Effects of attention on the reliability of individual neurons in monkey visual cortex

To determine the physiological mechanisms underlying the enhancement of per formance by attention, we examined how attention affects the ability of iso lated neurons to discriminate orientation by investigating the reliability of responses with and without attention. Recording from 262 neurons in cort ical area V4 while two rhesus macaques did a delayed match-to-sample task w ith oriented stimuli, we found that attention did not produce detectable ch anges in the variability of neuronal responses but did improve the orientat ion discriminability of the neurons. We also found that attention did not c hange the relationship between burst rate and response rate. Our results ar e consistent with the idea that attention selects groups of neurons for a m ultiplicative enhancement in response strength.