Is There an Object-Centered Coordinate Map in LOC?mark/2009_VSS_Lescroart... · º There is no...
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Conclusions º There is no millimeter-scale object-centered coordinate map in LOC. º The vast majority of the voxels, in all subjects, showed stronger modulation to changes in absolute (screen) position than object-centered position. º Thus it is likely that the circuits that mediate object-centered coding are smaller than the scale of MRI voxels. º Consistent with other results showing sensitivity to object-centered position in V4 and LOC, a secondary modulation of activity, i.e., a second peak in the Fourier spectrum at the frequency of the object-centered rotation, was observed in ~20% of the voxels in V4 and LO in experiments 1 and 2. º A productive direction for future work would be to determine whether the object- centered location of attention could be read out of higher-level visual areas using multi-voxel classifiers, the same way orientation can be read out of earlier visual areas. º 12 Screen rotations per run (32s each) º 16 Object rotations per run (24s each) º Both shapes changed at 2 Hz * McKyton, A., & Zohary, E. (2007). Beyond retinotopic mapping: the spatial representation of objects in the human lateral occipital complex. Cereb Cortex, 17(5), 1164-1172.; Yamane, Y., Tsunoda, K., Matsumoto, M., Phillips, A. N., & Tanifuji, M. (2006). Representation of the spatial relationship among object parts by neurons in macaque inferotemporal cortex. J Neurophysiol, 96(6), 3147-3156.; Committeri, G., Galati, G., Paradis, A. L., Pizzamiglio, L., Berthoz, A., & LeBihan, D. (2004). Reference frames for spatial cognition: different brain areas are involved in viewer-, object-, and landmark-centered judgments about object location. J Cogn Neurosci, 16(9), 1517-1535. ** Connor, C. E., Preddie, D. C., Gallant, J. L., & Van Essen, D. C. (1997). Spatial attention effects in macaque area V4. J Neurosci, 17(9), 3201-3214.; Womelsdorf, T., Anton-Erxleben, K., Pieper, F., & Treue, S. (2006). Dynamic shifts of visual receptive fields in cortical area MT by spatial attention. Nat Neurosci, 9(9), 1156-1160. Olshausen, B. A., Anderson, C. H., & Van Essen, D. C. (1993). A neurobiological model of visual attention and invariant pattern recognition based on dynamic routing of information. J Neurosci, 13(11), 4700-4719. Presented at Vision Sciences Society, Naples, Florida May 10, 2009 Supported by NSF BCS 04-20794, 05-31177, 06-17699 to I.B. LO V3v V4 V2d V3a V1 V3d V2v LO V2v V3v V4 V1 V3d V2d V3a pFs pFs pFs pFs LO V3v V4 V2d V3a V1 V3d V2v LO V2v V3v V4 V1 V3d V2d V3a pFs pFs pFs pFs LO V3v V4 V2d V3a V1 V3d V2v LO V2v V3v V4 V1 V3d V2d V3a pFs pFs Results - Experiment 2 Within-Object Border Shape IPS IPS LO V2v V3v V4 V3v V1 V3a V3d V2v LO V3d V2d V3a V1 V2d V4 pFs pFs IPS IPS LO V2v V3v V4 V3v V1 V3a V3d V2v LO V3d V2d V3a V1 V2d V4 pFs pFs IPS IPS LO V2v V3v V4 V3v V1 V3a V3d V2v LO V3d V2d V3a V1 V2d V4 pFs pFs Results - Experiment 3 Between-Object Relations LO V2v V3v V4 V3v V1 V3a V3d V2v LO V3d V2d V3a V1 V2d V4 pFs pFs LO V2v V3v V4 V3v V1 V3a V3d V2v LO V3d V2d V3a V1 V2d V4 pFs pFs LO V2v V3v V4 V3v V1 V3a V3d V2v LO V3d V2d V3a V1 V2d V4 pFs pFs V1 V1 LO LO pFs pFs V4 V4 Results - Experiment 1 Within-Object Puzzle Piece The number of voxels with a First, Second, or Third peak in the Fourier magnitude spectrum at each frequency was counted for four different regions of interest (V1, V4, LO, and pFs) n=2 n=1 n=2 Task: Subjects performed a matching task on the two images (periodically a scrambled image would appear in the object stream or vice-versa). Experiment 3 º Task: Subjects performed a one- back matching task on the color- highlighed boundary element, indicating match or non-match on cued trials Experiment 2 º Task: Subjects pressed a response key if the outer contour of the puzzle piece did NOT match the cutout in the shape (as shown here). Methods Experiment 1 º In each of three experiments, fixating subjects viewed one of three types of stimuli appearing in the periphery. º Subjects attended to a particular object- (or scene-) centered location on the stimulus. The attended spot rotated around the stimulus at a particular frequency as the whole stimulus rotated around the screen at a different frequency. º We assessed response modulation at each of the two frequencies by lagged correlation and Fourier analysis. º 4 Screen rotations per run (72s each) º 9 Object rotations per run (32s each) º Stimuli appeared once per second º 12 Screen rotations per run (32s each) º 16 Object rotations per run (24s each) º Boundary elements changed at 2 Hz Standard retinotopic mapping stimulus. The wedge occupies both a retinotopic and object-centered position. Attention shifting receptive fields in V4. (Connor et al, 1997) Olshausen and Andersen’s shifter-circuit model (1993) º Several studies* have shown evidence for object-centered tuning in macaque V4 and IT, as well as human LOC º Other studies** have shown that attention can change receptive field properties. º Computational models of “shifter circuits” explicitly predict a transformation of the coordinate system of the visual representation from absolute to object-centered space. º Standard retinotopic paradigms confound object-centered position and retina-centered position. º Could there be an object-centered map in LOC? Background Mark D. Lescroart, Kenneth J. Hayworth, Irving Biederman University of Southern California Neuroscience Program Is There an Object-Centered Coordinate Map in LOC? [email protected] http://geon.usc.edu/~mark
Transcript of Is There an Object-Centered Coordinate Map in LOC?mark/2009_VSS_Lescroart... · º There is no...
