Employing a combination of visual psychophysics and fMRI, I want to determine how detection of local image features interacts with scene perception. How are local features in an image selected and grouped to construct a mental representation of a scene or object? To what extent do internal templates determine feature selection and shape perception?
I also spend time investigating the linkage between what BOLD fMRI measures (changes in blood oxygenation) and what we want to know (the underlying neural activity). Is it the input or the output of a visual area that drives the blood flow response? Are excitation and inhibition always balanced, or can inhibition drive the BOLD response as well as excitation? How do spatial characteristics of vascular regulation distort our view of spatially distributed neural activity?
(For a comprehensive list of recent publications, refer to PubMed, a service provided by the National Library of Medicine.)
Qiu, C., Kersten, D. J., Olman, C. A. (under review). Responses in early visual areas to contour integration are context dependent. Journal of Vision in August, 2015.
Schallmo, M.-P., Burton, P. C., Grant, A. N., Olman, C. A., (under review). Attention reduces fMRI response suppression in V1. Submitted to Journal of Neurophysiology in September, 2015.
Schallmo, M.-P., Sponheim, S. R., Olman, C. A., (2015). Reduced contextual effects on visual contrast perception in schizophrenia and bipolar affective disorder. Psychological Medicine, 45(16):3527-37.
Mannion, D. J., Kersten, D. J., Olman, C. A. (2015). Scene coherence can affect the local response to natural images in human V1. European Journal of Neuroscience 42:2895-2903.
Schallmo MP, Sponheim SR, Olman CA. Reduced contextual effects on visual contrast perception in schizophrenia and bipolar affective disorder. Psychol Med. 2015 Aug 28:1-11.
Olman CA. What insights can fMRI offer into the structure and function of mid-tier visual areas? Vis Neurosci. 2015 Jan;32:E015.
Naselaris T, Olman CA, Stansbury DE, Ugurbil K, Gallant JL. A voxel-wise encoding model for early visual areas decodes mental images of remembered scenes. Neuroimage. 2015 Jan 15;105:215-28/j.neuroimage.2014.10.018.
Mannion DJ, Kersten DJ, Olman CA. Regions of mid-level human visual cortex sensitive to the global coherence of local image patches. J Cogn Neurosci. 2014 Aug;26(8):1764-74.
Thompson SK, Engel SA, Olman CA. Larger neural responses produce BOLD signals that begin earlier in time. Front Neurosci. 2014 Jun 12;8:159.
Qiu C, Kersten D, Olman CA. Segmentation decreases the magnitude of the tilt illusion. J Vis. 2013 Nov 20;13(13):19.
Mannion DJ, Kersten DJ, Olman CA. Consequences of polar form coherence for fMRI responses in human visual cortex. Neuroimage. 2013 Sep;78:152-8.
Schallmo MP, Sponheim SR, Olman CA. Abnormal contextual modulation of visual contour detection in patients with schizophrenia. PLoS One. 2013 Jun 18;8(6):e68090. Print 2013. Erratum in: PLoS One. 2013;8(10).
Olman, C. A., Harel, N., Feinberg, D., He, S., Zhang, P., Ugurbil, K., & Yacoub, E. Layer-specific FMRI reflects different neuronal computations at different depths in human V1. PLoS ONE 2012;7(3):e32536.
Olman CA, Yacoub E. High-field FMRI for human applications: an overview of spatial resolution and signal specificity. Open Neuroimag J. 2011;5:74-89. Epub 2011 Nov 4.
Schumacher JF, Quinn CF, Olman CA. An exploration of the spatial scale over which orientation-dependent surround effects affect contour detection. J Vis. 2011 Jul 21;11(8):12. doi: 10.1167/11.8.12. Print 2011.
Olman CA, Pickett KA, Schallmo MP, Kimberley TJ. Selective BOLD responses to individual finger movement measured with fMRI at 3T. Hum Brain Mapp. 2011 Jun 14. doi: 10.1002/hbm.21310.
Schumacher JF, Thompson SK, Olman CA. Contrast Response Functions for Single Gabor Patches: ROI-Based Analysis Over-Represents Low-Contrast Patches for GE BOLD. Front Syst Neurosci. 2011 Mar 24;5:19.
Olman CA, Van de Moortele PF, Schumacher JF, Guy JR, Uğurbil K, Yacoub E. Retinotopic mapping with spin echo BOLD at 7T. Magn Reson Imaging. 2010 Nov;28(9):1258-69. Epub 2010 Jul 24.
Moeller S, Yacoub E, Olman CA, Auerbach E, Strupp J, Harel N, Uğurbil K. Multiband multislice GE-EPI at 7 tesla, with 16-fold acceleration using partial parallel imaging with application to high spatial and temporal whole-brain fMRI. Magn Reson Med. 2010 May;63(5):1144-53.
Schumacher JF, Olman CA. High-resolution BOLD fMRI measurements of local orientation-dependent contextual modulation show a mismatch between predicted V1 output and local BOLD response. Vision Res. 2010 Jun 18;50(13):1214-24. Epub 2010 Apr 9.
Olman CA, Davachi L, Inati S. Distortion and signal loss in medial temporal lobe. PLoS One. 2009 Dec 3;4(12):e8160.
Mangia S, Giove F, Tkác I, Logothetis NK, Henry PG, Olman CA, Maraviglia B, Di Salle F, Uğurbil K. Metabolic and hemodynamic events after changes in neuronal activity: current hypotheses, theoretical predictions and in vivo NMR experimental findings. J Cereb Blood Flow Metab. 2009 Mar;29(3):441-63. Epub 2008 Nov 12.
Olman CA, Inati S, Heeger DH (2007). Large veins effects in spatial localization with 3T GE BOLD:displacement, not blurring. NeuroImage, 34:1126-1135.
Former Graduate Students:
Michael Paul Schallmo (Ph.D. 2014, Neuroscience, University of Minnesota).
Jennifer Schumacher (Ph.D. 2010, Neuroscience, University of Minnesota).
Serena Thompson (Ph.D. 2009, Neuroscience, University of Minnesota)