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.)
- Schallmo MP, Weldon KB, Burton PC, Sponheim SR, Olman CA. Assessing methods for geometric distortion compensation in 7 T gradient echo functional MRI data. Hum Brain Mapp. 2021 Jun 22. doi: 10.1002/hbm.25540.
- Klein SD, Olman CA, Sponheim SR. Perceptual mechanisms of visual hallucinations and illusions in psychosis. J Psychiatr Brain Sci. 2020;5:e200020.
- Breedlove JL, St-Yves G, Olman CA, Naselaris T. Generative feedback explains distinct brain activity codes for seen and mental images. Curr Biol. 2020 Apr 30. pii: S0960-9822(20)30494-2.
- Olman CA, Bao P, Engel SA, Grant AN, Purington C, Qiu C, Schallmo MP, Tjan BS. Hemifield columns co-opt ocular dominance column structure in human achiasma. Neuroimage. 2018;164:59-66.
- Allen EJ, Burton PC, Olman CA, Oxenham AJ. Representations of pitch and timbre variation in human auditory cortex. J Neurosci. 2017;37(5):1284-1293.
- Schallmo MP, Grant AN, Burton PC, Olman CA. The effects of orientation and attention during surround suppression of small image features: A 7 Tesla fMRI study. J Vis. 2016 Aug 1;16(10):19.
- Qiu C, Burton PC, Kersten D, Olman CA. Responses in early visual areas to contour integration are context dependent. J Vis. 2016 Jun 1;16(8):19.
- Mannion DJ, Kersten DJ, Olman CA. Scene coherence can affect the local response to natural images in human V1. Eur J Neurosci. 2015;42(11):2895-903
- Schallmo MP, Sponheim SR, Olman CA. Reduced contextual effects on visual contrast perception in schizophrenia and bipolar affective disorder. Psychol Med. 2015;45(16):3527-37.
- 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;105:215-228
- 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;26(8):1764-1774.
- 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;78:152-158.
- 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.
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)