Continuous processing in macaque frontal cortex during visual search

A central issue in mental chronometry is whether information is transferred between processing stages such as stimulus evaluation and response prepara tion in a continuous or discrete manner. We tested whether partial informat ion about a stimulus influences the response stage by recording the activit y of movement-related neurons in the frontal eye field of macaque monkeys p erforming a conjunction visual search and a feature visual search with a si ngleton distracter. While movement-related neurons were activated maximally when the target of the search array was in their movement field, they were also activated for distracters even though a saccade was successfully made to the target outside the movement field. Most importantly, the level of a ctivation depended on the properties of the distractor. with greater activa tion for distracters that shared a target feature or were the target during the previous session during conjunction search, and fur the singleton dist racter during feature search. These results support the model of continuous information processing and argue against a strictly discrete model, (C) 20 01 Elsevier Science Ltd. All rights reserved.