New insights on sensorimotor integration: from hand action to speech perception.

In the last two decades the integrative role of the frontal premotor cortex (a mosaic of agranular/disgranular areas lying in front of the primary motor cortex) have been more and more elucidated. Among its various functions, sensorimotor transformation, and action representation storage, also for nonstrictly motor purposes, are the most intriguing properties of this region, as shown by several researches. In this article we will mainly focus on the ventro-rostral part of the monkey premotor cortex (area F5) in which visual information describing objects and others' acting hands are associated with goal-directed motor representations of hand movements. We will describe the main characteristics of F5 premotor neurons and we will provide evidence in favor of a parallelism between monkeys and humans on the basis of new experimental observations. Finally, we will present some data indicating that, both in humans and in monkeys, action-related sensorimotor transformations are not restricted to visual information but concern also acoustic information.