The poster presented at the Annual Meeting of the Society for Neuroscience, New Orleans, October, 1997.

RESPONSE SPECIFICITY OF LATERAL GENICULATE NUCLEUS NEURONS

Svilen Tzonev, Sergei Rebrik, and Ken Miller Keck Center for Integrative Neuroscience, University of California at San Francisco, CA 94143-0444    177.1 svilen@phy.ucsf.edu, rebrik@phy.ucsf.edu, ken@phy.ucsf.edu       http://millerlab.ucsf.edu/

 INTRODUCTION

THE PRECISION OF NEURAL RESPONSES IN THE CNS HAS BEEN HOTLY DEBATED IN RECENT YEARS.  HERE WE REPORT THAT:

1. LGN RESPONSES TO TEMPORALLY MODULATED STIMULI ARE EXTREMELY TEMPORALLY PRECISE (~2 MS FOR BINARY
2. THIS RESPONSE PRECISION SHOWS LITTLE DEPENDENCE ON RESPONSE RELIABILITY: TEMPORAL PRECISION CHANGES LITTLE FOR WIDELY VARYING FIRING RATES AND FOR CONTRASTS OF 20-100%.

 A few words about spiker....

 RESPONSES TO FULL-FIELD BINARY STIMULI.

• Full-screen stimuli eliminate eye-position variability, allow one to study temporal precision of the responses.
• We consider responses following longer sequences of light and dark  frames and find that more fully specified stimuli produce responses with increased temporal precision down to ~ 2 ms.

Definition of the PSTH matrix.

PSTH matrix for 3 fixed frames.

PSTH matrix for 7 fixed frames.

 Responses to specific stimuli (8 frames fixed) are temporally very precise independent of contrast.

 Weaker stimuli change response latency but not temporal precision.

Measurement of information transfer provides another estimate of response precision.

 Spikes remain precise even when firing rate and total information transfer are low.

 Information per spike versus information rate in 1 ms windows.

Temporal precision of response initiation: ensemble average.

 Response initiation is extremely precise. Rise times ~ 2 ms independent of contrast.

RESPONSES TO FULL-FIELD SINUSOIDAL STIMULI.

First-spike responses to sinusoidally modulated full-screen stimuli also exhibit high temporal precision for different modulation frequencies.

 Response rise time  as a function of the modulation frequency. ( full-field sinusoidal modulation ).

RESPONSES TO DRIFTING GRATINGS.

SIMPLE RESPONSE MODEL.

Response interactions between bit values in a sequence.

Backward masking effect.

CONCLUSIONS:

1. LGN SPIKE RESPONSES OCCUR AT PRECISE TIMES (~2-8ms) FOR WELL SPECIFIED STIMULI.
2. RESPONSES REMAIN PRECISE EVEN WHEN THEY ARE NOT RELIABLE, E.G. AT LOW CONTRASTS/LOW SPIKE RATES;
3. THESE RESPONSES ARE QUALITATIVELY BUT NOT QUANTITATIVELY ACCOUNTED FOR BY A SIMPLE LINEAR THRESHOLD RESPONSE MODEL;

ACKNOWLEDGEMENTS

Work supported  by grant R01-NS33787 from the NINDS, Sloan Foundation Fellowship to S.T., and by the Searle Scholars' Program  (K.M.).