scholarly journals Speed encoding in human visual cortex revealed by fMRI adaptation

2009 ◽  
Vol 9 (13) ◽  
pp. 3-3 ◽  
Author(s):  
A. Lingnau ◽  
H. Ashida ◽  
M. B. Wall ◽  
A. T. Smith
Keyword(s):  
Visual Cortex ◽  
Human Visual Cortex ◽  
Fmri Adaptation

Orientation-Tuned fMRI Adaptation in Human Visual Cortex

2005 ◽  
Vol 94 (6) ◽  
pp. 4188-4195 ◽  
Author(s):  
Fang Fang ◽  
Scott O. Murray ◽  
Daniel Kersten ◽  
Sheng He
Keyword(s):  
Visual Cortex ◽  
Separate Experiment ◽  
Detection Thresholds ◽  
Human Visual Cortex ◽  
Contrast Detection ◽  
Neurophysiological Studies ◽  
Short Term Adaptation ◽  
Almost All ◽  
Fmri Adaptation

Adaptation is a general property of almost all neural systems and has been a longstanding tool of psychophysics because of its power to isolate and temporarily reduce the contribution of specific neural populations. Recently, adaptation designs have been extensively applied in functional MRI (fMRI) studies to infer neural selectivity in specific cortical areas. However, there has been considerable variability in the duration of adaptation used in these experiments. In particular, although long-term adaptation has been solidly established in psychophysical and neurophysiological studies, it has been incorporated into few fMRI studies. Furthermore, there has been little validation of fMRI adaptation using stimulus dimensions with well-known adaptive properties (e.g., orientation) and in better understood regions of cortex (e.g., primary visual cortex, V1). We used an event-related fMRI experiment to study long-term orientation adaptation in the human visual cortex. After long-term adaptation to an oriented pattern, the fMRI response in V1, V2, V3/VP, V3A, and V4 to a test stimulus was proportional to the angular difference between the adapting and test stimuli. However, only V3A and V4 showed this response pattern with short-term adaptation. In a separate experiment, we measured behavioral contrast detection thresholds after adaptation and found that the fMRI signal in V1 closely matched the psychophysically derived contrast detection thresholds. Similar to the fMRI results, adaptation induced threshold changes strongly depended on the duration of adaptation. In addition to supporting the existence of adaptable orientation-tuned neurons in human visual cortex, our results show the importance of considering timing parameters in fMRI adaptation experiments.

scholarly journals Area VO in human visual cortex is color selective as revealed by fMRI adaptation

2015 ◽  
Vol 15 (12) ◽  
pp. 23
Author(s):  
Dorita Chang ◽  
Robert Hess ◽  
Kathy Mullen
Keyword(s):  
Visual Cortex ◽  
Human Visual Cortex ◽  
Fmri Adaptation
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