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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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Center and surround shift for 2 example cells. (A, C) Receptive field maps for 2 example cells when attention was either on the left or on the right target (black circle filled white). Maps were rotated for convenience so that the fixation point (white square filled black) was up. The contour lines mark the quarter-height level of excitatory/inhibitory modulation at which center and surround were cut for the centroid analysis (white: center, gray: surround). The vertical lines show the volume centroids (white: center, gray: surround) along the target–distractor axis, calculated over the outlined area. For both cells, center and surround profiles shift toward the attended stimulus. (B, D) Difference maps for the same 2 cells were created by subtracting the probe responses with attention left from those with attention right. Regions of positive response differences (i.e., stronger response with attention right) are shown in red/yellow, whereas negative response differences are shown in blue/cyan. Contour lines mark the 5% level of the cRF for attention left (black contour) and attention right (white contour). The gray dots show the probe positions that were used to calculate the mean response differences left and right of both centers (see Methods for details). For both cells, the response differences are more positive on the left than on the right of the cRF, meaning that surround inhibition is weaker on the unattended side and stronger on the attended side.
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fig2: Center and surround shift for 2 example cells. (A, C) Receptive field maps for 2 example cells when attention was either on the left or on the right target (black circle filled white). Maps were rotated for convenience so that the fixation point (white square filled black) was up. The contour lines mark the quarter-height level of excitatory/inhibitory modulation at which center and surround were cut for the centroid analysis (white: center, gray: surround). The vertical lines show the volume centroids (white: center, gray: surround) along the target–distractor axis, calculated over the outlined area. For both cells, center and surround profiles shift toward the attended stimulus. (B, D) Difference maps for the same 2 cells were created by subtracting the probe responses with attention left from those with attention right. Regions of positive response differences (i.e., stronger response with attention right) are shown in red/yellow, whereas negative response differences are shown in blue/cyan. Contour lines mark the 5% level of the cRF for attention left (black contour) and attention right (white contour). The gray dots show the probe positions that were used to calculate the mean response differences left and right of both centers (see Methods for details). For both cells, the response differences are more positive on the left than on the right of the cRF, meaning that surround inhibition is weaker on the unattended side and stronger on the attended side.

Mentions: The receptive fields were mapped under 2 attentional conditions: attention was either on the left stimulus or on the right stimulus, whereas the sensory stimulation and mapping procedure were exactly the same. Figure 2 shows 2 example cells. Indicated in the maps are the outlines of the excitatory (white) and inhibitory (gray) receptive field regions over which volume centroids for center and surround were determined. Center and surround shifts were defined as the difference in position of the respective centroid (white/gray vertical line) between the 2 attentional conditions, normalized to the cRF diameter. Both cells show a shift of the center as well as the surround toward the attended stimulus.


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

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

Center and surround shift for 2 example cells. (A, C) Receptive field maps for 2 example cells when attention was either on the left or on the right target (black circle filled white). Maps were rotated for convenience so that the fixation point (white square filled black) was up. The contour lines mark the quarter-height level of excitatory/inhibitory modulation at which center and surround were cut for the centroid analysis (white: center, gray: surround). The vertical lines show the volume centroids (white: center, gray: surround) along the target–distractor axis, calculated over the outlined area. For both cells, center and surround profiles shift toward the attended stimulus. (B, D) Difference maps for the same 2 cells were created by subtracting the probe responses with attention left from those with attention right. Regions of positive response differences (i.e., stronger response with attention right) are shown in red/yellow, whereas negative response differences are shown in blue/cyan. Contour lines mark the 5% level of the cRF for attention left (black contour) and attention right (white contour). The gray dots show the probe positions that were used to calculate the mean response differences left and right of both centers (see Methods for details). For both cells, the response differences are more positive on the left than on the right of the cRF, meaning that surround inhibition is weaker on the unattended side and stronger on the attended side.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig2: Center and surround shift for 2 example cells. (A, C) Receptive field maps for 2 example cells when attention was either on the left or on the right target (black circle filled white). Maps were rotated for convenience so that the fixation point (white square filled black) was up. The contour lines mark the quarter-height level of excitatory/inhibitory modulation at which center and surround were cut for the centroid analysis (white: center, gray: surround). The vertical lines show the volume centroids (white: center, gray: surround) along the target–distractor axis, calculated over the outlined area. For both cells, center and surround profiles shift toward the attended stimulus. (B, D) Difference maps for the same 2 cells were created by subtracting the probe responses with attention left from those with attention right. Regions of positive response differences (i.e., stronger response with attention right) are shown in red/yellow, whereas negative response differences are shown in blue/cyan. Contour lines mark the 5% level of the cRF for attention left (black contour) and attention right (white contour). The gray dots show the probe positions that were used to calculate the mean response differences left and right of both centers (see Methods for details). For both cells, the response differences are more positive on the left than on the right of the cRF, meaning that surround inhibition is weaker on the unattended side and stronger on the attended side.
Mentions: The receptive fields were mapped under 2 attentional conditions: attention was either on the left stimulus or on the right stimulus, whereas the sensory stimulation and mapping procedure were exactly the same. Figure 2 shows 2 example cells. Indicated in the maps are the outlines of the excitatory (white) and inhibitory (gray) receptive field regions over which volume centroids for center and surround were determined. Center and surround shifts were defined as the difference in position of the respective centroid (white/gray vertical line) between the 2 attentional conditions, normalized to the cRF diameter. Both cells show a shift of the center as well as the surround toward the attended stimulus.

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