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

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