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FMRI adaptation reveals separate mechanisms for first-order and second-order motion.

Ashida, H; Lingnau, A; Wall, MB; Smith, AT; (2007) FMRI adaptation reveals separate mechanisms for first-order and second-order motion. Journal of neurophysiology , 97 (2) 1319–25-1319–25. 10.1152/jn.00723.2006.

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Abstract

A key unresolved debate in human vision concerns whether we have two different low-level mechanisms for encoding image motion. Separate neural mechanisms have been suggested for first-order (luminance modulation) and second-order (e.g., contrast modulation) motion in the retinal image but a single mechanism could handle both. Human functional magnetic resonance imaging (fMRI) has not so far convincingly revealed separate anatomical substrates. To examine whether two separate but co-localized mechanisms might exist, we used the technique of fast fMRI adaptation. We found direction-selective adaptation independently for each type of motion in the motion area V5/MT+ of the human brain. However, there was a total absence of cross-adaptation between first-order and second-order motion stimuli. This was true in both of the two subcomponents of MT+ (MT and MST) and similar results were found in V3A. This pattern of adaptation was consistent with psychophysical measurements of detection thresholds in similar stimulus sequences. The results provide strong evidence for separate neural populations that are responsible for detecting first- and second-order motion.

Type: Article
Title: FMRI adaptation reveals separate mechanisms for first-order and second-order motion.
DOI: 10.1152/jn.00723.2006
Publisher version: http://www.ncbi.nlm.nih.gov/pubmed/17065251
Additional information: file: :C$$:/Documents and Settings/mbw97807/Local Settings/Application Data/Mendeley Ltd./Mendeley Desktop/Downloaded/Ashida et al. - 2007 - FMRI adaptation reveals separate mechanisms for first-order and second-order motion..pdf:pdf keywords: Adaptation, Physiological,Adaptation, Physiological: physiology,Adult,Brain Mapping,Data Interpretation, Statistical,Female,Humans,Magnetic Resonance Imaging,Male,Motion Perception,Motion Perception: physiology,Oxygen,Oxygen: blood,Photic Stimulation,Psychophysics,Retina,Retina: physiology,Visual Cortex,Visual Cortex: physiology pmid: 17065251
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences > Clinical, Edu and Hlth Psychology
URI: http://discovery.ucl.ac.uk/id/eprint/21254
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