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. Author manuscript; available in PMC: 2011 Dec 1.
Published in final edited form as: Curr Opin Neurobiol. 2010 Nov 1;20(6):731–740. doi: 10.1016/j.conb.2010.09.015

Figure 2. Modulation of spatial responses by expected reward.

Figure 2

a. Population firing rates (normalized) following presentation of a CS+ (blue) or CS− (red) in the RF. Each CS category contained several individual, abstract patterns that were initially novel to the monkey and were equated for size and luminance. CS presentation (300 ms, thick horizontal bar), was followed by a 600 ms delay period during which monkeys maintained fixation. The stars show time bins when firing rates were significantly modulated by reward. The right panels show, for each CS category, a comparison of activity when the CS appeared inside the RF (black) or opposite the RF (gray). Cartoons indicate trial configurations, with the dashed oval showing the RF and the magenta start, the CS location. The y axis is truncated to highlight delay-period activity. After a CS+ (top panel) or CS− (bottom panel), sustainted activity was, respectively, higher or lower at the CS location relative to the opposite, non-stimulated location, indicating a spatial bias toward or away from the CS. b. After the end of the delay period a saccade target appeared unpredictably at either location and monkeys made a visually-guided saccade to the target. Bars show saccade accuracy for each configuration (mean and standard error, defined as the normalized angular distance between the target and the saccade endpoint). Accuracy was impaired specifically on CS− trials in which the target happened to coincide with the CS− location, indicating a repulsion from the location of the CS−. This impairment increased with training, being stronger following an over-learned relative to a newly-learned CS. c. The insets show saccade endpoints on CS− congruent trials on a representative session. Each point represents one saccade, and coordinates are rotated so that the target appears on the right horizontal. Saccades show a large degree of scatter, especially after an over-learned CS−. This is remarkable given that the target remains lit and clearly visible until the end of the movement. Modified, with permission, from [30].