Levels of nervous system at which temporal details are extracted. ("Charles S. Watson" )

Subject: Levels of nervous system at which temporal details are extracted.
From:    "Charles S. Watson"  <watson(at)INDIANA.EDU>
Date:    Tue, 3 Jun 1997 09:33:49 -0500

Note, Peter Cariani and others wrote objecting to my commment about fine
temporal detail being more likely processed earlier in the sensory
systems, which I attributed to Lloyd Jeffress.  The response below was
apparently lost in transmission, so I repeat it.

csw

Peter,

I certainly do not disagree in principle, nor did Lloyd who was well aware of
the potential power of the law of large numbers, as in averaging across lots
of neural elements, etc.  But still, 10 microsec thresholds (for auditory
localization/lateralization) are pretty darned small, and the combined jitter
of, say, 4 to 8 synapse-crossings (not to mention the temporal dispersion
created by a wide variety of element diameters)....  But, most telling of
all, there DOES seem to be a delay-to-place mapping at the level of the
olivary nucleus, as LAJ predicted.  So, while theoretically we might manage
to extract some of the super-fine-scale temporal information at the higher
levels it is not clear that we actually do anything like that (we have no
psychophysical evidence that we resolve anything monaurally much below 2
millisec), and we DO seem to have "both the mechanism and the motive" to
resolve the fine details (e.g. 10 microsec for lateralization) required for
binaural processing, at the lower levels.  Case rests.

Chuck Watson