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Attention and normalization circuits in macaque V1.

Sanayei M, Herrero JL, Distler C, Thiele A - Eur. J. Neurosci. (2015)

Bottom Line: Surround/mask stimuli provide an estimate to what extent V1 neurons are affected by normalization, which was compared against effects of spatial top down attention.In one class of models, attention contributed to normalization mechanisms, whereas in a different class of models it did not.Model selection based on Akaike's and on Bayesian information criteria demonstrated that in most cells the effects of attention were best described by models where attention did not contribute to normalization mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.

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(A) Suppression index (SI) plotted against the preferred orientation of a given cell. Preferred orientations in the cell sample were relatively uniformly distributed (spread of points along the x-axis in the upper graph). SIs were mostly positive, i.e. in most cells surround stimuli reduced the neuronal activity. (B) Orientation of the bars in the surround. Grey tick marks show the orientation of bars on the inner ring, and black tick marks show the orientation of bars on the outer ring of the surround stimulus. (C) Attentional modulation indices plotted against the preferred orientation of a given cell. Attentional modulation indices were mostly positive, i.e. in most cells attention increased neuronal activity. Neither suppression nor attentional modulation indices showed an obvious relationship to preferred orientation of the neurons, or to the distribution of orientations in the surround stimulus.
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fig03: (A) Suppression index (SI) plotted against the preferred orientation of a given cell. Preferred orientations in the cell sample were relatively uniformly distributed (spread of points along the x-axis in the upper graph). SIs were mostly positive, i.e. in most cells surround stimuli reduced the neuronal activity. (B) Orientation of the bars in the surround. Grey tick marks show the orientation of bars on the inner ring, and black tick marks show the orientation of bars on the outer ring of the surround stimulus. (C) Attentional modulation indices plotted against the preferred orientation of a given cell. Attentional modulation indices were mostly positive, i.e. in most cells attention increased neuronal activity. Neither suppression nor attentional modulation indices showed an obvious relationship to preferred orientation of the neurons, or to the distribution of orientations in the surround stimulus.

Mentions: The surround stimulus used was identical for all cells. The specific distribution of orientations present in the surround might therefore yield different effects on neurons, depending on their preferred orientation. This argument is based on the established differential effects of iso- and cross-orientation inhibition (Sengpiel et al., 1998; Jones et al., 2001, 2002; Freeman et al., 2002). Therefore we calculated the suppression index (SI) for each neuron and plotted this against the neuron's preferred orientation (Fig.3A). Neurons with stronger SI (larger than the median of the population) showed no obvious clustering around specific orientations, and there was also no obvious relationship between strength of SI, preferred orientation of a neuron and clustering of surround orientations (Fig.3B).


Attention and normalization circuits in macaque V1.

Sanayei M, Herrero JL, Distler C, Thiele A - Eur. J. Neurosci. (2015)

(A) Suppression index (SI) plotted against the preferred orientation of a given cell. Preferred orientations in the cell sample were relatively uniformly distributed (spread of points along the x-axis in the upper graph). SIs were mostly positive, i.e. in most cells surround stimuli reduced the neuronal activity. (B) Orientation of the bars in the surround. Grey tick marks show the orientation of bars on the inner ring, and black tick marks show the orientation of bars on the outer ring of the surround stimulus. (C) Attentional modulation indices plotted against the preferred orientation of a given cell. Attentional modulation indices were mostly positive, i.e. in most cells attention increased neuronal activity. Neither suppression nor attentional modulation indices showed an obvious relationship to preferred orientation of the neurons, or to the distribution of orientations in the surround stimulus.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402004&req=5

fig03: (A) Suppression index (SI) plotted against the preferred orientation of a given cell. Preferred orientations in the cell sample were relatively uniformly distributed (spread of points along the x-axis in the upper graph). SIs were mostly positive, i.e. in most cells surround stimuli reduced the neuronal activity. (B) Orientation of the bars in the surround. Grey tick marks show the orientation of bars on the inner ring, and black tick marks show the orientation of bars on the outer ring of the surround stimulus. (C) Attentional modulation indices plotted against the preferred orientation of a given cell. Attentional modulation indices were mostly positive, i.e. in most cells attention increased neuronal activity. Neither suppression nor attentional modulation indices showed an obvious relationship to preferred orientation of the neurons, or to the distribution of orientations in the surround stimulus.
Mentions: The surround stimulus used was identical for all cells. The specific distribution of orientations present in the surround might therefore yield different effects on neurons, depending on their preferred orientation. This argument is based on the established differential effects of iso- and cross-orientation inhibition (Sengpiel et al., 1998; Jones et al., 2001, 2002; Freeman et al., 2002). Therefore we calculated the suppression index (SI) for each neuron and plotted this against the neuron's preferred orientation (Fig.3A). Neurons with stronger SI (larger than the median of the population) showed no obvious clustering around specific orientations, and there was also no obvious relationship between strength of SI, preferred orientation of a neuron and clustering of surround orientations (Fig.3B).

Bottom Line: Surround/mask stimuli provide an estimate to what extent V1 neurons are affected by normalization, which was compared against effects of spatial top down attention.In one class of models, attention contributed to normalization mechanisms, whereas in a different class of models it did not.Model selection based on Akaike's and on Bayesian information criteria demonstrated that in most cells the effects of attention were best described by models where attention did not contribute to normalization mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.

Show MeSH
Related in: MedlinePlus