Encoding of visual stimuli and behavioral goals in distinct anatomical areas of monkey ventrolateral prefrontal cortex

The lateral prefrontal cortex has been classically defined as an associative region involved in the so-called executive functions, such as guiding behavior based on abstract rules and mnemonic information. However, most neurophysiological studies on monkeys did not address the issue of whether distinct anatomical sectors of lateral prefrontal cortex play different functional roles. The main aim of this work is to study functional properties of neurons recorded from a large part of ventrolateral prefrontal cortex (VLPF) of two monkeys performing passive visual tasks and a visuo-motor task, and to map them on the anatomical areas defined on the basis of our recent parcellations.

Our results show that distinct VLPF areas differently contribute to visual processing and action organization along the caudo-rostral axis. In particular, the processing of visual stimuli, independent of whether passively presented or exploited for guiding behavior, primarily involves posterior VLPF areas (especially caudal area 12r), while the elaboration of visual and contextual information for action organization mainly involves intermediate VLPF areas (especially middle 46v). In this latter sector, visual stimuli/instructions appear to be encoded in a pragmatic format, that is in terms of the associated behavioral outcome. Finally, more anterior areas are characterized by a low responsiveness to the employed tasks.

Altogether, our findings indicate that posterior VLPF areas represent the first processing stage of visual input, intermediate areas primarily contribute to the selection and planning of contextually appropriate behaviors, while rostral areas could be involved in more complex abstract processes.