spatial attention effects in V4 connor, preddie, gallant, van essen

1. spatial attention effects in V4 connor, preddie, gallant, van essen journal of neuroscience 17 (9), 1997 yan karklin. cns journal group. may 12 2004

2. attention affects perception • enhanced perception when attending • object centered or purely spatial? • at which level is the saliency enhanced? • neural correlates? • behaviorally relevant stimuli evoke higher responses (V2, V4, IT) • would like to explore the precise spatial effect of attention • paradigm • map receptive field while drawing attention to other regions of visual field

3. general paradigm • monkey required to attend to one of four circles (a, b, c, d) • receptive field probed with optimal bar (width, color, orientation)

4. 4ring/5bar • monkey required to attend to one of four circles (a, b, c, d) • receptive field probed with optimal bar (width, color, orientation)

5. 4ring/5bar • monkey required to attend to one of four circles (a, b, c, d) • receptive field probed with optimal bar (width, color, orientation)

6. 4ring/5bar • monkey required to attend to one of four circles (a, b, c, d) • receptive field probed with optimal bar (width, color, orientation)

7. 4ring/5bar • monkey required to attend to one of four circles (a, b, c, d) • receptive field probed with optimal bar (width, color, orientation)

8. 2ring/7bar • just two circles (a, b, c, d) • but 7 bars - better resolution for observing shift in responses 0 6

9. 12ring/bars • 12 circles (a, b, c, d, e, f, g, h, i, j, k, l) • bars flash at once, several times

10. 12ring/bars • just two circles (a, b, c, d) • but 7 bars - better resolution for observing shift in responses

11. 12ring/bars • just two circles (a, b, c, d) • but 7 bars - better resolution for observing shift in responses

12. sustained bar • same as 4ring/5bar - monkey attends to one circle (a, b, c, d) • draw attention with blink, check sustained response

13. sustained bar • same as 4ring/5bar - monkey attends to one circle (a, b, c, d) • draw attention with blink, check sustained response

14. analysis: response profile shift • how cell responds to bars in its RF as attention is drawn elsewhere

15. analysis: response profile shift • same cell, different stimulus orientation A B

16. analysis: response profile shift • peak position shift • fractional shift: how much the response shifts

17. analysis: response profile shift • distribution of fractional shift/peak position shift 4ring/5bar 4ring/5bar 2ring/7bar 2ring/7bar

18. analysis: response profile shift • average response profiles all 52 cells 39 cells w/sig frac shifts

19. analysis: assymetry in response profile shift • response profiles are modulated in 2D patterns

20. analysis: distributions of assymetries

21. broadness of tuning • distance to peak • analysis: spatial distribution of response profile shift • 12ring test gives better spatial sampling

22. analysis: an effect of extra-classical RF? summed bar response avg RF in ring strength of attentional effect correlation b/w RF values and 4ring/5bar responses position of fovea

23. implications: • spatial code for position relative to center of attention?