Conclusionsº There is no millimeter-scale object-centered coordinate map in LOC. º The vast majority of the voxels, in all subjects, showed stronger modulation to changes in absolute (screen) position than object-centered position.
º Thus it is likely that the circuits that mediate object-centered coding are smaller than the scale of MRI voxels.
º Consistent with other results showing sensitivity to object-centered position in V4 and LOC, a secondary modulation of activity, i.e., a second peak in the Fourier spectrum at the frequency of the object-centered rotation, was observed in ~20% of the voxels in V4 and LO in experiments 1 and 2.
º A productive direction for future work would be to determine whether the object-centered location of attention could be read out of higher-level visual areas using multi-voxel classifiers, the same way orientation can be read out of earlier visual areas.
º 12 Screen rotations per run (32s each)º 16 Object rotations per run (24s each)º Both shapes changed at 2 Hz
* McKyton, A., & Zohary, E. (2007). Beyond retinotopic mapping: the spatial representation of objects in the human lateral occipital complex. Cereb Cortex, 17(5), 1164-1172.; Yamane, Y., Tsunoda, K., Matsumoto, M., Phillips, A. N., & Tanifuji, M. (2006). Representation of the spatial relationship among object parts by neurons in macaque inferotemporal cortex. J Neurophysiol, 96(6), 3147-3156.; Committeri, G., Galati, G., Paradis, A. L., Pizzamiglio, L., Berthoz, A., & LeBihan, D. (2004). Reference frames for spatial cognition: different brain areas are involved in viewer-, object-, and landmark-centered judgments about object location. J Cogn Neurosci, 16(9), 1517-1535. ** Connor, C. E., Preddie, D. C., Gallant, J. L., & Van Essen, D. C. (1997). Spatial attention effects in macaque area V4. J Neurosci, 17(9), 3201-3214.; Womelsdorf, T., Anton-Erxleben, K., Pieper, F., & Treue, S. (2006). Dynamic shifts of visual receptive fields in cortical area MT by spatial attention. Nat Neurosci, 9(9), 1156-1160. Olshausen, B. A., Anderson, C. H., & Van Essen, D. C. (1993). A neurobiological model of visual attention and invariant pattern recognition based on dynamic routing of information. J Neurosci, 13(11), 4700-4719.
Presented at Vision Sciences Society, Naples, Florida May 10, 2009 Supported by NSF BCS 04-20794, 05-31177, 06-17699 to I.B.
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Results - Experiment 2Within-Object Border Shape
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Results - Experiment 1Within-Object Puzzle Piece
The number of voxels with a First, Second, or Third peak in the Fourier
magnitude spectrum at each frequency was counted for four different regions of
interest (V1, V4, LO, and pFs)
n=2n=1 n=2
Task: Subjects performed a matching task on the two images (periodically a scrambled image would appear in the object stream or vice-versa).
Experiment 3
º Task: Subjects performed a one-back matching task on the color-highlighed boundary element, indicating match or non-match on cued trials
Experiment 2
º Task: Subjects pressed a response key if the outer contour of the puzzle piece did NOT match the cutout in the shape (as shown here).
Methods
Experiment 1
º In each of three experiments, fixating subjects viewed one of three types of stimuli appearing in the periphery.º Subjects attended to a particular object- (or scene-) centered location on the stimulus. The attended spot rotated around the stimulus at a particular frequency as the whole stimulus rotated around the screen at a different frequency. º We assessed response modulation at each of the two frequencies by lagged correlation and Fourier analysis.
º 4 Screen rotations per run (72s each)º 9 Object rotations per run (32s each)º Stimuli appeared once per second
º 12 Screen rotations per run (32s each)º 16 Object rotations per run (24s each)º Boundary elements changed at 2 Hz
Standard retinotopic mapping stimulus. The wedge occupies both a retinotopic
and object-centered position.
Attention shifting receptive fields
in V4. (Connor et al,
1997)
Olshausen and Andersen’s
shifter-circuit model (1993)
º Several studies* have shown evidence for object-centered tuning in macaque V4 and IT, as well as human LOCº Other studies** have shown that attention can change receptive field properties. º Computational models of “shifter circuits” explicitly predict a transformation of the coordinate system of the visual representation from absolute to object-centered space.º Standard retinotopic paradigms confound object-centered position and retina-centered position.º Could there be an object-centered map in LOC?
Background
Mark D. Lescroart, Kenneth J. Hayworth, Irving BiedermanUniversity of Southern California Neuroscience Program
Is There an Object-Centered Coordinate Map in LOC? [email protected]://geon.usc.edu/~mark
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