AJDRAJNR - American Journal of Neuroradiology

This Article
Right arrow Abstract Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Liu, C.-S.J.
Right arrow Articles by Elliott, M.A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Liu, C.-S.J.
Right arrow Articles by Elliott, M.A.

Magnocellular and Parvocellular Visual Pathways Have Different Blood Oxygen Level–Dependent Signal Time Courses in Human Primary Visual Cortex

C.-S.J. Liua, R.N. Bryanb, A. Mikid, J.H. Woob, G.T. Liuc and M.A. Elliott

a Department of Biochemistry and Molecular Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pa
b Departments of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pa
c Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pa
d Department of Ophthalmology, Niigata University School of Medicine, Niigata, Japan


Figure 1
View larger version (46K):

[in a new window]
  		Fig 1. Time course analysis of the response in V1 to the M and P stimuli for a single subject. The average signal time course within V1 for the entire study is seen in the top graph, with the light boxes representing M stimulus onsets and the dark boxes representing P stimulus onsets. The average deconvolved HRFs of the M and P responses are depicted in the middle and bottom graphs, respectively. In this particular case, the P/M contrast ratio is 1.0, the TTP ratio is 0.84, and the FWHM ratio is 0.76.


Figure 2
View larger version (63K):

[in a new window]
  		Fig 2. Single subject activation maps to the M (red) and P (green) stimuli. The images are in radiologic convention (ie, left is right). The functional map is overlaid on a high resolution anatomic image. The regions showing overlapping M and P activity are yellow. Note that both stimuli generate robust activation of V1. The sections in the top picture depict active regions in the brain, and the bottom 2 sections show representative regions of activation. For the M stimulus response, V5 is activated. For the P stimulus, V4 is activated.


Figure 3
View larger version (56K):

[in a new window]
  		Fig 3. Group analysis of the 6 subjects. The images are in neurologic convention (ie, left is left). The SPMs for the response to the M and P stimulus compared with the rest condition as well as the SPMs of regions responding greater for one condition than the other (M>P and P>M) are shown. The maps are created with a threshold uncorrected for multiple comparison of P = .001 with an extent threshold of P < .05, corrected for multiple comparisons.


Figure 4
View larger version (10K):

[in a new window]
  		Fig 4. Regression analysis of the HRF metrics, with the M and P responses pooled together for the analysis. TTP versus percentage signal change (A) shows no statistically significant correlation, with r2 = 0.06408 and a slope that is not significantly different from 0 (slope = 0.453, P = .2557). The FWHM of the HRF is positively correlated with the percentage signal change (B), with r2 = 0.3114 and a slope that is significantly different from 0 (slope = 1.977, P = .0070). The FWHM of the HRF is also positively correlated with the TTP (C), with r2 = 0.2115 and a slope that is significantly different from zero (slope = 0.9105, P = .0313).





Copyright © 2008 by the American Society of Neuroradiology. Print ISSN: 0195-6108 Online ISSN: 1936-959X