1. Steven L. Bressler Cognitive Neurodynamics Laboratory Center for Complex Systems & Brain Sciences Department of Psychology Florida Atlantic University http://www.ccs.fau.edu/~bressler/

2. Richard Nakamura NIMH Richard Copolla NIMH Craig Richter FAU, ESI, ENS

3. Recording Paradigm Task Paradigm Analysis Paradigm Application to Sensorimotor Cortex Investigation of Top-down Processing in Visual Cortex

4.  Chronic Implant of Bipolar Electrodes  Multiple Distributed Electrode Sites  Simultaneous LFP Recording

5.  Visual Pattern Discrimination Task ◦ GO/NO-GO Response  Self-Initiated Trials  Prestimulus Anticipatory Period  Two Stimulus-Response Contingencies Stimuli

6. Spectral Coherenc e Spectral Granger Causality

8. Feedforward Sweep (0 - ~45 ms) Feedforward & Feedback Processing (> ~45 ms)

9. Top-Down Feedforward Processing (< 0 ms)

10. Synchronized beta rhythms between V1 & extrastriate cortex (V4, TEO) form a large-scale network in visual cortex before stimulus presentation. 1,2,3 – V1 5 – V4 6 –TEO

11. A.Prestimulus extrastriate & V1 beta rhythms are synchronized. B.Synchronized beta rhythms support top-down extrastriate- to-V1, but not bottom-up V1-to-extrastriate, influences. Beta rhythms are not evident in power spectra.

12. 1.The data were bisected 10000 times into training and test sets for each task contingency. 2.Training & test sets were bootstrap resampled to give 100 500-trial bivariate AR models for each striate-extrastriate pair. 3.A SVM was constructed from each training set. 4.The veridical distribution is from SVM classification of task contingency in the test sets. 5.The randomization distribution is from classification of contingency with the contingency labels randomly shuffled. Multivariate Pattern Analysis by Support Vector Machine classification of prestimulus top-down beta GC patterns between 2 stimulus-response task contingencies in 2 monkeys. veridical distribution (red); randomized distribution (blue). contingencies: line-go/diamond-nogo vs line-nogo/diamond-go

13. The size of the N1 evoked response at a V1 site to a stimulus (e.g. right slanted line) depends on task contingency. Mean rectified VER difference between contingencies over all stimulus types and all V1 sites Example for 1 stimulus type at 1 V1 site

14. Correlation between small-sample classification of unsigned distances of prestimulus top-down (extrastriate  V1) GC and V1 VER amplitude with poststimulus time.

15. Areas of extrastriate visual cortex exert top-down feedforward influences on V1 in monkeys having had repeated previous exposure to a closed set of simple stimuli as the monkey awaits the stimulus but before it is presented. The pattern of top-down influence from extrastriate cortex to V1 reflects task rules. Classifications of prestimulus top-down influences and poststimulus V1 evoked response are correlated, suggesting that a top-down gain control mechanism enhances the V1 stimulus evoked response.