<> ---- . <> ---- == Visual Contrast Response Function Program == vb.net program [[attachment:VisualResponseContrast]] Participants view 10 levels of contrast in sine wave gratings presented as dynamic moving images surrounding a central fixation target spotting task (spot the target 'x' in a continuous stream of letters). {{attachment:disc.PNG}} <
> Stimulus is displayed for 12 secs with a 6 sec blank screen rest period (target spotting task continues throughout rest and null trials) == Parameters == A block design is used to allow for maximal HRF values and return to baseline. Alternate runs of the constant stimulus and adaptive procedure. 4 epis (2 constant and 2 adaptive runs at 2.5 and 6.5 each) Measurements: 780<
> TR 1 (64x64 matrix, 3x3x3.75mm voxels)<
> 16 slices <
> V1 ROI <
> Scanning Protocol: <
> Gre_Field mappong sequence, EPIS (4 blocks, 12 minutes, 40 trials per block), standard CBU MPRAGE sequence == Example of Real-Time Output == {{attachment:graph.png}} <
> == Bold Guided Adaptive procedure == A neurometric model is fitted to the data using a Bayesian procedure. The adpative procedure presents the stimuli around the contrast level of the model best describing the threshold at that point (see figure below). <
> The constant stimulus procedure presents stimuli in a randomised order, irrespective of threshold estimates. {{attachment:graphs2.png}}