocortical-specific and non-specific loops.
Moreover, we proposed that the specific loops give the content of cognition,
and a non-specific loop gives the temporal binding required for the unity
of cognitive experience.
(end of abstract)

It would be interesting reading some comments on these issues, especially
on the functional significance of the 40-Hz oscillations. I for one, have
some reserves relatively to the sharp division of specific (sensory thalamo-
cortical) and non-specific (intralaminar nuclei-cortex) loops. I simply
wonders if the dense collaterals in the reticular thalamic nuclei would
prevent such functional division.

| JACQUES BRISSON              Ecole des Hautes Etudes Commerciales (HEC)  |
| X042 at HEC.CA (internet)       5255 Decelles (QM3333-S610)                 |
| X042 at HECMTL01.BITNET(bitnet) Montreal, Quebec, CANADA, H3T 1V6           |
| ...for the first time, it seems there may be hope of putting the slice   |
| back in the brain, not by the art of transplantation, but by the art of  |
| of computation.                                                          |
|                 B.L. Mc Naughton                                         |

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