Figure 5. Spatial Attention Causes a Multiplicative Scaling of Tuning Curves.

(A) Stimulus and task. On some trials, monkeys attended to the grating in the receptive field of the neuron being recorded (dashed red circle) to report whether two successive gratings were Identical or differed in orientation by 90°. On other trials, attention was instead directed to a colored blob appearing in the opposite hemifield (dashed blue circle) to report whether successive stimuli differed in color.

(B) Orientation tuning curves averaged across a population of V4 neurons, with and without attention (adapted from McAdams and Maunsell, 1999). These curves were obtained by fitting each neuron’s tuning curve with a Gaussian, shifting the neuron’s preferred orientation to align all tuning curves and then averaging the Gaussian fits. Red indicates orientation tuning when attention was directed to stimuli in she receptive field, to perform the orientation discrimination task. Blue, orientation tuning when attention was directed away from the receptive field to perform the color discrimination task. (C) Model simulation yielded similar results; multiplicative scaling of the tuning curve when spatial attention was directed to a stimulus in the receptive field. See Table 1 for simulation parameters.