Information processing bottlenecks in macaque posterior parietal cortex: an attentional blink?

When two brief stimuli are presented in rapid succession, our ability to attend and recognize the second stimulus is impaired if our attentional resources are devoted to processing the first. Such inability (termed the "attentional blink" in human studies) arises around 200-500 ms following the onset of the first stimulus. We trained two monkeys on a delayed-match-to-sample task where both the location and orientation of two successively presented grating patches had to be matched. When the delay between the two gratings was varied, monkey's behavioral performance (d') was affected in a way that was analogous to the attentional blink in humans. Furthermore, a subset of neurons in the monkey's lateral intraparietal area, known to be crucial in the control of attention, closely followed the variation in d', even on occasions when d' followed an atypical pattern. Our results provide the first behavioral demonstration of an attentional bottleneck in the macaque of a type similar to the human attentional blink as well as a possible single-neuron correlate of the phenomenon.