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Human visual cortex response to melanopsin-directed stimulation

  • Spitschan, M., Bock, A. S., Ryan, J., Frazzetta, G., Brainard, D. H., & Aguirre, G. K. (2017). The human visual cortex response to melanopsin-directed stimulation is accompanied by a distinct perceptual experience. Proceedings of the National Academy of Sciences, 114(46), 12291–12296.

These are the chi-squared, whole-brain statistical maps generated for each of the four observers (ASB, ASO, GKA, MXS) for experiments 1 (melanopsin) and 2 (LMS) of the linked paper.

Selective stimulation of penumbral cones reveals perception in the shadow of retinal blood vessels (Spitschan, Aguirre & Brainard, 2015)

  • The trial-by-trial data from the main and supplemental rating experiments. Each row corresponds to one trial.
  • Background and modulation spectra used for each of the three observers in the main and supplemental rating experiments.
  • Backgound and modulation spectrum viewed by the naive observer who sketched her percepts.

All data found here.

Linear face morphs derived from the NimStim Face Stimulus Set

Morphs were created using Gryphon Morph 2.5 in 25% increments between the two endpoint faces. Resulting faces were cropped using the same 3-pixel feathered elliptical outline in Photoshop and saved as grayscale bitmaps.

Synthetic face stimuli created using the GenHead software package.

The 50 male and 50 female faces were then used during an fMRI study. A binary attractiveness decision (hot or not) was obtained during scanning. These stimuli were also rated using a 1-10 Likert scale in a separate study. The stimuli are available for download from our Public FTP site. They are in TIFF format. The text file below provides the average (z-transformed) Likert scale rating across 10 subjects for the faces.

Philadelphia Face Perception Battery (PFPB) to assess of face perception ability

A test of facial perception using naturalistic stimuli that minimizes reliance on memory and motor requirements to complete successfully. The battery consists of four tests of facial perception. Each test consists of 75 items which are presented in order of ascending difficulty. The tests are administered using an E-Prime script. The order of tests is randomized by the script for each administration. E-prime, created by Psychology Software Tools Inc., is the shell program that is required to run the PFPB. A demo version of this shell program is available for piloting the program or running a very few patients. However, if a large number of patients/subjects will need to be tested, the full version will be required and this is a fairly large investment. Please see the link above for more information.

Radial Frequency Contour (RFC) Theory

Radial Frequency Contours (RFCs, or sometimes termed Fourier Descriptors (FDs)) allows for the parameterization of any closed contour. They were first described here:

  • Zahn, C. T., Roskies, R. Z., March 1972. Fourier descriptors for plane closed curves. IEEE Transactions on Computers C-21 (3), 269-281.

RFCs allow you to describe any closed contour shape with a series of values which progressively define the shape, by interpreting the outline of the shape as a waveform which is then broken down into Fourier components. The ‘popcorn’ style RFC shapes that Drucker and Aguirre (2009) used were created using code modified from Op de Beeck.

A digital atlas of the dog brain

The atlas is comprised of both low resolution (1 mm isotropic) and high resolution (0.33 mm isotropic) diffeomorphic templates of the canine brain, as well as cortical surface representations suitable for use in FreeSurfer. The atlas is free to use (with appropriate attribution) for academic or commercial purposes. The atlas may not be distributed for commercial gain.

While a white matter segmentation is included in the atlas and is the basis of a surface reconstruction, we have been unable to produce a gray-matter surface. Our images have a image intensity boundary at the outer surface of the gray matter that is unlike in-vivo specimens. Consequently, the FreeSurfer algorithms for growing a gray-matter layer atop the white matter volume do not perform properly.

We would welcome any assistance in modifying the FreeSurfer routines to accommodate the properties of our images. Please contact us if you know how to help!