Working memory and decision-making are essential to goal-directed behaviour. Working memory depends on two sources of information; transient representations of information recently experienced and transient representation of information retrieved from long-term memory. Decision-making involves evaluation of past, current and future events and their consequences. We are studying the neural substrates of these processes. We trained monkeys to perform in two visual discrimination tasks. Monkeys have to decide whether the orientation of a line is to the right or to the left of another previously perceived line and report their decision by an oculo-motor action. During the continuous discrimination task animals pay attention to the orientation of the first line, store some trace of it during the delay between the two stimuli and compare the stored trace to the orientation of the second line. In the fixed discrimination with implicit reference task only the second stimuli varied from trial to trial, and trials were presented in blocks corresponding to the same first stimulus, which was not shown. To solve this variant of the task subjects have to recall the first stimulus from long-term memory. After training, we recorded the extracellular activity in the ventral premotor cortex while the monkeys performed the tasks.

In this area neurons reflect the prediction and contextual relevance of the stimuli, their maintenance in working memory, the comparison/decision process, and the association between stimuli and task performance. Supported by MEC BFU2006-06657 to CA. JLPV and VL supported by MEC predoctoral grants.