1. Paper written by: Joseph F.X. DeSouza, Sean P. Dukelow and Tutis Vilis Presenter: Nachum Abraham Psychology 3890: Indep. Study

2. Objectives: 1) To describe how MT/MST and V4 areas act as visual motion processing sections of the human brain 2) Provide evidence to support that transformations of Retinotopic to egocentric coordinate frames are necessary for guiding action and recognition in humans 3) Depict how transformations are modulated by eye positions for humans (the difference in preferred direction of eye position signal reflects differences in transformation)

3. Background: Anatomy : Visual System V4/V8 MT MST

4. Figures 2A, 2B, and eye http://www.livescience.com/health/051128_eye_works.html

5. Helmholtz corollary discharge for eye position used to achieve consistency Shifting Locus Transforming reference frame How does our world stay stable? http://www.physics.gla.ac.uk/Physics3/Kelvin_online/Helmholtz.gif

6. How does our world stay stable? Motion Transformations Activation of Ventral collateral sulcus: V4v

7. Hypothesis Similar modulation by eye position is present in the human equivalent model of the monkey MT/MST and V4 areas = http://williamcalvin.com/portraits/Chimp/Arnhem%20283 sml.jpg http://www.oldunterrified.org/sitebuildercontent/sitebui lderpictures/screaming.jpg

8. Methods: Subject and training 5 paid male and 2 female paid subjects 3 training sessions 1 day prior to experiment Directly before experiment During experiment

9. Methods: Optic Flow Stimulus Fixation Optic Flow Stimulus Alteration: FR, FLof, FL, FRof, FR, FLof, FL, FRof, FR Length: 16 seconds per epoch, 4-6 reps

10. Methods: Data Acquisition & Image analysis 4.0 T Varian UNITY INOVA (whole body imaging) BOLD imaging technique Brain Voyager 4.3

11. Results: Mapping Optic Flow Stationary fixation stimulus as control Optic flow produces activation in MT and V4v/V8 Collateral sulcus activation had retinotopic representation

13. Results: Signals During Visual Fixation Comparing left and right fixations MT after 9 seconds (avg) V4v/V8 after 7 seconds

14. Key figures: 4B, 4D, 5A, 5B

15. Results: Signals During Optic Flow Comparing left and right flow stimuli No significant eye position signal difference Outliers Variances http://thailandy.files.wordpress.com/2006/11/eyes-3.jpg http://images.inmagine.com/168nwm/photoalto/paa073 /paa073000001.jpg

16. Results: Figure 7 Visual fixation Optic flow

17. Discussion Absence of moving stimulus and MT Eye position signal may be to transform coding retinal slip velocity into velocity regarding the head Disappearing fixation modulation Apposing V4v/V8 and MT data and coordinate transformations Ventral and Dorsal streams http://www.biomedcentral.com/graphics/journal/imageofthem onth/1005/200711large.jpg

18. Questions? And Thank You Joe!