Fig. 3.
Effects of 5-HT2A stimulation on RS neurons. A, Neuronal activity of an RS neuron showing a small response during the delay period for targets at 135° but not at 315° in the control condition. Iontophoresis of α-methyl-5-HT boosts the delay activity for the preferred direction while, at the same time, it depresses activity for the opposite location. The same cell tested with MDL100,907 (bottom panel) shows a complete abolition of its previous response. B, The memory field of this cell exhibits modest tuning during the control condition (top), which is sharpened by application of the agonist (middle), but delay activity loses spatial specificity altogether after application of MDL100,907.C, Population analysis for 11 RS cells tested with the agonist reveals signs of a spatial profile in response in control (left) that is dramatically augmented by the agonist (right). Note that one cell was excluded from this analysis because it showed changes in activity for opposite directions in space between the first and second half of the delay period.D, Overall, the agonist produces a larger reduction in the delay activity for nonpreferred target locations than that for the preferred location in this population of cells. Conventions as in previous figure.