Rbh. Tootell et al., FUNCTIONAL-ANALYSIS OF PRIMARY VISUAL-CORTEX (V1) IN HUMANS, Proceedings of the National Academy of Sciences of the United Statesof America, 95(3), 1998, pp. 811-817
Human area V1 offers an excellent opportunity to study, using function
al MRI, a range of properties in a specific cortical visual area, whos
e borders are defined objectively and convergently by retinotopic crit
eria. The retinotopy in V1 (also known as primary visual cortex, stria
te cortex, or Brodmann's area 17) was defined in each subject by using
both stationary and phase-encoded polar coordinate stimuli. Data from
V1 and neighboring retinotopic areas were displayed on flattened cort
ical maps. In additional tests we revealed the paired cortical represe
ntations of the monocular ''blind spot.'' We also activated area V1 pr
eferentially (relative to other extrastriate areas) by presenting radi
al gratings alternating between 6% and 100% contrast. Finally, we show
ed evidence for orientation selectivity in V1 by measuring transient f
unctional MRI increases produced at the change in response to gratings
of differing orientations. By systematically varying the orientations
presented, we were able to measure the bandwidth of the orientation '
'transients'' (45 degrees).