Abstract
Language after frontal injury is usually not overtly aphasic, i.e, the essential instrumentalities of language ? phonology, lexical-semantics, and most aspects of grammar ? are intact. Patients with frontal lobe lesions are impaired at level of assembly of complex language. This impairment has three prototypical forms although there is substantial overlap between the prototypes, both in the language procedures recruited and in the clinical phenomenology. Transcortical motor aphasia is impairment at the level of complex sentence construction. Dynamic aphasia is impairment at the level of schema assembly. Discourse disorder is an impairment of script assembly, reflected as deficient narrative capacity. One model for understanding these disorders is the “action planning” model. The capacity to utilize language instrumentalities to produce goal-directed communications requires the on-line recruitment of a number of procedures (schemas) at various levels of complexity. These procedures are learned within cultural constraints across the lifespan. They may be the single most practiced and over-learned capacities of humans.
