The effects of orientation and attention during surround suppression of small image features: A 7 Tesla fMRI study

The subthalamic nucleus (STN) is a small, subcortical brain structure. It is a target for deep brain stimulation, an invasive treatment that reduces motor symptoms of Parkinson's disease. Side effects of DBS are commonly explained using the tripartite model of STN organization, which proposes three functionally distinct subregions in the STN specialized in cognitive, limbic, and motor processing. However, evidence for the tripartite model exclusively comes from anatomical studies and functional studies using clinical patients. Here, we provide the first experimental tests of the tripartite model in healthy volunteers using ultra-high field 7 Tesla (T) functional magnetic resonance imaging (fMRI). 34 participants performed a random-dot motion decision-making task with a difficulty manipulation and a choice payoff manipulation aimed to differentially affect cognitive and limbic networks. Moreover, participants responded with their left and right index finger, differentially affecting motor networks. We analysed BOLD signal in three subregions of equal volume of the STN along the dorsolateral-ventromedial axis, identified using manually delineated high resolution anatomical images. Our results indicate that all segments responded equally to the experimental manipulations, and did not support the tripartite model.

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Effect of visual image features on neural activities: An fMRI study

IFMBE Proceedings - World Congress on Medical Physics and Biomedical Engineering, September 7 - 12, 2009, Munich, Germany ◽

10.1007/978-3-642-03879-2_88 ◽

2009 ◽

pp. 312-314

Author(s):

K. Kato ◽

O. Miura ◽

A. Shikoda ◽

K. Sugawara ◽

T. Kuroki ◽

...

Keyword(s):

Visual Image ◽

Image Features ◽

Neural Activities ◽

Fmri Study

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Acute effects of corticosterone on BOLD signal: A pharmacological fMRI study in rats at 7 tesla

Pharmacopsychiatry ◽

10.1055/s-2003-825509 ◽

2004 ◽

Vol 36 (05) ◽

Author(s):

MI Schubert ◽

S Droste ◽

R Kalisch ◽

F Holsboer ◽

JHMH Reul ◽

...

Keyword(s):

7 Tesla ◽

Bold Signal ◽

Acute Effects ◽

Fmri Study

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Distinct and common pathways of expectancy and recollection of emotional visual stimuli – a high resolution fMRI Study at 7 Tesla

NeuroImage ◽

10.1016/s1053-8119(09)72147-0 ◽

2009 ◽

Vol 47 ◽

pp. S191

Author(s):

C. Metzger ◽

J. Stadler ◽

J. Buchmann ◽

J. Steiner ◽

B. Bogerts ◽

...

Keyword(s):

High Resolution ◽

Visual Stimuli ◽

7 Tesla ◽

Fmri Study

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Spatial Organization and Magnitude of Orientation Contrast Interactions in Primate V1

Journal of Neurophysiology ◽

10.1152/jn.00403.2001 ◽

2002 ◽

Vol 88 (5) ◽

pp. 2796-2808 ◽

Cited By ~ 122

Author(s):

H. E. Jones ◽

W. Wang ◽

A. M. Sillito

Keyword(s):

Spatial Organization ◽

Image Features ◽

Response Patterns ◽

Surround Suppression ◽

Contrast Effects ◽

Specific Suppression ◽

Orientation Contrast ◽

Classical Receptive Field ◽

Simple Variation ◽

Different Response

We have explored the spatial organization of orientation contrast effects in primate V1. Our stimuli were either concentric patches of drifting grating of varying orientation and diameter or grating patches displaced in x–y coordinates around a central patch overlying the classical receptive field (CRF). All cells in the sample exhibited response suppression to iso-oriented stimuli exceeding the CRF. Changing the outer stimulus orientation revealed five response patterns: 1) orientation alignment suppression (17% of cells)—a suppressive component tuned to the same orientation as the cell's optimal, 2) orientation contrast facilitation (63%)—responses to orientation contrast stimuli exceeded those to the center stimulus alone, 3) nonorientation specific suppression (3%), 4) mixed general suppression and alignment suppression (14%), and 5) orientation contrast suppression (14%)—cross-oriented stimuli evoked stronger suppression than iso-oriented stimuli. Thus most cells (94%) showed larger responses to orientation contrast stimuli than to iso-oriented stimuli, and over one-half showed orientation contrast facilitation. There appeared to be a spatially structured organization of the zones driving the different response patterns with respect to the CRF. Nonorientation-specific suppression and orientation contrast suppression were predominantly evoked by orientation contrast borders located within the CRF, and orientation contrast facilitation was mainly driven by surround stimuli lying outside the CRF. This led to different response patterns according to border location. Zones driving orientation contrast facilitation were not necessarily contiguous to, nor uniformly distributed around, the CRF. Our data support two processes underlying orientation contrast enhancement effects: a simple variation in the strength of surround suppression drawing on the fact that surround suppression is tuned to the same orientation as the CRF and a second process driven by orientation contrast that enhanced cells' responses to CRF stimulation by either dis-inhibition or orientation contrast facilitation. We suggest these processes may serve to enhance response levels to salient image features such as junctions and corners and may contribute to orientation pop-out.

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