The ability to carry out this relatively specific task is thought to be done so by the most anterior region of the frontal cortex. It is interesting to note that the prefrontal cortex does not directly interact with any sensory or motor systems. Instead, the prefrontal cortex enters into a number of different projection pathways, which allow it to interact with a number of important structures such as the hippocampus, the amygdala, the thalamus, the brainstem and the cerebellum. It is for this reason that injury to the prefrontal cortex produces an inconsistent pattern of effects. On the one hand, there are few impairments of new learning, as measured by standardized tests.
Patients can still learn and remember paired associates, word lists, and line drawings.
Frontal lobe-injured patients exhibit a wide variety of mental dysfunctions, deficits in planning and decision making, loss of initiative as well as creativity, changes in personality, and impairment of memory processes. Evidence from a variety of sources has shown that the prefrontal cortex contributes to several important memory functions. Lesser, and poorly understood, roles are played by the association cortex of the right hemisphere and by subcortical structures, including especially the basal ganglia and posterior thalamus. Examining patients with language disorders is yet another important method for understanding human speech. Keep in mind that normal language depends on a complex interaction among sensory integration and symbolic association, motor skills, learned syntactic patterns, and verbal memory.