ABSTRACT
The frontal regions, perhaps achieving their greatest evolutionary development in our species, are slow to mature and vulnerable to the kinds of neurodevelopmental disorders with which this book is concerned. In this chapter we shall note the largely anterior±posterior hierarchical control of preparation for and execution of action, via the prefrontal cortex (dorsolateral, orbitofrontal, anterior cingulate), the premotor areas (lateral and mesial), and the primary motor cortex. Executive decisions will be seen to be taken by the dorsolateral regions, the anterior cingulate mediating intentionality and aspects of directed attention, and the orbitofrontal regions providing inhibitory control or self-monitoring aspects. The lateral premotor areas will be seen to respond more to externally directed action, and the mesial supplementary motor area to mediate the control of internally initiated complex, sequential behaviour. Circuits involving these cortical regions and the basal ganglia will be described, along with their release of behaviours mediated by the above cortical regions. We shall see that between them preparation for action can be described in terms of decisions about what, how, and when something is to be undertaken, and that breakdown in these circuits can explain the symptoms of a range of common neurodevelopmental frontostriatal disorders. Finally, we shall consider the roles of ``gut feelings'', attention, and consciousness in preparation for action.
