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Motion along the mental number line reveals shared representations for numerosity and space.

Schwiedrzik CM, Bernstein B, Melloni L - Elife (2016)

Bottom Line: Do such 'recycled' circuits retain their original functionality?The reference frame of this effect is spatiotopic.Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. 'Cortical recycling' thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neural Systems, The Rockefeller University, New York, United States.

ABSTRACT
Perception of number and space are tightly intertwined. It has been proposed that this is due to 'cortical recycling', where numerosity processing takes over circuits originally processing space. Do such 'recycled' circuits retain their original functionality? Here, we investigate interactions between numerosity and motion direction, two functions that both localize to parietal cortex. We describe a new phenomenon in which visual motion direction adapts nonsymbolic numerosity perception, giving rise to a repulsive aftereffect: motion to the left adapts small numbers, leading to overestimation of numerosity, while motion to the right adapts large numbers, resulting in underestimation. The reference frame of this effect is spatiotopic. Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. 'Cortical recycling' thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains.

No MeSH data available.


Related in: MedlinePlus

Additional example subjects from Experiment 1.(a) Psychometric functions of subject cpb26. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 56 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, cpb26’s PSE was 21 dots lower than after adaptation to rightwards motion, although number of dots in the two clouds were identical in both conditions. (b) Psychometric functions of subject tlq25. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 61 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, tlq25’s PSE was 7 dots lower than after adaptation to rightwards motion, exhibiting overestimation relative to rightward motion adaptation. All data shown here are publicly available at Figshare (Schwiedrzik et al., 2015).DOI:http://dx.doi.org/10.7554/eLife.10806.008
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fig2s3: Additional example subjects from Experiment 1.(a) Psychometric functions of subject cpb26. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 56 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, cpb26’s PSE was 21 dots lower than after adaptation to rightwards motion, although number of dots in the two clouds were identical in both conditions. (b) Psychometric functions of subject tlq25. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 61 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, tlq25’s PSE was 7 dots lower than after adaptation to rightwards motion, exhibiting overestimation relative to rightward motion adaptation. All data shown here are publicly available at Figshare (Schwiedrzik et al., 2015).DOI:http://dx.doi.org/10.7554/eLife.10806.008

Mentions: Figure 2a shows that adaptation to motion direction indeed resulted in a cross-adaptation effect on numerosity: Adaptation to rightward motion led subjects to perceive the test cloud as relatively less numerous than adaptation to leftwards motion (mean difference in PSE 7.12 dots, t(10)=2.555, p=0.029, dHedges=0.953), in accordance with a repulsive aftereffect. This effect, which was clearly evident in individual subjects (Figure 2a,b; Figure 2—figure supplement 3), shows that exposure to motion direction leads to over- and underestimation of nonsymbolic quantities, as if motion moves us up and down the number line. Motion direction exclusively affected the PSE but not psychometric slopes (mean difference -0.009, t(10)=−1.038, p=0.324, dHedges=−0.307). Note that all psychometric functions are shifted to the right because of strong, inevitable adaptation effects of large numerosities (Burr and Ross, 2008) and/or texture density (Durgin, 2008) that cause subjects to underestimate consecutively presented dot clouds, while the distance between leftward and rightward motion reflects the differential effect of motion direction on numerosity perception.10.7554/eLife.10806.005Figure 2.Effect of motion direction on numerosity perception.


Motion along the mental number line reveals shared representations for numerosity and space.

Schwiedrzik CM, Bernstein B, Melloni L - Elife (2016)

Additional example subjects from Experiment 1.(a) Psychometric functions of subject cpb26. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 56 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, cpb26’s PSE was 21 dots lower than after adaptation to rightwards motion, although number of dots in the two clouds were identical in both conditions. (b) Psychometric functions of subject tlq25. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 61 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, tlq25’s PSE was 7 dots lower than after adaptation to rightwards motion, exhibiting overestimation relative to rightward motion adaptation. All data shown here are publicly available at Figshare (Schwiedrzik et al., 2015).DOI:http://dx.doi.org/10.7554/eLife.10806.008
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Related In: Results  -  Collection

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fig2s3: Additional example subjects from Experiment 1.(a) Psychometric functions of subject cpb26. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 56 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, cpb26’s PSE was 21 dots lower than after adaptation to rightwards motion, although number of dots in the two clouds were identical in both conditions. (b) Psychometric functions of subject tlq25. After adaptation to 400 rightward moving dots in Experiment 1, this subject perceived 61 dots in the test dot cloud to be equivalent to 30 dots in the probe dot cloud, thus underestimating the number of dots in the test. After adaptation to leftwards motion, tlq25’s PSE was 7 dots lower than after adaptation to rightwards motion, exhibiting overestimation relative to rightward motion adaptation. All data shown here are publicly available at Figshare (Schwiedrzik et al., 2015).DOI:http://dx.doi.org/10.7554/eLife.10806.008
Mentions: Figure 2a shows that adaptation to motion direction indeed resulted in a cross-adaptation effect on numerosity: Adaptation to rightward motion led subjects to perceive the test cloud as relatively less numerous than adaptation to leftwards motion (mean difference in PSE 7.12 dots, t(10)=2.555, p=0.029, dHedges=0.953), in accordance with a repulsive aftereffect. This effect, which was clearly evident in individual subjects (Figure 2a,b; Figure 2—figure supplement 3), shows that exposure to motion direction leads to over- and underestimation of nonsymbolic quantities, as if motion moves us up and down the number line. Motion direction exclusively affected the PSE but not psychometric slopes (mean difference -0.009, t(10)=−1.038, p=0.324, dHedges=−0.307). Note that all psychometric functions are shifted to the right because of strong, inevitable adaptation effects of large numerosities (Burr and Ross, 2008) and/or texture density (Durgin, 2008) that cause subjects to underestimate consecutively presented dot clouds, while the distance between leftward and rightward motion reflects the differential effect of motion direction on numerosity perception.10.7554/eLife.10806.005Figure 2.Effect of motion direction on numerosity perception.

Bottom Line: Do such 'recycled' circuits retain their original functionality?The reference frame of this effect is spatiotopic.Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. 'Cortical recycling' thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neural Systems, The Rockefeller University, New York, United States.

ABSTRACT
Perception of number and space are tightly intertwined. It has been proposed that this is due to 'cortical recycling', where numerosity processing takes over circuits originally processing space. Do such 'recycled' circuits retain their original functionality? Here, we investigate interactions between numerosity and motion direction, two functions that both localize to parietal cortex. We describe a new phenomenon in which visual motion direction adapts nonsymbolic numerosity perception, giving rise to a repulsive aftereffect: motion to the left adapts small numbers, leading to overestimation of numerosity, while motion to the right adapts large numbers, resulting in underestimation. The reference frame of this effect is spatiotopic. Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. 'Cortical recycling' thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains.

No MeSH data available.


Related in: MedlinePlus