1. Spatial and temporal limits of fMRI Menon RS, Kim SG. Spatial and temporal limits in cognitive neuroimaging with fMRI. Trends Cogn Sci. 1999 Jun;3(6):207-216. With supplementary material from: Menon RS, Goodyear BG. Submillimeter functional localization in human striate cortex using BOLD contrast at 4 Tesla: implications for the vascular point-spread function. Magn Reson Med. 1999 Feb;41(2):230-5. Menon RS, Luknowsky DC, Gati JS. Mental chronometry using latency- resolved functional MRI. Proc Natl Acad Sci U S A. 1998 Sep 1;95(18):10902-7. Presentation by Robert Pinkerton

2. Resolution “The ability to resolve 2 different regions of neural activation.” fMRI System Parameters Temporal - Volume Acquisition Time (VAT) Spatial - Voxel size - Voxel size

3. Questions A)How fast? B)How small?

4. What are we measuring?

6. The signal Will this transceive surface coil array… …? i) 2 s ii) 13 s

7. Limitations -Technology -Signal to Noise Ratio (SNR) -Physiology -The ultimate limiting factor!

8. Limitations: Noise -Signal to Noise Ratio (SNR) Noise Sources: Physiological respiration, cardiac, motion Extrinsic System (RF Coil, Gradients, preamps etc.) Intrinsic Patient Loading

9. Ultimately… “Ultimately, it is the extent of the lateral connections and their inherent activity that will determine the cortical vasculature point spread function [spatial resolution] in different areas of the brain.” “Ultimately, it is the extent of the lateral connections and their inherent activity that will determine the cortical vasculature point spread function [spatial resolution] in different areas of the brain.”

10. Mapping ODC using the initial hyperoxygenated BOLD response

13. Methods to increase spatial resolution by using information in the time domain.

14. Dip TR ~ 500 ms

15. Mental Rotation: Figure 1, Menon & Kim

17. Width compare width to RT

18. Mental Chronometry Menon et al, Proc. Natl. Acad. Sci. USA 1998

19. Answers: It all depends! A)How fast? VAT ~ 50 ms - 3 s Resolution: ~ 2s normal for ROI studies ~ 500 ms for DIP measurements ~ 100 ms for single event trials ~ 50 ms for one slice, poor res

20. Answers: It all depends! B)How small?  x,  y ~ 0.1 - 3 mm Resolution: ~ 3.8 mm diameter of PSF for feline cortex due to 1mm 2 patch of activation ~ 0.6 mm diameter of PSF for human cortex odc ~ 0.1 mm capillary separation