IUBio

cortical latencies

Glenn A. Myers glenn_a_mnetnews at email.msn.com
Tue Sep 8 10:44:24 EST 1998


Larry Stark and I published three papers (all in the same issue of Biol
Cybernetics) on the latency of the light-pupil reflex (which involves the
LGN) as a function of light level.

Others had long held that latency was independent of light level, but our
work showed that there is a consistent modulation of latency with light
level, or phase lag in reponse to sinusoidal stimuli, and in high-gain
instability oscillations.

We suggested that these results could all be explained by a single
mechanism-in which the higher level signals 'flow' faster through the
multisynaptic network.

Ultimately, what we are describing is a nonlinear, non  space invariant
phenomenon.  Most (nearly all) of the tools of analysis we use are
predicated in whole or in part on the system under study being space
invariant and/or linear.

24. Myers, GA and Stark, L, "Level dependent signal flow in the light-pupil
reflex: I.  Latency of time domain responses to transient stimuli,",
Biological Cybernetics, 1991.
25. Myers, G.A., Gannon, J., and Stark, L., "Level dependent signal flow in
the light-pupil reflex:  II.  Phase velocity of responses to sinusoidal
inputs,", Biological Cybern, 1991.
26. Myers, G.A. and Stark, L., "Level dependent signal flow in the
light-pupil reflex:  III.  Phase velocity in high gain oscillations all,",
Biological Cybernetics, 1991.

>I have read that neurons in the visual cortex exhibit
>wide range of latencies (from around 40 to over 100
>miliseconds). However there was no more information
>about spatial characteristics of these latencies.
>I would like to ask if big differences in latencies
>are observed for the neurons with approximately
>the same number of synaptic stages between LGN and them?
>What about neurons with overlapping receptive fields ?
>Is there any systematic  relationship between latencies
>and distance between neurons. Of course one expects
>that the latencies in onset of firing will be longer
>for given neurons than for neurons 'relying' to them
>action potentials from LGN so I am mainly interested
>in latencies not arising from sequential transmission.
>I would appreciate any information and pointers to
>the literature.
>Thank you in advance.
>
>regards,
>slawek





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