Visuoimaginal constructional apraxia: on a case of selective deficit of imagery.

We report a case of a patient with a left occipital lesion who presented a peculiar behavioral dissociation. He was able to copy pictures but not to draw a simple object without a visual model; the relationship among the component parts was altered in drawings produced under the guidance of his mental representations. We have called this disturbance "visuoimaginal constructional apraxia." The mechanisms underlying visuoimaginal constructional apraxia are investigated in an attempt to contribute to studies on the nature of mental imagery.