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Attention reshapes center-surround receptive field structure in macaque cortical area MT.

Anton-Erxleben K, Stephan VM, Treue S - Cereb. Cortex (2009)

Bottom Line: Furthermore, cRF size is changed as a function of relative distance to the attentional focus: attention inside the cRF shrinks it, whereas directing attention next to the cRF expands it.In addition, we find systematic changes in surround inhibition and cRF amplitude.This nonmultiplicative push-pull modulation of the receptive field's center-surround structure optimizes processing at and near the attentional focus to strengthen the representation of the attended stimulus while reducing influences from distractors.

View Article: PubMed Central - PubMed

Affiliation: Cognitive Neuroscience Laboratory, German Primate Center, Göttingen, Germany. kantonerxleben@dpz.gwdg.de

ABSTRACT
Directing spatial attention to a location inside the classical receptive field (cRF) of a neuron in macaque medial temporal area (MT) shifts the center of the cRF toward the attended location. Here we investigate the influence of spatial attention on the profile of the inhibitory surround present in many MT neurons. Two monkeys attended to the fixation point or to 1 of 2 random dot patterns (RDPs) placed inside or next to the cRF, whereas a third RDP (the probe) was briefly presented in quick succession across the cRF and surround. The probe presentation responses were used to compute a map of the excitatory receptive field and its inhibitory surround. Attention systematically reshapes the receptive field profile, independently shifting both center and surround toward the attended location. Furthermore, cRF size is changed as a function of relative distance to the attentional focus: attention inside the cRF shrinks it, whereas directing attention next to the cRF expands it. In addition, we find systematic changes in surround inhibition and cRF amplitude. This nonmultiplicative push-pull modulation of the receptive field's center-surround structure optimizes processing at and near the attentional focus to strengthen the representation of the attended stimulus while reducing influences from distractors.

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Hypothetical difference map. Hypothetical difference maps were created by subtracting 2 receptive field maps, each simulated by the difference of a narrow and peaked 2D-Gaussian (the receptive field center) and a spatially overlapping broad and flat 2D-Gaussian (the receptive field surround). (A) Only the cRF is shifted between both conditions. Here, a leftward shift of the receptive field center was subtracted from a rightward shift, resulting in a peak of positive response differences on the right and a dip of negative response differences on the left. (B) Attention additionally shifts the surround, resulting in an additional peak of positive response differences on the left and an additional dip of negative response differences on the right along the shift axis. See supplementary materials for further examples, formulas and choice of parameters.
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fig4: Hypothetical difference map. Hypothetical difference maps were created by subtracting 2 receptive field maps, each simulated by the difference of a narrow and peaked 2D-Gaussian (the receptive field center) and a spatially overlapping broad and flat 2D-Gaussian (the receptive field surround). (A) Only the cRF is shifted between both conditions. Here, a leftward shift of the receptive field center was subtracted from a rightward shift, resulting in a peak of positive response differences on the right and a dip of negative response differences on the left. (B) Attention additionally shifts the surround, resulting in an additional peak of positive response differences on the left and an additional dip of negative response differences on the right along the shift axis. See supplementary materials for further examples, formulas and choice of parameters.

Mentions: Difference maps were calculated for the 58 surround cells by first subtracting the response rates for each probe position when attention was on the left target in the rotated map from the corresponding response rates when attention was on the right target. For a pure center shift, the differences between response rates outside the center should scatter around zero, independent of the specific center-surround configuration. If there is a true surround shift, however, it would be visible as a systematic bias of response differences within the inhibitory receptive field regions left and right of the attentional targets: If the surround shifts with attention, this would yield difference values in the surround to be more positive on the left than on the right of the cRF (see Results and Supplementary Materials for details). Figure 4 and Supplementary Figure 3 show theoretical examples for different center-surround configurations. The figures also illustrate that the changes of response differences correlated to a surround shift are restricted to specific regions besides the cRF, depending on the symmetric/asymmetric arrangement of inhibitory regions around the cRF: Although a circularly symmetric surround as well as a surround that is asymmetric along the attentional shift axis would affect response differences besides the cRF along this axis, surrounds that are strongly asymmetric along the orthogonal axis would affect regions that are displaced from the center along the orthogonal. We therefore restricted our analysis to relevant parts of the difference maps, treating surrounds that were strongly asymmetric along the orthogonal to the attentional shift axis as a special case.


