Chapter 24 Image generation and the territory of the left posterior cerebral artery

Abstract

This chapter addresses the question whether the left posterior cerebral artery (PCA) territory is responsible for image generation by a clinical study of patients with PCA lesions. The study supplemented by giving the same imagery tasks to healthy subjects and assessing rCBF. The studies employed the paradigm of low- and high-imagery sentences. High-imagery sentences are sentences that make predicates about the visual appearance of objects. When asked to verify their factual correctness, subjects introspectively report that they generate a mental visual image and derive the answer from an inspection of that image. Patients with an image generation deficit should be unable to distinguish correct from incorrect high-imagery sentences because they cannot generate the mental images necessary for verification. By contrast, they should be able to distinguish correct from incorrect pictorial presentations of the same alternative predicates, because picture verification does not call for image generation. If the deficit concerns the long-term memory information about the visual appearance of objects patients should fail with any version of the question.