Attention reshapes center-surround receptive field structure in macaque cortical area MT.

Anton-Erxleben K, Stephan VM, Treue S - Cereb. Cortex (2009)

Hypothetical difference map. Hypothetical difference maps were created by subtracting 2 receptive field maps, each simulated by the difference of a narrow and peaked 2D-Gaussian (the receptive field center) and a spatially overlapping broad and flat 2D-Gaussian (the receptive field surround). (A) Only the cRF is shifted between both conditions. Here, a leftward shift of the receptive field center was subtracted from a rightward shift, resulting in a peak of positive response differences on the right and a dip of negative response differences on the left. (B) Attention additionally shifts the surround, resulting in an additional peak of positive response differences on the left and an additional dip of negative response differences on the right along the shift axis. See supplementary materials for further examples, formulas and choice of parameters.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2742598&req=5

fig4: Hypothetical difference map. Hypothetical difference maps were created by subtracting 2 receptive field maps, each simulated by the difference of a narrow and peaked 2D-Gaussian (the receptive field center) and a spatially overlapping broad and flat 2D-Gaussian (the receptive field surround). (A) Only the cRF is shifted between both conditions. Here, a leftward shift of the receptive field center was subtracted from a rightward shift, resulting in a peak of positive response differences on the right and a dip of negative response differences on the left. (B) Attention additionally shifts the surround, resulting in an additional peak of positive response differences on the left and an additional dip of negative response differences on the right along the shift axis. See supplementary materials for further examples, formulas and choice of parameters.
Mentions: Difference maps were calculated for the 58 surround cells by first subtracting the response rates for each probe position when attention was on the left target in the rotated map from the corresponding response rates when attention was on the right target. For a pure center shift, the differences between response rates outside the center should scatter around zero, independent of the specific center-surround configuration. If there is a true surround shift, however, it would be visible as a systematic bias of response differences within the inhibitory receptive field regions left and right of the attentional targets: If the surround shifts with attention, this would yield difference values in the surround to be more positive on the left than on the right of the cRF (see Results and Supplementary Materials for details). Figure 4 and Supplementary Figure 3 show theoretical examples for different center-surround configurations. The figures also illustrate that the changes of response differences correlated to a surround shift are restricted to specific regions besides the cRF, depending on the symmetric/asymmetric arrangement of inhibitory regions around the cRF: Although a circularly symmetric surround as well as a surround that is asymmetric along the attentional shift axis would affect response differences besides the cRF along this axis, surrounds that are strongly asymmetric along the orthogonal axis would affect regions that are displaced from the center along the orthogonal. We therefore restricted our analysis to relevant parts of the difference maps, treating surrounds that were strongly asymmetric along the orthogonal to the attentional shift axis as a special case.

Bottom Line: Furthermore, cRF size is changed as a function of relative distance to the attentional focus: attention inside the cRF shrinks it, whereas directing attention next to the cRF expands it.In addition, we find systematic changes in surround inhibition and cRF amplitude.This nonmultiplicative push-pull modulation of the receptive field's center-surround structure optimizes processing at and near the attentional focus to strengthen the representation of the attended stimulus while reducing influences from distractors.

View Article: PubMed Central - PubMed

Affiliation: Cognitive Neuroscience Laboratory, German Primate Center, Göttingen, Germany. kantonerxleben@dpz.gwdg.de

ABSTRACT
Directing spatial attention to a location inside the classical receptive field (cRF) of a neuron in macaque medial temporal area (MT) shifts the center of the cRF toward the attended location. Here we investigate the influence of spatial attention on the profile of the inhibitory surround present in many MT neurons. Two monkeys attended to the fixation point or to 1 of 2 random dot patterns (RDPs) placed inside or next to the cRF, whereas a third RDP (the probe) was briefly presented in quick succession across the cRF and surround. The probe presentation responses were used to compute a map of the excitatory receptive field and its inhibitory surround. Attention systematically reshapes the receptive field profile, independently shifting both center and surround toward the attended location. Furthermore, cRF size is changed as a function of relative distance to the attentional focus: attention inside the cRF shrinks it, whereas directing attention next to the cRF expands it. In addition, we find systematic changes in surround inhibition and cRF amplitude. This nonmultiplicative push-pull modulation of the receptive field's center-surround structure optimizes processing at and near the attentional focus to strengthen the representation of the attended stimulus while reducing influences from distractors.

Show MeSH